[chore/bugfix] Switch markdown from blackfriday to goldmark (#1267)

Co-authored-by: Autumn! <autumnull@posteo.net>

go.mod

@@ -35,7 +35,6 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0
 	github.com/oklog/ulid v1.3.1
 	github.com/robfig/cron/v3 v3.0.1
-	github.com/russross/blackfriday/v2 v2.1.0
 	github.com/spf13/cobra v1.6.1
 	github.com/spf13/viper v1.14.0
 	github.com/stretchr/testify v1.8.1
@@ -48,6 +47,7 @@ require (
 	github.com/uptrace/bun/dialect/pgdialect v1.1.9
 	github.com/uptrace/bun/dialect/sqlitedialect v1.1.9
 	github.com/wagslane/go-password-validator v0.3.0
+	github.com/yuin/goldmark v1.5.3
 	golang.org/x/crypto v0.0.0-20220829220503-c86fa9a7ed90
 	golang.org/x/exp v0.0.0-20220613132600-b0d781184e0d
 	golang.org/x/image v0.2.0

go.sum

@@ -521,7 +521,6 @@ github.com/rs/xid v1.4.0 h1:qd7wPTDkN6KQx2VmMBLrpHkiyQwgFXRnkOLacUiaSNY=
 github.com/rs/xid v1.4.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
 github.com/rs/zerolog v1.13.0/go.mod h1:YbFCdg8HfsridGWAh22vktObvhZbQsZXe4/zB0OKkWU=
 github.com/rs/zerolog v1.15.0/go.mod h1:xYTKnLHcpfU2225ny5qZjxnj9NvkumZYjJHlAThCjNc=
-github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/satori/go.uuid v1.2.0/go.mod h1:dA0hQrYB0VpLJoorglMZABFdXlWrHn1NEOzdhQKdks0=
 github.com/sclevine/agouti v3.0.0+incompatible/go.mod h1:b4WX9W9L1sfQKXeJf1mUTLZKJ48R1S7H23Ji7oFO5Bw=
@@ -645,6 +644,8 @@ github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9de
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+github.com/yuin/goldmark v1.5.3 h1:3HUJmBFbQW9fhQOzMgseU134xfi6hU+mjWywx5Ty+/M=
+github.com/yuin/goldmark v1.5.3/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 github.com/zeebo/assert v1.1.0/go.mod h1:Pq9JiuJQpG8JLJdtkwrJESF0Foym2/D9XMU5ciN/wJ0=
 github.com/zeebo/blake3 v0.2.1/go.mod h1:TSQ0KjMH+pht+bRyvVooJ1rBpvvngSGaPISafq9MxJk=
 github.com/zeebo/pcg v1.0.1/go.mod h1:09F0S9iiKrwn9rlI5yjLkmrug154/YRW6KnnXVDM/l4=

internal/api/client/status/statuscreate_test.go

@@ -44,7 +44,7 @@ type StatusCreateTestSuite struct {
 const (
 	statusWithLinksAndTags = "#test alright, should be able to post #links with fragments in them now, let's see........\n\nhttps://docs.gotosocial.org/en/latest/user_guide/posts/#links\n\n#gotosocial\n\n(tobi remember to pull the docker image challenge)"
 	statusMarkdown         = "# Title\n\n## Smaller title\n\nThis is a post written in [markdown](https://www.markdownguide.org/)\n\n<img src=\"https://d33wubrfki0l68.cloudfront.net/f1f475a6fda1c2c4be4cac04033db5c3293032b4/513a4/assets/images/markdown-mark-white.svg\"/>"
-	statusMarkdownExpected = "<h1>Title</h1><h2>Smaller title</h2><p>This is a post written in <a href=\"https://www.markdownguide.org/\" rel=\"nofollow noreferrer noopener\" target=\"_blank\">markdown</a></p><p><img src=\"https://d33wubrfki0l68.cloudfront.net/f1f475a6fda1c2c4be4cac04033db5c3293032b4/513a4/assets/images/markdown-mark-white.svg\" crossorigin=\"anonymous\"></p>"
+	statusMarkdownExpected = "<h1>Title</h1><h2>Smaller title</h2><p>This is a post written in <a href=\"https://www.markdownguide.org/\" rel=\"nofollow noreferrer noopener\" target=\"_blank\">markdown</a></p><img src=\"https://d33wubrfki0l68.cloudfront.net/f1f475a6fda1c2c4be4cac04033db5c3293032b4/513a4/assets/images/markdown-mark-white.svg\" crossorigin=\"anonymous\">"
 )
 
 // Post a new status with some custom visibility settings

internal/text/markdown.go

@@ -21,62 +21,23 @@
 import (
 	"bytes"
 	"context"
-	"io"
 	"strings"
 
-	"github.com/russross/blackfriday/v2"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 	"github.com/tdewolff/minify/v2"
-	"github.com/tdewolff/minify/v2/html"
+	minifyHtml "github.com/tdewolff/minify/v2/html"
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/extension"
+	"github.com/yuin/goldmark/renderer/html"
 )
 
 var (
-	bfExtensions = blackfriday.NoIntraEmphasis | blackfriday.FencedCode | blackfriday.Autolink | blackfriday.Strikethrough | blackfriday.SpaceHeadings | blackfriday.HardLineBreak
-	m            *minify.M
+	m *minify.M
 )
 
-type renderer struct {
-	f        *formatter
-	ctx      context.Context
-	mentions []*gtsmodel.Mention
-	tags     []*gtsmodel.Tag
-	blackfriday.HTMLRenderer
-}
-
-func (r *renderer) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
-	if node.Type == blackfriday.Text {
-		// call RenderNode to do the html escaping
-		var buff bytes.Buffer
-		status := r.HTMLRenderer.RenderNode(&buff, node, entering)
-
-		html := buff.String()
-		html = r.f.ReplaceTags(r.ctx, html, r.tags)
-		html = r.f.ReplaceMentions(r.ctx, html, r.mentions)
-
-		// we don't have much recourse if this fails
-		if _, err := io.WriteString(w, html); err != nil {
-			log.Errorf("error outputting markdown text: %s", err)
-		}
-		return status
-	}
-	return r.HTMLRenderer.RenderNode(w, node, entering)
-}
-
 func (f *formatter) FromMarkdown(ctx context.Context, markdownText string, mentions []*gtsmodel.Mention, tags []*gtsmodel.Tag, emojis []*gtsmodel.Emoji) string {
 
-	renderer := &renderer{
-		f:        f,
-		ctx:      ctx,
-		mentions: mentions,
-		tags:     tags,
-		HTMLRenderer: *blackfriday.NewHTMLRenderer(blackfriday.HTMLRendererParameters{
-			// same as blackfriday.CommonHTMLFlags, but with Smartypants disabled
-			// ref: https://github.com/superseriousbusiness/gotosocial/issues/1028
-			Flags: blackfriday.UseXHTML,
-		}),
-	}
-
 	// Temporarily replace all found emoji shortcodes in the markdown text with
 	// their ID so that they're not parsed as anything by the markdown parser -
 	// this fixes cases where emojis with some underscores in them are parsed as
@@ -89,8 +50,25 @@ func (f *formatter) FromMarkdown(ctx context.Context, markdownText string, menti
 	}
 
 	// parse markdown text into html, using custom renderer to add hashtag/mention links
-	htmlContentBytes := blackfriday.Run([]byte(markdownText), blackfriday.WithExtensions(bfExtensions), blackfriday.WithRenderer(renderer))
-	htmlContent := string(htmlContentBytes)
+	md := goldmark.New(
+		goldmark.WithRendererOptions(
+			html.WithXHTML(),
+			html.WithHardWraps(),
+			html.WithUnsafe(), // allows raw HTML
+		),
+		goldmark.WithExtensions(
+			&customRenderer{f, ctx, mentions, tags},
+			extension.Linkify, // turns URLs into links
+			extension.Strikethrough,
+		),
+	)
+
+	var htmlContentBytes bytes.Buffer
+	err := md.Convert([]byte(markdownText), &htmlContentBytes)
+	if err != nil {
+		log.Errorf("error rendering markdown to HTML: %s", err)
+	}
+	htmlContent := htmlContentBytes.String()
 
 	// Replace emoji IDs in the parsed html content with their shortcodes again
 	for _, e := range emojis {
@@ -102,7 +80,7 @@ func (f *formatter) FromMarkdown(ctx context.Context, markdownText string, menti
 
 	if m == nil {
 		m = minify.New()
-		m.Add("text/html", &html.Minifier{
+		m.Add("text/html", &minifyHtml.Minifier{
 			KeepEndTags: true,
 			KeepQuotes:  true,
 		})

internal/text/markdown_test.go

@@ -71,6 +71,12 @@
 	mdMentionAndCodeBlockExpected   = "<p><span class=\"h-card\"><a href=\"http://localhost:8080/@the_mighty_zork\" class=\"u-url mention\" rel=\"nofollow noreferrer noopener\" target=\"_blank\">@<span>the_mighty_zork</span></a></span></p><pre><code>@the_mighty_zork\n</code></pre>"
 	mdWithSmartypants               = "\"you have to quargle the bleepflorp\" they said with 1/2 of nominal speed and 1/3 of the usual glumping"
 	mdWithSmartypantsExpected       = "<p>\"you have to quargle the bleepflorp\" they said with 1/2 of nominal speed and 1/3 of the usual glumping</p>"
+	mdWithAsciiHeart                = "hello <3 old friend <3 i loved u </3 :(( you stole my heart"
+	mdWithAsciiHeartExpected        = "<p>hello &lt;3 old friend &lt;3 i loved u &lt;/3 :(( you stole my heart</p>"
+	mdWithStrikethrough             = "I have ~~mdae~~ made an error"
+	mdWithStrikethroughExpected     = "<p>I have <del>mdae</del> made an error</p>"
+	mdWithLink                      = "Check out this code, i heard it was written by a sloth https://github.com/superseriousbusiness/gotosocial"
+	mdWithLinkExpected              = "<p>Check out this code, i heard it was written by a sloth <a href=\"https://github.com/superseriousbusiness/gotosocial\" rel=\"nofollow noreferrer noopener\" target=\"_blank\">https://github.com/superseriousbusiness/gotosocial</a></p>"
 )
 
 type MarkdownTestSuite struct {
@@ -160,6 +166,21 @@ func (suite *MarkdownTestSuite) TestParseSmartypants() {
 	suite.Equal(mdWithSmartypantsExpected, s)
 }
 
+func (suite *MarkdownTestSuite) TestParseAsciiHeart() {
+	s := suite.formatter.FromMarkdown(context.Background(), mdWithAsciiHeart, nil, nil, nil)
+	suite.Equal(mdWithAsciiHeartExpected, s)
+}
+
+func (suite *MarkdownTestSuite) TestParseStrikethrough() {
+	s := suite.formatter.FromMarkdown(context.Background(), mdWithStrikethrough, nil, nil, nil)
+	suite.Equal(mdWithStrikethroughExpected, s)
+}
+
+func (suite *MarkdownTestSuite) TestParseLink() {
+	s := suite.formatter.FromMarkdown(context.Background(), mdWithLink, nil, nil, nil)
+	suite.Equal(mdWithLinkExpected, s)
+}
+
 func TestMarkdownTestSuite(t *testing.T) {
 	suite.Run(t, new(MarkdownTestSuite))
 }

internal/text/markdownextension.go

@@ -0,0 +1,215 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package text
+
+import (
+	"context"
+	"unicode"
+
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/regexes"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/text"
+	mdutil "github.com/yuin/goldmark/util"
+)
+
+// A goldmark extension that parses potential mentions and hashtags separately from regular
+// text, so that they stay as one contiguous text fragment in the AST, and then renders
+// them separately too, to avoid scanning normal text for mentions and tags.
+
+// mention and hashtag fulfil the goldmark ast.Node interface.
+type mention struct {
+	ast.BaseInline
+	Segment text.Segment
+}
+
+type hashtag struct {
+	ast.BaseInline
+	Segment text.Segment
+}
+
+var kindMention = ast.NewNodeKind("Mention")
+var kindHashtag = ast.NewNodeKind("Hashtag")
+
+func (n *mention) Kind() ast.NodeKind {
+	return kindMention
+}
+
+func (n *hashtag) Kind() ast.NodeKind {
+	return kindHashtag
+}
+
+// Dump is used by goldmark for debugging. It is implemented only minimally because
+// it is not used in our code.
+func (n *mention) Dump(source []byte, level int) {
+	ast.DumpHelper(n, source, level, nil, nil)
+}
+
+func (n *hashtag) Dump(source []byte, level int) {
+	ast.DumpHelper(n, source, level, nil, nil)
+}
+
+// newMention and newHashtag create a goldmark ast.Node from a goldmark text.Segment.
+// The contained segment is used in rendering.
+func newMention(s text.Segment) *mention {
+	return &mention{
+		BaseInline: ast.BaseInline{},
+		Segment:    s,
+	}
+}
+
+func newHashtag(s text.Segment) *hashtag {
+	return &hashtag{
+		BaseInline: ast.BaseInline{},
+		Segment:    s,
+	}
+}
+
+// mentionParser and hashtagParser fulfil the goldmark parser.InlineParser interface.
+type mentionParser struct {
+}
+
+type hashtagParser struct {
+}
+
+func (p *mentionParser) Trigger() []byte {
+	return []byte{'@'}
+}
+
+func (p *hashtagParser) Trigger() []byte {
+	return []byte{'#'}
+}
+
+func (p *mentionParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node {
+	before := block.PrecendingCharacter()
+	line, segment := block.PeekLine()
+
+	if !unicode.IsSpace(before) {
+		return nil
+	}
+
+	// unideal for performance but makes use of existing regex
+	loc := regexes.MentionFinder.FindIndex(line)
+	switch {
+	case loc == nil:
+		fallthrough
+	case loc[0] != 0: // fail if not found at start
+		return nil
+	default:
+		block.Advance(loc[1])
+		return newMention(segment.WithStop(segment.Start + loc[1]))
+	}
+}
+
+func (p *hashtagParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node {
+	before := block.PrecendingCharacter()
+	line, segment := block.PeekLine()
+	s := string(line)
+
+	if !util.IsHashtagBoundary(before) {
+		return nil
+	}
+
+	for i, r := range s {
+		switch {
+		case r == '#' && i == 0:
+			continue
+		case !util.IsPermittedInHashtag(r) && !util.IsHashtagBoundary(r):
+			// Fake hashtag, don't trust it
+			return nil
+		case util.IsHashtagBoundary(r):
+			// End of hashtag
+			block.Advance(i)
+			return newHashtag(segment.WithStop(segment.Start + i))
+		}
+	}
+	// If we don't find invalid characters before the end of the line then it's good
+	block.Advance(len(s))
+	return newHashtag(segment)
+}
+
+// customRenderer fulfils both the renderer.NodeRenderer and goldmark.Extender interfaces.
+// It is created in FromMarkdown to be used a goldmark extension, and the fields are used
+// when rendering mentions and tags.
+type customRenderer struct {
+	f        *formatter
+	ctx      context.Context
+	mentions []*gtsmodel.Mention
+	tags     []*gtsmodel.Tag
+}
+
+func (r *customRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(kindMention, r.renderMention)
+	reg.Register(kindHashtag, r.renderHashtag)
+}
+
+func (r *customRenderer) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithInlineParsers(
+		// 500 is pretty arbitrary here, it was copied from example goldmark extension code.
+		// https://github.com/yuin/goldmark/blob/75d8cce5b78c7e1d5d9c4ca32c1164f0a1e57b53/extension/strikethrough.go#L111
+		mdutil.Prioritized(&mentionParser{}, 500),
+		mdutil.Prioritized(&hashtagParser{}, 500),
+	))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		mdutil.Prioritized(r, 500),
+	))
+}
+
+// renderMention and renderHashtag take a mention or a hashtag ast.Node and render it as HTML.
+func (r *customRenderer) renderMention(w mdutil.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+
+	n, ok := node.(*mention) // this function is only registered for kindMention
+	if !ok {
+		log.Errorf("type assertion failed")
+	}
+	text := string(n.Segment.Value(source))
+
+	html := r.f.ReplaceMentions(r.ctx, text, r.mentions)
+
+	// we don't have much recourse if this fails
+	if _, err := w.WriteString(html); err != nil {
+		log.Errorf("error outputting markdown text: %s", err)
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *customRenderer) renderHashtag(w mdutil.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+
+	n, ok := node.(*hashtag) // this function is only registered for kindHashtag
+	if !ok {
+		log.Errorf("type assertion failed")
+	}
+	text := string(n.Segment.Value(source))
+
+	html := r.f.ReplaceTags(r.ctx, text, r.tags)
+
+	// we don't have much recourse if this fails
+	if _, err := w.WriteString(html); err != nil {
+		log.Errorf("error outputting markdown text: %s", err)
+	}
+	return ast.WalkContinue, nil
+}

internal/util/statustools.go

@@ -78,14 +78,14 @@ func FindHashtagSpansInText(text string) []Span {
 	inTag := false
 
 	for i, r := range text {
-		if r == '#' && isHashtagBoundary(prev) {
+		if r == '#' && IsHashtagBoundary(prev) {
 			// Start of hashtag.
 			inTag = true
 			start = i
-		} else if inTag && !isPermittedInHashtag(r) && !isHashtagBoundary(r) {
+		} else if inTag && !IsPermittedInHashtag(r) && !IsHashtagBoundary(r) {
 			// Inside the hashtag, but it was a phoney, gottem.
 			inTag = false
-		} else if inTag && isHashtagBoundary(r) {
+		} else if inTag && IsHashtagBoundary(r) {
 			// End of hashtag.
 			inTag = false
 			appendTag(&tags, text, start, i)
@@ -119,12 +119,12 @@ func DeriveEmojisFromText(text string) []string {
 	return UniqueStrings(emojis)
 }
 
-func isPermittedInHashtag(r rune) bool {
+func IsPermittedInHashtag(r rune) bool {
 	return unicode.IsLetter(r) || unicode.IsNumber(r)
 }
 
 // Decides where to break before or after a hashtag.
-func isHashtagBoundary(r rune) bool {
+func IsHashtagBoundary(r rune) bool {
 	return r == '#' || // `###lol` should work
 		unicode.IsSpace(r) || // All kinds of Unicode whitespace.
 		unicode.IsControl(r) || // All kinds of control characters, like tab.

vendor/github.com/russross/blackfriday/v2/.gitignore

@@ -1,8 +0,0 @@
-*.out
-*.swp
-*.8
-*.6
-_obj
-_test*
-markdown
-tags

vendor/github.com/russross/blackfriday/v2/.travis.yml

@@ -1,17 +0,0 @@
-sudo: false
-language: go
-go:
-  - "1.10.x"
-  - "1.11.x"
-  - tip
-matrix:
-  fast_finish: true
-  allow_failures:
-    - go: tip
-install:
-  - # Do nothing. This is needed to prevent default install action "go get -t -v ./..." from happening here (we want it to happen inside script step).
-script:
-  - go get -t -v ./...
-  - diff -u <(echo -n) <(gofmt -d -s .)
-  - go tool vet .
-  - go test -v ./...

vendor/github.com/russross/blackfriday/v2/LICENSE.txt

@@ -1,29 +0,0 @@
-Blackfriday is distributed under the Simplified BSD License:
-
-> Copyright © 2011 Russ Ross
-> All rights reserved.
->
-> Redistribution and use in source and binary forms, with or without
-> modification, are permitted provided that the following conditions
-> are met:
->
-> 1.  Redistributions of source code must retain the above copyright
->     notice, this list of conditions and the following disclaimer.
->
-> 2.  Redistributions in binary form must reproduce the above
->     copyright notice, this list of conditions and the following
->     disclaimer in the documentation and/or other materials provided with
->     the distribution.
->
-> THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-> "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-> LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
-> FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
-> COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
-> INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
-> BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-> LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-> CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
-> LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
-> ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-> POSSIBILITY OF SUCH DAMAGE.

vendor/github.com/russross/blackfriday/v2/README.md

@@ -1,335 +0,0 @@
-Blackfriday
-[![Build Status][BuildV2SVG]][BuildV2URL]
-[![PkgGoDev][PkgGoDevV2SVG]][PkgGoDevV2URL]
-===========
-
-Blackfriday is a [Markdown][1] processor implemented in [Go][2]. It
-is paranoid about its input (so you can safely feed it user-supplied
-data), it is fast, it supports common extensions (tables, smart
-punctuation substitutions, etc.), and it is safe for all utf-8
-(unicode) input.
-
-HTML output is currently supported, along with Smartypants
-extensions.
-
-It started as a translation from C of [Sundown][3].
-
-
-Installation
-------------
-
-Blackfriday is compatible with modern Go releases in module mode.
-With Go installed:
-
-    go get github.com/russross/blackfriday/v2
-
-will resolve and add the package to the current development module,
-then build and install it. Alternatively, you can achieve the same
-if you import it in a package:
-
-    import "github.com/russross/blackfriday/v2"
-
-and `go get` without parameters.
-
-Legacy GOPATH mode is unsupported.
-
-
-Versions
---------
-
-Currently maintained and recommended version of Blackfriday is `v2`. It's being
-developed on its own branch: https://github.com/russross/blackfriday/tree/v2 and the
-documentation is available at
-https://pkg.go.dev/github.com/russross/blackfriday/v2.
-
-It is `go get`-able in module mode at `github.com/russross/blackfriday/v2`.
-
-Version 2 offers a number of improvements over v1:
-
-* Cleaned up API
-* A separate call to [`Parse`][4], which produces an abstract syntax tree for
-  the document
-* Latest bug fixes
-* Flexibility to easily add your own rendering extensions
-
-Potential drawbacks:
-
-* Our benchmarks show v2 to be slightly slower than v1. Currently in the
-  ballpark of around 15%.
-* API breakage. If you can't afford modifying your code to adhere to the new API
-  and don't care too much about the new features, v2 is probably not for you.
-* Several bug fixes are trailing behind and still need to be forward-ported to
-  v2. See issue [#348](https://github.com/russross/blackfriday/issues/348) for
-  tracking.
-
-If you are still interested in the legacy `v1`, you can import it from
-`github.com/russross/blackfriday`. Documentation for the legacy v1 can be found
-here: https://pkg.go.dev/github.com/russross/blackfriday.
-
-
-Usage
------
-
-For the most sensible markdown processing, it is as simple as getting your input
-into a byte slice and calling:
-
-```go
-output := blackfriday.Run(input)
-```
-
-Your input will be parsed and the output rendered with a set of most popular
-extensions enabled. If you want the most basic feature set, corresponding with
-the bare Markdown specification, use:
-
-```go
-output := blackfriday.Run(input, blackfriday.WithNoExtensions())
-```
-
-### Sanitize untrusted content
-
-Blackfriday itself does nothing to protect against malicious content. If you are
-dealing with user-supplied markdown, we recommend running Blackfriday's output
-through HTML sanitizer such as [Bluemonday][5].
-
-Here's an example of simple usage of Blackfriday together with Bluemonday:
-
-```go
-import (
-    "github.com/microcosm-cc/bluemonday"
-    "github.com/russross/blackfriday/v2"
-)
-
-// ...
-unsafe := blackfriday.Run(input)
-html := bluemonday.UGCPolicy().SanitizeBytes(unsafe)
-```
-
-### Custom options
-
-If you want to customize the set of options, use `blackfriday.WithExtensions`,
-`blackfriday.WithRenderer` and `blackfriday.WithRefOverride`.
-
-### `blackfriday-tool`
-
-You can also check out `blackfriday-tool` for a more complete example
-of how to use it. Download and install it using:
-
-    go get github.com/russross/blackfriday-tool
-
-This is a simple command-line tool that allows you to process a
-markdown file using a standalone program.  You can also browse the
-source directly on github if you are just looking for some example
-code:
-
-* <https://github.com/russross/blackfriday-tool>
-
-Note that if you have not already done so, installing
-`blackfriday-tool` will be sufficient to download and install
-blackfriday in addition to the tool itself. The tool binary will be
-installed in `$GOPATH/bin`.  This is a statically-linked binary that
-can be copied to wherever you need it without worrying about
-dependencies and library versions.
-
-### Sanitized anchor names
-
-Blackfriday includes an algorithm for creating sanitized anchor names
-corresponding to a given input text. This algorithm is used to create
-anchors for headings when `AutoHeadingIDs` extension is enabled. The
-algorithm has a specification, so that other packages can create
-compatible anchor names and links to those anchors.
-
-The specification is located at https://pkg.go.dev/github.com/russross/blackfriday/v2#hdr-Sanitized_Anchor_Names.
-
-[`SanitizedAnchorName`](https://pkg.go.dev/github.com/russross/blackfriday/v2#SanitizedAnchorName) exposes this functionality, and can be used to
-create compatible links to the anchor names generated by blackfriday.
-This algorithm is also implemented in a small standalone package at
-[`github.com/shurcooL/sanitized_anchor_name`](https://pkg.go.dev/github.com/shurcooL/sanitized_anchor_name). It can be useful for clients
-that want a small package and don't need full functionality of blackfriday.
-
-
-Features
---------
-
-All features of Sundown are supported, including:
-
-*   **Compatibility**. The Markdown v1.0.3 test suite passes with
-    the `--tidy` option.  Without `--tidy`, the differences are
-    mostly in whitespace and entity escaping, where blackfriday is
-    more consistent and cleaner.
-
-*   **Common extensions**, including table support, fenced code
-    blocks, autolinks, strikethroughs, non-strict emphasis, etc.
-
-*   **Safety**. Blackfriday is paranoid when parsing, making it safe
-    to feed untrusted user input without fear of bad things
-    happening. The test suite stress tests this and there are no
-    known inputs that make it crash.  If you find one, please let me
-    know and send me the input that does it.
-
-    NOTE: "safety" in this context means *runtime safety only*. In order to
-    protect yourself against JavaScript injection in untrusted content, see
-    [this example](https://github.com/russross/blackfriday#sanitize-untrusted-content).
-
-*   **Fast processing**. It is fast enough to render on-demand in
-    most web applications without having to cache the output.
-
-*   **Thread safety**. You can run multiple parsers in different
-    goroutines without ill effect. There is no dependence on global
-    shared state.
-
-*   **Minimal dependencies**. Blackfriday only depends on standard
-    library packages in Go. The source code is pretty
-    self-contained, so it is easy to add to any project, including
-    Google App Engine projects.
-
-*   **Standards compliant**. Output successfully validates using the
-    W3C validation tool for HTML 4.01 and XHTML 1.0 Transitional.
-
-
-Extensions
-----------
-
-In addition to the standard markdown syntax, this package
-implements the following extensions:
-
-*   **Intra-word emphasis supression**. The `_` character is
-    commonly used inside words when discussing code, so having
-    markdown interpret it as an emphasis command is usually the
-    wrong thing. Blackfriday lets you treat all emphasis markers as
-    normal characters when they occur inside a word.
-
-*   **Tables**. Tables can be created by drawing them in the input
-    using a simple syntax:
-
-    ```
-    Name    | Age
-    --------|------
-    Bob     | 27
-    Alice   | 23
-    ```
-
-*   **Fenced code blocks**. In addition to the normal 4-space
-    indentation to mark code blocks, you can explicitly mark them
-    and supply a language (to make syntax highlighting simple). Just
-    mark it like this:
-
-        ```go
-        func getTrue() bool {
-            return true
-        }
-        ```
-
-    You can use 3 or more backticks to mark the beginning of the
-    block, and the same number to mark the end of the block.
-
-    To preserve classes of fenced code blocks while using the bluemonday
-    HTML sanitizer, use the following policy:
-
-    ```go
-    p := bluemonday.UGCPolicy()
-    p.AllowAttrs("class").Matching(regexp.MustCompile("^language-[a-zA-Z0-9]+$")).OnElements("code")
-    html := p.SanitizeBytes(unsafe)
-    ```
-
-*   **Definition lists**. A simple definition list is made of a single-line
-    term followed by a colon and the definition for that term.
-
-        Cat
-        : Fluffy animal everyone likes
-
-        Internet
-        : Vector of transmission for pictures of cats
-
-    Terms must be separated from the previous definition by a blank line.
-
-*   **Footnotes**. A marker in the text that will become a superscript number;
-    a footnote definition that will be placed in a list of footnotes at the
-    end of the document. A footnote looks like this:
-
-        This is a footnote.[^1]
-
-        [^1]: the footnote text.
-
-*   **Autolinking**. Blackfriday can find URLs that have not been
-    explicitly marked as links and turn them into links.
-
-*   **Strikethrough**. Use two tildes (`~~`) to mark text that
-    should be crossed out.
-
-*   **Hard line breaks**. With this extension enabled newlines in the input
-    translate into line breaks in the output. This extension is off by default.
-
-*   **Smart quotes**. Smartypants-style punctuation substitution is
-    supported, turning normal double- and single-quote marks into
-    curly quotes, etc.
-
-*   **LaTeX-style dash parsing** is an additional option, where `--`
-    is translated into `&ndash;`, and `---` is translated into
-    `&mdash;`. This differs from most smartypants processors, which
-    turn a single hyphen into an ndash and a double hyphen into an
-    mdash.
-
-*   **Smart fractions**, where anything that looks like a fraction
-    is translated into suitable HTML (instead of just a few special
-    cases like most smartypant processors). For example, `4/5`
-    becomes `<sup>4</sup>&frasl;<sub>5</sub>`, which renders as
-    <sup>4</sup>&frasl;<sub>5</sub>.
-
-
-Other renderers
----------------
-
-Blackfriday is structured to allow alternative rendering engines. Here
-are a few of note:
-
-*   [github_flavored_markdown](https://pkg.go.dev/github.com/shurcooL/github_flavored_markdown):
-    provides a GitHub Flavored Markdown renderer with fenced code block
-    highlighting, clickable heading anchor links.
-
-    It's not customizable, and its goal is to produce HTML output
-    equivalent to the [GitHub Markdown API endpoint](https://developer.github.com/v3/markdown/#render-a-markdown-document-in-raw-mode),
-    except the rendering is performed locally.
-
-*   [markdownfmt](https://github.com/shurcooL/markdownfmt): like gofmt,
-    but for markdown.
-
-*   [LaTeX output](https://gitlab.com/ambrevar/blackfriday-latex):
-    renders output as LaTeX.
-
-*   [bfchroma](https://github.com/Depado/bfchroma/): provides convenience
-    integration with the [Chroma](https://github.com/alecthomas/chroma) code
-    highlighting library. bfchroma is only compatible with v2 of Blackfriday and
-    provides a drop-in renderer ready to use with Blackfriday, as well as
-    options and means for further customization.
-
-*   [Blackfriday-Confluence](https://github.com/kentaro-m/blackfriday-confluence): provides a [Confluence Wiki Markup](https://confluence.atlassian.com/doc/confluence-wiki-markup-251003035.html) renderer.
-
-*   [Blackfriday-Slack](https://github.com/karriereat/blackfriday-slack): converts markdown to slack message style
-
-
-TODO
-----
-
-*   More unit testing
-*   Improve Unicode support. It does not understand all Unicode
-    rules (about what constitutes a letter, a punctuation symbol,
-    etc.), so it may fail to detect word boundaries correctly in
-    some instances. It is safe on all UTF-8 input.
-
-
-License
--------
-
-[Blackfriday is distributed under the Simplified BSD License](LICENSE.txt)
-
-
-   [1]: https://daringfireball.net/projects/markdown/ "Markdown"
-   [2]: https://golang.org/ "Go Language"
-   [3]: https://github.com/vmg/sundown "Sundown"
-   [4]: https://pkg.go.dev/github.com/russross/blackfriday/v2#Parse "Parse func"
-   [5]: https://github.com/microcosm-cc/bluemonday "Bluemonday"
-
-   [BuildV2SVG]: https://travis-ci.org/russross/blackfriday.svg?branch=v2
-   [BuildV2URL]: https://travis-ci.org/russross/blackfriday
-   [PkgGoDevV2SVG]: https://pkg.go.dev/badge/github.com/russross/blackfriday/v2
-   [PkgGoDevV2URL]: https://pkg.go.dev/github.com/russross/blackfriday/v2

vendor/github.com/russross/blackfriday/v2/doc.go

@@ -1,46 +0,0 @@
-// Package blackfriday is a markdown processor.
-//
-// It translates plain text with simple formatting rules into an AST, which can
-// then be further processed to HTML (provided by Blackfriday itself) or other
-// formats (provided by the community).
-//
-// The simplest way to invoke Blackfriday is to call the Run function. It will
-// take a text input and produce a text output in HTML (or other format).
-//
-// A slightly more sophisticated way to use Blackfriday is to create a Markdown
-// processor and to call Parse, which returns a syntax tree for the input
-// document. You can leverage Blackfriday's parsing for content extraction from
-// markdown documents. You can assign a custom renderer and set various options
-// to the Markdown processor.
-//
-// If you're interested in calling Blackfriday from command line, see
-// https://github.com/russross/blackfriday-tool.
-//
-// Sanitized Anchor Names
-//
-// Blackfriday includes an algorithm for creating sanitized anchor names
-// corresponding to a given input text. This algorithm is used to create
-// anchors for headings when AutoHeadingIDs extension is enabled. The
-// algorithm is specified below, so that other packages can create
-// compatible anchor names and links to those anchors.
-//
-// The algorithm iterates over the input text, interpreted as UTF-8,
-// one Unicode code point (rune) at a time. All runes that are letters (category L)
-// or numbers (category N) are considered valid characters. They are mapped to
-// lower case, and included in the output. All other runes are considered
-// invalid characters. Invalid characters that precede the first valid character,
-// as well as invalid character that follow the last valid character
-// are dropped completely. All other sequences of invalid characters
-// between two valid characters are replaced with a single dash character '-'.
-//
-// SanitizedAnchorName exposes this functionality, and can be used to
-// create compatible links to the anchor names generated by blackfriday.
-// This algorithm is also implemented in a small standalone package at
-// github.com/shurcooL/sanitized_anchor_name. It can be useful for clients
-// that want a small package and don't need full functionality of blackfriday.
-package blackfriday
-
-// NOTE: Keep Sanitized Anchor Name algorithm in sync with package
-//       github.com/shurcooL/sanitized_anchor_name.
-//       Otherwise, users of sanitized_anchor_name will get anchor names
-//       that are incompatible with those generated by blackfriday.

vendor/github.com/russross/blackfriday/v2/esc.go

@@ -1,70 +0,0 @@
-package blackfriday
-
-import (
-	"html"
-	"io"
-)
-
-var htmlEscaper = [256][]byte{
-	'&': []byte("&"),
-	'<': []byte("&lt;"),
-	'>': []byte("&gt;"),
-	'"': []byte("&quot;"),
-}
-
-func escapeHTML(w io.Writer, s []byte) {
-	escapeEntities(w, s, false)
-}
-
-func escapeAllHTML(w io.Writer, s []byte) {
-	escapeEntities(w, s, true)
-}
-
-func escapeEntities(w io.Writer, s []byte, escapeValidEntities bool) {
-	var start, end int
-	for end < len(s) {
-		escSeq := htmlEscaper[s[end]]
-		if escSeq != nil {
-			isEntity, entityEnd := nodeIsEntity(s, end)
-			if isEntity && !escapeValidEntities {
-				w.Write(s[start : entityEnd+1])
-				start = entityEnd + 1
-			} else {
-				w.Write(s[start:end])
-				w.Write(escSeq)
-				start = end + 1
-			}
-		}
-		end++
-	}
-	if start < len(s) && end <= len(s) {
-		w.Write(s[start:end])
-	}
-}
-
-func nodeIsEntity(s []byte, end int) (isEntity bool, endEntityPos int) {
-	isEntity = false
-	endEntityPos = end + 1
-
-	if s[end] == '&' {
-		for endEntityPos < len(s) {
-			if s[endEntityPos] == ';' {
-				if entities[string(s[end:endEntityPos+1])] {
-					isEntity = true
-					break
-				}
-			}
-			if !isalnum(s[endEntityPos]) && s[endEntityPos] != '&' && s[endEntityPos] != '#' {
-				break
-			}
-			endEntityPos++
-		}
-	}
-
-	return isEntity, endEntityPos
-}
-
-func escLink(w io.Writer, text []byte) {
-	unesc := html.UnescapeString(string(text))
-	escapeHTML(w, []byte(unesc))
-}

vendor/github.com/russross/blackfriday/v2/html.go

@@ -1,952 +0,0 @@
-//
-// Blackfriday Markdown Processor
-// Available at http://github.com/russross/blackfriday
-//
-// Copyright © 2011 Russ Ross <russ@russross.com>.
-// Distributed under the Simplified BSD License.
-// See README.md for details.
-//
-
-//
-//
-// HTML rendering backend
-//
-//
-
-package blackfriday
-
-import (
-	"bytes"
-	"fmt"
-	"io"
-	"regexp"
-	"strings"
-)
-
-// HTMLFlags control optional behavior of HTML renderer.
-type HTMLFlags int
-
-// HTML renderer configuration options.
-const (
-	HTMLFlagsNone           HTMLFlags = 0
-	SkipHTML                HTMLFlags = 1 << iota // Skip preformatted HTML blocks
-	SkipImages                                    // Skip embedded images
-	SkipLinks                                     // Skip all links
-	Safelink                                      // Only link to trusted protocols
-	NofollowLinks                                 // Only link with rel="nofollow"
-	NoreferrerLinks                               // Only link with rel="noreferrer"
-	NoopenerLinks                                 // Only link with rel="noopener"
-	HrefTargetBlank                               // Add a blank target
-	CompletePage                                  // Generate a complete HTML page
-	UseXHTML                                      // Generate XHTML output instead of HTML
-	FootnoteReturnLinks                           // Generate a link at the end of a footnote to return to the source
-	Smartypants                                   // Enable smart punctuation substitutions
-	SmartypantsFractions                          // Enable smart fractions (with Smartypants)
-	SmartypantsDashes                             // Enable smart dashes (with Smartypants)
-	SmartypantsLatexDashes                        // Enable LaTeX-style dashes (with Smartypants)
-	SmartypantsAngledQuotes                       // Enable angled double quotes (with Smartypants) for double quotes rendering
-	SmartypantsQuotesNBSP                         // Enable « French guillemets » (with Smartypants)
-	TOC                                           // Generate a table of contents
-)
-
-var (
-	htmlTagRe = regexp.MustCompile("(?i)^" + htmlTag)
-)
-
-const (
-	htmlTag = "(?:" + openTag + "|" + closeTag + "|" + htmlComment + "|" +
-		processingInstruction + "|" + declaration + "|" + cdata + ")"
-	closeTag              = "</" + tagName + "\\s*[>]"
-	openTag               = "<" + tagName + attribute + "*" + "\\s*/?>"
-	attribute             = "(?:" + "\\s+" + attributeName + attributeValueSpec + "?)"
-	attributeValue        = "(?:" + unquotedValue + "|" + singleQuotedValue + "|" + doubleQuotedValue + ")"
-	attributeValueSpec    = "(?:" + "\\s*=" + "\\s*" + attributeValue + ")"
-	attributeName         = "[a-zA-Z_:][a-zA-Z0-9:._-]*"
-	cdata                 = "<!\\[CDATA\\[[\\s\\S]*?\\]\\]>"
-	declaration           = "<![A-Z]+" + "\\s+[^>]*>"
-	doubleQuotedValue     = "\"[^\"]*\""
-	htmlComment           = "<!---->|<!--(?:-?[^>-])(?:-?[^-])*-->"
-	processingInstruction = "[<][?].*?[?][>]"
-	singleQuotedValue     = "'[^']*'"
-	tagName               = "[A-Za-z][A-Za-z0-9-]*"
-	unquotedValue         = "[^\"'=<>`\\x00-\\x20]+"
-)
-
-// HTMLRendererParameters is a collection of supplementary parameters tweaking
-// the behavior of various parts of HTML renderer.
-type HTMLRendererParameters struct {
-	// Prepend this text to each relative URL.
-	AbsolutePrefix string
-	// Add this text to each footnote anchor, to ensure uniqueness.
-	FootnoteAnchorPrefix string
-	// Show this text inside the <a> tag for a footnote return link, if the
-	// HTML_FOOTNOTE_RETURN_LINKS flag is enabled. If blank, the string
-	// <sup>[return]</sup> is used.
-	FootnoteReturnLinkContents string
-	// If set, add this text to the front of each Heading ID, to ensure
-	// uniqueness.
-	HeadingIDPrefix string
-	// If set, add this text to the back of each Heading ID, to ensure uniqueness.
-	HeadingIDSuffix string
-	// Increase heading levels: if the offset is 1, <h1> becomes <h2> etc.
-	// Negative offset is also valid.
-	// Resulting levels are clipped between 1 and 6.
-	HeadingLevelOffset int
-
-	Title string // Document title (used if CompletePage is set)
-	CSS   string // Optional CSS file URL (used if CompletePage is set)
-	Icon  string // Optional icon file URL (used if CompletePage is set)
-
-	Flags HTMLFlags // Flags allow customizing this renderer's behavior
-}
-
-// HTMLRenderer is a type that implements the Renderer interface for HTML output.
-//
-// Do not create this directly, instead use the NewHTMLRenderer function.
-type HTMLRenderer struct {
-	HTMLRendererParameters
-
-	closeTag string // how to end singleton tags: either " />" or ">"
-
-	// Track heading IDs to prevent ID collision in a single generation.
-	headingIDs map[string]int
-
-	lastOutputLen int
-	disableTags   int
-
-	sr *SPRenderer
-}
-
-const (
-	xhtmlClose = " />"
-	htmlClose  = ">"
-)
-
-// NewHTMLRenderer creates and configures an HTMLRenderer object, which
-// satisfies the Renderer interface.
-func NewHTMLRenderer(params HTMLRendererParameters) *HTMLRenderer {
-	// configure the rendering engine
-	closeTag := htmlClose
-	if params.Flags&UseXHTML != 0 {
-		closeTag = xhtmlClose
-	}
-
-	if params.FootnoteReturnLinkContents == "" {
-		// U+FE0E is VARIATION SELECTOR-15.
-		// It suppresses automatic emoji presentation of the preceding
-		// U+21A9 LEFTWARDS ARROW WITH HOOK on iOS and iPadOS.
-		params.FootnoteReturnLinkContents = "<span aria-label='Return'>↩\ufe0e</span>"
-	}
-
-	return &HTMLRenderer{
-		HTMLRendererParameters: params,
-
-		closeTag:   closeTag,
-		headingIDs: make(map[string]int),
-
-		sr: NewSmartypantsRenderer(params.Flags),
-	}
-}
-
-func isHTMLTag(tag []byte, tagname string) bool {
-	found, _ := findHTMLTagPos(tag, tagname)
-	return found
-}
-
-// Look for a character, but ignore it when it's in any kind of quotes, it
-// might be JavaScript
-func skipUntilCharIgnoreQuotes(html []byte, start int, char byte) int {
-	inSingleQuote := false
-	inDoubleQuote := false
-	inGraveQuote := false
-	i := start
-	for i < len(html) {
-		switch {
-		case html[i] == char && !inSingleQuote && !inDoubleQuote && !inGraveQuote:
-			return i
-		case html[i] == '\'':
-			inSingleQuote = !inSingleQuote
-		case html[i] == '"':
-			inDoubleQuote = !inDoubleQuote
-		case html[i] == '`':
-			inGraveQuote = !inGraveQuote
-		}
-		i++
-	}
-	return start
-}
-
-func findHTMLTagPos(tag []byte, tagname string) (bool, int) {
-	i := 0
-	if i < len(tag) && tag[0] != '<' {
-		return false, -1
-	}
-	i++
-	i = skipSpace(tag, i)
-
-	if i < len(tag) && tag[i] == '/' {
-		i++
-	}
-
-	i = skipSpace(tag, i)
-	j := 0
-	for ; i < len(tag); i, j = i+1, j+1 {
-		if j >= len(tagname) {
-			break
-		}
-
-		if strings.ToLower(string(tag[i]))[0] != tagname[j] {
-			return false, -1
-		}
-	}
-
-	if i == len(tag) {
-		return false, -1
-	}
-
-	rightAngle := skipUntilCharIgnoreQuotes(tag, i, '>')
-	if rightAngle >= i {
-		return true, rightAngle
-	}
-
-	return false, -1
-}
-
-func skipSpace(tag []byte, i int) int {
-	for i < len(tag) && isspace(tag[i]) {
-		i++
-	}
-	return i
-}
-
-func isRelativeLink(link []byte) (yes bool) {
-	// a tag begin with '#'
-	if link[0] == '#' {
-		return true
-	}
-
-	// link begin with '/' but not '//', the second maybe a protocol relative link
-	if len(link) >= 2 && link[0] == '/' && link[1] != '/' {
-		return true
-	}
-
-	// only the root '/'
-	if len(link) == 1 && link[0] == '/' {
-		return true
-	}
-
-	// current directory : begin with "./"
-	if bytes.HasPrefix(link, []byte("./")) {
-		return true
-	}
-
-	// parent directory : begin with "../"
-	if bytes.HasPrefix(link, []byte("../")) {
-		return true
-	}
-
-	return false
-}
-
-func (r *HTMLRenderer) ensureUniqueHeadingID(id string) string {
-	for count, found := r.headingIDs[id]; found; count, found = r.headingIDs[id] {
-		tmp := fmt.Sprintf("%s-%d", id, count+1)
-
-		if _, tmpFound := r.headingIDs[tmp]; !tmpFound {
-			r.headingIDs[id] = count + 1
-			id = tmp
-		} else {
-			id = id + "-1"
-		}
-	}
-
-	if _, found := r.headingIDs[id]; !found {
-		r.headingIDs[id] = 0
-	}
-
-	return id
-}
-
-func (r *HTMLRenderer) addAbsPrefix(link []byte) []byte {
-	if r.AbsolutePrefix != "" && isRelativeLink(link) && link[0] != '.' {
-		newDest := r.AbsolutePrefix
-		if link[0] != '/' {
-			newDest += "/"
-		}
-		newDest += string(link)
-		return []byte(newDest)
-	}
-	return link
-}
-
-func appendLinkAttrs(attrs []string, flags HTMLFlags, link []byte) []string {
-	if isRelativeLink(link) {
-		return attrs
-	}
-	val := []string{}
-	if flags&NofollowLinks != 0 {
-		val = append(val, "nofollow")
-	}
-	if flags&NoreferrerLinks != 0 {
-		val = append(val, "noreferrer")
-	}
-	if flags&NoopenerLinks != 0 {
-		val = append(val, "noopener")
-	}
-	if flags&HrefTargetBlank != 0 {
-		attrs = append(attrs, "target=\"_blank\"")
-	}
-	if len(val) == 0 {
-		return attrs
-	}
-	attr := fmt.Sprintf("rel=%q", strings.Join(val, " "))
-	return append(attrs, attr)
-}
-
-func isMailto(link []byte) bool {
-	return bytes.HasPrefix(link, []byte("mailto:"))
-}
-
-func needSkipLink(flags HTMLFlags, dest []byte) bool {
-	if flags&SkipLinks != 0 {
-		return true
-	}
-	return flags&Safelink != 0 && !isSafeLink(dest) && !isMailto(dest)
-}
-
-func isSmartypantable(node *Node) bool {
-	pt := node.Parent.Type
-	return pt != Link && pt != CodeBlock && pt != Code
-}
-
-func appendLanguageAttr(attrs []string, info []byte) []string {
-	if len(info) == 0 {
-		return attrs
-	}
-	endOfLang := bytes.IndexAny(info, "\t ")
-	if endOfLang < 0 {
-		endOfLang = len(info)
-	}
-	return append(attrs, fmt.Sprintf("class=\"language-%s\"", info[:endOfLang]))
-}
-
-func (r *HTMLRenderer) tag(w io.Writer, name []byte, attrs []string) {
-	w.Write(name)
-	if len(attrs) > 0 {
-		w.Write(spaceBytes)
-		w.Write([]byte(strings.Join(attrs, " ")))
-	}
-	w.Write(gtBytes)
-	r.lastOutputLen = 1
-}
-
-func footnoteRef(prefix string, node *Node) []byte {
-	urlFrag := prefix + string(slugify(node.Destination))
-	anchor := fmt.Sprintf(`<a href="#fn:%s">%d</a>`, urlFrag, node.NoteID)
-	return []byte(fmt.Sprintf(`<sup class="footnote-ref" id="fnref:%s">%s</sup>`, urlFrag, anchor))
-}
-
-func footnoteItem(prefix string, slug []byte) []byte {
-	return []byte(fmt.Sprintf(`<li id="fn:%s%s">`, prefix, slug))
-}
-
-func footnoteReturnLink(prefix, returnLink string, slug []byte) []byte {
-	const format = ` <a class="footnote-return" href="#fnref:%s%s">%s</a>`
-	return []byte(fmt.Sprintf(format, prefix, slug, returnLink))
-}
-
-func itemOpenCR(node *Node) bool {
-	if node.Prev == nil {
-		return false
-	}
-	ld := node.Parent.ListData
-	return !ld.Tight && ld.ListFlags&ListTypeDefinition == 0
-}
-
-func skipParagraphTags(node *Node) bool {
-	grandparent := node.Parent.Parent
-	if grandparent == nil || grandparent.Type != List {
-		return false
-	}
-	tightOrTerm := grandparent.Tight || node.Parent.ListFlags&ListTypeTerm != 0
-	return grandparent.Type == List && tightOrTerm
-}
-
-func cellAlignment(align CellAlignFlags) string {
-	switch align {
-	case TableAlignmentLeft:
-		return "left"
-	case TableAlignmentRight:
-		return "right"
-	case TableAlignmentCenter:
-		return "center"
-	default:
-		return ""
-	}
-}
-
-func (r *HTMLRenderer) out(w io.Writer, text []byte) {
-	if r.disableTags > 0 {
-		w.Write(htmlTagRe.ReplaceAll(text, []byte{}))
-	} else {
-		w.Write(text)
-	}
-	r.lastOutputLen = len(text)
-}
-
-func (r *HTMLRenderer) cr(w io.Writer) {
-	if r.lastOutputLen > 0 {
-		r.out(w, nlBytes)
-	}
-}
-
-var (
-	nlBytes    = []byte{'\n'}
-	gtBytes    = []byte{'>'}
-	spaceBytes = []byte{' '}
-)
-
-var (
-	brTag              = []byte("<br>")
-	brXHTMLTag         = []byte("<br />")
-	emTag              = []byte("<em>")
-	emCloseTag         = []byte("</em>")
-	strongTag          = []byte("<strong>")
-	strongCloseTag     = []byte("</strong>")
-	delTag             = []byte("<del>")
-	delCloseTag        = []byte("</del>")
-	ttTag              = []byte("<tt>")
-	ttCloseTag         = []byte("</tt>")
-	aTag               = []byte("<a")
-	aCloseTag          = []byte("</a>")
-	preTag             = []byte("<pre>")
-	preCloseTag        = []byte("</pre>")
-	codeTag            = []byte("<code>")
-	codeCloseTag       = []byte("</code>")
-	pTag               = []byte("<p>")
-	pCloseTag          = []byte("</p>")
-	blockquoteTag      = []byte("<blockquote>")
-	blockquoteCloseTag = []byte("</blockquote>")
-	hrTag              = []byte("<hr>")
-	hrXHTMLTag         = []byte("<hr />")
-	ulTag              = []byte("<ul>")
-	ulCloseTag         = []byte("</ul>")
-	olTag              = []byte("<ol>")
-	olCloseTag         = []byte("</ol>")
-	dlTag              = []byte("<dl>")
-	dlCloseTag         = []byte("</dl>")
-	liTag              = []byte("<li>")
-	liCloseTag         = []byte("</li>")
-	ddTag              = []byte("<dd>")
-	ddCloseTag         = []byte("</dd>")
-	dtTag              = []byte("<dt>")
-	dtCloseTag         = []byte("</dt>")
-	tableTag           = []byte("<table>")
-	tableCloseTag      = []byte("</table>")
-	tdTag              = []byte("<td")
-	tdCloseTag         = []byte("</td>")
-	thTag              = []byte("<th")
-	thCloseTag         = []byte("</th>")
-	theadTag           = []byte("<thead>")
-	theadCloseTag      = []byte("</thead>")
-	tbodyTag           = []byte("<tbody>")
-	tbodyCloseTag      = []byte("</tbody>")
-	trTag              = []byte("<tr>")
-	trCloseTag         = []byte("</tr>")
-	h1Tag              = []byte("<h1")
-	h1CloseTag         = []byte("</h1>")
-	h2Tag              = []byte("<h2")
-	h2CloseTag         = []byte("</h2>")
-	h3Tag              = []byte("<h3")
-	h3CloseTag         = []byte("</h3>")
-	h4Tag              = []byte("<h4")
-	h4CloseTag         = []byte("</h4>")
-	h5Tag              = []byte("<h5")
-	h5CloseTag         = []byte("</h5>")
-	h6Tag              = []byte("<h6")
-	h6CloseTag         = []byte("</h6>")
-
-	footnotesDivBytes      = []byte("\n<div class=\"footnotes\">\n\n")
-	footnotesCloseDivBytes = []byte("\n</div>\n")
-)
-
-func headingTagsFromLevel(level int) ([]byte, []byte) {
-	if level <= 1 {
-		return h1Tag, h1CloseTag
-	}
-	switch level {
-	case 2:
-		return h2Tag, h2CloseTag
-	case 3:
-		return h3Tag, h3CloseTag
-	case 4:
-		return h4Tag, h4CloseTag
-	case 5:
-		return h5Tag, h5CloseTag
-	}
-	return h6Tag, h6CloseTag
-}
-
-func (r *HTMLRenderer) outHRTag(w io.Writer) {
-	if r.Flags&UseXHTML == 0 {
-		r.out(w, hrTag)
-	} else {
-		r.out(w, hrXHTMLTag)
-	}
-}
-
-// RenderNode is a default renderer of a single node of a syntax tree. For
-// block nodes it will be called twice: first time with entering=true, second
-// time with entering=false, so that it could know when it's working on an open
-// tag and when on close. It writes the result to w.
-//
-// The return value is a way to tell the calling walker to adjust its walk
-// pattern: e.g. it can terminate the traversal by returning Terminate. Or it
-// can ask the walker to skip a subtree of this node by returning SkipChildren.
-// The typical behavior is to return GoToNext, which asks for the usual
-// traversal to the next node.
-func (r *HTMLRenderer) RenderNode(w io.Writer, node *Node, entering bool) WalkStatus {
-	attrs := []string{}
-	switch node.Type {
-	case Text:
-		if r.Flags&Smartypants != 0 {
-			var tmp bytes.Buffer
-			escapeHTML(&tmp, node.Literal)
-			r.sr.Process(w, tmp.Bytes())
-		} else {
-			if node.Parent.Type == Link {
-				escLink(w, node.Literal)
-			} else {
-				escapeHTML(w, node.Literal)
-			}
-		}
-	case Softbreak:
-		r.cr(w)
-		// TODO: make it configurable via out(renderer.softbreak)
-	case Hardbreak:
-		if r.Flags&UseXHTML == 0 {
-			r.out(w, brTag)
-		} else {
-			r.out(w, brXHTMLTag)
-		}
-		r.cr(w)
-	case Emph:
-		if entering {
-			r.out(w, emTag)
-		} else {
-			r.out(w, emCloseTag)
-		}
-	case Strong:
-		if entering {
-			r.out(w, strongTag)
-		} else {
-			r.out(w, strongCloseTag)
-		}
-	case Del:
-		if entering {
-			r.out(w, delTag)
-		} else {
-			r.out(w, delCloseTag)
-		}
-	case HTMLSpan:
-		if r.Flags&SkipHTML != 0 {
-			break
-		}
-		r.out(w, node.Literal)
-	case Link:
-		// mark it but don't link it if it is not a safe link: no smartypants
-		dest := node.LinkData.Destination
-		if needSkipLink(r.Flags, dest) {
-			if entering {
-				r.out(w, ttTag)
-			} else {
-				r.out(w, ttCloseTag)
-			}
-		} else {
-			if entering {
-				dest = r.addAbsPrefix(dest)
-				var hrefBuf bytes.Buffer
-				hrefBuf.WriteString("href=\"")
-				escLink(&hrefBuf, dest)
-				hrefBuf.WriteByte('"')
-				attrs = append(attrs, hrefBuf.String())
-				if node.NoteID != 0 {
-					r.out(w, footnoteRef(r.FootnoteAnchorPrefix, node))
-					break
-				}
-				attrs = appendLinkAttrs(attrs, r.Flags, dest)
-				if len(node.LinkData.Title) > 0 {
-					var titleBuff bytes.Buffer
-					titleBuff.WriteString("title=\"")
-					escapeHTML(&titleBuff, node.LinkData.Title)
-					titleBuff.WriteByte('"')
-					attrs = append(attrs, titleBuff.String())
-				}
-				r.tag(w, aTag, attrs)
-			} else {
-				if node.NoteID != 0 {
-					break
-				}
-				r.out(w, aCloseTag)
-			}
-		}
-	case Image:
-		if r.Flags&SkipImages != 0 {
-			return SkipChildren
-		}
-		if entering {
-			dest := node.LinkData.Destination
-			dest = r.addAbsPrefix(dest)
-			if r.disableTags == 0 {
-				//if options.safe && potentiallyUnsafe(dest) {
-				//out(w, `<img src="" alt="`)
-				//} else {
-				r.out(w, []byte(`<img src="`))
-				escLink(w, dest)
-				r.out(w, []byte(`" alt="`))
-				//}
-			}
-			r.disableTags++
-		} else {
-			r.disableTags--
-			if r.disableTags == 0 {
-				if node.LinkData.Title != nil {
-					r.out(w, []byte(`" title="`))
-					escapeHTML(w, node.LinkData.Title)
-				}
-				r.out(w, []byte(`" />`))
-			}
-		}
-	case Code:
-		r.out(w, codeTag)
-		escapeAllHTML(w, node.Literal)
-		r.out(w, codeCloseTag)
-	case Document:
-		break
-	case Paragraph:
-		if skipParagraphTags(node) {
-			break
-		}
-		if entering {
-			// TODO: untangle this clusterfuck about when the newlines need
-			// to be added and when not.
-			if node.Prev != nil {
-				switch node.Prev.Type {
-				case HTMLBlock, List, Paragraph, Heading, CodeBlock, BlockQuote, HorizontalRule:
-					r.cr(w)
-				}
-			}
-			if node.Parent.Type == BlockQuote && node.Prev == nil {
-				r.cr(w)
-			}
-			r.out(w, pTag)
-		} else {
-			r.out(w, pCloseTag)
-			if !(node.Parent.Type == Item && node.Next == nil) {
-				r.cr(w)
-			}
-		}
-	case BlockQuote:
-		if entering {
-			r.cr(w)
-			r.out(w, blockquoteTag)
-		} else {
-			r.out(w, blockquoteCloseTag)
-			r.cr(w)
-		}
-	case HTMLBlock:
-		if r.Flags&SkipHTML != 0 {
-			break
-		}
-		r.cr(w)
-		r.out(w, node.Literal)
-		r.cr(w)
-	case Heading:
-		headingLevel := r.HTMLRendererParameters.HeadingLevelOffset + node.Level
-		openTag, closeTag := headingTagsFromLevel(headingLevel)
-		if entering {
-			if node.IsTitleblock {
-				attrs = append(attrs, `class="title"`)
-			}
-			if node.HeadingID != "" {
-				id := r.ensureUniqueHeadingID(node.HeadingID)
-				if r.HeadingIDPrefix != "" {
-					id = r.HeadingIDPrefix + id
-				}
-				if r.HeadingIDSuffix != "" {
-					id = id + r.HeadingIDSuffix
-				}
-				attrs = append(attrs, fmt.Sprintf(`id="%s"`, id))
-			}
-			r.cr(w)
-			r.tag(w, openTag, attrs)
-		} else {
-			r.out(w, closeTag)
-			if !(node.Parent.Type == Item && node.Next == nil) {
-				r.cr(w)
-			}
-		}
-	case HorizontalRule:
-		r.cr(w)
-		r.outHRTag(w)
-		r.cr(w)
-	case List:
-		openTag := ulTag
-		closeTag := ulCloseTag
-		if node.ListFlags&ListTypeOrdered != 0 {
-			openTag = olTag
-			closeTag = olCloseTag
-		}
-		if node.ListFlags&ListTypeDefinition != 0 {
-			openTag = dlTag
-			closeTag = dlCloseTag
-		}
-		if entering {
-			if node.IsFootnotesList {
-				r.out(w, footnotesDivBytes)
-				r.outHRTag(w)
-				r.cr(w)
-			}
-			r.cr(w)
-			if node.Parent.Type == Item && node.Parent.Parent.Tight {
-				r.cr(w)
-			}
-			r.tag(w, openTag[:len(openTag)-1], attrs)
-			r.cr(w)
-		} else {
-			r.out(w, closeTag)
-			//cr(w)
-			//if node.parent.Type != Item {
-			//	cr(w)
-			//}
-			if node.Parent.Type == Item && node.Next != nil {
-				r.cr(w)
-			}
-			if node.Parent.Type == Document || node.Parent.Type == BlockQuote {
-				r.cr(w)
-			}
-			if node.IsFootnotesList {
-				r.out(w, footnotesCloseDivBytes)
-			}
-		}
-	case Item:
-		openTag := liTag
-		closeTag := liCloseTag
-		if node.ListFlags&ListTypeDefinition != 0 {
-			openTag = ddTag
-			closeTag = ddCloseTag
-		}
-		if node.ListFlags&ListTypeTerm != 0 {
-			openTag = dtTag
-			closeTag = dtCloseTag
-		}
-		if entering {
-			if itemOpenCR(node) {
-				r.cr(w)
-			}
-			if node.ListData.RefLink != nil {
-				slug := slugify(node.ListData.RefLink)
-				r.out(w, footnoteItem(r.FootnoteAnchorPrefix, slug))
-				break
-			}
-			r.out(w, openTag)
-		} else {
-			if node.ListData.RefLink != nil {
-				slug := slugify(node.ListData.RefLink)
-				if r.Flags&FootnoteReturnLinks != 0 {
-					r.out(w, footnoteReturnLink(r.FootnoteAnchorPrefix, r.FootnoteReturnLinkContents, slug))
-				}
-			}
-			r.out(w, closeTag)
-			r.cr(w)
-		}
-	case CodeBlock:
-		attrs = appendLanguageAttr(attrs, node.Info)
-		r.cr(w)
-		r.out(w, preTag)
-		r.tag(w, codeTag[:len(codeTag)-1], attrs)
-		escapeAllHTML(w, node.Literal)
-		r.out(w, codeCloseTag)
-		r.out(w, preCloseTag)
-		if node.Parent.Type != Item {
-			r.cr(w)
-		}
-	case Table:
-		if entering {
-			r.cr(w)
-			r.out(w, tableTag)
-		} else {
-			r.out(w, tableCloseTag)
-			r.cr(w)
-		}
-	case TableCell:
-		openTag := tdTag
-		closeTag := tdCloseTag
-		if node.IsHeader {
-			openTag = thTag
-			closeTag = thCloseTag
-		}
-		if entering {
-			align := cellAlignment(node.Align)
-			if align != "" {
-				attrs = append(attrs, fmt.Sprintf(`align="%s"`, align))
-			}
-			if node.Prev == nil {
-				r.cr(w)
-			}
-			r.tag(w, openTag, attrs)
-		} else {
-			r.out(w, closeTag)
-			r.cr(w)
-		}
-	case TableHead:
-		if entering {
-			r.cr(w)
-			r.out(w, theadTag)
-		} else {
-			r.out(w, theadCloseTag)
-			r.cr(w)
-		}
-	case TableBody:
-		if entering {
-			r.cr(w)
-			r.out(w, tbodyTag)
-			// XXX: this is to adhere to a rather silly test. Should fix test.
-			if node.FirstChild == nil {
-				r.cr(w)
-			}
-		} else {
-			r.out(w, tbodyCloseTag)
-			r.cr(w)
-		}
-	case TableRow:
-		if entering {
-			r.cr(w)
-			r.out(w, trTag)
-		} else {
-			r.out(w, trCloseTag)
-			r.cr(w)
-		}
-	default:
-		panic("Unknown node type " + node.Type.String())
-	}
-	return GoToNext
-}
-
-// RenderHeader writes HTML document preamble and TOC if requested.
-func (r *HTMLRenderer) RenderHeader(w io.Writer, ast *Node) {
-	r.writeDocumentHeader(w)
-	if r.Flags&TOC != 0 {
-		r.writeTOC(w, ast)
-	}
-}
-
-// RenderFooter writes HTML document footer.
-func (r *HTMLRenderer) RenderFooter(w io.Writer, ast *Node) {
-	if r.Flags&CompletePage == 0 {
-		return
-	}
-	io.WriteString(w, "\n</body>\n</html>\n")
-}
-
-func (r *HTMLRenderer) writeDocumentHeader(w io.Writer) {
-	if r.Flags&CompletePage == 0 {
-		return
-	}
-	ending := ""
-	if r.Flags&UseXHTML != 0 {
-		io.WriteString(w, "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\" ")
-		io.WriteString(w, "\"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">\n")
-		io.WriteString(w, "<html xmlns=\"http://www.w3.org/1999/xhtml\">\n")
-		ending = " /"
-	} else {
-		io.WriteString(w, "<!DOCTYPE html>\n")
-		io.WriteString(w, "<html>\n")
-	}
-	io.WriteString(w, "<head>\n")
-	io.WriteString(w, "  <title>")
-	if r.Flags&Smartypants != 0 {
-		r.sr.Process(w, []byte(r.Title))
-	} else {
-		escapeHTML(w, []byte(r.Title))
-	}
-	io.WriteString(w, "</title>\n")
-	io.WriteString(w, "  <meta name=\"GENERATOR\" content=\"Blackfriday Markdown Processor v")
-	io.WriteString(w, Version)
-	io.WriteString(w, "\"")
-	io.WriteString(w, ending)
-	io.WriteString(w, ">\n")
-	io.WriteString(w, "  <meta charset=\"utf-8\"")
-	io.WriteString(w, ending)
-	io.WriteString(w, ">\n")
-	if r.CSS != "" {
-		io.WriteString(w, "  <link rel=\"stylesheet\" type=\"text/css\" href=\"")
-		escapeHTML(w, []byte(r.CSS))
-		io.WriteString(w, "\"")
-		io.WriteString(w, ending)
-		io.WriteString(w, ">\n")
-	}
-	if r.Icon != "" {
-		io.WriteString(w, "  <link rel=\"icon\" type=\"image/x-icon\" href=\"")
-		escapeHTML(w, []byte(r.Icon))
-		io.WriteString(w, "\"")
-		io.WriteString(w, ending)
-		io.WriteString(w, ">\n")
-	}
-	io.WriteString(w, "</head>\n")
-	io.WriteString(w, "<body>\n\n")
-}
-
-func (r *HTMLRenderer) writeTOC(w io.Writer, ast *Node) {
-	buf := bytes.Buffer{}
-
-	inHeading := false
-	tocLevel := 0
-	headingCount := 0
-
-	ast.Walk(func(node *Node, entering bool) WalkStatus {
-		if node.Type == Heading && !node.HeadingData.IsTitleblock {
-			inHeading = entering
-			if entering {
-				node.HeadingID = fmt.Sprintf("toc_%d", headingCount)
-				if node.Level == tocLevel {
-					buf.WriteString("</li>\n\n<li>")
-				} else if node.Level < tocLevel {
-					for node.Level < tocLevel {
-						tocLevel--
-						buf.WriteString("</li>\n</ul>")
-					}
-					buf.WriteString("</li>\n\n<li>")
-				} else {
-					for node.Level > tocLevel {
-						tocLevel++
-						buf.WriteString("\n<ul>\n<li>")
-					}
-				}
-
-				fmt.Fprintf(&buf, `<a href="#toc_%d">`, headingCount)
-				headingCount++
-			} else {
-				buf.WriteString("</a>")
-			}
-			return GoToNext
-		}
-
-		if inHeading {
-			return r.RenderNode(&buf, node, entering)
-		}
-
-		return GoToNext
-	})
-
-	for ; tocLevel > 0; tocLevel-- {
-		buf.WriteString("</li>\n</ul>")
-	}
-
-	if buf.Len() > 0 {
-		io.WriteString(w, "<nav>\n")
-		w.Write(buf.Bytes())
-		io.WriteString(w, "\n\n</nav>\n")
-	}
-	r.lastOutputLen = buf.Len()
-}

vendor/github.com/russross/blackfriday/v2/markdown.go

@@ -1,950 +0,0 @@
-// Blackfriday Markdown Processor
-// Available at http://github.com/russross/blackfriday
-//
-// Copyright © 2011 Russ Ross <russ@russross.com>.
-// Distributed under the Simplified BSD License.
-// See README.md for details.
-
-package blackfriday
-
-import (
-	"bytes"
-	"fmt"
-	"io"
-	"strings"
-	"unicode/utf8"
-)
-
-//
-// Markdown parsing and processing
-//
-
-// Version string of the package. Appears in the rendered document when
-// CompletePage flag is on.
-const Version = "2.0"
-
-// Extensions is a bitwise or'ed collection of enabled Blackfriday's
-// extensions.
-type Extensions int
-
-// These are the supported markdown parsing extensions.
-// OR these values together to select multiple extensions.
-const (
-	NoExtensions           Extensions = 0
-	NoIntraEmphasis        Extensions = 1 << iota // Ignore emphasis markers inside words
-	Tables                                        // Render tables
-	FencedCode                                    // Render fenced code blocks
-	Autolink                                      // Detect embedded URLs that are not explicitly marked
-	Strikethrough                                 // Strikethrough text using ~~test~~
-	LaxHTMLBlocks                                 // Loosen up HTML block parsing rules
-	SpaceHeadings                                 // Be strict about prefix heading rules
-	HardLineBreak                                 // Translate newlines into line breaks
-	TabSizeEight                                  // Expand tabs to eight spaces instead of four
-	Footnotes                                     // Pandoc-style footnotes
-	NoEmptyLineBeforeBlock                        // No need to insert an empty line to start a (code, quote, ordered list, unordered list) block
-	HeadingIDs                                    // specify heading IDs  with {#id}
-	Titleblock                                    // Titleblock ala pandoc
-	AutoHeadingIDs                                // Create the heading ID from the text
-	BackslashLineBreak                            // Translate trailing backslashes into line breaks
-	DefinitionLists                               // Render definition lists
-
-	CommonHTMLFlags HTMLFlags = UseXHTML | Smartypants |
-		SmartypantsFractions | SmartypantsDashes | SmartypantsLatexDashes
-
-	CommonExtensions Extensions = NoIntraEmphasis | Tables | FencedCode |
-		Autolink | Strikethrough | SpaceHeadings | HeadingIDs |
-		BackslashLineBreak | DefinitionLists
-)
-
-// ListType contains bitwise or'ed flags for list and list item objects.
-type ListType int
-
-// These are the possible flag values for the ListItem renderer.
-// Multiple flag values may be ORed together.
-// These are mostly of interest if you are writing a new output format.
-const (
-	ListTypeOrdered ListType = 1 << iota
-	ListTypeDefinition
-	ListTypeTerm
-
-	ListItemContainsBlock
-	ListItemBeginningOfList // TODO: figure out if this is of any use now
-	ListItemEndOfList
-)
-
-// CellAlignFlags holds a type of alignment in a table cell.
-type CellAlignFlags int
-
-// These are the possible flag values for the table cell renderer.
-// Only a single one of these values will be used; they are not ORed together.
-// These are mostly of interest if you are writing a new output format.
-const (
-	TableAlignmentLeft CellAlignFlags = 1 << iota
-	TableAlignmentRight
-	TableAlignmentCenter = (TableAlignmentLeft | TableAlignmentRight)
-)
-
-// The size of a tab stop.
-const (
-	TabSizeDefault = 4
-	TabSizeDouble  = 8
-)
-
-// blockTags is a set of tags that are recognized as HTML block tags.
-// Any of these can be included in markdown text without special escaping.
-var blockTags = map[string]struct{}{
-	"blockquote": {},
-	"del":        {},
-	"div":        {},
-	"dl":         {},
-	"fieldset":   {},
-	"form":       {},
-	"h1":         {},
-	"h2":         {},
-	"h3":         {},
-	"h4":         {},
-	"h5":         {},
-	"h6":         {},
-	"iframe":     {},
-	"ins":        {},
-	"math":       {},
-	"noscript":   {},
-	"ol":         {},
-	"pre":        {},
-	"p":          {},
-	"script":     {},
-	"style":      {},
-	"table":      {},
-	"ul":         {},
-
-	// HTML5
-	"address":    {},
-	"article":    {},
-	"aside":      {},
-	"canvas":     {},
-	"figcaption": {},
-	"figure":     {},
-	"footer":     {},
-	"header":     {},
-	"hgroup":     {},
-	"main":       {},
-	"nav":        {},
-	"output":     {},
-	"progress":   {},
-	"section":    {},
-	"video":      {},
-}
-
-// Renderer is the rendering interface. This is mostly of interest if you are
-// implementing a new rendering format.
-//
-// Only an HTML implementation is provided in this repository, see the README
-// for external implementations.
-type Renderer interface {
-	// RenderNode is the main rendering method. It will be called once for
-	// every leaf node and twice for every non-leaf node (first with
-	// entering=true, then with entering=false). The method should write its
-	// rendition of the node to the supplied writer w.
-	RenderNode(w io.Writer, node *Node, entering bool) WalkStatus
-
-	// RenderHeader is a method that allows the renderer to produce some
-	// content preceding the main body of the output document. The header is
-	// understood in the broad sense here. For example, the default HTML
-	// renderer will write not only the HTML document preamble, but also the
-	// table of contents if it was requested.
-	//
-	// The method will be passed an entire document tree, in case a particular
-	// implementation needs to inspect it to produce output.
-	//
-	// The output should be written to the supplied writer w. If your
-	// implementation has no header to write, supply an empty implementation.
-	RenderHeader(w io.Writer, ast *Node)
-
-	// RenderFooter is a symmetric counterpart of RenderHeader.
-	RenderFooter(w io.Writer, ast *Node)
-}
-
-// Callback functions for inline parsing. One such function is defined
-// for each character that triggers a response when parsing inline data.
-type inlineParser func(p *Markdown, data []byte, offset int) (int, *Node)
-
-// Markdown is a type that holds extensions and the runtime state used by
-// Parse, and the renderer. You can not use it directly, construct it with New.
-type Markdown struct {
-	renderer          Renderer
-	referenceOverride ReferenceOverrideFunc
-	refs              map[string]*reference
-	inlineCallback    [256]inlineParser
-	extensions        Extensions
-	nesting           int
-	maxNesting        int
-	insideLink        bool
-
-	// Footnotes need to be ordered as well as available to quickly check for
-	// presence. If a ref is also a footnote, it's stored both in refs and here
-	// in notes. Slice is nil if footnotes not enabled.
-	notes []*reference
-
-	doc                  *Node
-	tip                  *Node // = doc
-	oldTip               *Node
-	lastMatchedContainer *Node // = doc
-	allClosed            bool
-}
-
-func (p *Markdown) getRef(refid string) (ref *reference, found bool) {
-	if p.referenceOverride != nil {
-		r, overridden := p.referenceOverride(refid)
-		if overridden {
-			if r == nil {
-				return nil, false
-			}
-			return &reference{
-				link:     []byte(r.Link),
-				title:    []byte(r.Title),
-				noteID:   0,
-				hasBlock: false,
-				text:     []byte(r.Text)}, true
-		}
-	}
-	// refs are case insensitive
-	ref, found = p.refs[strings.ToLower(refid)]
-	return ref, found
-}
-
-func (p *Markdown) finalize(block *Node) {
-	above := block.Parent
-	block.open = false
-	p.tip = above
-}
-
-func (p *Markdown) addChild(node NodeType, offset uint32) *Node {
-	return p.addExistingChild(NewNode(node), offset)
-}
-
-func (p *Markdown) addExistingChild(node *Node, offset uint32) *Node {
-	for !p.tip.canContain(node.Type) {
-		p.finalize(p.tip)
-	}
-	p.tip.AppendChild(node)
-	p.tip = node
-	return node
-}
-
-func (p *Markdown) closeUnmatchedBlocks() {
-	if !p.allClosed {
-		for p.oldTip != p.lastMatchedContainer {
-			parent := p.oldTip.Parent
-			p.finalize(p.oldTip)
-			p.oldTip = parent
-		}
-		p.allClosed = true
-	}
-}
-
-//
-//
-// Public interface
-//
-//
-
-// Reference represents the details of a link.
-// See the documentation in Options for more details on use-case.
-type Reference struct {
-	// Link is usually the URL the reference points to.
-	Link string
-	// Title is the alternate text describing the link in more detail.
-	Title string
-	// Text is the optional text to override the ref with if the syntax used was
-	// [refid][]
-	Text string
-}
-
-// ReferenceOverrideFunc is expected to be called with a reference string and
-// return either a valid Reference type that the reference string maps to or
-// nil. If overridden is false, the default reference logic will be executed.
-// See the documentation in Options for more details on use-case.
-type ReferenceOverrideFunc func(reference string) (ref *Reference, overridden bool)
-
-// New constructs a Markdown processor. You can use the same With* functions as
-// for Run() to customize parser's behavior and the renderer.
-func New(opts ...Option) *Markdown {
-	var p Markdown
-	for _, opt := range opts {
-		opt(&p)
-	}
-	p.refs = make(map[string]*reference)
-	p.maxNesting = 16
-	p.insideLink = false
-	docNode := NewNode(Document)
-	p.doc = docNode
-	p.tip = docNode
-	p.oldTip = docNode
-	p.lastMatchedContainer = docNode
-	p.allClosed = true
-	// register inline parsers
-	p.inlineCallback[' '] = maybeLineBreak
-	p.inlineCallback['*'] = emphasis
-	p.inlineCallback['_'] = emphasis
-	if p.extensions&Strikethrough != 0 {
-		p.inlineCallback['~'] = emphasis
-	}
-	p.inlineCallback['`'] = codeSpan
-	p.inlineCallback['\n'] = lineBreak
-	p.inlineCallback['['] = link
-	p.inlineCallback['<'] = leftAngle
-	p.inlineCallback['\\'] = escape
-	p.inlineCallback['&'] = entity
-	p.inlineCallback['!'] = maybeImage
-	p.inlineCallback['^'] = maybeInlineFootnote
-	if p.extensions&Autolink != 0 {
-		p.inlineCallback['h'] = maybeAutoLink
-		p.inlineCallback['m'] = maybeAutoLink
-		p.inlineCallback['f'] = maybeAutoLink
-		p.inlineCallback['H'] = maybeAutoLink
-		p.inlineCallback['M'] = maybeAutoLink
-		p.inlineCallback['F'] = maybeAutoLink
-	}
-	if p.extensions&Footnotes != 0 {
-		p.notes = make([]*reference, 0)
-	}
-	return &p
-}
-
-// Option customizes the Markdown processor's default behavior.
-type Option func(*Markdown)
-
-// WithRenderer allows you to override the default renderer.
-func WithRenderer(r Renderer) Option {
-	return func(p *Markdown) {
-		p.renderer = r
-	}
-}
-
-// WithExtensions allows you to pick some of the many extensions provided by
-// Blackfriday. You can bitwise OR them.
-func WithExtensions(e Extensions) Option {
-	return func(p *Markdown) {
-		p.extensions = e
-	}
-}
-
-// WithNoExtensions turns off all extensions and custom behavior.
-func WithNoExtensions() Option {
-	return func(p *Markdown) {
-		p.extensions = NoExtensions
-		p.renderer = NewHTMLRenderer(HTMLRendererParameters{
-			Flags: HTMLFlagsNone,
-		})
-	}
-}
-
-// WithRefOverride sets an optional function callback that is called every
-// time a reference is resolved.
-//
-// In Markdown, the link reference syntax can be made to resolve a link to
-// a reference instead of an inline URL, in one of the following ways:
-//
-//  * [link text][refid]
-//  * [refid][]
-//
-// Usually, the refid is defined at the bottom of the Markdown document. If
-// this override function is provided, the refid is passed to the override
-// function first, before consulting the defined refids at the bottom. If
-// the override function indicates an override did not occur, the refids at
-// the bottom will be used to fill in the link details.
-func WithRefOverride(o ReferenceOverrideFunc) Option {
-	return func(p *Markdown) {
-		p.referenceOverride = o
-	}
-}
-
-// Run is the main entry point to Blackfriday. It parses and renders a
-// block of markdown-encoded text.
-//
-// The simplest invocation of Run takes one argument, input:
-//     output := Run(input)
-// This will parse the input with CommonExtensions enabled and render it with
-// the default HTMLRenderer (with CommonHTMLFlags).
-//
-// Variadic arguments opts can customize the default behavior. Since Markdown
-// type does not contain exported fields, you can not use it directly. Instead,
-// use the With* functions. For example, this will call the most basic
-// functionality, with no extensions:
-//     output := Run(input, WithNoExtensions())
-//
-// You can use any number of With* arguments, even contradicting ones. They
-// will be applied in order of appearance and the latter will override the
-// former:
-//     output := Run(input, WithNoExtensions(), WithExtensions(exts),
-//         WithRenderer(yourRenderer))
-func Run(input []byte, opts ...Option) []byte {
-	r := NewHTMLRenderer(HTMLRendererParameters{
-		Flags: CommonHTMLFlags,
-	})
-	optList := []Option{WithRenderer(r), WithExtensions(CommonExtensions)}
-	optList = append(optList, opts...)
-	parser := New(optList...)
-	ast := parser.Parse(input)
-	var buf bytes.Buffer
-	parser.renderer.RenderHeader(&buf, ast)
-	ast.Walk(func(node *Node, entering bool) WalkStatus {
-		return parser.renderer.RenderNode(&buf, node, entering)
-	})
-	parser.renderer.RenderFooter(&buf, ast)
-	return buf.Bytes()
-}
-
-// Parse is an entry point to the parsing part of Blackfriday. It takes an
-// input markdown document and produces a syntax tree for its contents. This
-// tree can then be rendered with a default or custom renderer, or
-// analyzed/transformed by the caller to whatever non-standard needs they have.
-// The return value is the root node of the syntax tree.
-func (p *Markdown) Parse(input []byte) *Node {
-	p.block(input)
-	// Walk the tree and finish up some of unfinished blocks
-	for p.tip != nil {
-		p.finalize(p.tip)
-	}
-	// Walk the tree again and process inline markdown in each block
-	p.doc.Walk(func(node *Node, entering bool) WalkStatus {
-		if node.Type == Paragraph || node.Type == Heading || node.Type == TableCell {
-			p.inline(node, node.content)
-			node.content = nil
-		}
-		return GoToNext
-	})
-	p.parseRefsToAST()
-	return p.doc
-}
-
-func (p *Markdown) parseRefsToAST() {
-	if p.extensions&Footnotes == 0 || len(p.notes) == 0 {
-		return
-	}
-	p.tip = p.doc
-	block := p.addBlock(List, nil)
-	block.IsFootnotesList = true
-	block.ListFlags = ListTypeOrdered
-	flags := ListItemBeginningOfList
-	// Note: this loop is intentionally explicit, not range-form. This is
-	// because the body of the loop will append nested footnotes to p.notes and
-	// we need to process those late additions. Range form would only walk over
-	// the fixed initial set.
-	for i := 0; i < len(p.notes); i++ {
-		ref := p.notes[i]
-		p.addExistingChild(ref.footnote, 0)
-		block := ref.footnote
-		block.ListFlags = flags | ListTypeOrdered
-		block.RefLink = ref.link
-		if ref.hasBlock {
-			flags |= ListItemContainsBlock
-			p.block(ref.title)
-		} else {
-			p.inline(block, ref.title)
-		}
-		flags &^= ListItemBeginningOfList | ListItemContainsBlock
-	}
-	above := block.Parent
-	finalizeList(block)
-	p.tip = above
-	block.Walk(func(node *Node, entering bool) WalkStatus {
-		if node.Type == Paragraph || node.Type == Heading {
-			p.inline(node, node.content)
-			node.content = nil
-		}
-		return GoToNext
-	})
-}
-
-//
-// Link references
-//
-// This section implements support for references that (usually) appear
-// as footnotes in a document, and can be referenced anywhere in the document.
-// The basic format is:
-//
-//    [1]: http://www.google.com/ "Google"
-//    [2]: http://www.github.com/ "Github"
-//
-// Anywhere in the document, the reference can be linked by referring to its
-// label, i.e., 1 and 2 in this example, as in:
-//
-//    This library is hosted on [Github][2], a git hosting site.
-//
-// Actual footnotes as specified in Pandoc and supported by some other Markdown
-// libraries such as php-markdown are also taken care of. They look like this:
-//
-//    This sentence needs a bit of further explanation.[^note]
-//
-//    [^note]: This is the explanation.
-//
-// Footnotes should be placed at the end of the document in an ordered list.
-// Finally, there are inline footnotes such as:
-//
-//    Inline footnotes^[Also supported.] provide a quick inline explanation,
-//    but are rendered at the bottom of the document.
-//
-
-// reference holds all information necessary for a reference-style links or
-// footnotes.
-//
-// Consider this markdown with reference-style links:
-//
-//     [link][ref]
-//
-//     [ref]: /url/ "tooltip title"
-//
-// It will be ultimately converted to this HTML:
-//
-//     <p><a href=\"/url/\" title=\"title\">link</a></p>
-//
-// And a reference structure will be populated as follows:
-//
-//     p.refs["ref"] = &reference{
-//         link: "/url/",
-//         title: "tooltip title",
-//     }
-//
-// Alternatively, reference can contain information about a footnote. Consider
-// this markdown:
-//
-//     Text needing a footnote.[^a]
-//
-//     [^a]: This is the note
-//
-// A reference structure will be populated as follows:
-//
-//     p.refs["a"] = &reference{
-//         link: "a",
-//         title: "This is the note",
-//         noteID: <some positive int>,
-//     }
-//
-// TODO: As you can see, it begs for splitting into two dedicated structures
-// for refs and for footnotes.
-type reference struct {
-	link     []byte
-	title    []byte
-	noteID   int // 0 if not a footnote ref
-	hasBlock bool
-	footnote *Node // a link to the Item node within a list of footnotes
-
-	text []byte // only gets populated by refOverride feature with Reference.Text
-}
-
-func (r *reference) String() string {
-	return fmt.Sprintf("{link: %q, title: %q, text: %q, noteID: %d, hasBlock: %v}",
-		r.link, r.title, r.text, r.noteID, r.hasBlock)
-}
-
-// Check whether or not data starts with a reference link.
-// If so, it is parsed and stored in the list of references
-// (in the render struct).
-// Returns the number of bytes to skip to move past it,
-// or zero if the first line is not a reference.
-func isReference(p *Markdown, data []byte, tabSize int) int {
-	// up to 3 optional leading spaces
-	if len(data) < 4 {
-		return 0
-	}
-	i := 0
-	for i < 3 && data[i] == ' ' {
-		i++
-	}
-
-	noteID := 0
-
-	// id part: anything but a newline between brackets
-	if data[i] != '[' {
-		return 0
-	}
-	i++
-	if p.extensions&Footnotes != 0 {
-		if i < len(data) && data[i] == '^' {
-			// we can set it to anything here because the proper noteIds will
-			// be assigned later during the second pass. It just has to be != 0
-			noteID = 1
-			i++
-		}
-	}
-	idOffset := i
-	for i < len(data) && data[i] != '\n' && data[i] != '\r' && data[i] != ']' {
-		i++
-	}
-	if i >= len(data) || data[i] != ']' {
-		return 0
-	}
-	idEnd := i
-	// footnotes can have empty ID, like this: [^], but a reference can not be
-	// empty like this: []. Break early if it's not a footnote and there's no ID
-	if noteID == 0 && idOffset == idEnd {
-		return 0
-	}
-	// spacer: colon (space | tab)* newline? (space | tab)*
-	i++
-	if i >= len(data) || data[i] != ':' {
-		return 0
-	}
-	i++
-	for i < len(data) && (data[i] == ' ' || data[i] == '\t') {
-		i++
-	}
-	if i < len(data) && (data[i] == '\n' || data[i] == '\r') {
-		i++
-		if i < len(data) && data[i] == '\n' && data[i-1] == '\r' {
-			i++
-		}
-	}
-	for i < len(data) && (data[i] == ' ' || data[i] == '\t') {
-		i++
-	}
-	if i >= len(data) {
-		return 0
-	}
-
-	var (
-		linkOffset, linkEnd   int
-		titleOffset, titleEnd int
-		lineEnd               int
-		raw                   []byte
-		hasBlock              bool
-	)
-
-	if p.extensions&Footnotes != 0 && noteID != 0 {
-		linkOffset, linkEnd, raw, hasBlock = scanFootnote(p, data, i, tabSize)
-		lineEnd = linkEnd
-	} else {
-		linkOffset, linkEnd, titleOffset, titleEnd, lineEnd = scanLinkRef(p, data, i)
-	}
-	if lineEnd == 0 {
-		return 0
-	}
-
-	// a valid ref has been found
-
-	ref := &reference{
-		noteID:   noteID,
-		hasBlock: hasBlock,
-	}
-
-	if noteID > 0 {
-		// reusing the link field for the id since footnotes don't have links
-		ref.link = data[idOffset:idEnd]
-		// if footnote, it's not really a title, it's the contained text
-		ref.title = raw
-	} else {
-		ref.link = data[linkOffset:linkEnd]
-		ref.title = data[titleOffset:titleEnd]
-	}
-
-	// id matches are case-insensitive
-	id := string(bytes.ToLower(data[idOffset:idEnd]))
-
-	p.refs[id] = ref
-
-	return lineEnd
-}
-
-func scanLinkRef(p *Markdown, data []byte, i int) (linkOffset, linkEnd, titleOffset, titleEnd, lineEnd int) {
-	// link: whitespace-free sequence, optionally between angle brackets
-	if data[i] == '<' {
-		i++
-	}
-	linkOffset = i
-	for i < len(data) && data[i] != ' ' && data[i] != '\t' && data[i] != '\n' && data[i] != '\r' {
-		i++
-	}
-	linkEnd = i
-	if data[linkOffset] == '<' && data[linkEnd-1] == '>' {
-		linkOffset++
-		linkEnd--
-	}
-
-	// optional spacer: (space | tab)* (newline | '\'' | '"' | '(' )
-	for i < len(data) && (data[i] == ' ' || data[i] == '\t') {
-		i++
-	}
-	if i < len(data) && data[i] != '\n' && data[i] != '\r' && data[i] != '\'' && data[i] != '"' && data[i] != '(' {
-		return
-	}
-
-	// compute end-of-line
-	if i >= len(data) || data[i] == '\r' || data[i] == '\n' {
-		lineEnd = i
-	}
-	if i+1 < len(data) && data[i] == '\r' && data[i+1] == '\n' {
-		lineEnd++
-	}
-
-	// optional (space|tab)* spacer after a newline
-	if lineEnd > 0 {
-		i = lineEnd + 1
-		for i < len(data) && (data[i] == ' ' || data[i] == '\t') {
-			i++
-		}
-	}
-
-	// optional title: any non-newline sequence enclosed in '"() alone on its line
-	if i+1 < len(data) && (data[i] == '\'' || data[i] == '"' || data[i] == '(') {
-		i++
-		titleOffset = i
-
-		// look for EOL
-		for i < len(data) && data[i] != '\n' && data[i] != '\r' {
-			i++
-		}
-		if i+1 < len(data) && data[i] == '\n' && data[i+1] == '\r' {
-			titleEnd = i + 1
-		} else {
-			titleEnd = i
-		}
-
-		// step back
-		i--
-		for i > titleOffset && (data[i] == ' ' || data[i] == '\t') {
-			i--
-		}
-		if i > titleOffset && (data[i] == '\'' || data[i] == '"' || data[i] == ')') {
-			lineEnd = titleEnd
-			titleEnd = i
-		}
-	}
-
-	return
-}
-
-// The first bit of this logic is the same as Parser.listItem, but the rest
-// is much simpler. This function simply finds the entire block and shifts it
-// over by one tab if it is indeed a block (just returns the line if it's not).
-// blockEnd is the end of the section in the input buffer, and contents is the
-// extracted text that was shifted over one tab. It will need to be rendered at
-// the end of the document.
-func scanFootnote(p *Markdown, data []byte, i, indentSize int) (blockStart, blockEnd int, contents []byte, hasBlock bool) {
-	if i == 0 || len(data) == 0 {
-		return
-	}
-
-	// skip leading whitespace on first line
-	for i < len(data) && data[i] == ' ' {
-		i++
-	}
-
-	blockStart = i
-
-	// find the end of the line
-	blockEnd = i
-	for i < len(data) && data[i-1] != '\n' {
-		i++
-	}
-
-	// get working buffer
-	var raw bytes.Buffer
-
-	// put the first line into the working buffer
-	raw.Write(data[blockEnd:i])
-	blockEnd = i
-
-	// process the following lines
-	containsBlankLine := false
-
-gatherLines:
-	for blockEnd < len(data) {
-		i++
-
-		// find the end of this line
-		for i < len(data) && data[i-1] != '\n' {
-			i++
-		}
-
-		// if it is an empty line, guess that it is part of this item
-		// and move on to the next line
-		if p.isEmpty(data[blockEnd:i]) > 0 {
-			containsBlankLine = true
-			blockEnd = i
-			continue
-		}
-
-		n := 0
-		if n = isIndented(data[blockEnd:i], indentSize); n == 0 {
-			// this is the end of the block.
-			// we don't want to include this last line in the index.
-			break gatherLines
-		}
-
-		// if there were blank lines before this one, insert a new one now
-		if containsBlankLine {
-			raw.WriteByte('\n')
-			containsBlankLine = false
-		}
-
-		// get rid of that first tab, write to buffer
-		raw.Write(data[blockEnd+n : i])
-		hasBlock = true
-
-		blockEnd = i
-	}
-
-	if data[blockEnd-1] != '\n' {
-		raw.WriteByte('\n')
-	}
-
-	contents = raw.Bytes()
-
-	return
-}
-
-//
-//
-// Miscellaneous helper functions
-//
-//
-
-// Test if a character is a punctuation symbol.
-// Taken from a private function in regexp in the stdlib.
-func ispunct(c byte) bool {
-	for _, r := range []byte("!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~") {
-		if c == r {
-			return true
-		}
-	}
-	return false
-}
-
-// Test if a character is a whitespace character.
-func isspace(c byte) bool {
-	return ishorizontalspace(c) || isverticalspace(c)
-}
-
-// Test if a character is a horizontal whitespace character.
-func ishorizontalspace(c byte) bool {
-	return c == ' ' || c == '\t'
-}
-
-// Test if a character is a vertical character.
-func isverticalspace(c byte) bool {
-	return c == '\n' || c == '\r' || c == '\f' || c == '\v'
-}
-
-// Test if a character is letter.
-func isletter(c byte) bool {
-	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
-}
-
-// Test if a character is a letter or a digit.
-// TODO: check when this is looking for ASCII alnum and when it should use unicode
-func isalnum(c byte) bool {
-	return (c >= '0' && c <= '9') || isletter(c)
-}
-
-// Replace tab characters with spaces, aligning to the next TAB_SIZE column.
-// always ends output with a newline
-func expandTabs(out *bytes.Buffer, line []byte, tabSize int) {
-	// first, check for common cases: no tabs, or only tabs at beginning of line
-	i, prefix := 0, 0
-	slowcase := false
-	for i = 0; i < len(line); i++ {
-		if line[i] == '\t' {
-			if prefix == i {
-				prefix++
-			} else {
-				slowcase = true
-				break
-			}
-		}
-	}
-
-	// no need to decode runes if all tabs are at the beginning of the line
-	if !slowcase {
-		for i = 0; i < prefix*tabSize; i++ {
-			out.WriteByte(' ')
-		}
-		out.Write(line[prefix:])
-		return
-	}
-
-	// the slow case: we need to count runes to figure out how
-	// many spaces to insert for each tab
-	column := 0
-	i = 0
-	for i < len(line) {
-		start := i
-		for i < len(line) && line[i] != '\t' {
-			_, size := utf8.DecodeRune(line[i:])
-			i += size
-			column++
-		}
-
-		if i > start {
-			out.Write(line[start:i])
-		}
-
-		if i >= len(line) {
-			break
-		}
-
-		for {
-			out.WriteByte(' ')
-			column++
-			if column%tabSize == 0 {
-				break
-			}
-		}
-
-		i++
-	}
-}
-
-// Find if a line counts as indented or not.
-// Returns number of characters the indent is (0 = not indented).
-func isIndented(data []byte, indentSize int) int {
-	if len(data) == 0 {
-		return 0
-	}
-	if data[0] == '\t' {
-		return 1
-	}
-	if len(data) < indentSize {
-		return 0
-	}
-	for i := 0; i < indentSize; i++ {
-		if data[i] != ' ' {
-			return 0
-		}
-	}
-	return indentSize
-}
-
-// Create a url-safe slug for fragments
-func slugify(in []byte) []byte {
-	if len(in) == 0 {
-		return in
-	}
-	out := make([]byte, 0, len(in))
-	sym := false
-
-	for _, ch := range in {
-		if isalnum(ch) {
-			sym = false
-			out = append(out, ch)
-		} else if sym {
-			continue
-		} else {
-			out = append(out, '-')
-			sym = true
-		}
-	}
-	var a, b int
-	var ch byte
-	for a, ch = range out {
-		if ch != '-' {
-			break
-		}
-	}
-	for b = len(out) - 1; b > 0; b-- {
-		if out[b] != '-' {
-			break
-		}
-	}
-	return out[a : b+1]
-}

vendor/github.com/russross/blackfriday/v2/node.go

@@ -1,360 +0,0 @@
-package blackfriday
-
-import (
-	"bytes"
-	"fmt"
-)
-
-// NodeType specifies a type of a single node of a syntax tree. Usually one
-// node (and its type) corresponds to a single markdown feature, e.g. emphasis
-// or code block.
-type NodeType int
-
-// Constants for identifying different types of nodes. See NodeType.
-const (
-	Document NodeType = iota
-	BlockQuote
-	List
-	Item
-	Paragraph
-	Heading
-	HorizontalRule
-	Emph
-	Strong
-	Del
-	Link
-	Image
-	Text
-	HTMLBlock
-	CodeBlock
-	Softbreak
-	Hardbreak
-	Code
-	HTMLSpan
-	Table
-	TableCell
-	TableHead
-	TableBody
-	TableRow
-)
-
-var nodeTypeNames = []string{
-	Document:       "Document",
-	BlockQuote:     "BlockQuote",
-	List:           "List",
-	Item:           "Item",
-	Paragraph:      "Paragraph",
-	Heading:        "Heading",
-	HorizontalRule: "HorizontalRule",
-	Emph:           "Emph",
-	Strong:         "Strong",
-	Del:            "Del",
-	Link:           "Link",
-	Image:          "Image",
-	Text:           "Text",
-	HTMLBlock:      "HTMLBlock",
-	CodeBlock:      "CodeBlock",
-	Softbreak:      "Softbreak",
-	Hardbreak:      "Hardbreak",
-	Code:           "Code",
-	HTMLSpan:       "HTMLSpan",
-	Table:          "Table",
-	TableCell:      "TableCell",
-	TableHead:      "TableHead",
-	TableBody:      "TableBody",
-	TableRow:       "TableRow",
-}
-
-func (t NodeType) String() string {
-	return nodeTypeNames[t]
-}
-
-// ListData contains fields relevant to a List and Item node type.
-type ListData struct {
-	ListFlags       ListType
-	Tight           bool   // Skip <p>s around list item data if true
-	BulletChar      byte   // '*', '+' or '-' in bullet lists
-	Delimiter       byte   // '.' or ')' after the number in ordered lists
-	RefLink         []byte // If not nil, turns this list item into a footnote item and triggers different rendering
-	IsFootnotesList bool   // This is a list of footnotes
-}
-
-// LinkData contains fields relevant to a Link node type.
-type LinkData struct {
-	Destination []byte // Destination is what goes into a href
-	Title       []byte // Title is the tooltip thing that goes in a title attribute
-	NoteID      int    // NoteID contains a serial number of a footnote, zero if it's not a footnote
-	Footnote    *Node  // If it's a footnote, this is a direct link to the footnote Node. Otherwise nil.
-}
-
-// CodeBlockData contains fields relevant to a CodeBlock node type.
-type CodeBlockData struct {
-	IsFenced    bool   // Specifies whether it's a fenced code block or an indented one
-	Info        []byte // This holds the info string
-	FenceChar   byte
-	FenceLength int
-	FenceOffset int
-}
-
-// TableCellData contains fields relevant to a TableCell node type.
-type TableCellData struct {
-	IsHeader bool           // This tells if it's under the header row
-	Align    CellAlignFlags // This holds the value for align attribute
-}
-
-// HeadingData contains fields relevant to a Heading node type.
-type HeadingData struct {
-	Level        int    // This holds the heading level number
-	HeadingID    string // This might hold heading ID, if present
-	IsTitleblock bool   // Specifies whether it's a title block
-}
-
-// Node is a single element in the abstract syntax tree of the parsed document.
-// It holds connections to the structurally neighboring nodes and, for certain
-// types of nodes, additional information that might be needed when rendering.
-type Node struct {
-	Type       NodeType // Determines the type of the node
-	Parent     *Node    // Points to the parent
-	FirstChild *Node    // Points to the first child, if any
-	LastChild  *Node    // Points to the last child, if any
-	Prev       *Node    // Previous sibling; nil if it's the first child
-	Next       *Node    // Next sibling; nil if it's the last child
-
-	Literal []byte // Text contents of the leaf nodes
-
-	HeadingData   // Populated if Type is Heading
-	ListData      // Populated if Type is List
-	CodeBlockData // Populated if Type is CodeBlock
-	LinkData      // Populated if Type is Link
-	TableCellData // Populated if Type is TableCell
-
-	content []byte // Markdown content of the block nodes
-	open    bool   // Specifies an open block node that has not been finished to process yet
-}
-
-// NewNode allocates a node of a specified type.
-func NewNode(typ NodeType) *Node {
-	return &Node{
-		Type: typ,
-		open: true,
-	}
-}
-
-func (n *Node) String() string {
-	ellipsis := ""
-	snippet := n.Literal
-	if len(snippet) > 16 {
-		snippet = snippet[:16]
-		ellipsis = "..."
-	}
-	return fmt.Sprintf("%s: '%s%s'", n.Type, snippet, ellipsis)
-}
-
-// Unlink removes node 'n' from the tree.
-// It panics if the node is nil.
-func (n *Node) Unlink() {
-	if n.Prev != nil {
-		n.Prev.Next = n.Next
-	} else if n.Parent != nil {
-		n.Parent.FirstChild = n.Next
-	}
-	if n.Next != nil {
-		n.Next.Prev = n.Prev
-	} else if n.Parent != nil {
-		n.Parent.LastChild = n.Prev
-	}
-	n.Parent = nil
-	n.Next = nil
-	n.Prev = nil
-}
-
-// AppendChild adds a node 'child' as a child of 'n'.
-// It panics if either node is nil.
-func (n *Node) AppendChild(child *Node) {
-	child.Unlink()
-	child.Parent = n
-	if n.LastChild != nil {
-		n.LastChild.Next = child
-		child.Prev = n.LastChild
-		n.LastChild = child
-	} else {
-		n.FirstChild = child
-		n.LastChild = child
-	}
-}
-
-// InsertBefore inserts 'sibling' immediately before 'n'.
-// It panics if either node is nil.
-func (n *Node) InsertBefore(sibling *Node) {
-	sibling.Unlink()
-	sibling.Prev = n.Prev
-	if sibling.Prev != nil {
-		sibling.Prev.Next = sibling
-	}
-	sibling.Next = n
-	n.Prev = sibling
-	sibling.Parent = n.Parent
-	if sibling.Prev == nil {
-		sibling.Parent.FirstChild = sibling
-	}
-}
-
-// IsContainer returns true if 'n' can contain children.
-func (n *Node) IsContainer() bool {
-	switch n.Type {
-	case Document:
-		fallthrough
-	case BlockQuote:
-		fallthrough
-	case List:
-		fallthrough
-	case Item:
-		fallthrough
-	case Paragraph:
-		fallthrough
-	case Heading:
-		fallthrough
-	case Emph:
-		fallthrough
-	case Strong:
-		fallthrough
-	case Del:
-		fallthrough
-	case Link:
-		fallthrough
-	case Image:
-		fallthrough
-	case Table:
-		fallthrough
-	case TableHead:
-		fallthrough
-	case TableBody:
-		fallthrough
-	case TableRow:
-		fallthrough
-	case TableCell:
-		return true
-	default:
-		return false
-	}
-}
-
-// IsLeaf returns true if 'n' is a leaf node.
-func (n *Node) IsLeaf() bool {
-	return !n.IsContainer()
-}
-
-func (n *Node) canContain(t NodeType) bool {
-	if n.Type == List {
-		return t == Item
-	}
-	if n.Type == Document || n.Type == BlockQuote || n.Type == Item {
-		return t != Item
-	}
-	if n.Type == Table {
-		return t == TableHead || t == TableBody
-	}
-	if n.Type == TableHead || n.Type == TableBody {
-		return t == TableRow
-	}
-	if n.Type == TableRow {
-		return t == TableCell
-	}
-	return false
-}
-
-// WalkStatus allows NodeVisitor to have some control over the tree traversal.
-// It is returned from NodeVisitor and different values allow Node.Walk to
-// decide which node to go to next.
-type WalkStatus int
-
-const (
-	// GoToNext is the default traversal of every node.
-	GoToNext WalkStatus = iota
-	// SkipChildren tells walker to skip all children of current node.
-	SkipChildren
-	// Terminate tells walker to terminate the traversal.
-	Terminate
-)
-
-// NodeVisitor is a callback to be called when traversing the syntax tree.
-// Called twice for every node: once with entering=true when the branch is
-// first visited, then with entering=false after all the children are done.
-type NodeVisitor func(node *Node, entering bool) WalkStatus
-
-// Walk is a convenience method that instantiates a walker and starts a
-// traversal of subtree rooted at n.
-func (n *Node) Walk(visitor NodeVisitor) {
-	w := newNodeWalker(n)
-	for w.current != nil {
-		status := visitor(w.current, w.entering)
-		switch status {
-		case GoToNext:
-			w.next()
-		case SkipChildren:
-			w.entering = false
-			w.next()
-		case Terminate:
-			return
-		}
-	}
-}
-
-type nodeWalker struct {
-	current  *Node
-	root     *Node
-	entering bool
-}
-
-func newNodeWalker(root *Node) *nodeWalker {
-	return &nodeWalker{
-		current:  root,
-		root:     root,
-		entering: true,
-	}
-}
-
-func (nw *nodeWalker) next() {
-	if (!nw.current.IsContainer() || !nw.entering) && nw.current == nw.root {
-		nw.current = nil
-		return
-	}
-	if nw.entering && nw.current.IsContainer() {
-		if nw.current.FirstChild != nil {
-			nw.current = nw.current.FirstChild
-			nw.entering = true
-		} else {
-			nw.entering = false
-		}
-	} else if nw.current.Next == nil {
-		nw.current = nw.current.Parent
-		nw.entering = false
-	} else {
-		nw.current = nw.current.Next
-		nw.entering = true
-	}
-}
-
-func dump(ast *Node) {
-	fmt.Println(dumpString(ast))
-}
-
-func dumpR(ast *Node, depth int) string {
-	if ast == nil {
-		return ""
-	}
-	indent := bytes.Repeat([]byte("\t"), depth)
-	content := ast.Literal
-	if content == nil {
-		content = ast.content
-	}
-	result := fmt.Sprintf("%s%s(%q)\n", indent, ast.Type, content)
-	for n := ast.FirstChild; n != nil; n = n.Next {
-		result += dumpR(n, depth+1)
-	}
-	return result
-}
-
-func dumpString(ast *Node) string {
-	return dumpR(ast, 0)
-}

vendor/github.com/russross/blackfriday/v2/smartypants.go

@@ -1,457 +0,0 @@
-//
-// Blackfriday Markdown Processor
-// Available at http://github.com/russross/blackfriday
-//
-// Copyright © 2011 Russ Ross <russ@russross.com>.
-// Distributed under the Simplified BSD License.
-// See README.md for details.
-//
-
-//
-//
-// SmartyPants rendering
-//
-//
-
-package blackfriday
-
-import (
-	"bytes"
-	"io"
-)
-
-// SPRenderer is a struct containing state of a Smartypants renderer.
-type SPRenderer struct {
-	inSingleQuote bool
-	inDoubleQuote bool
-	callbacks     [256]smartCallback
-}
-
-func wordBoundary(c byte) bool {
-	return c == 0 || isspace(c) || ispunct(c)
-}
-
-func tolower(c byte) byte {
-	if c >= 'A' && c <= 'Z' {
-		return c - 'A' + 'a'
-	}
-	return c
-}
-
-func isdigit(c byte) bool {
-	return c >= '0' && c <= '9'
-}
-
-func smartQuoteHelper(out *bytes.Buffer, previousChar byte, nextChar byte, quote byte, isOpen *bool, addNBSP bool) bool {
-	// edge of the buffer is likely to be a tag that we don't get to see,
-	// so we treat it like text sometimes
-
-	// enumerate all sixteen possibilities for (previousChar, nextChar)
-	// each can be one of {0, space, punct, other}
-	switch {
-	case previousChar == 0 && nextChar == 0:
-		// context is not any help here, so toggle
-		*isOpen = !*isOpen
-	case isspace(previousChar) && nextChar == 0:
-		// [ "] might be [ "<code>foo...]
-		*isOpen = true
-	case ispunct(previousChar) && nextChar == 0:
-		// [!"] hmm... could be [Run!"] or [("<code>...]
-		*isOpen = false
-	case /* isnormal(previousChar) && */ nextChar == 0:
-		// [a"] is probably a close
-		*isOpen = false
-	case previousChar == 0 && isspace(nextChar):
-		// [" ] might be [...foo</code>" ]
-		*isOpen = false
-	case isspace(previousChar) && isspace(nextChar):
-		// [ " ] context is not any help here, so toggle
-		*isOpen = !*isOpen
-	case ispunct(previousChar) && isspace(nextChar):
-		// [!" ] is probably a close
-		*isOpen = false
-	case /* isnormal(previousChar) && */ isspace(nextChar):
-		// [a" ] this is one of the easy cases
-		*isOpen = false
-	case previousChar == 0 && ispunct(nextChar):
-		// ["!] hmm... could be ["$1.95] or [</code>"!...]
-		*isOpen = false
-	case isspace(previousChar) && ispunct(nextChar):
-		// [ "!] looks more like [ "$1.95]
-		*isOpen = true
-	case ispunct(previousChar) && ispunct(nextChar):
-		// [!"!] context is not any help here, so toggle
-		*isOpen = !*isOpen
-	case /* isnormal(previousChar) && */ ispunct(nextChar):
-		// [a"!] is probably a close
-		*isOpen = false
-	case previousChar == 0 /* && isnormal(nextChar) */ :
-		// ["a] is probably an open
-		*isOpen = true
-	case isspace(previousChar) /* && isnormal(nextChar) */ :
-		// [ "a] this is one of the easy cases
-		*isOpen = true
-	case ispunct(previousChar) /* && isnormal(nextChar) */ :
-		// [!"a] is probably an open
-		*isOpen = true
-	default:
-		// [a'b] maybe a contraction?
-		*isOpen = false
-	}
-
-	// Note that with the limited lookahead, this non-breaking
-	// space will also be appended to single double quotes.
-	if addNBSP && !*isOpen {
-		out.WriteString("&nbsp;")
-	}
-
-	out.WriteByte('&')
-	if *isOpen {
-		out.WriteByte('l')
-	} else {
-		out.WriteByte('r')
-	}
-	out.WriteByte(quote)
-	out.WriteString("quo;")
-
-	if addNBSP && *isOpen {
-		out.WriteString("&nbsp;")
-	}
-
-	return true
-}
-
-func (r *SPRenderer) smartSingleQuote(out *bytes.Buffer, previousChar byte, text []byte) int {
-	if len(text) >= 2 {
-		t1 := tolower(text[1])
-
-		if t1 == '\'' {
-			nextChar := byte(0)
-			if len(text) >= 3 {
-				nextChar = text[2]
-			}
-			if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote, false) {
-				return 1
-			}
-		}
-
-		if (t1 == 's' || t1 == 't' || t1 == 'm' || t1 == 'd') && (len(text) < 3 || wordBoundary(text[2])) {
-			out.WriteString("&rsquo;")
-			return 0
-		}
-
-		if len(text) >= 3 {
-			t2 := tolower(text[2])
-
-			if ((t1 == 'r' && t2 == 'e') || (t1 == 'l' && t2 == 'l') || (t1 == 'v' && t2 == 'e')) &&
-				(len(text) < 4 || wordBoundary(text[3])) {
-				out.WriteString("&rsquo;")
-				return 0
-			}
-		}
-	}
-
-	nextChar := byte(0)
-	if len(text) > 1 {
-		nextChar = text[1]
-	}
-	if smartQuoteHelper(out, previousChar, nextChar, 's', &r.inSingleQuote, false) {
-		return 0
-	}
-
-	out.WriteByte(text[0])
-	return 0
-}
-
-func (r *SPRenderer) smartParens(out *bytes.Buffer, previousChar byte, text []byte) int {
-	if len(text) >= 3 {
-		t1 := tolower(text[1])
-		t2 := tolower(text[2])
-
-		if t1 == 'c' && t2 == ')' {
-			out.WriteString("&copy;")
-			return 2
-		}
-
-		if t1 == 'r' && t2 == ')' {
-			out.WriteString("&reg;")
-			return 2
-		}
-
-		if len(text) >= 4 && t1 == 't' && t2 == 'm' && text[3] == ')' {
-			out.WriteString("&trade;")
-			return 3
-		}
-	}
-
-	out.WriteByte(text[0])
-	return 0
-}
-
-func (r *SPRenderer) smartDash(out *bytes.Buffer, previousChar byte, text []byte) int {
-	if len(text) >= 2 {
-		if text[1] == '-' {
-			out.WriteString("&mdash;")
-			return 1
-		}
-
-		if wordBoundary(previousChar) && wordBoundary(text[1]) {
-			out.WriteString("&ndash;")
-			return 0
-		}
-	}
-
-	out.WriteByte(text[0])
-	return 0
-}
-
-func (r *SPRenderer) smartDashLatex(out *bytes.Buffer, previousChar byte, text []byte) int {
-	if len(text) >= 3 && text[1] == '-' && text[2] == '-' {
-		out.WriteString("&mdash;")
-		return 2
-	}
-	if len(text) >= 2 && text[1] == '-' {
-		out.WriteString("&ndash;")
-		return 1
-	}
-
-	out.WriteByte(text[0])
-	return 0
-}
-
-func (r *SPRenderer) smartAmpVariant(out *bytes.Buffer, previousChar byte, text []byte, quote byte, addNBSP bool) int {
-	if bytes.HasPrefix(text, []byte("&quot;")) {
-		nextChar := byte(0)
-		if len(text) >= 7 {
-			nextChar = text[6]
-		}
-		if smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote, addNBSP) {
-			return 5
-		}
-	}
-
-	if bytes.HasPrefix(text, []byte("&#0;")) {
-		return 3
-	}
-
-	out.WriteByte('&')
-	return 0
-}
-
-func (r *SPRenderer) smartAmp(angledQuotes, addNBSP bool) func(*bytes.Buffer, byte, []byte) int {
-	var quote byte = 'd'
-	if angledQuotes {
-		quote = 'a'
-	}
-
-	return func(out *bytes.Buffer, previousChar byte, text []byte) int {
-		return r.smartAmpVariant(out, previousChar, text, quote, addNBSP)
-	}
-}
-
-func (r *SPRenderer) smartPeriod(out *bytes.Buffer, previousChar byte, text []byte) int {
-	if len(text) >= 3 && text[1] == '.' && text[2] == '.' {
-		out.WriteString("&hellip;")
-		return 2
-	}
-
-	if len(text) >= 5 && text[1] == ' ' && text[2] == '.' && text[3] == ' ' && text[4] == '.' {
-		out.WriteString("&hellip;")
-		return 4
-	}
-
-	out.WriteByte(text[0])
-	return 0
-}
-
-func (r *SPRenderer) smartBacktick(out *bytes.Buffer, previousChar byte, text []byte) int {
-	if len(text) >= 2 && text[1] == '`' {
-		nextChar := byte(0)
-		if len(text) >= 3 {
-			nextChar = text[2]
-		}
-		if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote, false) {
-			return 1
-		}
-	}
-
-	out.WriteByte(text[0])
-	return 0
-}
-
-func (r *SPRenderer) smartNumberGeneric(out *bytes.Buffer, previousChar byte, text []byte) int {
-	if wordBoundary(previousChar) && previousChar != '/' && len(text) >= 3 {
-		// is it of the form digits/digits(word boundary)?, i.e., \d+/\d+\b
-		// note: check for regular slash (/) or fraction slash (⁄, 0x2044, or 0xe2 81 84 in utf-8)
-		//       and avoid changing dates like 1/23/2005 into fractions.
-		numEnd := 0
-		for len(text) > numEnd && isdigit(text[numEnd]) {
-			numEnd++
-		}
-		if numEnd == 0 {
-			out.WriteByte(text[0])
-			return 0
-		}
-		denStart := numEnd + 1
-		if len(text) > numEnd+3 && text[numEnd] == 0xe2 && text[numEnd+1] == 0x81 && text[numEnd+2] == 0x84 {
-			denStart = numEnd + 3
-		} else if len(text) < numEnd+2 || text[numEnd] != '/' {
-			out.WriteByte(text[0])
-			return 0
-		}
-		denEnd := denStart
-		for len(text) > denEnd && isdigit(text[denEnd]) {
-			denEnd++
-		}
-		if denEnd == denStart {
-			out.WriteByte(text[0])
-			return 0
-		}
-		if len(text) == denEnd || wordBoundary(text[denEnd]) && text[denEnd] != '/' {
-			out.WriteString("<sup>")
-			out.Write(text[:numEnd])
-			out.WriteString("</sup>&frasl;<sub>")
-			out.Write(text[denStart:denEnd])
-			out.WriteString("</sub>")
-			return denEnd - 1
-		}
-	}
-
-	out.WriteByte(text[0])
-	return 0
-}
-
-func (r *SPRenderer) smartNumber(out *bytes.Buffer, previousChar byte, text []byte) int {
-	if wordBoundary(previousChar) && previousChar != '/' && len(text) >= 3 {
-		if text[0] == '1' && text[1] == '/' && text[2] == '2' {
-			if len(text) < 4 || wordBoundary(text[3]) && text[3] != '/' {
-				out.WriteString("&frac12;")
-				return 2
-			}
-		}
-
-		if text[0] == '1' && text[1] == '/' && text[2] == '4' {
-			if len(text) < 4 || wordBoundary(text[3]) && text[3] != '/' || (len(text) >= 5 && tolower(text[3]) == 't' && tolower(text[4]) == 'h') {
-				out.WriteString("&frac14;")
-				return 2
-			}
-		}
-
-		if text[0] == '3' && text[1] == '/' && text[2] == '4' {
-			if len(text) < 4 || wordBoundary(text[3]) && text[3] != '/' || (len(text) >= 6 && tolower(text[3]) == 't' && tolower(text[4]) == 'h' && tolower(text[5]) == 's') {
-				out.WriteString("&frac34;")
-				return 2
-			}
-		}
-	}
-
-	out.WriteByte(text[0])
-	return 0
-}
-
-func (r *SPRenderer) smartDoubleQuoteVariant(out *bytes.Buffer, previousChar byte, text []byte, quote byte) int {
-	nextChar := byte(0)
-	if len(text) > 1 {
-		nextChar = text[1]
-	}
-	if !smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote, false) {
-		out.WriteString("&quot;")
-	}
-
-	return 0
-}
-
-func (r *SPRenderer) smartDoubleQuote(out *bytes.Buffer, previousChar byte, text []byte) int {
-	return r.smartDoubleQuoteVariant(out, previousChar, text, 'd')
-}
-
-func (r *SPRenderer) smartAngledDoubleQuote(out *bytes.Buffer, previousChar byte, text []byte) int {
-	return r.smartDoubleQuoteVariant(out, previousChar, text, 'a')
-}
-
-func (r *SPRenderer) smartLeftAngle(out *bytes.Buffer, previousChar byte, text []byte) int {
-	i := 0
-
-	for i < len(text) && text[i] != '>' {
-		i++
-	}
-
-	out.Write(text[:i+1])
-	return i
-}
-
-type smartCallback func(out *bytes.Buffer, previousChar byte, text []byte) int
-
-// NewSmartypantsRenderer constructs a Smartypants renderer object.
-func NewSmartypantsRenderer(flags HTMLFlags) *SPRenderer {
-	var (
-		r SPRenderer
-
-		smartAmpAngled      = r.smartAmp(true, false)
-		smartAmpAngledNBSP  = r.smartAmp(true, true)
-		smartAmpRegular     = r.smartAmp(false, false)
-		smartAmpRegularNBSP = r.smartAmp(false, true)
-
-		addNBSP = flags&SmartypantsQuotesNBSP != 0
-	)
-
-	if flags&SmartypantsAngledQuotes == 0 {
-		r.callbacks['"'] = r.smartDoubleQuote
-		if !addNBSP {
-			r.callbacks['&'] = smartAmpRegular
-		} else {
-			r.callbacks['&'] = smartAmpRegularNBSP
-		}
-	} else {
-		r.callbacks['"'] = r.smartAngledDoubleQuote
-		if !addNBSP {
-			r.callbacks['&'] = smartAmpAngled
-		} else {
-			r.callbacks['&'] = smartAmpAngledNBSP
-		}
-	}
-	r.callbacks['\''] = r.smartSingleQuote
-	r.callbacks['('] = r.smartParens
-	if flags&SmartypantsDashes != 0 {
-		if flags&SmartypantsLatexDashes == 0 {
-			r.callbacks['-'] = r.smartDash
-		} else {
-			r.callbacks['-'] = r.smartDashLatex
-		}
-	}
-	r.callbacks['.'] = r.smartPeriod
-	if flags&SmartypantsFractions == 0 {
-		r.callbacks['1'] = r.smartNumber
-		r.callbacks['3'] = r.smartNumber
-	} else {
-		for ch := '1'; ch <= '9'; ch++ {
-			r.callbacks[ch] = r.smartNumberGeneric
-		}
-	}
-	r.callbacks['<'] = r.smartLeftAngle
-	r.callbacks['`'] = r.smartBacktick
-	return &r
-}
-
-// Process is the entry point of the Smartypants renderer.
-func (r *SPRenderer) Process(w io.Writer, text []byte) {
-	mark := 0
-	for i := 0; i < len(text); i++ {
-		if action := r.callbacks[text[i]]; action != nil {
-			if i > mark {
-				w.Write(text[mark:i])
-			}
-			previousChar := byte(0)
-			if i > 0 {
-				previousChar = text[i-1]
-			}
-			var tmp bytes.Buffer
-			i += action(&tmp, previousChar, text[i:])
-			w.Write(tmp.Bytes())
-			mark = i + 1
-		}
-	}
-	if mark < len(text) {
-		w.Write(text[mark:])
-	}
-}

vendor/github.com/yuin/goldmark/.gitignore

@@ -0,0 +1,19 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, build with `go test -c`
+*.test
+*.pprof
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+.DS_Store
+fuzz/corpus
+fuzz/crashers
+fuzz/suppressions
+fuzz/fuzz-fuzz.zip

vendor/github.com/yuin/goldmark/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2019 Yusuke Inuzuka
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/yuin/goldmark/Makefile

@@ -0,0 +1,10 @@
+.PHONY: test fuzz
+
+test:
+	go test -coverprofile=profile.out -coverpkg=github.com/yuin/goldmark,github.com/yuin/goldmark/ast,github.com/yuin/goldmark/extension,github.com/yuin/goldmark/extension/ast,github.com/yuin/goldmark/parser,github.com/yuin/goldmark/renderer,github.com/yuin/goldmark/renderer/html,github.com/yuin/goldmark/text,github.com/yuin/goldmark/util ./...
+
+cov: test
+	go tool cover -html=profile.out
+
+fuzz:
+	cd ./fuzz && go test -fuzz=Fuzz

vendor/github.com/yuin/goldmark/README.md

@@ -0,0 +1,513 @@
+goldmark
+==========================================
+
+[![https://pkg.go.dev/github.com/yuin/goldmark](https://pkg.go.dev/badge/github.com/yuin/goldmark.svg)](https://pkg.go.dev/github.com/yuin/goldmark)
+[![https://github.com/yuin/goldmark/actions?query=workflow:test](https://github.com/yuin/goldmark/workflows/test/badge.svg?branch=master&event=push)](https://github.com/yuin/goldmark/actions?query=workflow:test)
+[![https://coveralls.io/github/yuin/goldmark](https://coveralls.io/repos/github/yuin/goldmark/badge.svg?branch=master)](https://coveralls.io/github/yuin/goldmark)
+[![https://goreportcard.com/report/github.com/yuin/goldmark](https://goreportcard.com/badge/github.com/yuin/goldmark)](https://goreportcard.com/report/github.com/yuin/goldmark)
+
+> A Markdown parser written in Go. Easy to extend, standards-compliant, well-structured.
+
+goldmark is compliant with CommonMark 0.30.
+
+Motivation
+----------------------
+I needed a Markdown parser for Go that satisfies the following requirements:
+
+- Easy to extend.
+    - Markdown is poor in document expressions compared to other light markup languages such as reStructuredText.
+    - We have extensions to the Markdown syntax, e.g. PHP Markdown Extra, GitHub Flavored Markdown.
+- Standards-compliant.
+    - Markdown has many dialects.
+    - GitHub-Flavored Markdown is widely used and is based upon CommonMark, effectively mooting the question of whether or not CommonMark is an ideal specification.
+        - CommonMark is complicated and hard to implement.
+- Well-structured.
+    - AST-based; preserves source position of nodes.
+- Written in pure Go.
+
+[golang-commonmark](https://gitlab.com/golang-commonmark/markdown) may be a good choice, but it seems to be a copy of [markdown-it](https://github.com/markdown-it).
+
+[blackfriday.v2](https://github.com/russross/blackfriday/tree/v2) is a fast and widely-used implementation, but is not CommonMark-compliant and cannot be extended from outside of the package, since its AST uses structs instead of interfaces.
+
+Furthermore, its behavior differs from other implementations in some cases, especially regarding lists: [Deep nested lists don't output correctly #329](https://github.com/russross/blackfriday/issues/329), [List block cannot have a second line #244](https://github.com/russross/blackfriday/issues/244), etc.
+
+This behavior sometimes causes problems. If you migrate your Markdown text from GitHub to blackfriday-based wikis, many lists will immediately be broken.
+
+As mentioned above, CommonMark is complicated and hard to implement, so Markdown parsers based on CommonMark are few and far between.
+
+Features
+----------------------
+
+- **Standards-compliant.**  goldmark is fully compliant with the latest [CommonMark](https://commonmark.org/) specification.
+- **Extensible.**  Do you want to add a `@username` mention syntax to Markdown?
+  You can easily do so in goldmark. You can add your AST nodes,
+  parsers for block-level elements, parsers for inline-level elements,
+  transformers for paragraphs, transformers for the whole AST structure, and
+  renderers.
+- **Performance.**  goldmark's performance is on par with that of cmark,
+  the CommonMark reference implementation written in C.
+- **Robust.**  goldmark is tested with `go test --fuzz`.
+- **Built-in extensions.**  goldmark ships with common extensions like tables, strikethrough,
+  task lists, and definition lists.
+- **Depends only on standard libraries.**
+
+Installation
+----------------------
+```bash
+$ go get github.com/yuin/goldmark
+```
+
+
+Usage
+----------------------
+Import packages:
+
+```go
+import (
+    "bytes"
+    "github.com/yuin/goldmark"
+)
+```
+
+
+Convert Markdown documents with the CommonMark-compliant mode:
+
+```go
+var buf bytes.Buffer
+if err := goldmark.Convert(source, &buf); err != nil {
+  panic(err)
+}
+```
+
+With options
+------------------------------
+
+```go
+var buf bytes.Buffer
+if err := goldmark.Convert(source, &buf, parser.WithContext(ctx)); err != nil {
+  panic(err)
+}
+```
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `parser.WithContext` | A `parser.Context` | Context for the parsing phase. |
+
+Context options
+----------------------
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `parser.WithIDs` | A `parser.IDs` | `IDs` allows you to change logics that are related to element id(ex: Auto heading id generation). |
+
+
+Custom parser and renderer
+--------------------------
+```go
+import (
+    "bytes"
+    "github.com/yuin/goldmark"
+    "github.com/yuin/goldmark/extension"
+    "github.com/yuin/goldmark/parser"
+    "github.com/yuin/goldmark/renderer/html"
+)
+
+md := goldmark.New(
+          goldmark.WithExtensions(extension.GFM),
+          goldmark.WithParserOptions(
+              parser.WithAutoHeadingID(),
+          ),
+          goldmark.WithRendererOptions(
+              html.WithHardWraps(),
+              html.WithXHTML(),
+          ),
+      )
+var buf bytes.Buffer
+if err := md.Convert(source, &buf); err != nil {
+    panic(err)
+}
+```
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `goldmark.WithParser` | `parser.Parser`  | This option must be passed before `goldmark.WithParserOptions` and `goldmark.WithExtensions` |
+| `goldmark.WithRenderer` | `renderer.Renderer`  | This option must be passed before `goldmark.WithRendererOptions` and `goldmark.WithExtensions`  |
+| `goldmark.WithParserOptions` | `...parser.Option`  |  |
+| `goldmark.WithRendererOptions` | `...renderer.Option` |  |
+| `goldmark.WithExtensions` | `...goldmark.Extender`  |  |
+
+Parser and Renderer options
+------------------------------
+
+### Parser options
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `parser.WithBlockParsers` | A `util.PrioritizedSlice` whose elements are `parser.BlockParser` | Parsers for parsing block level elements. |
+| `parser.WithInlineParsers` | A `util.PrioritizedSlice` whose elements are `parser.InlineParser` | Parsers for parsing inline level elements. |
+| `parser.WithParagraphTransformers` | A `util.PrioritizedSlice` whose elements are `parser.ParagraphTransformer` | Transformers for transforming paragraph nodes. |
+| `parser.WithASTTransformers` | A `util.PrioritizedSlice` whose elements are `parser.ASTTransformer` | Transformers for transforming an AST. |
+| `parser.WithAutoHeadingID` | `-` | Enables auto heading ids. |
+| `parser.WithAttribute` | `-` | Enables custom attributes. Currently only headings supports attributes. |
+
+### HTML Renderer options
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `html.WithWriter` | `html.Writer` | `html.Writer` for writing contents to an `io.Writer`. |
+| `html.WithHardWraps` | `-` | Render newlines as `<br>`.|
+| `html.WithXHTML` | `-` | Render as XHTML. |
+| `html.WithUnsafe` | `-` | By default, goldmark does not render raw HTML or potentially dangerous links. With this option, goldmark renders such content as written. |
+
+### Built-in extensions
+
+- `extension.Table`
+    - [GitHub Flavored Markdown: Tables](https://github.github.com/gfm/#tables-extension-)
+- `extension.Strikethrough`
+    - [GitHub Flavored Markdown: Strikethrough](https://github.github.com/gfm/#strikethrough-extension-)
+- `extension.Linkify`
+    - [GitHub Flavored Markdown: Autolinks](https://github.github.com/gfm/#autolinks-extension-)
+- `extension.TaskList`
+    - [GitHub Flavored Markdown: Task list items](https://github.github.com/gfm/#task-list-items-extension-)
+- `extension.GFM`
+    - This extension enables Table, Strikethrough, Linkify and TaskList.
+    - This extension does not filter tags defined in [6.11: Disallowed Raw HTML (extension)](https://github.github.com/gfm/#disallowed-raw-html-extension-).
+    If you need to filter HTML tags, see [Security](#security).
+    - If you need to parse github emojis, you can use [goldmark-emoji](https://github.com/yuin/goldmark-emoji) extension.
+- `extension.DefinitionList`
+    - [PHP Markdown Extra: Definition lists](https://michelf.ca/projects/php-markdown/extra/#def-list)
+- `extension.Footnote`
+    - [PHP Markdown Extra: Footnotes](https://michelf.ca/projects/php-markdown/extra/#footnotes)
+- `extension.Typographer`
+    - This extension substitutes punctuations with typographic entities like [smartypants](https://daringfireball.net/projects/smartypants/).
+- `extension.CJK`
+    - This extension is a shortcut for CJK related functionalities.
+
+### Attributes
+The `parser.WithAttribute` option allows you to define attributes on some elements.
+
+Currently only headings support attributes.
+
+**Attributes are being discussed in the
+[CommonMark forum](https://talk.commonmark.org/t/consistent-attribute-syntax/272).
+This syntax may possibly change in the future.**
+
+
+#### Headings
+
+```
+## heading ## {#id .className attrName=attrValue class="class1 class2"}
+
+## heading {#id .className attrName=attrValue class="class1 class2"}
+```
+
+```
+heading {#id .className attrName=attrValue}
+============
+```
+
+### Table extension
+The Table extension implements [Table(extension)](https://github.github.com/gfm/#tables-extension-), as
+defined in [GitHub Flavored Markdown Spec](https://github.github.com/gfm/).
+
+Specs are defined for XHTML, so specs use some deprecated attributes for HTML5.
+
+You can override alignment rendering method via options.
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `extension.WithTableCellAlignMethod` | `extension.TableCellAlignMethod` | Option indicates how are table cells aligned. |
+
+### Typographer extension
+
+The Typographer extension translates plain ASCII punctuation characters into typographic-punctuation HTML entities.
+
+Default substitutions are:
+
+| Punctuation | Default entity |
+| ------------ | ---------- |
+| `'`           | `&lsquo;`, `&rsquo;` |
+| `"`           | `&ldquo;`, `&rdquo;` |
+| `--`       | `&ndash;` |
+| `---`      | `&mdash;` |
+| `...`      | `&hellip;` |
+| `<<`       | `&laquo;` |
+| `>>`       | `&raquo;` |
+
+You can override the default substitutions via `extensions.WithTypographicSubstitutions`:
+
+```go
+markdown := goldmark.New(
+    goldmark.WithExtensions(
+        extension.NewTypographer(
+            extension.WithTypographicSubstitutions(extension.TypographicSubstitutions{
+                extension.LeftSingleQuote:  []byte("&sbquo;"),
+                extension.RightSingleQuote: nil, // nil disables a substitution
+            }),
+        ),
+    ),
+)
+```
+
+### Linkify extension
+
+The Linkify extension implements [Autolinks(extension)](https://github.github.com/gfm/#autolinks-extension-), as
+defined in [GitHub Flavored Markdown Spec](https://github.github.com/gfm/).
+
+Since the spec does not define details about URLs, there are numerous ambiguous cases.
+
+You can override autolinking patterns via options.
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `extension.WithLinkifyAllowedProtocols` | `[][]byte` | List of allowed protocols such as `[][]byte{ []byte("http:") }` |
+| `extension.WithLinkifyURLRegexp` | `*regexp.Regexp` | Regexp that defines URLs, including protocols |
+| `extension.WithLinkifyWWWRegexp` | `*regexp.Regexp` | Regexp that defines URL starting with `www.`. This pattern corresponds to [the extended www autolink](https://github.github.com/gfm/#extended-www-autolink) |
+| `extension.WithLinkifyEmailRegexp` | `*regexp.Regexp` | Regexp that defines email addresses` |
+
+Example, using [xurls](https://github.com/mvdan/xurls):
+
+```go
+import "mvdan.cc/xurls/v2"
+
+markdown := goldmark.New(
+    goldmark.WithRendererOptions(
+        html.WithXHTML(),
+        html.WithUnsafe(),
+    ),
+    goldmark.WithExtensions(
+        extension.NewLinkify(
+            extension.WithLinkifyAllowedProtocols([][]byte{
+                []byte("http:"),
+                []byte("https:"),
+            }),
+            extension.WithLinkifyURLRegexp(
+                xurls.Strict,
+            ),
+        ),
+    ),
+)
+```
+
+### Footnotes extension
+
+The Footnote extension implements [PHP Markdown Extra: Footnotes](https://michelf.ca/projects/php-markdown/extra/#footnotes).
+
+This extension has some options:
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `extension.WithFootnoteIDPrefix` | `[]byte` |  a prefix for the id attributes.|
+| `extension.WithFootnoteIDPrefixFunction` | `func(gast.Node) []byte` |  a function that determines the id attribute for given Node.|
+| `extension.WithFootnoteLinkTitle` | `[]byte` |  an optional title attribute for footnote links.|
+| `extension.WithFootnoteBacklinkTitle` | `[]byte` |  an optional title attribute for footnote backlinks. |
+| `extension.WithFootnoteLinkClass` | `[]byte` |  a class for footnote links. This defaults to `footnote-ref`. |
+| `extension.WithFootnoteBacklinkClass` | `[]byte` |  a class for footnote backlinks. This defaults to `footnote-backref`. |
+| `extension.WithFootnoteBacklinkHTML` | `[]byte` |  a class for footnote backlinks. This defaults to `&#x21a9;&#xfe0e;`. |
+
+Some options can have special substitutions. Occurrences of “^^” in the string will be replaced by the corresponding footnote number in the HTML output. Occurrences of “%%” will be replaced by a number for the reference (footnotes can have multiple references).
+
+`extension.WithFootnoteIDPrefix` and `extension.WithFootnoteIDPrefixFunction` are useful if you have multiple Markdown documents displayed inside one HTML document to avoid footnote ids to clash each other.
+
+`extension.WithFootnoteIDPrefix` sets fixed id prefix, so you may write codes like the following:
+
+```go
+for _, path := range files {
+    source := readAll(path)
+    prefix := getPrefix(path)
+
+    markdown := goldmark.New(
+        goldmark.WithExtensions(
+            NewFootnote(
+                WithFootnoteIDPrefix([]byte(path)),
+            ),
+        ),
+    )
+    var b bytes.Buffer
+    err := markdown.Convert(source, &b)
+    if err != nil {
+        t.Error(err.Error())
+    }
+}
+```
+
+`extension.WithFootnoteIDPrefixFunction` determines an id prefix by calling given function, so you may write codes like the following:
+
+```go
+markdown := goldmark.New(
+    goldmark.WithExtensions(
+        NewFootnote(
+                WithFootnoteIDPrefixFunction(func(n gast.Node) []byte {
+                    v, ok := n.OwnerDocument().Meta()["footnote-prefix"]
+                    if ok {
+                        return util.StringToReadOnlyBytes(v.(string))
+                    }
+                    return nil
+                }),
+        ),
+    ),
+)
+
+for _, path := range files {
+    source := readAll(path)
+    var b bytes.Buffer
+
+    doc := markdown.Parser().Parse(text.NewReader(source))
+    doc.Meta()["footnote-prefix"] = getPrefix(path)
+    err := markdown.Renderer().Render(&b, source, doc)
+}
+```
+
+You can use [goldmark-meta](https://github.com/yuin/goldmark-meta) to define a id prefix in the markdown document:
+
+
+```markdown
+---
+title: document title
+slug: article1
+footnote-prefix: article1
+---
+
+# My article
+
+```
+
+### CJK extension
+CommonMark gives compatibilities a high priority and original markdown was designed by westerners. So CommonMark lacks considerations for languages like CJK.
+
+This extension provides additional options for CJK users.
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `extension.WithEastAsianLineBreaks` | `-` | Soft line breaks are rendered as a newline. Some asian users will see it as an unnecessary space. With this option, soft line breaks between east asian wide characters will be ignored. |
+| `extension.WithEscapedSpace` | `-` | Without spaces around an emphasis started with east asian punctuations, it is not interpreted as an emphasis(as defined in CommonMark spec). With this option, you can avoid this inconvenient behavior by putting 'not rendered' spaces around an emphasis like `太郎は\ **「こんにちわ」**\ といった`. |
+
+ 
+Security
+--------------------
+By default, goldmark does not render raw HTML or potentially-dangerous URLs.
+If you need to gain more control over untrusted contents, it is recommended that you
+use an HTML sanitizer such as [bluemonday](https://github.com/microcosm-cc/bluemonday).
+
+Benchmark
+--------------------
+You can run this benchmark in the `_benchmark` directory.
+
+### against other golang libraries
+
+blackfriday v2 seems to be the fastest, but as it is not CommonMark compliant, its performance cannot be directly compared to that of the CommonMark-compliant libraries.
+
+goldmark, meanwhile, builds a clean, extensible AST structure, achieves full compliance with
+CommonMark, and consumes less memory, all while being reasonably fast.
+
+- MBP 2019 13″(i5, 16GB), Go1.17
+
+```
+BenchmarkMarkdown/Blackfriday-v2-8                   302           3743747 ns/op         3290445 B/op      20050 allocs/op
+BenchmarkMarkdown/GoldMark-8                         280           4200974 ns/op         2559738 B/op      13435 allocs/op
+BenchmarkMarkdown/CommonMark-8                       226           5283686 ns/op         2702490 B/op      20792 allocs/op
+BenchmarkMarkdown/Lute-8                              12          92652857 ns/op        10602649 B/op      40555 allocs/op
+BenchmarkMarkdown/GoMarkdown-8                        13          81380167 ns/op         2245002 B/op      22889 allocs/op
+```
+
+### against cmark (CommonMark reference implementation written in C)
+
+- MBP 2019 13″(i5, 16GB), Go1.17
+
+```
+----------- cmark -----------
+file: _data.md
+iteration: 50
+average: 0.0044073057 sec
+------- goldmark -------
+file: _data.md
+iteration: 50
+average: 0.0041611990 sec
+```
+
+As you can see, goldmark's performance is on par with cmark's.
+
+Extensions
+--------------------
+
+- [goldmark-meta](https://github.com/yuin/goldmark-meta): A YAML metadata
+  extension for the goldmark Markdown parser.
+- [goldmark-highlighting](https://github.com/yuin/goldmark-highlighting): A syntax-highlighting extension
+  for the goldmark markdown parser.
+- [goldmark-emoji](https://github.com/yuin/goldmark-emoji): An emoji
+  extension for the goldmark Markdown parser.
+- [goldmark-mathjax](https://github.com/litao91/goldmark-mathjax): Mathjax support for the goldmark markdown parser
+- [goldmark-pdf](https://github.com/stephenafamo/goldmark-pdf): A PDF renderer that can be passed to `goldmark.WithRenderer()`.
+- [goldmark-hashtag](https://github.com/abhinav/goldmark-hashtag): Adds support for `#hashtag`-based tagging to goldmark.
+- [goldmark-wikilink](https://github.com/abhinav/goldmark-wikilink): Adds support for `[[wiki]]`-style links to goldmark.
+- [goldmark-toc](https://github.com/abhinav/goldmark-toc): Adds support for generating tables-of-contents for goldmark documents.
+- [goldmark-mermaid](https://github.com/abhinav/goldmark-mermaid): Adds support for rendering [Mermaid](https://mermaid-js.github.io/mermaid/) diagrams in goldmark documents.
+- [goldmark-pikchr](https://github.com/jchenry/goldmark-pikchr): Adds support for rendering [Pikchr](https://pikchr.org/home/doc/trunk/homepage.md) diagrams in goldmark documents.
+- [goldmark-embed](https://github.com/13rac1/goldmark-embed): Adds support for rendering embeds from YouTube links.
+- [goldmark-latex](https://github.com/soypat/goldmark-latex): A $\LaTeX$ renderer that can be passed to `goldmark.WithRenderer()`.
+- [goldmark-fences](https://github.com/stefanfritsch/goldmark-fences): Support for pandoc-style [fenced divs](https://pandoc.org/MANUAL.html#divs-and-spans) in goldmark.
+
+
+goldmark internal(for extension developers)
+----------------------------------------------
+### Overview
+goldmark's Markdown processing is outlined in the diagram below.
+
+```
+            <Markdown in []byte, parser.Context>
+                           |
+                           V
+            +-------- parser.Parser ---------------------------
+            | 1. Parse block elements into AST
+            |   1. If a parsed block is a paragraph, apply 
+            |      ast.ParagraphTransformer
+            | 2. Traverse AST and parse blocks.
+            |   1. Process delimiters(emphasis) at the end of
+            |      block parsing
+            | 3. Apply parser.ASTTransformers to AST
+                           |
+                           V
+                      <ast.Node>
+                           |
+                           V
+            +------- renderer.Renderer ------------------------
+            | 1. Traverse AST and apply renderer.NodeRenderer
+            |    corespond to the node type
+
+                           |
+                           V
+                        <Output>
+```
+
+### Parsing
+Markdown documents are read through `text.Reader` interface.
+
+AST nodes do not have concrete text. AST nodes have segment information of the documents, represented by `text.Segment` .
+
+`text.Segment` has 3 attributes: `Start`, `End`, `Padding` .
+
+(TBC)
+
+**TODO**
+
+See `extension` directory for examples of extensions.
+
+Summary:
+
+1. Define AST Node as a struct in which `ast.BaseBlock` or `ast.BaseInline` is embedded.
+2. Write a parser that implements `parser.BlockParser` or `parser.InlineParser`.
+3. Write a renderer that implements `renderer.NodeRenderer`.
+4. Define your goldmark extension that implements `goldmark.Extender`.
+
+
+Donation
+--------------------
+BTC: 1NEDSyUmo4SMTDP83JJQSWi1MvQUGGNMZB
+
+License
+--------------------
+MIT
+
+Author
+--------------------
+Yusuke Inuzuka

vendor/github.com/yuin/goldmark/ast/ast.go

@@ -0,0 +1,508 @@
+// Package ast defines AST nodes that represent markdown elements.
+package ast
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	textm "github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// A NodeType indicates what type a node belongs to.
+type NodeType int
+
+const (
+	// TypeBlock indicates that a node is kind of block nodes.
+	TypeBlock NodeType = iota + 1
+	// TypeInline indicates that a node is kind of inline nodes.
+	TypeInline
+	// TypeDocument indicates that a node is kind of document nodes.
+	TypeDocument
+)
+
+// NodeKind indicates more specific type than NodeType.
+type NodeKind int
+
+func (k NodeKind) String() string {
+	return kindNames[k]
+}
+
+var kindMax NodeKind
+var kindNames = []string{""}
+
+// NewNodeKind returns a new Kind value.
+func NewNodeKind(name string) NodeKind {
+	kindMax++
+	kindNames = append(kindNames, name)
+	return kindMax
+}
+
+// An Attribute is an attribute of the Node
+type Attribute struct {
+	Name  []byte
+	Value interface{}
+}
+
+// A Node interface defines basic AST node functionalities.
+type Node interface {
+	// Type returns a type of this node.
+	Type() NodeType
+
+	// Kind returns a kind of this node.
+	Kind() NodeKind
+
+	// NextSibling returns a next sibling node of this node.
+	NextSibling() Node
+
+	// PreviousSibling returns a previous sibling node of this node.
+	PreviousSibling() Node
+
+	// Parent returns a parent node of this node.
+	Parent() Node
+
+	// SetParent sets a parent node to this node.
+	SetParent(Node)
+
+	// SetPreviousSibling sets a previous sibling node to this node.
+	SetPreviousSibling(Node)
+
+	// SetNextSibling sets a next sibling node to this node.
+	SetNextSibling(Node)
+
+	// HasChildren returns true if this node has any children, otherwise false.
+	HasChildren() bool
+
+	// ChildCount returns a total number of children.
+	ChildCount() int
+
+	// FirstChild returns a first child of this node.
+	FirstChild() Node
+
+	// LastChild returns a last child of this node.
+	LastChild() Node
+
+	// AppendChild append a node child to the tail of the children.
+	AppendChild(self, child Node)
+
+	// RemoveChild removes a node child from this node.
+	// If a node child is not children of this node, RemoveChild nothing to do.
+	RemoveChild(self, child Node)
+
+	// RemoveChildren removes all children from this node.
+	RemoveChildren(self Node)
+
+	// SortChildren sorts childrens by comparator.
+	SortChildren(comparator func(n1, n2 Node) int)
+
+	// ReplaceChild replace a node v1 with a node insertee.
+	// If v1 is not children of this node, ReplaceChild append a insetee to the
+	// tail of the children.
+	ReplaceChild(self, v1, insertee Node)
+
+	// InsertBefore inserts a node insertee before a node v1.
+	// If v1 is not children of this node, InsertBefore append a insetee to the
+	// tail of the children.
+	InsertBefore(self, v1, insertee Node)
+
+	// InsertAfterinserts a node insertee after a node v1.
+	// If v1 is not children of this node, InsertBefore append a insetee to the
+	// tail of the children.
+	InsertAfter(self, v1, insertee Node)
+
+	// OwnerDocument returns this node's owner document.
+	// If this node is not a child of the Document node, OwnerDocument
+	// returns nil.
+	OwnerDocument() *Document
+
+	// Dump dumps an AST tree structure to stdout.
+	// This function completely aimed for debugging.
+	// level is a indent level. Implementer should indent informations with
+	// 2 * level spaces.
+	Dump(source []byte, level int)
+
+	// Text returns text values of this node.
+	Text(source []byte) []byte
+
+	// HasBlankPreviousLines returns true if the row before this node is blank,
+	// otherwise false.
+	// This method is valid only for block nodes.
+	HasBlankPreviousLines() bool
+
+	// SetBlankPreviousLines sets whether the row before this node is blank.
+	// This method is valid only for block nodes.
+	SetBlankPreviousLines(v bool)
+
+	// Lines returns text segments that hold positions in a source.
+	// This method is valid only for block nodes.
+	Lines() *textm.Segments
+
+	// SetLines sets text segments that hold positions in a source.
+	// This method is valid only for block nodes.
+	SetLines(*textm.Segments)
+
+	// IsRaw returns true if contents should be rendered as 'raw' contents.
+	IsRaw() bool
+
+	// SetAttribute sets the given value to the attributes.
+	SetAttribute(name []byte, value interface{})
+
+	// SetAttributeString sets the given value to the attributes.
+	SetAttributeString(name string, value interface{})
+
+	// Attribute returns a (attribute value, true) if an attribute
+	// associated with the given name is found, otherwise
+	// (nil, false)
+	Attribute(name []byte) (interface{}, bool)
+
+	// AttributeString returns a (attribute value, true) if an attribute
+	// associated with the given name is found, otherwise
+	// (nil, false)
+	AttributeString(name string) (interface{}, bool)
+
+	// Attributes returns a list of attributes.
+	// This may be a nil if there are no attributes.
+	Attributes() []Attribute
+
+	// RemoveAttributes removes all attributes from this node.
+	RemoveAttributes()
+}
+
+// A BaseNode struct implements the Node interface partialliy.
+type BaseNode struct {
+	firstChild Node
+	lastChild  Node
+	parent     Node
+	next       Node
+	prev       Node
+	childCount int
+	attributes []Attribute
+}
+
+func ensureIsolated(v Node) {
+	if p := v.Parent(); p != nil {
+		p.RemoveChild(p, v)
+	}
+}
+
+// HasChildren implements Node.HasChildren .
+func (n *BaseNode) HasChildren() bool {
+	return n.firstChild != nil
+}
+
+// SetPreviousSibling implements Node.SetPreviousSibling .
+func (n *BaseNode) SetPreviousSibling(v Node) {
+	n.prev = v
+}
+
+// SetNextSibling implements Node.SetNextSibling .
+func (n *BaseNode) SetNextSibling(v Node) {
+	n.next = v
+}
+
+// PreviousSibling implements Node.PreviousSibling .
+func (n *BaseNode) PreviousSibling() Node {
+	return n.prev
+}
+
+// NextSibling implements Node.NextSibling .
+func (n *BaseNode) NextSibling() Node {
+	return n.next
+}
+
+// RemoveChild implements Node.RemoveChild .
+func (n *BaseNode) RemoveChild(self, v Node) {
+	if v.Parent() != self {
+		return
+	}
+	n.childCount--
+	prev := v.PreviousSibling()
+	next := v.NextSibling()
+	if prev != nil {
+		prev.SetNextSibling(next)
+	} else {
+		n.firstChild = next
+	}
+	if next != nil {
+		next.SetPreviousSibling(prev)
+	} else {
+		n.lastChild = prev
+	}
+	v.SetParent(nil)
+	v.SetPreviousSibling(nil)
+	v.SetNextSibling(nil)
+}
+
+// RemoveChildren implements Node.RemoveChildren .
+func (n *BaseNode) RemoveChildren(self Node) {
+	for c := n.firstChild; c != nil; {
+		c.SetParent(nil)
+		c.SetPreviousSibling(nil)
+		next := c.NextSibling()
+		c.SetNextSibling(nil)
+		c = next
+	}
+	n.firstChild = nil
+	n.lastChild = nil
+	n.childCount = 0
+}
+
+// SortChildren implements Node.SortChildren
+func (n *BaseNode) SortChildren(comparator func(n1, n2 Node) int) {
+	var sorted Node
+	current := n.firstChild
+	for current != nil {
+		next := current.NextSibling()
+		if sorted == nil || comparator(sorted, current) >= 0 {
+			current.SetNextSibling(sorted)
+			if sorted != nil {
+				sorted.SetPreviousSibling(current)
+			}
+			sorted = current
+			sorted.SetPreviousSibling(nil)
+		} else {
+			c := sorted
+			for c.NextSibling() != nil && comparator(c.NextSibling(), current) < 0 {
+				c = c.NextSibling()
+			}
+			current.SetNextSibling(c.NextSibling())
+			current.SetPreviousSibling(c)
+			if c.NextSibling() != nil {
+				c.NextSibling().SetPreviousSibling(current)
+			}
+			c.SetNextSibling(current)
+		}
+		current = next
+	}
+	n.firstChild = sorted
+	for c := n.firstChild; c != nil; c = c.NextSibling() {
+		n.lastChild = c
+	}
+}
+
+// FirstChild implements Node.FirstChild .
+func (n *BaseNode) FirstChild() Node {
+	return n.firstChild
+}
+
+// LastChild implements Node.LastChild .
+func (n *BaseNode) LastChild() Node {
+	return n.lastChild
+}
+
+// ChildCount implements Node.ChildCount .
+func (n *BaseNode) ChildCount() int {
+	return n.childCount
+}
+
+// Parent implements Node.Parent .
+func (n *BaseNode) Parent() Node {
+	return n.parent
+}
+
+// SetParent implements Node.SetParent .
+func (n *BaseNode) SetParent(v Node) {
+	n.parent = v
+}
+
+// AppendChild implements Node.AppendChild .
+func (n *BaseNode) AppendChild(self, v Node) {
+	ensureIsolated(v)
+	if n.firstChild == nil {
+		n.firstChild = v
+		v.SetNextSibling(nil)
+		v.SetPreviousSibling(nil)
+	} else {
+		last := n.lastChild
+		last.SetNextSibling(v)
+		v.SetPreviousSibling(last)
+	}
+	v.SetParent(self)
+	n.lastChild = v
+	n.childCount++
+}
+
+// ReplaceChild implements Node.ReplaceChild .
+func (n *BaseNode) ReplaceChild(self, v1, insertee Node) {
+	n.InsertBefore(self, v1, insertee)
+	n.RemoveChild(self, v1)
+}
+
+// InsertAfter implements Node.InsertAfter .
+func (n *BaseNode) InsertAfter(self, v1, insertee Node) {
+	n.InsertBefore(self, v1.NextSibling(), insertee)
+}
+
+// InsertBefore implements Node.InsertBefore .
+func (n *BaseNode) InsertBefore(self, v1, insertee Node) {
+	n.childCount++
+	if v1 == nil {
+		n.AppendChild(self, insertee)
+		return
+	}
+	ensureIsolated(insertee)
+	if v1.Parent() == self {
+		c := v1
+		prev := c.PreviousSibling()
+		if prev != nil {
+			prev.SetNextSibling(insertee)
+			insertee.SetPreviousSibling(prev)
+		} else {
+			n.firstChild = insertee
+			insertee.SetPreviousSibling(nil)
+		}
+		insertee.SetNextSibling(c)
+		c.SetPreviousSibling(insertee)
+		insertee.SetParent(self)
+	}
+}
+
+// OwnerDocument implements Node.OwnerDocument
+func (n *BaseNode) OwnerDocument() *Document {
+	d := n.Parent()
+	for {
+		p := d.Parent()
+		if p == nil {
+			if v, ok := d.(*Document); ok {
+				return v
+			}
+			break
+		}
+		d = p
+	}
+	return nil
+}
+
+// Text implements Node.Text  .
+func (n *BaseNode) Text(source []byte) []byte {
+	var buf bytes.Buffer
+	for c := n.firstChild; c != nil; c = c.NextSibling() {
+		buf.Write(c.Text(source))
+	}
+	return buf.Bytes()
+}
+
+// SetAttribute implements Node.SetAttribute.
+func (n *BaseNode) SetAttribute(name []byte, value interface{}) {
+	if n.attributes == nil {
+		n.attributes = make([]Attribute, 0, 10)
+	} else {
+		for i, a := range n.attributes {
+			if bytes.Equal(a.Name, name) {
+				n.attributes[i].Name = name
+				n.attributes[i].Value = value
+				return
+			}
+		}
+	}
+	n.attributes = append(n.attributes, Attribute{name, value})
+}
+
+// SetAttributeString implements Node.SetAttributeString
+func (n *BaseNode) SetAttributeString(name string, value interface{}) {
+	n.SetAttribute(util.StringToReadOnlyBytes(name), value)
+}
+
+// Attribute implements Node.Attribute.
+func (n *BaseNode) Attribute(name []byte) (interface{}, bool) {
+	if n.attributes == nil {
+		return nil, false
+	}
+	for i, a := range n.attributes {
+		if bytes.Equal(a.Name, name) {
+			return n.attributes[i].Value, true
+		}
+	}
+	return nil, false
+}
+
+// AttributeString implements Node.AttributeString.
+func (n *BaseNode) AttributeString(s string) (interface{}, bool) {
+	return n.Attribute(util.StringToReadOnlyBytes(s))
+}
+
+// Attributes implements Node.Attributes
+func (n *BaseNode) Attributes() []Attribute {
+	return n.attributes
+}
+
+// RemoveAttributes implements Node.RemoveAttributes
+func (n *BaseNode) RemoveAttributes() {
+	n.attributes = nil
+}
+
+// DumpHelper is a helper function to implement Node.Dump.
+// kv is pairs of an attribute name and an attribute value.
+// cb is a function called after wrote a name and attributes.
+func DumpHelper(v Node, source []byte, level int, kv map[string]string, cb func(int)) {
+	name := v.Kind().String()
+	indent := strings.Repeat("    ", level)
+	fmt.Printf("%s%s {\n", indent, name)
+	indent2 := strings.Repeat("    ", level+1)
+	if v.Type() == TypeBlock {
+		fmt.Printf("%sRawText: \"", indent2)
+		for i := 0; i < v.Lines().Len(); i++ {
+			line := v.Lines().At(i)
+			fmt.Printf("%s", line.Value(source))
+		}
+		fmt.Printf("\"\n")
+		fmt.Printf("%sHasBlankPreviousLines: %v\n", indent2, v.HasBlankPreviousLines())
+	}
+	for name, value := range kv {
+		fmt.Printf("%s%s: %s\n", indent2, name, value)
+	}
+	if cb != nil {
+		cb(level + 1)
+	}
+	for c := v.FirstChild(); c != nil; c = c.NextSibling() {
+		c.Dump(source, level+1)
+	}
+	fmt.Printf("%s}\n", indent)
+}
+
+// WalkStatus represents a current status of the Walk function.
+type WalkStatus int
+
+const (
+	// WalkStop indicates no more walking needed.
+	WalkStop WalkStatus = iota + 1
+
+	// WalkSkipChildren indicates that Walk wont walk on children of current
+	// node.
+	WalkSkipChildren
+
+	// WalkContinue indicates that Walk can continue to walk.
+	WalkContinue
+)
+
+// Walker is a function that will be called when Walk find a
+// new node.
+// entering is set true before walks children, false after walked children.
+// If Walker returns error, Walk function immediately stop walking.
+type Walker func(n Node, entering bool) (WalkStatus, error)
+
+// Walk walks a AST tree by the depth first search algorithm.
+func Walk(n Node, walker Walker) error {
+	_, err := walkHelper(n, walker)
+	return err
+}
+
+func walkHelper(n Node, walker Walker) (WalkStatus, error) {
+	status, err := walker(n, true)
+	if err != nil || status == WalkStop {
+		return status, err
+	}
+	if status != WalkSkipChildren {
+		for c := n.FirstChild(); c != nil; c = c.NextSibling() {
+			if st, err := walkHelper(c, walker); err != nil || st == WalkStop {
+				return WalkStop, err
+			}
+		}
+	}
+	status, err = walker(n, false)
+	if err != nil || status == WalkStop {
+		return WalkStop, err
+	}
+	return WalkContinue, nil
+}

vendor/github.com/yuin/goldmark/ast/block.go

@@ -0,0 +1,508 @@
+package ast
+
+import (
+	"fmt"
+	"strings"
+
+	textm "github.com/yuin/goldmark/text"
+)
+
+// A BaseBlock struct implements the Node interface partialliy.
+type BaseBlock struct {
+	BaseNode
+	blankPreviousLines bool
+	lines              *textm.Segments
+}
+
+// Type implements Node.Type
+func (b *BaseBlock) Type() NodeType {
+	return TypeBlock
+}
+
+// IsRaw implements Node.IsRaw
+func (b *BaseBlock) IsRaw() bool {
+	return false
+}
+
+// HasBlankPreviousLines implements Node.HasBlankPreviousLines.
+func (b *BaseBlock) HasBlankPreviousLines() bool {
+	return b.blankPreviousLines
+}
+
+// SetBlankPreviousLines implements Node.SetBlankPreviousLines.
+func (b *BaseBlock) SetBlankPreviousLines(v bool) {
+	b.blankPreviousLines = v
+}
+
+// Lines implements Node.Lines
+func (b *BaseBlock) Lines() *textm.Segments {
+	if b.lines == nil {
+		b.lines = textm.NewSegments()
+	}
+	return b.lines
+}
+
+// SetLines implements Node.SetLines
+func (b *BaseBlock) SetLines(v *textm.Segments) {
+	b.lines = v
+}
+
+// A Document struct is a root node of Markdown text.
+type Document struct {
+	BaseBlock
+
+	meta map[string]interface{}
+}
+
+// KindDocument is a NodeKind of the Document node.
+var KindDocument = NewNodeKind("Document")
+
+// Dump implements Node.Dump .
+func (n *Document) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// Type implements Node.Type .
+func (n *Document) Type() NodeType {
+	return TypeDocument
+}
+
+// Kind implements Node.Kind.
+func (n *Document) Kind() NodeKind {
+	return KindDocument
+}
+
+// OwnerDocument implements Node.OwnerDocument
+func (n *Document) OwnerDocument() *Document {
+	return n
+}
+
+// Meta returns metadata of this document.
+func (n *Document) Meta() map[string]interface{} {
+	if n.meta == nil {
+		n.meta = map[string]interface{}{}
+	}
+	return n.meta
+}
+
+// SetMeta sets given metadata to this document.
+func (n *Document) SetMeta(meta map[string]interface{}) {
+	if n.meta == nil {
+		n.meta = map[string]interface{}{}
+	}
+	for k, v := range meta {
+		n.meta[k] = v
+	}
+}
+
+// AddMeta adds given metadata to this document.
+func (n *Document) AddMeta(key string, value interface{}) {
+	if n.meta == nil {
+		n.meta = map[string]interface{}{}
+	}
+	n.meta[key] = value
+}
+
+// NewDocument returns a new Document node.
+func NewDocument() *Document {
+	return &Document{
+		BaseBlock: BaseBlock{},
+		meta:      nil,
+	}
+}
+
+// A TextBlock struct is a node whose lines
+// should be rendered without any containers.
+type TextBlock struct {
+	BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *TextBlock) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindTextBlock is a NodeKind of the TextBlock node.
+var KindTextBlock = NewNodeKind("TextBlock")
+
+// Kind implements Node.Kind.
+func (n *TextBlock) Kind() NodeKind {
+	return KindTextBlock
+}
+
+// NewTextBlock returns a new TextBlock node.
+func NewTextBlock() *TextBlock {
+	return &TextBlock{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// A Paragraph struct represents a paragraph of Markdown text.
+type Paragraph struct {
+	BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *Paragraph) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindParagraph is a NodeKind of the Paragraph node.
+var KindParagraph = NewNodeKind("Paragraph")
+
+// Kind implements Node.Kind.
+func (n *Paragraph) Kind() NodeKind {
+	return KindParagraph
+}
+
+// NewParagraph returns a new Paragraph node.
+func NewParagraph() *Paragraph {
+	return &Paragraph{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// IsParagraph returns true if the given node implements the Paragraph interface,
+// otherwise false.
+func IsParagraph(node Node) bool {
+	_, ok := node.(*Paragraph)
+	return ok
+}
+
+// A Heading struct represents headings like SetextHeading and ATXHeading.
+type Heading struct {
+	BaseBlock
+	// Level returns a level of this heading.
+	// This value is between 1 and 6.
+	Level int
+}
+
+// Dump implements Node.Dump .
+func (n *Heading) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Level": fmt.Sprintf("%d", n.Level),
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindHeading is a NodeKind of the Heading node.
+var KindHeading = NewNodeKind("Heading")
+
+// Kind implements Node.Kind.
+func (n *Heading) Kind() NodeKind {
+	return KindHeading
+}
+
+// NewHeading returns a new Heading node.
+func NewHeading(level int) *Heading {
+	return &Heading{
+		BaseBlock: BaseBlock{},
+		Level:     level,
+	}
+}
+
+// A ThematicBreak struct represents a thematic break of Markdown text.
+type ThematicBreak struct {
+	BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *ThematicBreak) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindThematicBreak is a NodeKind of the ThematicBreak node.
+var KindThematicBreak = NewNodeKind("ThematicBreak")
+
+// Kind implements Node.Kind.
+func (n *ThematicBreak) Kind() NodeKind {
+	return KindThematicBreak
+}
+
+// NewThematicBreak returns a new ThematicBreak node.
+func NewThematicBreak() *ThematicBreak {
+	return &ThematicBreak{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// A CodeBlock interface represents an indented code block of Markdown text.
+type CodeBlock struct {
+	BaseBlock
+}
+
+// IsRaw implements Node.IsRaw.
+func (n *CodeBlock) IsRaw() bool {
+	return true
+}
+
+// Dump implements Node.Dump .
+func (n *CodeBlock) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindCodeBlock is a NodeKind of the CodeBlock node.
+var KindCodeBlock = NewNodeKind("CodeBlock")
+
+// Kind implements Node.Kind.
+func (n *CodeBlock) Kind() NodeKind {
+	return KindCodeBlock
+}
+
+// NewCodeBlock returns a new CodeBlock node.
+func NewCodeBlock() *CodeBlock {
+	return &CodeBlock{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// A FencedCodeBlock struct represents a fenced code block of Markdown text.
+type FencedCodeBlock struct {
+	BaseBlock
+	// Info returns a info text of this fenced code block.
+	Info *Text
+
+	language []byte
+}
+
+// Language returns an language in an info string.
+// Language returns nil if this node does not have an info string.
+func (n *FencedCodeBlock) Language(source []byte) []byte {
+	if n.language == nil && n.Info != nil {
+		segment := n.Info.Segment
+		info := segment.Value(source)
+		i := 0
+		for ; i < len(info); i++ {
+			if info[i] == ' ' {
+				break
+			}
+		}
+		n.language = info[:i]
+	}
+	return n.language
+}
+
+// IsRaw implements Node.IsRaw.
+func (n *FencedCodeBlock) IsRaw() bool {
+	return true
+}
+
+// Dump implements Node.Dump .
+func (n *FencedCodeBlock) Dump(source []byte, level int) {
+	m := map[string]string{}
+	if n.Info != nil {
+		m["Info"] = fmt.Sprintf("\"%s\"", n.Info.Text(source))
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindFencedCodeBlock is a NodeKind of the FencedCodeBlock node.
+var KindFencedCodeBlock = NewNodeKind("FencedCodeBlock")
+
+// Kind implements Node.Kind.
+func (n *FencedCodeBlock) Kind() NodeKind {
+	return KindFencedCodeBlock
+}
+
+// NewFencedCodeBlock return a new FencedCodeBlock node.
+func NewFencedCodeBlock(info *Text) *FencedCodeBlock {
+	return &FencedCodeBlock{
+		BaseBlock: BaseBlock{},
+		Info:      info,
+	}
+}
+
+// A Blockquote struct represents an blockquote block of Markdown text.
+type Blockquote struct {
+	BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *Blockquote) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindBlockquote is a NodeKind of the Blockquote node.
+var KindBlockquote = NewNodeKind("Blockquote")
+
+// Kind implements Node.Kind.
+func (n *Blockquote) Kind() NodeKind {
+	return KindBlockquote
+}
+
+// NewBlockquote returns a new Blockquote node.
+func NewBlockquote() *Blockquote {
+	return &Blockquote{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// A List struct represents a list of Markdown text.
+type List struct {
+	BaseBlock
+
+	// Marker is a marker character like '-', '+', ')' and '.'.
+	Marker byte
+
+	// IsTight is a true if this list is a 'tight' list.
+	// See https://spec.commonmark.org/0.30/#loose for details.
+	IsTight bool
+
+	// Start is an initial number of this ordered list.
+	// If this list is not an ordered list, Start is 0.
+	Start int
+}
+
+// IsOrdered returns true if this list is an ordered list, otherwise false.
+func (l *List) IsOrdered() bool {
+	return l.Marker == '.' || l.Marker == ')'
+}
+
+// CanContinue returns true if this list can continue with
+// the given mark and a list type, otherwise false.
+func (l *List) CanContinue(marker byte, isOrdered bool) bool {
+	return marker == l.Marker && isOrdered == l.IsOrdered()
+}
+
+// Dump implements Node.Dump.
+func (l *List) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Ordered": fmt.Sprintf("%v", l.IsOrdered()),
+		"Marker":  fmt.Sprintf("%c", l.Marker),
+		"Tight":   fmt.Sprintf("%v", l.IsTight),
+	}
+	if l.IsOrdered() {
+		m["Start"] = fmt.Sprintf("%d", l.Start)
+	}
+	DumpHelper(l, source, level, m, nil)
+}
+
+// KindList is a NodeKind of the List node.
+var KindList = NewNodeKind("List")
+
+// Kind implements Node.Kind.
+func (l *List) Kind() NodeKind {
+	return KindList
+}
+
+// NewList returns a new List node.
+func NewList(marker byte) *List {
+	return &List{
+		BaseBlock: BaseBlock{},
+		Marker:    marker,
+		IsTight:   true,
+	}
+}
+
+// A ListItem struct represents a list item of Markdown text.
+type ListItem struct {
+	BaseBlock
+
+	// Offset is an offset position of this item.
+	Offset int
+}
+
+// Dump implements Node.Dump.
+func (n *ListItem) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Offset": fmt.Sprintf("%d", n.Offset),
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindListItem is a NodeKind of the ListItem node.
+var KindListItem = NewNodeKind("ListItem")
+
+// Kind implements Node.Kind.
+func (n *ListItem) Kind() NodeKind {
+	return KindListItem
+}
+
+// NewListItem returns a new ListItem node.
+func NewListItem(offset int) *ListItem {
+	return &ListItem{
+		BaseBlock: BaseBlock{},
+		Offset:    offset,
+	}
+}
+
+// HTMLBlockType represents kinds of an html blocks.
+// See https://spec.commonmark.org/0.30/#html-blocks
+type HTMLBlockType int
+
+const (
+	// HTMLBlockType1 represents type 1 html blocks
+	HTMLBlockType1 HTMLBlockType = iota + 1
+	// HTMLBlockType2 represents type 2 html blocks
+	HTMLBlockType2
+	// HTMLBlockType3 represents type 3 html blocks
+	HTMLBlockType3
+	// HTMLBlockType4 represents type 4 html blocks
+	HTMLBlockType4
+	// HTMLBlockType5 represents type 5 html blocks
+	HTMLBlockType5
+	// HTMLBlockType6 represents type 6 html blocks
+	HTMLBlockType6
+	// HTMLBlockType7 represents type 7 html blocks
+	HTMLBlockType7
+)
+
+// An HTMLBlock struct represents an html block of Markdown text.
+type HTMLBlock struct {
+	BaseBlock
+
+	// Type is a type of this html block.
+	HTMLBlockType HTMLBlockType
+
+	// ClosureLine is a line that closes this html block.
+	ClosureLine textm.Segment
+}
+
+// IsRaw implements Node.IsRaw.
+func (n *HTMLBlock) IsRaw() bool {
+	return true
+}
+
+// HasClosure returns true if this html block has a closure line,
+// otherwise false.
+func (n *HTMLBlock) HasClosure() bool {
+	return n.ClosureLine.Start >= 0
+}
+
+// Dump implements Node.Dump.
+func (n *HTMLBlock) Dump(source []byte, level int) {
+	indent := strings.Repeat("    ", level)
+	fmt.Printf("%s%s {\n", indent, "HTMLBlock")
+	indent2 := strings.Repeat("    ", level+1)
+	fmt.Printf("%sRawText: \"", indent2)
+	for i := 0; i < n.Lines().Len(); i++ {
+		s := n.Lines().At(i)
+		fmt.Print(string(source[s.Start:s.Stop]))
+	}
+	fmt.Printf("\"\n")
+	for c := n.FirstChild(); c != nil; c = c.NextSibling() {
+		c.Dump(source, level+1)
+	}
+	if n.HasClosure() {
+		cl := n.ClosureLine
+		fmt.Printf("%sClosure: \"%s\"\n", indent2, string(cl.Value(source)))
+	}
+	fmt.Printf("%s}\n", indent)
+}
+
+// KindHTMLBlock is a NodeKind of the HTMLBlock node.
+var KindHTMLBlock = NewNodeKind("HTMLBlock")
+
+// Kind implements Node.Kind.
+func (n *HTMLBlock) Kind() NodeKind {
+	return KindHTMLBlock
+}
+
+// NewHTMLBlock returns a new HTMLBlock node.
+func NewHTMLBlock(typ HTMLBlockType) *HTMLBlock {
+	return &HTMLBlock{
+		BaseBlock:     BaseBlock{},
+		HTMLBlockType: typ,
+		ClosureLine:   textm.NewSegment(-1, -1),
+	}
+}

vendor/github.com/yuin/goldmark/ast/inline.go

@@ -0,0 +1,548 @@
+package ast
+
+import (
+	"fmt"
+	"strings"
+
+	textm "github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// A BaseInline struct implements the Node interface partialliy.
+type BaseInline struct {
+	BaseNode
+}
+
+// Type implements Node.Type
+func (b *BaseInline) Type() NodeType {
+	return TypeInline
+}
+
+// IsRaw implements Node.IsRaw
+func (b *BaseInline) IsRaw() bool {
+	return false
+}
+
+// HasBlankPreviousLines implements Node.HasBlankPreviousLines.
+func (b *BaseInline) HasBlankPreviousLines() bool {
+	panic("can not call with inline nodes.")
+}
+
+// SetBlankPreviousLines implements Node.SetBlankPreviousLines.
+func (b *BaseInline) SetBlankPreviousLines(v bool) {
+	panic("can not call with inline nodes.")
+}
+
+// Lines implements Node.Lines
+func (b *BaseInline) Lines() *textm.Segments {
+	panic("can not call with inline nodes.")
+}
+
+// SetLines implements Node.SetLines
+func (b *BaseInline) SetLines(v *textm.Segments) {
+	panic("can not call with inline nodes.")
+}
+
+// A Text struct represents a textual content of the Markdown text.
+type Text struct {
+	BaseInline
+	// Segment is a position in a source text.
+	Segment textm.Segment
+
+	flags uint8
+}
+
+const (
+	textSoftLineBreak = 1 << iota
+	textHardLineBreak
+	textRaw
+	textCode
+)
+
+func textFlagsString(flags uint8) string {
+	buf := []string{}
+	if flags&textSoftLineBreak != 0 {
+		buf = append(buf, "SoftLineBreak")
+	}
+	if flags&textHardLineBreak != 0 {
+		buf = append(buf, "HardLineBreak")
+	}
+	if flags&textRaw != 0 {
+		buf = append(buf, "Raw")
+	}
+	if flags&textCode != 0 {
+		buf = append(buf, "Code")
+	}
+	return strings.Join(buf, ", ")
+}
+
+// Inline implements Inline.Inline.
+func (n *Text) Inline() {
+}
+
+// SoftLineBreak returns true if this node ends with a new line,
+// otherwise false.
+func (n *Text) SoftLineBreak() bool {
+	return n.flags&textSoftLineBreak != 0
+}
+
+// SetSoftLineBreak sets whether this node ends with a new line.
+func (n *Text) SetSoftLineBreak(v bool) {
+	if v {
+		n.flags |= textSoftLineBreak
+	} else {
+		n.flags = n.flags &^ textSoftLineBreak
+	}
+}
+
+// IsRaw returns true if this text should be rendered without unescaping
+// back slash escapes and resolving references.
+func (n *Text) IsRaw() bool {
+	return n.flags&textRaw != 0
+}
+
+// SetRaw sets whether this text should be rendered as raw contents.
+func (n *Text) SetRaw(v bool) {
+	if v {
+		n.flags |= textRaw
+	} else {
+		n.flags = n.flags &^ textRaw
+	}
+}
+
+// HardLineBreak returns true if this node ends with a hard line break.
+// See https://spec.commonmark.org/0.30/#hard-line-breaks for details.
+func (n *Text) HardLineBreak() bool {
+	return n.flags&textHardLineBreak != 0
+}
+
+// SetHardLineBreak sets whether this node ends with a hard line break.
+func (n *Text) SetHardLineBreak(v bool) {
+	if v {
+		n.flags |= textHardLineBreak
+	} else {
+		n.flags = n.flags &^ textHardLineBreak
+	}
+}
+
+// Merge merges a Node n into this node.
+// Merge returns true if the given node has been merged, otherwise false.
+func (n *Text) Merge(node Node, source []byte) bool {
+	t, ok := node.(*Text)
+	if !ok {
+		return false
+	}
+	if n.Segment.Stop != t.Segment.Start || t.Segment.Padding != 0 || source[n.Segment.Stop-1] == '\n' || t.IsRaw() != n.IsRaw() {
+		return false
+	}
+	n.Segment.Stop = t.Segment.Stop
+	n.SetSoftLineBreak(t.SoftLineBreak())
+	n.SetHardLineBreak(t.HardLineBreak())
+	return true
+}
+
+// Text implements Node.Text.
+func (n *Text) Text(source []byte) []byte {
+	return n.Segment.Value(source)
+}
+
+// Dump implements Node.Dump.
+func (n *Text) Dump(source []byte, level int) {
+	fs := textFlagsString(n.flags)
+	if len(fs) != 0 {
+		fs = "(" + fs + ")"
+	}
+	fmt.Printf("%sText%s: \"%s\"\n", strings.Repeat("    ", level), fs, strings.TrimRight(string(n.Text(source)), "\n"))
+}
+
+// KindText is a NodeKind of the Text node.
+var KindText = NewNodeKind("Text")
+
+// Kind implements Node.Kind.
+func (n *Text) Kind() NodeKind {
+	return KindText
+}
+
+// NewText returns a new Text node.
+func NewText() *Text {
+	return &Text{
+		BaseInline: BaseInline{},
+	}
+}
+
+// NewTextSegment returns a new Text node with the given source position.
+func NewTextSegment(v textm.Segment) *Text {
+	return &Text{
+		BaseInline: BaseInline{},
+		Segment:    v,
+	}
+}
+
+// NewRawTextSegment returns a new Text node with the given source position.
+// The new node should be rendered as raw contents.
+func NewRawTextSegment(v textm.Segment) *Text {
+	t := &Text{
+		BaseInline: BaseInline{},
+		Segment:    v,
+	}
+	t.SetRaw(true)
+	return t
+}
+
+// MergeOrAppendTextSegment merges a given s into the last child of the parent if
+// it can be merged, otherwise creates a new Text node and appends it to after current
+// last child.
+func MergeOrAppendTextSegment(parent Node, s textm.Segment) {
+	last := parent.LastChild()
+	t, ok := last.(*Text)
+	if ok && t.Segment.Stop == s.Start && !t.SoftLineBreak() {
+		t.Segment = t.Segment.WithStop(s.Stop)
+	} else {
+		parent.AppendChild(parent, NewTextSegment(s))
+	}
+}
+
+// MergeOrReplaceTextSegment merges a given s into a previous sibling of the node n
+// if a previous sibling of the node n is *Text, otherwise replaces Node n with s.
+func MergeOrReplaceTextSegment(parent Node, n Node, s textm.Segment) {
+	prev := n.PreviousSibling()
+	if t, ok := prev.(*Text); ok && t.Segment.Stop == s.Start && !t.SoftLineBreak() {
+		t.Segment = t.Segment.WithStop(s.Stop)
+		parent.RemoveChild(parent, n)
+	} else {
+		parent.ReplaceChild(parent, n, NewTextSegment(s))
+	}
+}
+
+// A String struct is a textual content that has a concrete value
+type String struct {
+	BaseInline
+
+	Value []byte
+	flags uint8
+}
+
+// Inline implements Inline.Inline.
+func (n *String) Inline() {
+}
+
+// IsRaw returns true if this text should be rendered without unescaping
+// back slash escapes and resolving references.
+func (n *String) IsRaw() bool {
+	return n.flags&textRaw != 0
+}
+
+// SetRaw sets whether this text should be rendered as raw contents.
+func (n *String) SetRaw(v bool) {
+	if v {
+		n.flags |= textRaw
+	} else {
+		n.flags = n.flags &^ textRaw
+	}
+}
+
+// IsCode returns true if this text should be rendered without any
+// modifications.
+func (n *String) IsCode() bool {
+	return n.flags&textCode != 0
+}
+
+// SetCode sets whether this text should be rendered without any modifications.
+func (n *String) SetCode(v bool) {
+	if v {
+		n.flags |= textCode
+	} else {
+		n.flags = n.flags &^ textCode
+	}
+}
+
+// Text implements Node.Text.
+func (n *String) Text(source []byte) []byte {
+	return n.Value
+}
+
+// Dump implements Node.Dump.
+func (n *String) Dump(source []byte, level int) {
+	fs := textFlagsString(n.flags)
+	if len(fs) != 0 {
+		fs = "(" + fs + ")"
+	}
+	fmt.Printf("%sString%s: \"%s\"\n", strings.Repeat("    ", level), fs, strings.TrimRight(string(n.Value), "\n"))
+}
+
+// KindString is a NodeKind of the String node.
+var KindString = NewNodeKind("String")
+
+// Kind implements Node.Kind.
+func (n *String) Kind() NodeKind {
+	return KindString
+}
+
+// NewString returns a new String node.
+func NewString(v []byte) *String {
+	return &String{
+		Value: v,
+	}
+}
+
+// A CodeSpan struct represents a code span of Markdown text.
+type CodeSpan struct {
+	BaseInline
+}
+
+// Inline implements Inline.Inline .
+func (n *CodeSpan) Inline() {
+}
+
+// IsBlank returns true if this node consists of spaces, otherwise false.
+func (n *CodeSpan) IsBlank(source []byte) bool {
+	for c := n.FirstChild(); c != nil; c = c.NextSibling() {
+		text := c.(*Text).Segment
+		if !util.IsBlank(text.Value(source)) {
+			return false
+		}
+	}
+	return true
+}
+
+// Dump implements Node.Dump
+func (n *CodeSpan) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindCodeSpan is a NodeKind of the CodeSpan node.
+var KindCodeSpan = NewNodeKind("CodeSpan")
+
+// Kind implements Node.Kind.
+func (n *CodeSpan) Kind() NodeKind {
+	return KindCodeSpan
+}
+
+// NewCodeSpan returns a new CodeSpan node.
+func NewCodeSpan() *CodeSpan {
+	return &CodeSpan{
+		BaseInline: BaseInline{},
+	}
+}
+
+// An Emphasis struct represents an emphasis of Markdown text.
+type Emphasis struct {
+	BaseInline
+
+	// Level is a level of the emphasis.
+	Level int
+}
+
+// Dump implements Node.Dump.
+func (n *Emphasis) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Level": fmt.Sprintf("%v", n.Level),
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindEmphasis is a NodeKind of the Emphasis node.
+var KindEmphasis = NewNodeKind("Emphasis")
+
+// Kind implements Node.Kind.
+func (n *Emphasis) Kind() NodeKind {
+	return KindEmphasis
+}
+
+// NewEmphasis returns a new Emphasis node with the given level.
+func NewEmphasis(level int) *Emphasis {
+	return &Emphasis{
+		BaseInline: BaseInline{},
+		Level:      level,
+	}
+}
+
+type baseLink struct {
+	BaseInline
+
+	// Destination is a destination(URL) of this link.
+	Destination []byte
+
+	// Title is a title of this link.
+	Title []byte
+}
+
+// Inline implements Inline.Inline.
+func (n *baseLink) Inline() {
+}
+
+// A Link struct represents a link of the Markdown text.
+type Link struct {
+	baseLink
+}
+
+// Dump implements Node.Dump.
+func (n *Link) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Destination"] = string(n.Destination)
+	m["Title"] = string(n.Title)
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindLink is a NodeKind of the Link node.
+var KindLink = NewNodeKind("Link")
+
+// Kind implements Node.Kind.
+func (n *Link) Kind() NodeKind {
+	return KindLink
+}
+
+// NewLink returns a new Link node.
+func NewLink() *Link {
+	c := &Link{
+		baseLink: baseLink{
+			BaseInline: BaseInline{},
+		},
+	}
+	return c
+}
+
+// An Image struct represents an image of the Markdown text.
+type Image struct {
+	baseLink
+}
+
+// Dump implements Node.Dump.
+func (n *Image) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Destination"] = string(n.Destination)
+	m["Title"] = string(n.Title)
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindImage is a NodeKind of the Image node.
+var KindImage = NewNodeKind("Image")
+
+// Kind implements Node.Kind.
+func (n *Image) Kind() NodeKind {
+	return KindImage
+}
+
+// NewImage returns a new Image node.
+func NewImage(link *Link) *Image {
+	c := &Image{
+		baseLink: baseLink{
+			BaseInline: BaseInline{},
+		},
+	}
+	c.Destination = link.Destination
+	c.Title = link.Title
+	for n := link.FirstChild(); n != nil; {
+		next := n.NextSibling()
+		link.RemoveChild(link, n)
+		c.AppendChild(c, n)
+		n = next
+	}
+
+	return c
+}
+
+// AutoLinkType defines kind of auto links.
+type AutoLinkType int
+
+const (
+	// AutoLinkEmail indicates that an autolink is an email address.
+	AutoLinkEmail AutoLinkType = iota + 1
+	// AutoLinkURL indicates that an autolink is a generic URL.
+	AutoLinkURL
+)
+
+// An AutoLink struct represents an autolink of the Markdown text.
+type AutoLink struct {
+	BaseInline
+	// Type is a type of this autolink.
+	AutoLinkType AutoLinkType
+
+	// Protocol specified a protocol of the link.
+	Protocol []byte
+
+	value *Text
+}
+
+// Inline implements Inline.Inline.
+func (n *AutoLink) Inline() {}
+
+// Dump implements Node.Dump
+func (n *AutoLink) Dump(source []byte, level int) {
+	segment := n.value.Segment
+	m := map[string]string{
+		"Value": string(segment.Value(source)),
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindAutoLink is a NodeKind of the AutoLink node.
+var KindAutoLink = NewNodeKind("AutoLink")
+
+// Kind implements Node.Kind.
+func (n *AutoLink) Kind() NodeKind {
+	return KindAutoLink
+}
+
+// URL returns an url of this node.
+func (n *AutoLink) URL(source []byte) []byte {
+	if n.Protocol != nil {
+		s := n.value.Segment
+		ret := make([]byte, 0, len(n.Protocol)+s.Len()+3)
+		ret = append(ret, n.Protocol...)
+		ret = append(ret, ':', '/', '/')
+		ret = append(ret, n.value.Text(source)...)
+		return ret
+	}
+	return n.value.Text(source)
+}
+
+// Label returns a label of this node.
+func (n *AutoLink) Label(source []byte) []byte {
+	return n.value.Text(source)
+}
+
+// NewAutoLink returns a new AutoLink node.
+func NewAutoLink(typ AutoLinkType, value *Text) *AutoLink {
+	return &AutoLink{
+		BaseInline:   BaseInline{},
+		value:        value,
+		AutoLinkType: typ,
+	}
+}
+
+// A RawHTML struct represents an inline raw HTML of the Markdown text.
+type RawHTML struct {
+	BaseInline
+	Segments *textm.Segments
+}
+
+// Inline implements Inline.Inline.
+func (n *RawHTML) Inline() {}
+
+// Dump implements Node.Dump.
+func (n *RawHTML) Dump(source []byte, level int) {
+	m := map[string]string{}
+	t := []string{}
+	for i := 0; i < n.Segments.Len(); i++ {
+		segment := n.Segments.At(i)
+		t = append(t, string(segment.Value(source)))
+	}
+	m["RawText"] = strings.Join(t, "")
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindRawHTML is a NodeKind of the RawHTML node.
+var KindRawHTML = NewNodeKind("RawHTML")
+
+// Kind implements Node.Kind.
+func (n *RawHTML) Kind() NodeKind {
+	return KindRawHTML
+}
+
+// NewRawHTML returns a new RawHTML node.
+func NewRawHTML() *RawHTML {
+	return &RawHTML{
+		Segments: textm.NewSegments(),
+	}
+}

vendor/github.com/yuin/goldmark/extension/ast/definition_list.go

@@ -0,0 +1,83 @@
+package ast
+
+import (
+	gast "github.com/yuin/goldmark/ast"
+)
+
+// A DefinitionList struct represents a definition list of Markdown
+// (PHPMarkdownExtra) text.
+type DefinitionList struct {
+	gast.BaseBlock
+	Offset             int
+	TemporaryParagraph *gast.Paragraph
+}
+
+// Dump implements Node.Dump.
+func (n *DefinitionList) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindDefinitionList is a NodeKind of the DefinitionList node.
+var KindDefinitionList = gast.NewNodeKind("DefinitionList")
+
+// Kind implements Node.Kind.
+func (n *DefinitionList) Kind() gast.NodeKind {
+	return KindDefinitionList
+}
+
+// NewDefinitionList returns a new DefinitionList node.
+func NewDefinitionList(offset int, para *gast.Paragraph) *DefinitionList {
+	return &DefinitionList{
+		Offset:             offset,
+		TemporaryParagraph: para,
+	}
+}
+
+// A DefinitionTerm struct represents a definition list term of Markdown
+// (PHPMarkdownExtra) text.
+type DefinitionTerm struct {
+	gast.BaseBlock
+}
+
+// Dump implements Node.Dump.
+func (n *DefinitionTerm) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindDefinitionTerm is a NodeKind of the DefinitionTerm node.
+var KindDefinitionTerm = gast.NewNodeKind("DefinitionTerm")
+
+// Kind implements Node.Kind.
+func (n *DefinitionTerm) Kind() gast.NodeKind {
+	return KindDefinitionTerm
+}
+
+// NewDefinitionTerm returns a new DefinitionTerm node.
+func NewDefinitionTerm() *DefinitionTerm {
+	return &DefinitionTerm{}
+}
+
+// A DefinitionDescription struct represents a definition list description of Markdown
+// (PHPMarkdownExtra) text.
+type DefinitionDescription struct {
+	gast.BaseBlock
+	IsTight bool
+}
+
+// Dump implements Node.Dump.
+func (n *DefinitionDescription) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindDefinitionDescription is a NodeKind of the DefinitionDescription node.
+var KindDefinitionDescription = gast.NewNodeKind("DefinitionDescription")
+
+// Kind implements Node.Kind.
+func (n *DefinitionDescription) Kind() gast.NodeKind {
+	return KindDefinitionDescription
+}
+
+// NewDefinitionDescription returns a new DefinitionDescription node.
+func NewDefinitionDescription() *DefinitionDescription {
+	return &DefinitionDescription{}
+}

vendor/github.com/yuin/goldmark/extension/ast/footnote.go

@@ -0,0 +1,138 @@
+package ast
+
+import (
+	"fmt"
+
+	gast "github.com/yuin/goldmark/ast"
+)
+
+// A FootnoteLink struct represents a link to a footnote of Markdown
+// (PHP Markdown Extra) text.
+type FootnoteLink struct {
+	gast.BaseInline
+	Index    int
+	RefCount int
+	RefIndex int
+}
+
+// Dump implements Node.Dump.
+func (n *FootnoteLink) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Index"] = fmt.Sprintf("%v", n.Index)
+	m["RefCount"] = fmt.Sprintf("%v", n.RefCount)
+	m["RefIndex"] = fmt.Sprintf("%v", n.RefIndex)
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindFootnoteLink is a NodeKind of the FootnoteLink node.
+var KindFootnoteLink = gast.NewNodeKind("FootnoteLink")
+
+// Kind implements Node.Kind.
+func (n *FootnoteLink) Kind() gast.NodeKind {
+	return KindFootnoteLink
+}
+
+// NewFootnoteLink returns a new FootnoteLink node.
+func NewFootnoteLink(index int) *FootnoteLink {
+	return &FootnoteLink{
+		Index:    index,
+		RefCount: 0,
+		RefIndex: 0,
+	}
+}
+
+// A FootnoteBacklink struct represents a link to a footnote of Markdown
+// (PHP Markdown Extra) text.
+type FootnoteBacklink struct {
+	gast.BaseInline
+	Index    int
+	RefCount int
+	RefIndex int
+}
+
+// Dump implements Node.Dump.
+func (n *FootnoteBacklink) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Index"] = fmt.Sprintf("%v", n.Index)
+	m["RefCount"] = fmt.Sprintf("%v", n.RefCount)
+	m["RefIndex"] = fmt.Sprintf("%v", n.RefIndex)
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindFootnoteBacklink is a NodeKind of the FootnoteBacklink node.
+var KindFootnoteBacklink = gast.NewNodeKind("FootnoteBacklink")
+
+// Kind implements Node.Kind.
+func (n *FootnoteBacklink) Kind() gast.NodeKind {
+	return KindFootnoteBacklink
+}
+
+// NewFootnoteBacklink returns a new FootnoteBacklink node.
+func NewFootnoteBacklink(index int) *FootnoteBacklink {
+	return &FootnoteBacklink{
+		Index:    index,
+		RefCount: 0,
+		RefIndex: 0,
+	}
+}
+
+// A Footnote struct represents a footnote of Markdown
+// (PHP Markdown Extra) text.
+type Footnote struct {
+	gast.BaseBlock
+	Ref   []byte
+	Index int
+}
+
+// Dump implements Node.Dump.
+func (n *Footnote) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Index"] = fmt.Sprintf("%v", n.Index)
+	m["Ref"] = fmt.Sprintf("%s", n.Ref)
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindFootnote is a NodeKind of the Footnote node.
+var KindFootnote = gast.NewNodeKind("Footnote")
+
+// Kind implements Node.Kind.
+func (n *Footnote) Kind() gast.NodeKind {
+	return KindFootnote
+}
+
+// NewFootnote returns a new Footnote node.
+func NewFootnote(ref []byte) *Footnote {
+	return &Footnote{
+		Ref:   ref,
+		Index: -1,
+	}
+}
+
+// A FootnoteList struct represents footnotes of Markdown
+// (PHP Markdown Extra) text.
+type FootnoteList struct {
+	gast.BaseBlock
+	Count int
+}
+
+// Dump implements Node.Dump.
+func (n *FootnoteList) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Count"] = fmt.Sprintf("%v", n.Count)
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindFootnoteList is a NodeKind of the FootnoteList node.
+var KindFootnoteList = gast.NewNodeKind("FootnoteList")
+
+// Kind implements Node.Kind.
+func (n *FootnoteList) Kind() gast.NodeKind {
+	return KindFootnoteList
+}
+
+// NewFootnoteList returns a new FootnoteList node.
+func NewFootnoteList() *FootnoteList {
+	return &FootnoteList{
+		Count: 0,
+	}
+}

vendor/github.com/yuin/goldmark/extension/ast/strikethrough.go

@@ -0,0 +1,29 @@
+// Package ast defines AST nodes that represents extension's elements
+package ast
+
+import (
+	gast "github.com/yuin/goldmark/ast"
+)
+
+// A Strikethrough struct represents a strikethrough of GFM text.
+type Strikethrough struct {
+	gast.BaseInline
+}
+
+// Dump implements Node.Dump.
+func (n *Strikethrough) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindStrikethrough is a NodeKind of the Strikethrough node.
+var KindStrikethrough = gast.NewNodeKind("Strikethrough")
+
+// Kind implements Node.Kind.
+func (n *Strikethrough) Kind() gast.NodeKind {
+	return KindStrikethrough
+}
+
+// NewStrikethrough returns a new Strikethrough node.
+func NewStrikethrough() *Strikethrough {
+	return &Strikethrough{}
+}

vendor/github.com/yuin/goldmark/extension/ast/table.go

@@ -0,0 +1,157 @@
+package ast
+
+import (
+	"fmt"
+	gast "github.com/yuin/goldmark/ast"
+	"strings"
+)
+
+// Alignment is a text alignment of table cells.
+type Alignment int
+
+const (
+	// AlignLeft indicates text should be left justified.
+	AlignLeft Alignment = iota + 1
+
+	// AlignRight indicates text should be right justified.
+	AlignRight
+
+	// AlignCenter indicates text should be centered.
+	AlignCenter
+
+	// AlignNone indicates text should be aligned by default manner.
+	AlignNone
+)
+
+func (a Alignment) String() string {
+	switch a {
+	case AlignLeft:
+		return "left"
+	case AlignRight:
+		return "right"
+	case AlignCenter:
+		return "center"
+	case AlignNone:
+		return "none"
+	}
+	return ""
+}
+
+// A Table struct represents a table of Markdown(GFM) text.
+type Table struct {
+	gast.BaseBlock
+
+	// Alignments returns alignments of the columns.
+	Alignments []Alignment
+}
+
+// Dump implements Node.Dump
+func (n *Table) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, func(level int) {
+		indent := strings.Repeat("    ", level)
+		fmt.Printf("%sAlignments {\n", indent)
+		for i, alignment := range n.Alignments {
+			indent2 := strings.Repeat("    ", level+1)
+			fmt.Printf("%s%s", indent2, alignment.String())
+			if i != len(n.Alignments)-1 {
+				fmt.Println("")
+			}
+		}
+		fmt.Printf("\n%s}\n", indent)
+	})
+}
+
+// KindTable is a NodeKind of the Table node.
+var KindTable = gast.NewNodeKind("Table")
+
+// Kind implements Node.Kind.
+func (n *Table) Kind() gast.NodeKind {
+	return KindTable
+}
+
+// NewTable returns a new Table node.
+func NewTable() *Table {
+	return &Table{
+		Alignments: []Alignment{},
+	}
+}
+
+// A TableRow struct represents a table row of Markdown(GFM) text.
+type TableRow struct {
+	gast.BaseBlock
+	Alignments []Alignment
+}
+
+// Dump implements Node.Dump.
+func (n *TableRow) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindTableRow is a NodeKind of the TableRow node.
+var KindTableRow = gast.NewNodeKind("TableRow")
+
+// Kind implements Node.Kind.
+func (n *TableRow) Kind() gast.NodeKind {
+	return KindTableRow
+}
+
+// NewTableRow returns a new TableRow node.
+func NewTableRow(alignments []Alignment) *TableRow {
+	return &TableRow{Alignments: alignments}
+}
+
+// A TableHeader struct represents a table header of Markdown(GFM) text.
+type TableHeader struct {
+	gast.BaseBlock
+	Alignments []Alignment
+}
+
+// KindTableHeader is a NodeKind of the TableHeader node.
+var KindTableHeader = gast.NewNodeKind("TableHeader")
+
+// Kind implements Node.Kind.
+func (n *TableHeader) Kind() gast.NodeKind {
+	return KindTableHeader
+}
+
+// Dump implements Node.Dump.
+func (n *TableHeader) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// NewTableHeader returns a new TableHeader node.
+func NewTableHeader(row *TableRow) *TableHeader {
+	n := &TableHeader{}
+	for c := row.FirstChild(); c != nil; {
+		next := c.NextSibling()
+		n.AppendChild(n, c)
+		c = next
+	}
+	return n
+}
+
+// A TableCell struct represents a table cell of a Markdown(GFM) text.
+type TableCell struct {
+	gast.BaseBlock
+	Alignment Alignment
+}
+
+// Dump implements Node.Dump.
+func (n *TableCell) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindTableCell is a NodeKind of the TableCell node.
+var KindTableCell = gast.NewNodeKind("TableCell")
+
+// Kind implements Node.Kind.
+func (n *TableCell) Kind() gast.NodeKind {
+	return KindTableCell
+}
+
+// NewTableCell returns a new TableCell node.
+func NewTableCell() *TableCell {
+	return &TableCell{
+		Alignment: AlignNone,
+	}
+}

vendor/github.com/yuin/goldmark/extension/ast/tasklist.go

@@ -0,0 +1,35 @@
+package ast
+
+import (
+	"fmt"
+	gast "github.com/yuin/goldmark/ast"
+)
+
+// A TaskCheckBox struct represents a checkbox of a task list.
+type TaskCheckBox struct {
+	gast.BaseInline
+	IsChecked bool
+}
+
+// Dump implements Node.Dump.
+func (n *TaskCheckBox) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Checked": fmt.Sprintf("%v", n.IsChecked),
+	}
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindTaskCheckBox is a NodeKind of the TaskCheckBox node.
+var KindTaskCheckBox = gast.NewNodeKind("TaskCheckBox")
+
+// Kind implements Node.Kind.
+func (n *TaskCheckBox) Kind() gast.NodeKind {
+	return KindTaskCheckBox
+}
+
+// NewTaskCheckBox returns a new TaskCheckBox node.
+func NewTaskCheckBox(checked bool) *TaskCheckBox {
+	return &TaskCheckBox{
+		IsChecked: checked,
+	}
+}

vendor/github.com/yuin/goldmark/extension/cjk.go

@@ -0,0 +1,51 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer/html"
+)
+
+// A CJKOption sets options for CJK support mostly for HTML based renderers.
+type CJKOption func(*cjk)
+
+// WithEastAsianLineBreaks is a functional option that indicates whether softline breaks
+// between east asian wide characters should be ignored.
+func WithEastAsianLineBreaks() CJKOption {
+	return func(c *cjk) {
+		c.EastAsianLineBreaks = true
+	}
+}
+
+// WithEscapedSpace is a functional option that indicates that a '\' escaped half-space(0x20) should not be rendered.
+func WithEscapedSpace() CJKOption {
+	return func(c *cjk) {
+		c.EscapedSpace = true
+	}
+}
+
+type cjk struct {
+	EastAsianLineBreaks bool
+	EscapedSpace        bool
+}
+
+var CJK = NewCJK(WithEastAsianLineBreaks(), WithEscapedSpace())
+
+// NewCJK returns a new extension with given options.
+func NewCJK(opts ...CJKOption) goldmark.Extender {
+	e := &cjk{}
+	for _, opt := range opts {
+		opt(e)
+	}
+	return e
+}
+
+func (e *cjk) Extend(m goldmark.Markdown) {
+	if e.EastAsianLineBreaks {
+		m.Renderer().AddOptions(html.WithEastAsianLineBreaks())
+	}
+	if e.EscapedSpace {
+		m.Renderer().AddOptions(html.WithWriter(html.NewWriter(html.WithEscapedSpace())))
+		m.Parser().AddOptions(parser.WithEscapedSpace())
+	}
+}

vendor/github.com/yuin/goldmark/extension/definition_list.go

@@ -0,0 +1,270 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type definitionListParser struct {
+}
+
+var defaultDefinitionListParser = &definitionListParser{}
+
+// NewDefinitionListParser return a new parser.BlockParser that
+// can parse PHP Markdown Extra Definition lists.
+func NewDefinitionListParser() parser.BlockParser {
+	return defaultDefinitionListParser
+}
+
+func (b *definitionListParser) Trigger() []byte {
+	return []byte{':'}
+}
+
+func (b *definitionListParser) Open(parent gast.Node, reader text.Reader, pc parser.Context) (gast.Node, parser.State) {
+	if _, ok := parent.(*ast.DefinitionList); ok {
+		return nil, parser.NoChildren
+	}
+	line, _ := reader.PeekLine()
+	pos := pc.BlockOffset()
+	indent := pc.BlockIndent()
+	if pos < 0 || line[pos] != ':' || indent != 0 {
+		return nil, parser.NoChildren
+	}
+
+	last := parent.LastChild()
+	// need 1 or more spaces after ':'
+	w, _ := util.IndentWidth(line[pos+1:], pos+1)
+	if w < 1 {
+		return nil, parser.NoChildren
+	}
+	if w >= 8 { // starts with indented code
+		w = 5
+	}
+	w += pos + 1 /* 1 = ':' */
+
+	para, lastIsParagraph := last.(*gast.Paragraph)
+	var list *ast.DefinitionList
+	status := parser.HasChildren
+	var ok bool
+	if lastIsParagraph {
+		list, ok = last.PreviousSibling().(*ast.DefinitionList)
+		if ok { // is not first item
+			list.Offset = w
+			list.TemporaryParagraph = para
+		} else { // is first item
+			list = ast.NewDefinitionList(w, para)
+			status |= parser.RequireParagraph
+		}
+	} else if list, ok = last.(*ast.DefinitionList); ok { // multiple description
+		list.Offset = w
+		list.TemporaryParagraph = nil
+	} else {
+		return nil, parser.NoChildren
+	}
+
+	return list, status
+}
+
+func (b *definitionListParser) Continue(node gast.Node, reader text.Reader, pc parser.Context) parser.State {
+	line, _ := reader.PeekLine()
+	if util.IsBlank(line) {
+		return parser.Continue | parser.HasChildren
+	}
+	list, _ := node.(*ast.DefinitionList)
+	w, _ := util.IndentWidth(line, reader.LineOffset())
+	if w < list.Offset {
+		return parser.Close
+	}
+	pos, padding := util.IndentPosition(line, reader.LineOffset(), list.Offset)
+	reader.AdvanceAndSetPadding(pos, padding)
+	return parser.Continue | parser.HasChildren
+}
+
+func (b *definitionListParser) Close(node gast.Node, reader text.Reader, pc parser.Context) {
+	// nothing to do
+}
+
+func (b *definitionListParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *definitionListParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+type definitionDescriptionParser struct {
+}
+
+var defaultDefinitionDescriptionParser = &definitionDescriptionParser{}
+
+// NewDefinitionDescriptionParser return a new parser.BlockParser that
+// can parse definition description starts with ':'.
+func NewDefinitionDescriptionParser() parser.BlockParser {
+	return defaultDefinitionDescriptionParser
+}
+
+func (b *definitionDescriptionParser) Trigger() []byte {
+	return []byte{':'}
+}
+
+func (b *definitionDescriptionParser) Open(parent gast.Node, reader text.Reader, pc parser.Context) (gast.Node, parser.State) {
+	line, _ := reader.PeekLine()
+	pos := pc.BlockOffset()
+	indent := pc.BlockIndent()
+	if pos < 0 || line[pos] != ':' || indent != 0 {
+		return nil, parser.NoChildren
+	}
+	list, _ := parent.(*ast.DefinitionList)
+	if list == nil {
+		return nil, parser.NoChildren
+	}
+	para := list.TemporaryParagraph
+	list.TemporaryParagraph = nil
+	if para != nil {
+		lines := para.Lines()
+		l := lines.Len()
+		for i := 0; i < l; i++ {
+			term := ast.NewDefinitionTerm()
+			segment := lines.At(i)
+			term.Lines().Append(segment.TrimRightSpace(reader.Source()))
+			list.AppendChild(list, term)
+		}
+		para.Parent().RemoveChild(para.Parent(), para)
+	}
+	cpos, padding := util.IndentPosition(line[pos+1:], pos+1, list.Offset-pos-1)
+	reader.AdvanceAndSetPadding(cpos+1, padding)
+
+	return ast.NewDefinitionDescription(), parser.HasChildren
+}
+
+func (b *definitionDescriptionParser) Continue(node gast.Node, reader text.Reader, pc parser.Context) parser.State {
+	// definitionListParser detects end of the description.
+	// so this method will never be called.
+	return parser.Continue | parser.HasChildren
+}
+
+func (b *definitionDescriptionParser) Close(node gast.Node, reader text.Reader, pc parser.Context) {
+	desc := node.(*ast.DefinitionDescription)
+	desc.IsTight = !desc.HasBlankPreviousLines()
+	if desc.IsTight {
+		for gc := desc.FirstChild(); gc != nil; gc = gc.NextSibling() {
+			paragraph, ok := gc.(*gast.Paragraph)
+			if ok {
+				textBlock := gast.NewTextBlock()
+				textBlock.SetLines(paragraph.Lines())
+				desc.ReplaceChild(desc, paragraph, textBlock)
+			}
+		}
+	}
+}
+
+func (b *definitionDescriptionParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *definitionDescriptionParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+// DefinitionListHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders DefinitionList nodes.
+type DefinitionListHTMLRenderer struct {
+	html.Config
+}
+
+// NewDefinitionListHTMLRenderer returns a new DefinitionListHTMLRenderer.
+func NewDefinitionListHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &DefinitionListHTMLRenderer{
+		Config: html.NewConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *DefinitionListHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindDefinitionList, r.renderDefinitionList)
+	reg.Register(ast.KindDefinitionTerm, r.renderDefinitionTerm)
+	reg.Register(ast.KindDefinitionDescription, r.renderDefinitionDescription)
+}
+
+// DefinitionListAttributeFilter defines attribute names which dl elements can have.
+var DefinitionListAttributeFilter = html.GlobalAttributeFilter
+
+func (r *DefinitionListHTMLRenderer) renderDefinitionList(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<dl")
+			html.RenderAttributes(w, n, DefinitionListAttributeFilter)
+			_, _ = w.WriteString(">\n")
+		} else {
+			_, _ = w.WriteString("<dl>\n")
+		}
+	} else {
+		_, _ = w.WriteString("</dl>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+// DefinitionTermAttributeFilter defines attribute names which dd elements can have.
+var DefinitionTermAttributeFilter = html.GlobalAttributeFilter
+
+func (r *DefinitionListHTMLRenderer) renderDefinitionTerm(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<dt")
+			html.RenderAttributes(w, n, DefinitionTermAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<dt>")
+		}
+	} else {
+		_, _ = w.WriteString("</dt>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+// DefinitionDescriptionAttributeFilter defines attribute names which dd elements can have.
+var DefinitionDescriptionAttributeFilter = html.GlobalAttributeFilter
+
+func (r *DefinitionListHTMLRenderer) renderDefinitionDescription(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		n := node.(*ast.DefinitionDescription)
+		_, _ = w.WriteString("<dd")
+		if n.Attributes() != nil {
+			html.RenderAttributes(w, n, DefinitionDescriptionAttributeFilter)
+		}
+		if n.IsTight {
+			_, _ = w.WriteString(">")
+		} else {
+			_, _ = w.WriteString(">\n")
+		}
+	} else {
+		_, _ = w.WriteString("</dd>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+type definitionList struct {
+}
+
+// DefinitionList is an extension that allow you to use PHP Markdown Extra Definition lists.
+var DefinitionList = &definitionList{}
+
+func (e *definitionList) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithBlockParsers(
+		util.Prioritized(NewDefinitionListParser(), 101),
+		util.Prioritized(NewDefinitionDescriptionParser(), 102),
+	))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewDefinitionListHTMLRenderer(), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/footnote.go

@@ -0,0 +1,687 @@
+package extension
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var footnoteListKey = parser.NewContextKey()
+var footnoteLinkListKey = parser.NewContextKey()
+
+type footnoteBlockParser struct {
+}
+
+var defaultFootnoteBlockParser = &footnoteBlockParser{}
+
+// NewFootnoteBlockParser returns a new parser.BlockParser that can parse
+// footnotes of the Markdown(PHP Markdown Extra) text.
+func NewFootnoteBlockParser() parser.BlockParser {
+	return defaultFootnoteBlockParser
+}
+
+func (b *footnoteBlockParser) Trigger() []byte {
+	return []byte{'['}
+}
+
+func (b *footnoteBlockParser) Open(parent gast.Node, reader text.Reader, pc parser.Context) (gast.Node, parser.State) {
+	line, segment := reader.PeekLine()
+	pos := pc.BlockOffset()
+	if pos < 0 || line[pos] != '[' {
+		return nil, parser.NoChildren
+	}
+	pos++
+	if pos > len(line)-1 || line[pos] != '^' {
+		return nil, parser.NoChildren
+	}
+	open := pos + 1
+	closes := 0
+	closure := util.FindClosure(line[pos+1:], '[', ']', false, false)
+	closes = pos + 1 + closure
+	next := closes + 1
+	if closure > -1 {
+		if next >= len(line) || line[next] != ':' {
+			return nil, parser.NoChildren
+		}
+	} else {
+		return nil, parser.NoChildren
+	}
+	padding := segment.Padding
+	label := reader.Value(text.NewSegment(segment.Start+open-padding, segment.Start+closes-padding))
+	if util.IsBlank(label) {
+		return nil, parser.NoChildren
+	}
+	item := ast.NewFootnote(label)
+
+	pos = next + 1 - padding
+	if pos >= len(line) {
+		reader.Advance(pos)
+		return item, parser.NoChildren
+	}
+	reader.AdvanceAndSetPadding(pos, padding)
+	return item, parser.HasChildren
+}
+
+func (b *footnoteBlockParser) Continue(node gast.Node, reader text.Reader, pc parser.Context) parser.State {
+	line, _ := reader.PeekLine()
+	if util.IsBlank(line) {
+		return parser.Continue | parser.HasChildren
+	}
+	childpos, padding := util.IndentPosition(line, reader.LineOffset(), 4)
+	if childpos < 0 {
+		return parser.Close
+	}
+	reader.AdvanceAndSetPadding(childpos, padding)
+	return parser.Continue | parser.HasChildren
+}
+
+func (b *footnoteBlockParser) Close(node gast.Node, reader text.Reader, pc parser.Context) {
+	var list *ast.FootnoteList
+	if tlist := pc.Get(footnoteListKey); tlist != nil {
+		list = tlist.(*ast.FootnoteList)
+	} else {
+		list = ast.NewFootnoteList()
+		pc.Set(footnoteListKey, list)
+		node.Parent().InsertBefore(node.Parent(), node, list)
+	}
+	node.Parent().RemoveChild(node.Parent(), node)
+	list.AppendChild(list, node)
+}
+
+func (b *footnoteBlockParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *footnoteBlockParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+type footnoteParser struct {
+}
+
+var defaultFootnoteParser = &footnoteParser{}
+
+// NewFootnoteParser returns a new parser.InlineParser that can parse
+// footnote links of the Markdown(PHP Markdown Extra) text.
+func NewFootnoteParser() parser.InlineParser {
+	return defaultFootnoteParser
+}
+
+func (s *footnoteParser) Trigger() []byte {
+	// footnote syntax probably conflict with the image syntax.
+	// So we need trigger this parser with '!'.
+	return []byte{'!', '['}
+}
+
+func (s *footnoteParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+	line, segment := block.PeekLine()
+	pos := 1
+	if len(line) > 0 && line[0] == '!' {
+		pos++
+	}
+	if pos >= len(line) || line[pos] != '^' {
+		return nil
+	}
+	pos++
+	if pos >= len(line) {
+		return nil
+	}
+	open := pos
+	closure := util.FindClosure(line[pos:], '[', ']', false, false)
+	if closure < 0 {
+		return nil
+	}
+	closes := pos + closure
+	value := block.Value(text.NewSegment(segment.Start+open, segment.Start+closes))
+	block.Advance(closes + 1)
+
+	var list *ast.FootnoteList
+	if tlist := pc.Get(footnoteListKey); tlist != nil {
+		list = tlist.(*ast.FootnoteList)
+	}
+	if list == nil {
+		return nil
+	}
+	index := 0
+	for def := list.FirstChild(); def != nil; def = def.NextSibling() {
+		d := def.(*ast.Footnote)
+		if bytes.Equal(d.Ref, value) {
+			if d.Index < 0 {
+				list.Count += 1
+				d.Index = list.Count
+			}
+			index = d.Index
+			break
+		}
+	}
+	if index == 0 {
+		return nil
+	}
+
+	fnlink := ast.NewFootnoteLink(index)
+	var fnlist []*ast.FootnoteLink
+	if tmp := pc.Get(footnoteLinkListKey); tmp != nil {
+		fnlist = tmp.([]*ast.FootnoteLink)
+	} else {
+		fnlist = []*ast.FootnoteLink{}
+		pc.Set(footnoteLinkListKey, fnlist)
+	}
+	pc.Set(footnoteLinkListKey, append(fnlist, fnlink))
+	if line[0] == '!' {
+		parent.AppendChild(parent, gast.NewTextSegment(text.NewSegment(segment.Start, segment.Start+1)))
+	}
+
+	return fnlink
+}
+
+type footnoteASTTransformer struct {
+}
+
+var defaultFootnoteASTTransformer = &footnoteASTTransformer{}
+
+// NewFootnoteASTTransformer returns a new parser.ASTTransformer that
+// insert a footnote list to the last of the document.
+func NewFootnoteASTTransformer() parser.ASTTransformer {
+	return defaultFootnoteASTTransformer
+}
+
+func (a *footnoteASTTransformer) Transform(node *gast.Document, reader text.Reader, pc parser.Context) {
+	var list *ast.FootnoteList
+	var fnlist []*ast.FootnoteLink
+	if tmp := pc.Get(footnoteListKey); tmp != nil {
+		list = tmp.(*ast.FootnoteList)
+	}
+	if tmp := pc.Get(footnoteLinkListKey); tmp != nil {
+		fnlist = tmp.([]*ast.FootnoteLink)
+	}
+
+	pc.Set(footnoteListKey, nil)
+	pc.Set(footnoteLinkListKey, nil)
+
+	if list == nil {
+		return
+	}
+
+	counter := map[int]int{}
+	if fnlist != nil {
+		for _, fnlink := range fnlist {
+			if fnlink.Index >= 0 {
+				counter[fnlink.Index]++
+			}
+		}
+		refCounter := map[int]int{}
+		for _, fnlink := range fnlist {
+			fnlink.RefCount = counter[fnlink.Index]
+			if _, ok := refCounter[fnlink.Index]; !ok {
+				refCounter[fnlink.Index] = 0
+			}
+			fnlink.RefIndex = refCounter[fnlink.Index]
+			refCounter[fnlink.Index]++
+		}
+	}
+	for footnote := list.FirstChild(); footnote != nil; {
+		var container gast.Node = footnote
+		next := footnote.NextSibling()
+		if fc := container.LastChild(); fc != nil && gast.IsParagraph(fc) {
+			container = fc
+		}
+		fn := footnote.(*ast.Footnote)
+		index := fn.Index
+		if index < 0 {
+			list.RemoveChild(list, footnote)
+		} else {
+			refCount := counter[index]
+			backLink := ast.NewFootnoteBacklink(index)
+			backLink.RefCount = refCount
+			backLink.RefIndex = 0
+			container.AppendChild(container, backLink)
+			if refCount > 1 {
+				for i := 1; i < refCount; i++ {
+					backLink := ast.NewFootnoteBacklink(index)
+					backLink.RefCount = refCount
+					backLink.RefIndex = i
+					container.AppendChild(container, backLink)
+				}
+			}
+		}
+		footnote = next
+	}
+	list.SortChildren(func(n1, n2 gast.Node) int {
+		if n1.(*ast.Footnote).Index < n2.(*ast.Footnote).Index {
+			return -1
+		}
+		return 1
+	})
+	if list.Count <= 0 {
+		list.Parent().RemoveChild(list.Parent(), list)
+		return
+	}
+
+	node.AppendChild(node, list)
+}
+
+// FootnoteConfig holds configuration values for the footnote extension.
+//
+// Link* and Backlink* configurations have some variables:
+// Occurrances of “^^” in the string will be replaced by the
+// corresponding footnote number in the HTML output.
+// Occurrances of “%%” will be replaced by a number for the
+// reference (footnotes can have multiple references).
+type FootnoteConfig struct {
+	html.Config
+
+	// IDPrefix is a prefix for the id attributes generated by footnotes.
+	IDPrefix []byte
+
+	// IDPrefix is a function that determines the id attribute for given Node.
+	IDPrefixFunction func(gast.Node) []byte
+
+	// LinkTitle is an optional title attribute for footnote links.
+	LinkTitle []byte
+
+	// BacklinkTitle is an optional title attribute for footnote backlinks.
+	BacklinkTitle []byte
+
+	// LinkClass is a class for footnote links.
+	LinkClass []byte
+
+	// BacklinkClass is a class for footnote backlinks.
+	BacklinkClass []byte
+
+	// BacklinkHTML is an HTML content for footnote backlinks.
+	BacklinkHTML []byte
+}
+
+// FootnoteOption interface is a functional option interface for the extension.
+type FootnoteOption interface {
+	renderer.Option
+	// SetFootnoteOption sets given option to the extension.
+	SetFootnoteOption(*FootnoteConfig)
+}
+
+// NewFootnoteConfig returns a new Config with defaults.
+func NewFootnoteConfig() FootnoteConfig {
+	return FootnoteConfig{
+		Config:        html.NewConfig(),
+		LinkTitle:     []byte(""),
+		BacklinkTitle: []byte(""),
+		LinkClass:     []byte("footnote-ref"),
+		BacklinkClass: []byte("footnote-backref"),
+		BacklinkHTML:  []byte("&#x21a9;&#xfe0e;"),
+	}
+}
+
+// SetOption implements renderer.SetOptioner.
+func (c *FootnoteConfig) SetOption(name renderer.OptionName, value interface{}) {
+	switch name {
+	case optFootnoteIDPrefixFunction:
+		c.IDPrefixFunction = value.(func(gast.Node) []byte)
+	case optFootnoteIDPrefix:
+		c.IDPrefix = value.([]byte)
+	case optFootnoteLinkTitle:
+		c.LinkTitle = value.([]byte)
+	case optFootnoteBacklinkTitle:
+		c.BacklinkTitle = value.([]byte)
+	case optFootnoteLinkClass:
+		c.LinkClass = value.([]byte)
+	case optFootnoteBacklinkClass:
+		c.BacklinkClass = value.([]byte)
+	case optFootnoteBacklinkHTML:
+		c.BacklinkHTML = value.([]byte)
+	default:
+		c.Config.SetOption(name, value)
+	}
+}
+
+type withFootnoteHTMLOptions struct {
+	value []html.Option
+}
+
+func (o *withFootnoteHTMLOptions) SetConfig(c *renderer.Config) {
+	if o.value != nil {
+		for _, v := range o.value {
+			v.(renderer.Option).SetConfig(c)
+		}
+	}
+}
+
+func (o *withFootnoteHTMLOptions) SetFootnoteOption(c *FootnoteConfig) {
+	if o.value != nil {
+		for _, v := range o.value {
+			v.SetHTMLOption(&c.Config)
+		}
+	}
+}
+
+// WithFootnoteHTMLOptions is functional option that wraps goldmark HTMLRenderer options.
+func WithFootnoteHTMLOptions(opts ...html.Option) FootnoteOption {
+	return &withFootnoteHTMLOptions{opts}
+}
+
+const optFootnoteIDPrefix renderer.OptionName = "FootnoteIDPrefix"
+
+type withFootnoteIDPrefix struct {
+	value []byte
+}
+
+func (o *withFootnoteIDPrefix) SetConfig(c *renderer.Config) {
+	c.Options[optFootnoteIDPrefix] = o.value
+}
+
+func (o *withFootnoteIDPrefix) SetFootnoteOption(c *FootnoteConfig) {
+	c.IDPrefix = o.value
+}
+
+// WithFootnoteIDPrefix is a functional option that is a prefix for the id attributes generated by footnotes.
+func WithFootnoteIDPrefix(a []byte) FootnoteOption {
+	return &withFootnoteIDPrefix{a}
+}
+
+const optFootnoteIDPrefixFunction renderer.OptionName = "FootnoteIDPrefixFunction"
+
+type withFootnoteIDPrefixFunction struct {
+	value func(gast.Node) []byte
+}
+
+func (o *withFootnoteIDPrefixFunction) SetConfig(c *renderer.Config) {
+	c.Options[optFootnoteIDPrefixFunction] = o.value
+}
+
+func (o *withFootnoteIDPrefixFunction) SetFootnoteOption(c *FootnoteConfig) {
+	c.IDPrefixFunction = o.value
+}
+
+// WithFootnoteIDPrefixFunction is a functional option that is a prefix for the id attributes generated by footnotes.
+func WithFootnoteIDPrefixFunction(a func(gast.Node) []byte) FootnoteOption {
+	return &withFootnoteIDPrefixFunction{a}
+}
+
+const optFootnoteLinkTitle renderer.OptionName = "FootnoteLinkTitle"
+
+type withFootnoteLinkTitle struct {
+	value []byte
+}
+
+func (o *withFootnoteLinkTitle) SetConfig(c *renderer.Config) {
+	c.Options[optFootnoteLinkTitle] = o.value
+}
+
+func (o *withFootnoteLinkTitle) SetFootnoteOption(c *FootnoteConfig) {
+	c.LinkTitle = o.value
+}
+
+// WithFootnoteLinkTitle is a functional option that is an optional title attribute for footnote links.
+func WithFootnoteLinkTitle(a []byte) FootnoteOption {
+	return &withFootnoteLinkTitle{a}
+}
+
+const optFootnoteBacklinkTitle renderer.OptionName = "FootnoteBacklinkTitle"
+
+type withFootnoteBacklinkTitle struct {
+	value []byte
+}
+
+func (o *withFootnoteBacklinkTitle) SetConfig(c *renderer.Config) {
+	c.Options[optFootnoteBacklinkTitle] = o.value
+}
+
+func (o *withFootnoteBacklinkTitle) SetFootnoteOption(c *FootnoteConfig) {
+	c.BacklinkTitle = o.value
+}
+
+// WithFootnoteBacklinkTitle is a functional option that is an optional title attribute for footnote backlinks.
+func WithFootnoteBacklinkTitle(a []byte) FootnoteOption {
+	return &withFootnoteBacklinkTitle{a}
+}
+
+const optFootnoteLinkClass renderer.OptionName = "FootnoteLinkClass"
+
+type withFootnoteLinkClass struct {
+	value []byte
+}
+
+func (o *withFootnoteLinkClass) SetConfig(c *renderer.Config) {
+	c.Options[optFootnoteLinkClass] = o.value
+}
+
+func (o *withFootnoteLinkClass) SetFootnoteOption(c *FootnoteConfig) {
+	c.LinkClass = o.value
+}
+
+// WithFootnoteLinkClass is a functional option that is a class for footnote links.
+func WithFootnoteLinkClass(a []byte) FootnoteOption {
+	return &withFootnoteLinkClass{a}
+}
+
+const optFootnoteBacklinkClass renderer.OptionName = "FootnoteBacklinkClass"
+
+type withFootnoteBacklinkClass struct {
+	value []byte
+}
+
+func (o *withFootnoteBacklinkClass) SetConfig(c *renderer.Config) {
+	c.Options[optFootnoteBacklinkClass] = o.value
+}
+
+func (o *withFootnoteBacklinkClass) SetFootnoteOption(c *FootnoteConfig) {
+	c.BacklinkClass = o.value
+}
+
+// WithFootnoteBacklinkClass is a functional option that is a class for footnote backlinks.
+func WithFootnoteBacklinkClass(a []byte) FootnoteOption {
+	return &withFootnoteBacklinkClass{a}
+}
+
+const optFootnoteBacklinkHTML renderer.OptionName = "FootnoteBacklinkHTML"
+
+type withFootnoteBacklinkHTML struct {
+	value []byte
+}
+
+func (o *withFootnoteBacklinkHTML) SetConfig(c *renderer.Config) {
+	c.Options[optFootnoteBacklinkHTML] = o.value
+}
+
+func (o *withFootnoteBacklinkHTML) SetFootnoteOption(c *FootnoteConfig) {
+	c.BacklinkHTML = o.value
+}
+
+// WithFootnoteBacklinkHTML is an HTML content for footnote backlinks.
+func WithFootnoteBacklinkHTML(a []byte) FootnoteOption {
+	return &withFootnoteBacklinkHTML{a}
+}
+
+// FootnoteHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders FootnoteLink nodes.
+type FootnoteHTMLRenderer struct {
+	FootnoteConfig
+}
+
+// NewFootnoteHTMLRenderer returns a new FootnoteHTMLRenderer.
+func NewFootnoteHTMLRenderer(opts ...FootnoteOption) renderer.NodeRenderer {
+	r := &FootnoteHTMLRenderer{
+		FootnoteConfig: NewFootnoteConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetFootnoteOption(&r.FootnoteConfig)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *FootnoteHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindFootnoteLink, r.renderFootnoteLink)
+	reg.Register(ast.KindFootnoteBacklink, r.renderFootnoteBacklink)
+	reg.Register(ast.KindFootnote, r.renderFootnote)
+	reg.Register(ast.KindFootnoteList, r.renderFootnoteList)
+}
+
+func (r *FootnoteHTMLRenderer) renderFootnoteLink(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		n := node.(*ast.FootnoteLink)
+		is := strconv.Itoa(n.Index)
+		_, _ = w.WriteString(`<sup id="`)
+		_, _ = w.Write(r.idPrefix(node))
+		_, _ = w.WriteString(`fnref`)
+		if n.RefIndex > 0 {
+			_, _ = w.WriteString(fmt.Sprintf("%v", n.RefIndex))
+		}
+		_ = w.WriteByte(':')
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`"><a href="#`)
+		_, _ = w.Write(r.idPrefix(node))
+		_, _ = w.WriteString(`fn:`)
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`" class="`)
+		_, _ = w.Write(applyFootnoteTemplate(r.FootnoteConfig.LinkClass,
+			n.Index, n.RefCount))
+		if len(r.FootnoteConfig.LinkTitle) > 0 {
+			_, _ = w.WriteString(`" title="`)
+			_, _ = w.Write(util.EscapeHTML(applyFootnoteTemplate(r.FootnoteConfig.LinkTitle, n.Index, n.RefCount)))
+		}
+		_, _ = w.WriteString(`" role="doc-noteref">`)
+
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`</a></sup>`)
+	}
+	return gast.WalkContinue, nil
+}
+
+func (r *FootnoteHTMLRenderer) renderFootnoteBacklink(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		n := node.(*ast.FootnoteBacklink)
+		is := strconv.Itoa(n.Index)
+		_, _ = w.WriteString(`&#160;<a href="#`)
+		_, _ = w.Write(r.idPrefix(node))
+		_, _ = w.WriteString(`fnref`)
+		if n.RefIndex > 0 {
+			_, _ = w.WriteString(fmt.Sprintf("%v", n.RefIndex))
+		}
+		_ = w.WriteByte(':')
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`" class="`)
+		_, _ = w.Write(applyFootnoteTemplate(r.FootnoteConfig.BacklinkClass, n.Index, n.RefCount))
+		if len(r.FootnoteConfig.BacklinkTitle) > 0 {
+			_, _ = w.WriteString(`" title="`)
+			_, _ = w.Write(util.EscapeHTML(applyFootnoteTemplate(r.FootnoteConfig.BacklinkTitle, n.Index, n.RefCount)))
+		}
+		_, _ = w.WriteString(`" role="doc-backlink">`)
+		_, _ = w.Write(applyFootnoteTemplate(r.FootnoteConfig.BacklinkHTML, n.Index, n.RefCount))
+		_, _ = w.WriteString(`</a>`)
+	}
+	return gast.WalkContinue, nil
+}
+
+func (r *FootnoteHTMLRenderer) renderFootnote(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	n := node.(*ast.Footnote)
+	is := strconv.Itoa(n.Index)
+	if entering {
+		_, _ = w.WriteString(`<li id="`)
+		_, _ = w.Write(r.idPrefix(node))
+		_, _ = w.WriteString(`fn:`)
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`"`)
+		if node.Attributes() != nil {
+			html.RenderAttributes(w, node, html.ListItemAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+	} else {
+		_, _ = w.WriteString("</li>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+func (r *FootnoteHTMLRenderer) renderFootnoteList(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		_, _ = w.WriteString(`<div class="footnotes" role="doc-endnotes"`)
+		if node.Attributes() != nil {
+			html.RenderAttributes(w, node, html.GlobalAttributeFilter)
+		}
+		_ = w.WriteByte('>')
+		if r.Config.XHTML {
+			_, _ = w.WriteString("\n<hr />\n")
+		} else {
+			_, _ = w.WriteString("\n<hr>\n")
+		}
+		_, _ = w.WriteString("<ol>\n")
+	} else {
+		_, _ = w.WriteString("</ol>\n")
+		_, _ = w.WriteString("</div>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+func (r *FootnoteHTMLRenderer) idPrefix(node gast.Node) []byte {
+	if r.FootnoteConfig.IDPrefix != nil {
+		return r.FootnoteConfig.IDPrefix
+	}
+	if r.FootnoteConfig.IDPrefixFunction != nil {
+		return r.FootnoteConfig.IDPrefixFunction(node)
+	}
+	return []byte("")
+}
+
+func applyFootnoteTemplate(b []byte, index, refCount int) []byte {
+	fast := true
+	for i, c := range b {
+		if i != 0 {
+			if b[i-1] == '^' && c == '^' {
+				fast = false
+				break
+			}
+			if b[i-1] == '%' && c == '%' {
+				fast = false
+				break
+			}
+		}
+	}
+	if fast {
+		return b
+	}
+	is := []byte(strconv.Itoa(index))
+	rs := []byte(strconv.Itoa(refCount))
+	ret := bytes.Replace(b, []byte("^^"), is, -1)
+	return bytes.Replace(ret, []byte("%%"), rs, -1)
+}
+
+type footnote struct {
+	options []FootnoteOption
+}
+
+// Footnote is an extension that allow you to use PHP Markdown Extra Footnotes.
+var Footnote = &footnote{
+	options: []FootnoteOption{},
+}
+
+// NewFootnote returns a new extension with given options.
+func NewFootnote(opts ...FootnoteOption) goldmark.Extender {
+	return &footnote{
+		options: opts,
+	}
+}
+
+func (e *footnote) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithBlockParsers(
+			util.Prioritized(NewFootnoteBlockParser(), 999),
+		),
+		parser.WithInlineParsers(
+			util.Prioritized(NewFootnoteParser(), 101),
+		),
+		parser.WithASTTransformers(
+			util.Prioritized(NewFootnoteASTTransformer(), 999),
+		),
+	)
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewFootnoteHTMLRenderer(e.options...), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/gfm.go

@@ -0,0 +1,18 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+)
+
+type gfm struct {
+}
+
+// GFM is an extension that provides Github Flavored markdown functionalities.
+var GFM = &gfm{}
+
+func (e *gfm) Extend(m goldmark.Markdown) {
+	Linkify.Extend(m)
+	Table.Extend(m)
+	Strikethrough.Extend(m)
+	TaskList.Extend(m)
+}

vendor/github.com/yuin/goldmark/extension/linkify.go

@@ -0,0 +1,318 @@
+package extension
+
+import (
+	"bytes"
+	"regexp"
+
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var wwwURLRegxp = regexp.MustCompile(`^www\.[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-z]+(?:[/#?][-a-zA-Z0-9@:%_\+.~#!?&/=\(\);,'">\^{}\[\]` + "`" + `]*)?`)
+
+var urlRegexp = regexp.MustCompile(`^(?:http|https|ftp)://[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-z]+(?::\d+)?(?:[/#?][-a-zA-Z0-9@:%_+.~#$!?&/=\(\);,'">\^{}\[\]` + "`" + `]*)?`)
+
+// An LinkifyConfig struct is a data structure that holds configuration of the
+// Linkify extension.
+type LinkifyConfig struct {
+	AllowedProtocols [][]byte
+	URLRegexp        *regexp.Regexp
+	WWWRegexp        *regexp.Regexp
+	EmailRegexp      *regexp.Regexp
+}
+
+const (
+	optLinkifyAllowedProtocols parser.OptionName = "LinkifyAllowedProtocols"
+	optLinkifyURLRegexp        parser.OptionName = "LinkifyURLRegexp"
+	optLinkifyWWWRegexp        parser.OptionName = "LinkifyWWWRegexp"
+	optLinkifyEmailRegexp      parser.OptionName = "LinkifyEmailRegexp"
+)
+
+// SetOption implements SetOptioner.
+func (c *LinkifyConfig) SetOption(name parser.OptionName, value interface{}) {
+	switch name {
+	case optLinkifyAllowedProtocols:
+		c.AllowedProtocols = value.([][]byte)
+	case optLinkifyURLRegexp:
+		c.URLRegexp = value.(*regexp.Regexp)
+	case optLinkifyWWWRegexp:
+		c.WWWRegexp = value.(*regexp.Regexp)
+	case optLinkifyEmailRegexp:
+		c.EmailRegexp = value.(*regexp.Regexp)
+	}
+}
+
+// A LinkifyOption interface sets options for the LinkifyOption.
+type LinkifyOption interface {
+	parser.Option
+	SetLinkifyOption(*LinkifyConfig)
+}
+
+type withLinkifyAllowedProtocols struct {
+	value [][]byte
+}
+
+func (o *withLinkifyAllowedProtocols) SetParserOption(c *parser.Config) {
+	c.Options[optLinkifyAllowedProtocols] = o.value
+}
+
+func (o *withLinkifyAllowedProtocols) SetLinkifyOption(p *LinkifyConfig) {
+	p.AllowedProtocols = o.value
+}
+
+// WithLinkifyAllowedProtocols is a functional option that specify allowed
+// protocols in autolinks. Each protocol must end with ':' like
+// 'http:' .
+func WithLinkifyAllowedProtocols(value [][]byte) LinkifyOption {
+	return &withLinkifyAllowedProtocols{
+		value: value,
+	}
+}
+
+type withLinkifyURLRegexp struct {
+	value *regexp.Regexp
+}
+
+func (o *withLinkifyURLRegexp) SetParserOption(c *parser.Config) {
+	c.Options[optLinkifyURLRegexp] = o.value
+}
+
+func (o *withLinkifyURLRegexp) SetLinkifyOption(p *LinkifyConfig) {
+	p.URLRegexp = o.value
+}
+
+// WithLinkifyURLRegexp is a functional option that specify
+// a pattern of the URL including a protocol.
+func WithLinkifyURLRegexp(value *regexp.Regexp) LinkifyOption {
+	return &withLinkifyURLRegexp{
+		value: value,
+	}
+}
+
+// WithLinkifyWWWRegexp is a functional option that specify
+// a pattern of the URL without a protocol.
+// This pattern must start with 'www.' .
+type withLinkifyWWWRegexp struct {
+	value *regexp.Regexp
+}
+
+func (o *withLinkifyWWWRegexp) SetParserOption(c *parser.Config) {
+	c.Options[optLinkifyWWWRegexp] = o.value
+}
+
+func (o *withLinkifyWWWRegexp) SetLinkifyOption(p *LinkifyConfig) {
+	p.WWWRegexp = o.value
+}
+
+func WithLinkifyWWWRegexp(value *regexp.Regexp) LinkifyOption {
+	return &withLinkifyWWWRegexp{
+		value: value,
+	}
+}
+
+// WithLinkifyWWWRegexp is a functional otpion that specify
+// a pattern of the email address.
+type withLinkifyEmailRegexp struct {
+	value *regexp.Regexp
+}
+
+func (o *withLinkifyEmailRegexp) SetParserOption(c *parser.Config) {
+	c.Options[optLinkifyEmailRegexp] = o.value
+}
+
+func (o *withLinkifyEmailRegexp) SetLinkifyOption(p *LinkifyConfig) {
+	p.EmailRegexp = o.value
+}
+
+func WithLinkifyEmailRegexp(value *regexp.Regexp) LinkifyOption {
+	return &withLinkifyEmailRegexp{
+		value: value,
+	}
+}
+
+type linkifyParser struct {
+	LinkifyConfig
+}
+
+// NewLinkifyParser return a new InlineParser can parse
+// text that seems like a URL.
+func NewLinkifyParser(opts ...LinkifyOption) parser.InlineParser {
+	p := &linkifyParser{
+		LinkifyConfig: LinkifyConfig{
+			AllowedProtocols: nil,
+			URLRegexp:        urlRegexp,
+			WWWRegexp:        wwwURLRegxp,
+		},
+	}
+	for _, o := range opts {
+		o.SetLinkifyOption(&p.LinkifyConfig)
+	}
+	return p
+}
+
+func (s *linkifyParser) Trigger() []byte {
+	// ' ' indicates any white spaces and a line head
+	return []byte{' ', '*', '_', '~', '('}
+}
+
+var (
+	protoHTTP  = []byte("http:")
+	protoHTTPS = []byte("https:")
+	protoFTP   = []byte("ftp:")
+	domainWWW  = []byte("www.")
+)
+
+func (s *linkifyParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node {
+	if pc.IsInLinkLabel() {
+		return nil
+	}
+	line, segment := block.PeekLine()
+	consumes := 0
+	start := segment.Start
+	c := line[0]
+	// advance if current position is not a line head.
+	if c == ' ' || c == '*' || c == '_' || c == '~' || c == '(' {
+		consumes++
+		start++
+		line = line[1:]
+	}
+
+	var m []int
+	var protocol []byte
+	var typ ast.AutoLinkType = ast.AutoLinkURL
+	if s.LinkifyConfig.AllowedProtocols == nil {
+		if bytes.HasPrefix(line, protoHTTP) || bytes.HasPrefix(line, protoHTTPS) || bytes.HasPrefix(line, protoFTP) {
+			m = s.LinkifyConfig.URLRegexp.FindSubmatchIndex(line)
+		}
+	} else {
+		for _, prefix := range s.LinkifyConfig.AllowedProtocols {
+			if bytes.HasPrefix(line, prefix) {
+				m = s.LinkifyConfig.URLRegexp.FindSubmatchIndex(line)
+				break
+			}
+		}
+	}
+	if m == nil && bytes.HasPrefix(line, domainWWW) {
+		m = s.LinkifyConfig.WWWRegexp.FindSubmatchIndex(line)
+		protocol = []byte("http")
+	}
+	if m != nil && m[0] != 0 {
+		m = nil
+	}
+	if m != nil && m[0] == 0 {
+		lastChar := line[m[1]-1]
+		if lastChar == '.' {
+			m[1]--
+		} else if lastChar == ')' {
+			closing := 0
+			for i := m[1] - 1; i >= m[0]; i-- {
+				if line[i] == ')' {
+					closing++
+				} else if line[i] == '(' {
+					closing--
+				}
+			}
+			if closing > 0 {
+				m[1] -= closing
+			}
+		} else if lastChar == ';' {
+			i := m[1] - 2
+			for ; i >= m[0]; i-- {
+				if util.IsAlphaNumeric(line[i]) {
+					continue
+				}
+				break
+			}
+			if i != m[1]-2 {
+				if line[i] == '&' {
+					m[1] -= m[1] - i
+				}
+			}
+		}
+	}
+	if m == nil {
+		if len(line) > 0 && util.IsPunct(line[0]) {
+			return nil
+		}
+		typ = ast.AutoLinkEmail
+		stop := -1
+		if s.LinkifyConfig.EmailRegexp == nil {
+			stop = util.FindEmailIndex(line)
+		} else {
+			m := s.LinkifyConfig.EmailRegexp.FindSubmatchIndex(line)
+			if m != nil && m[0] == 0 {
+				stop = m[1]
+			}
+		}
+		if stop < 0 {
+			return nil
+		}
+		at := bytes.IndexByte(line, '@')
+		m = []int{0, stop, at, stop - 1}
+		if m == nil || bytes.IndexByte(line[m[2]:m[3]], '.') < 0 {
+			return nil
+		}
+		lastChar := line[m[1]-1]
+		if lastChar == '.' {
+			m[1]--
+		}
+		if m[1] < len(line) {
+			nextChar := line[m[1]]
+			if nextChar == '-' || nextChar == '_' {
+				return nil
+			}
+		}
+	}
+	if m == nil {
+		return nil
+	}
+	if consumes != 0 {
+		s := segment.WithStop(segment.Start + 1)
+		ast.MergeOrAppendTextSegment(parent, s)
+	}
+	i := m[1] - 1
+	for ; i > 0; i-- {
+		c := line[i]
+		switch c {
+		case '?', '!', '.', ',', ':', '*', '_', '~':
+		default:
+			goto endfor
+		}
+	}
+endfor:
+	i++
+	consumes += i
+	block.Advance(consumes)
+	n := ast.NewTextSegment(text.NewSegment(start, start+i))
+	link := ast.NewAutoLink(typ, n)
+	link.Protocol = protocol
+	return link
+}
+
+func (s *linkifyParser) CloseBlock(parent ast.Node, pc parser.Context) {
+	// nothing to do
+}
+
+type linkify struct {
+	options []LinkifyOption
+}
+
+// Linkify is an extension that allow you to parse text that seems like a URL.
+var Linkify = &linkify{}
+
+func NewLinkify(opts ...LinkifyOption) goldmark.Extender {
+	return &linkify{
+		options: opts,
+	}
+}
+
+func (e *linkify) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithInlineParsers(
+			util.Prioritized(NewLinkifyParser(e.options...), 999),
+		),
+	)
+}

vendor/github.com/yuin/goldmark/extension/strikethrough.go

@@ -0,0 +1,116 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type strikethroughDelimiterProcessor struct {
+}
+
+func (p *strikethroughDelimiterProcessor) IsDelimiter(b byte) bool {
+	return b == '~'
+}
+
+func (p *strikethroughDelimiterProcessor) CanOpenCloser(opener, closer *parser.Delimiter) bool {
+	return opener.Char == closer.Char
+}
+
+func (p *strikethroughDelimiterProcessor) OnMatch(consumes int) gast.Node {
+	return ast.NewStrikethrough()
+}
+
+var defaultStrikethroughDelimiterProcessor = &strikethroughDelimiterProcessor{}
+
+type strikethroughParser struct {
+}
+
+var defaultStrikethroughParser = &strikethroughParser{}
+
+// NewStrikethroughParser return a new InlineParser that parses
+// strikethrough expressions.
+func NewStrikethroughParser() parser.InlineParser {
+	return defaultStrikethroughParser
+}
+
+func (s *strikethroughParser) Trigger() []byte {
+	return []byte{'~'}
+}
+
+func (s *strikethroughParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+	before := block.PrecendingCharacter()
+	line, segment := block.PeekLine()
+	node := parser.ScanDelimiter(line, before, 2, defaultStrikethroughDelimiterProcessor)
+	if node == nil {
+		return nil
+	}
+	node.Segment = segment.WithStop(segment.Start + node.OriginalLength)
+	block.Advance(node.OriginalLength)
+	pc.PushDelimiter(node)
+	return node
+}
+
+func (s *strikethroughParser) CloseBlock(parent gast.Node, pc parser.Context) {
+	// nothing to do
+}
+
+// StrikethroughHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders Strikethrough nodes.
+type StrikethroughHTMLRenderer struct {
+	html.Config
+}
+
+// NewStrikethroughHTMLRenderer returns a new StrikethroughHTMLRenderer.
+func NewStrikethroughHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &StrikethroughHTMLRenderer{
+		Config: html.NewConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *StrikethroughHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindStrikethrough, r.renderStrikethrough)
+}
+
+// StrikethroughAttributeFilter defines attribute names which dd elements can have.
+var StrikethroughAttributeFilter = html.GlobalAttributeFilter
+
+func (r *StrikethroughHTMLRenderer) renderStrikethrough(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<del")
+			html.RenderAttributes(w, n, StrikethroughAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<del>")
+		}
+	} else {
+		_, _ = w.WriteString("</del>")
+	}
+	return gast.WalkContinue, nil
+}
+
+type strikethrough struct {
+}
+
+// Strikethrough is an extension that allow you to use strikethrough expression like '~~text~~' .
+var Strikethrough = &strikethrough{}
+
+func (e *strikethrough) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithInlineParsers(
+		util.Prioritized(NewStrikethroughParser(), 500),
+	))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewStrikethroughHTMLRenderer(), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/table.go

@@ -0,0 +1,556 @@
+package extension
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var escapedPipeCellListKey = parser.NewContextKey()
+
+type escapedPipeCell struct {
+	Cell        *ast.TableCell
+	Pos         []int
+	Transformed bool
+}
+
+// TableCellAlignMethod indicates how are table cells aligned in HTML format.indicates how are table cells aligned in HTML format.
+type TableCellAlignMethod int
+
+const (
+	// TableCellAlignDefault renders alignments by default method.
+	// With XHTML, alignments are rendered as an align attribute.
+	// With HTML5, alignments are rendered as a style attribute.
+	TableCellAlignDefault TableCellAlignMethod = iota
+
+	// TableCellAlignAttribute renders alignments as an align attribute.
+	TableCellAlignAttribute
+
+	// TableCellAlignStyle renders alignments as a style attribute.
+	TableCellAlignStyle
+
+	// TableCellAlignNone does not care about alignments.
+	// If you using classes or other styles, you can add these attributes
+	// in an ASTTransformer.
+	TableCellAlignNone
+)
+
+// TableConfig struct holds options for the extension.
+type TableConfig struct {
+	html.Config
+
+	// TableCellAlignMethod indicates how are table celss aligned.
+	TableCellAlignMethod TableCellAlignMethod
+}
+
+// TableOption interface is a functional option interface for the extension.
+type TableOption interface {
+	renderer.Option
+	// SetTableOption sets given option to the extension.
+	SetTableOption(*TableConfig)
+}
+
+// NewTableConfig returns a new Config with defaults.
+func NewTableConfig() TableConfig {
+	return TableConfig{
+		Config:               html.NewConfig(),
+		TableCellAlignMethod: TableCellAlignDefault,
+	}
+}
+
+// SetOption implements renderer.SetOptioner.
+func (c *TableConfig) SetOption(name renderer.OptionName, value interface{}) {
+	switch name {
+	case optTableCellAlignMethod:
+		c.TableCellAlignMethod = value.(TableCellAlignMethod)
+	default:
+		c.Config.SetOption(name, value)
+	}
+}
+
+type withTableHTMLOptions struct {
+	value []html.Option
+}
+
+func (o *withTableHTMLOptions) SetConfig(c *renderer.Config) {
+	if o.value != nil {
+		for _, v := range o.value {
+			v.(renderer.Option).SetConfig(c)
+		}
+	}
+}
+
+func (o *withTableHTMLOptions) SetTableOption(c *TableConfig) {
+	if o.value != nil {
+		for _, v := range o.value {
+			v.SetHTMLOption(&c.Config)
+		}
+	}
+}
+
+// WithTableHTMLOptions is functional option that wraps goldmark HTMLRenderer options.
+func WithTableHTMLOptions(opts ...html.Option) TableOption {
+	return &withTableHTMLOptions{opts}
+}
+
+const optTableCellAlignMethod renderer.OptionName = "TableTableCellAlignMethod"
+
+type withTableCellAlignMethod struct {
+	value TableCellAlignMethod
+}
+
+func (o *withTableCellAlignMethod) SetConfig(c *renderer.Config) {
+	c.Options[optTableCellAlignMethod] = o.value
+}
+
+func (o *withTableCellAlignMethod) SetTableOption(c *TableConfig) {
+	c.TableCellAlignMethod = o.value
+}
+
+// WithTableCellAlignMethod is a functional option that indicates how are table cells aligned in HTML format.
+func WithTableCellAlignMethod(a TableCellAlignMethod) TableOption {
+	return &withTableCellAlignMethod{a}
+}
+
+func isTableDelim(bs []byte) bool {
+	if w, _ := util.IndentWidth(bs, 0); w > 3 {
+		return false
+	}
+	for _, b := range bs {
+		if !(util.IsSpace(b) || b == '-' || b == '|' || b == ':') {
+			return false
+		}
+	}
+	return true
+}
+
+var tableDelimLeft = regexp.MustCompile(`^\s*\:\-+\s*$`)
+var tableDelimRight = regexp.MustCompile(`^\s*\-+\:\s*$`)
+var tableDelimCenter = regexp.MustCompile(`^\s*\:\-+\:\s*$`)
+var tableDelimNone = regexp.MustCompile(`^\s*\-+\s*$`)
+
+type tableParagraphTransformer struct {
+}
+
+var defaultTableParagraphTransformer = &tableParagraphTransformer{}
+
+// NewTableParagraphTransformer returns  a new ParagraphTransformer
+// that can transform paragraphs into tables.
+func NewTableParagraphTransformer() parser.ParagraphTransformer {
+	return defaultTableParagraphTransformer
+}
+
+func (b *tableParagraphTransformer) Transform(node *gast.Paragraph, reader text.Reader, pc parser.Context) {
+	lines := node.Lines()
+	if lines.Len() < 2 {
+		return
+	}
+	for i := 1; i < lines.Len(); i++ {
+		alignments := b.parseDelimiter(lines.At(i), reader)
+		if alignments == nil {
+			continue
+		}
+		header := b.parseRow(lines.At(i-1), alignments, true, reader, pc)
+		if header == nil || len(alignments) != header.ChildCount() {
+			return
+		}
+		table := ast.NewTable()
+		table.Alignments = alignments
+		table.AppendChild(table, ast.NewTableHeader(header))
+		for j := i + 1; j < lines.Len(); j++ {
+			table.AppendChild(table, b.parseRow(lines.At(j), alignments, false, reader, pc))
+		}
+		node.Lines().SetSliced(0, i-1)
+		node.Parent().InsertAfter(node.Parent(), node, table)
+		if node.Lines().Len() == 0 {
+			node.Parent().RemoveChild(node.Parent(), node)
+		} else {
+			last := node.Lines().At(i - 2)
+			last.Stop = last.Stop - 1 // trim last newline(\n)
+			node.Lines().Set(i-2, last)
+		}
+	}
+}
+
+func (b *tableParagraphTransformer) parseRow(segment text.Segment, alignments []ast.Alignment, isHeader bool, reader text.Reader, pc parser.Context) *ast.TableRow {
+	source := reader.Source()
+	line := segment.Value(source)
+	pos := 0
+	pos += util.TrimLeftSpaceLength(line)
+	limit := len(line)
+	limit -= util.TrimRightSpaceLength(line)
+	row := ast.NewTableRow(alignments)
+	if len(line) > 0 && line[pos] == '|' {
+		pos++
+	}
+	if len(line) > 0 && line[limit-1] == '|' {
+		limit--
+	}
+	i := 0
+	for ; pos < limit; i++ {
+		alignment := ast.AlignNone
+		if i >= len(alignments) {
+			if !isHeader {
+				return row
+			}
+		} else {
+			alignment = alignments[i]
+		}
+
+		var escapedCell *escapedPipeCell
+		node := ast.NewTableCell()
+		node.Alignment = alignment
+		hasBacktick := false
+		closure := pos
+		for ; closure < limit; closure++ {
+			if line[closure] == '`' {
+				hasBacktick = true
+			}
+			if line[closure] == '|' {
+				if closure == 0 || line[closure-1] != '\\' {
+					break
+				} else if hasBacktick {
+					if escapedCell == nil {
+						escapedCell = &escapedPipeCell{node, []int{}, false}
+						escapedList := pc.ComputeIfAbsent(escapedPipeCellListKey,
+							func() interface{} {
+								return []*escapedPipeCell{}
+							}).([]*escapedPipeCell)
+						escapedList = append(escapedList, escapedCell)
+						pc.Set(escapedPipeCellListKey, escapedList)
+					}
+					escapedCell.Pos = append(escapedCell.Pos, segment.Start+closure-1)
+				}
+			}
+		}
+		seg := text.NewSegment(segment.Start+pos, segment.Start+closure)
+		seg = seg.TrimLeftSpace(source)
+		seg = seg.TrimRightSpace(source)
+		node.Lines().Append(seg)
+		row.AppendChild(row, node)
+		pos = closure + 1
+	}
+	for ; i < len(alignments); i++ {
+		row.AppendChild(row, ast.NewTableCell())
+	}
+	return row
+}
+
+func (b *tableParagraphTransformer) parseDelimiter(segment text.Segment, reader text.Reader) []ast.Alignment {
+
+	line := segment.Value(reader.Source())
+	if !isTableDelim(line) {
+		return nil
+	}
+	cols := bytes.Split(line, []byte{'|'})
+	if util.IsBlank(cols[0]) {
+		cols = cols[1:]
+	}
+	if len(cols) > 0 && util.IsBlank(cols[len(cols)-1]) {
+		cols = cols[:len(cols)-1]
+	}
+
+	var alignments []ast.Alignment
+	for _, col := range cols {
+		if tableDelimLeft.Match(col) {
+			alignments = append(alignments, ast.AlignLeft)
+		} else if tableDelimRight.Match(col) {
+			alignments = append(alignments, ast.AlignRight)
+		} else if tableDelimCenter.Match(col) {
+			alignments = append(alignments, ast.AlignCenter)
+		} else if tableDelimNone.Match(col) {
+			alignments = append(alignments, ast.AlignNone)
+		} else {
+			return nil
+		}
+	}
+	return alignments
+}
+
+type tableASTTransformer struct {
+}
+
+var defaultTableASTTransformer = &tableASTTransformer{}
+
+// NewTableASTTransformer returns a parser.ASTTransformer for tables.
+func NewTableASTTransformer() parser.ASTTransformer {
+	return defaultTableASTTransformer
+}
+
+func (a *tableASTTransformer) Transform(node *gast.Document, reader text.Reader, pc parser.Context) {
+	lst := pc.Get(escapedPipeCellListKey)
+	if lst == nil {
+		return
+	}
+	pc.Set(escapedPipeCellListKey, nil)
+	for _, v := range lst.([]*escapedPipeCell) {
+		if v.Transformed {
+			continue
+		}
+		_ = gast.Walk(v.Cell, func(n gast.Node, entering bool) (gast.WalkStatus, error) {
+			if !entering || n.Kind() != gast.KindCodeSpan {
+				return gast.WalkContinue, nil
+			}
+
+			for c := n.FirstChild(); c != nil; {
+				next := c.NextSibling()
+				if c.Kind() != gast.KindText {
+					c = next
+					continue
+				}
+				parent := c.Parent()
+				ts := &c.(*gast.Text).Segment
+				n := c
+				for _, v := range lst.([]*escapedPipeCell) {
+					for _, pos := range v.Pos {
+						if ts.Start <= pos && pos < ts.Stop {
+							segment := n.(*gast.Text).Segment
+							n1 := gast.NewRawTextSegment(segment.WithStop(pos))
+							n2 := gast.NewRawTextSegment(segment.WithStart(pos + 1))
+							parent.InsertAfter(parent, n, n1)
+							parent.InsertAfter(parent, n1, n2)
+							parent.RemoveChild(parent, n)
+							n = n2
+							v.Transformed = true
+						}
+					}
+				}
+				c = next
+			}
+			return gast.WalkContinue, nil
+		})
+	}
+}
+
+// TableHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders Table nodes.
+type TableHTMLRenderer struct {
+	TableConfig
+}
+
+// NewTableHTMLRenderer returns a new TableHTMLRenderer.
+func NewTableHTMLRenderer(opts ...TableOption) renderer.NodeRenderer {
+	r := &TableHTMLRenderer{
+		TableConfig: NewTableConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetTableOption(&r.TableConfig)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *TableHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindTable, r.renderTable)
+	reg.Register(ast.KindTableHeader, r.renderTableHeader)
+	reg.Register(ast.KindTableRow, r.renderTableRow)
+	reg.Register(ast.KindTableCell, r.renderTableCell)
+}
+
+// TableAttributeFilter defines attribute names which table elements can have.
+var TableAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("align"),       // [Deprecated]
+	[]byte("bgcolor"),     // [Deprecated]
+	[]byte("border"),      // [Deprecated]
+	[]byte("cellpadding"), // [Deprecated]
+	[]byte("cellspacing"), // [Deprecated]
+	[]byte("frame"),       // [Deprecated]
+	[]byte("rules"),       // [Deprecated]
+	[]byte("summary"),     // [Deprecated]
+	[]byte("width"),       // [Deprecated]
+)
+
+func (r *TableHTMLRenderer) renderTable(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		_, _ = w.WriteString("<table")
+		if n.Attributes() != nil {
+			html.RenderAttributes(w, n, TableAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+	} else {
+		_, _ = w.WriteString("</table>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+// TableHeaderAttributeFilter defines attribute names which <thead> elements can have.
+var TableHeaderAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("align"),   // [Deprecated since HTML4] [Obsolete since HTML5]
+	[]byte("bgcolor"), // [Not Standardized]
+	[]byte("char"),    // [Deprecated since HTML4] [Obsolete since HTML5]
+	[]byte("charoff"), // [Deprecated since HTML4] [Obsolete since HTML5]
+	[]byte("valign"),  // [Deprecated since HTML4] [Obsolete since HTML5]
+)
+
+func (r *TableHTMLRenderer) renderTableHeader(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		_, _ = w.WriteString("<thead")
+		if n.Attributes() != nil {
+			html.RenderAttributes(w, n, TableHeaderAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+		_, _ = w.WriteString("<tr>\n") // Header <tr> has no separate handle
+	} else {
+		_, _ = w.WriteString("</tr>\n")
+		_, _ = w.WriteString("</thead>\n")
+		if n.NextSibling() != nil {
+			_, _ = w.WriteString("<tbody>\n")
+		}
+	}
+	return gast.WalkContinue, nil
+}
+
+// TableRowAttributeFilter defines attribute names which <tr> elements can have.
+var TableRowAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("align"),   // [Obsolete since HTML5]
+	[]byte("bgcolor"), // [Obsolete since HTML5]
+	[]byte("char"),    // [Obsolete since HTML5]
+	[]byte("charoff"), // [Obsolete since HTML5]
+	[]byte("valign"),  // [Obsolete since HTML5]
+)
+
+func (r *TableHTMLRenderer) renderTableRow(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		_, _ = w.WriteString("<tr")
+		if n.Attributes() != nil {
+			html.RenderAttributes(w, n, TableRowAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+	} else {
+		_, _ = w.WriteString("</tr>\n")
+		if n.Parent().LastChild() == n {
+			_, _ = w.WriteString("</tbody>\n")
+		}
+	}
+	return gast.WalkContinue, nil
+}
+
+// TableThCellAttributeFilter defines attribute names which table <th> cells can have.
+var TableThCellAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("abbr"), // [OK] Contains a short abbreviated description of the cell's content [NOT OK in <td>]
+
+	[]byte("align"),   // [Obsolete since HTML5]
+	[]byte("axis"),    // [Obsolete since HTML5]
+	[]byte("bgcolor"), // [Not Standardized]
+	[]byte("char"),    // [Obsolete since HTML5]
+	[]byte("charoff"), // [Obsolete since HTML5]
+
+	[]byte("colspan"), // [OK] Number of columns that the cell is to span
+	[]byte("headers"), // [OK] This attribute contains a list of space-separated strings, each corresponding to the id attribute of the <th> elements that apply to this element
+
+	[]byte("height"), // [Deprecated since HTML4] [Obsolete since HTML5]
+
+	[]byte("rowspan"), // [OK] Number of rows that the cell is to span
+	[]byte("scope"),   // [OK] This enumerated attribute defines the cells that the header (defined in the <th>) element relates to [NOT OK in <td>]
+
+	[]byte("valign"), // [Obsolete since HTML5]
+	[]byte("width"),  // [Deprecated since HTML4] [Obsolete since HTML5]
+)
+
+// TableTdCellAttributeFilter defines attribute names which table <td> cells can have.
+var TableTdCellAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("abbr"),    // [Obsolete since HTML5] [OK in <th>]
+	[]byte("align"),   // [Obsolete since HTML5]
+	[]byte("axis"),    // [Obsolete since HTML5]
+	[]byte("bgcolor"), // [Not Standardized]
+	[]byte("char"),    // [Obsolete since HTML5]
+	[]byte("charoff"), // [Obsolete since HTML5]
+
+	[]byte("colspan"), // [OK] Number of columns that the cell is to span
+	[]byte("headers"), // [OK] This attribute contains a list of space-separated strings, each corresponding to the id attribute of the <th> elements that apply to this element
+
+	[]byte("height"), // [Deprecated since HTML4] [Obsolete since HTML5]
+
+	[]byte("rowspan"), // [OK] Number of rows that the cell is to span
+
+	[]byte("scope"),  // [Obsolete since HTML5] [OK in <th>]
+	[]byte("valign"), // [Obsolete since HTML5]
+	[]byte("width"),  // [Deprecated since HTML4] [Obsolete since HTML5]
+)
+
+func (r *TableHTMLRenderer) renderTableCell(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	n := node.(*ast.TableCell)
+	tag := "td"
+	if n.Parent().Kind() == ast.KindTableHeader {
+		tag = "th"
+	}
+	if entering {
+		fmt.Fprintf(w, "<%s", tag)
+		if n.Alignment != ast.AlignNone {
+			amethod := r.TableConfig.TableCellAlignMethod
+			if amethod == TableCellAlignDefault {
+				if r.Config.XHTML {
+					amethod = TableCellAlignAttribute
+				} else {
+					amethod = TableCellAlignStyle
+				}
+			}
+			switch amethod {
+			case TableCellAlignAttribute:
+				if _, ok := n.AttributeString("align"); !ok { // Skip align render if overridden
+					fmt.Fprintf(w, ` align="%s"`, n.Alignment.String())
+				}
+			case TableCellAlignStyle:
+				v, ok := n.AttributeString("style")
+				var cob util.CopyOnWriteBuffer
+				if ok {
+					cob = util.NewCopyOnWriteBuffer(v.([]byte))
+					cob.AppendByte(';')
+				}
+				style := fmt.Sprintf("text-align:%s", n.Alignment.String())
+				cob.AppendString(style)
+				n.SetAttributeString("style", cob.Bytes())
+			}
+		}
+		if n.Attributes() != nil {
+			if tag == "td" {
+				html.RenderAttributes(w, n, TableTdCellAttributeFilter) // <td>
+			} else {
+				html.RenderAttributes(w, n, TableThCellAttributeFilter) // <th>
+			}
+		}
+		_ = w.WriteByte('>')
+	} else {
+		fmt.Fprintf(w, "</%s>\n", tag)
+	}
+	return gast.WalkContinue, nil
+}
+
+type table struct {
+	options []TableOption
+}
+
+// Table is an extension that allow you to use GFM tables .
+var Table = &table{
+	options: []TableOption{},
+}
+
+// NewTable returns a new extension with given options.
+func NewTable(opts ...TableOption) goldmark.Extender {
+	return &table{
+		options: opts,
+	}
+}
+
+func (e *table) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithParagraphTransformers(
+			util.Prioritized(NewTableParagraphTransformer(), 200),
+		),
+		parser.WithASTTransformers(
+			util.Prioritized(defaultTableASTTransformer, 0),
+		),
+	)
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewTableHTMLRenderer(e.options...), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/tasklist.go

@@ -0,0 +1,115 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+	"regexp"
+)
+
+var taskListRegexp = regexp.MustCompile(`^\[([\sxX])\]\s*`)
+
+type taskCheckBoxParser struct {
+}
+
+var defaultTaskCheckBoxParser = &taskCheckBoxParser{}
+
+// NewTaskCheckBoxParser returns a new  InlineParser that can parse
+// checkboxes in list items.
+// This parser must take precedence over the parser.LinkParser.
+func NewTaskCheckBoxParser() parser.InlineParser {
+	return defaultTaskCheckBoxParser
+}
+
+func (s *taskCheckBoxParser) Trigger() []byte {
+	return []byte{'['}
+}
+
+func (s *taskCheckBoxParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+	// Given AST structure must be like
+	// - List
+	//   - ListItem         : parent.Parent
+	//     - TextBlock      : parent
+	//       (current line)
+	if parent.Parent() == nil || parent.Parent().FirstChild() != parent {
+		return nil
+	}
+
+	if _, ok := parent.Parent().(*gast.ListItem); !ok {
+		return nil
+	}
+	line, _ := block.PeekLine()
+	m := taskListRegexp.FindSubmatchIndex(line)
+	if m == nil {
+		return nil
+	}
+	value := line[m[2]:m[3]][0]
+	block.Advance(m[1])
+	checked := value == 'x' || value == 'X'
+	return ast.NewTaskCheckBox(checked)
+}
+
+func (s *taskCheckBoxParser) CloseBlock(parent gast.Node, pc parser.Context) {
+	// nothing to do
+}
+
+// TaskCheckBoxHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders checkboxes in list items.
+type TaskCheckBoxHTMLRenderer struct {
+	html.Config
+}
+
+// NewTaskCheckBoxHTMLRenderer returns a new TaskCheckBoxHTMLRenderer.
+func NewTaskCheckBoxHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &TaskCheckBoxHTMLRenderer{
+		Config: html.NewConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *TaskCheckBoxHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindTaskCheckBox, r.renderTaskCheckBox)
+}
+
+func (r *TaskCheckBoxHTMLRenderer) renderTaskCheckBox(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	if !entering {
+		return gast.WalkContinue, nil
+	}
+	n := node.(*ast.TaskCheckBox)
+
+	if n.IsChecked {
+		w.WriteString(`<input checked="" disabled="" type="checkbox"`)
+	} else {
+		w.WriteString(`<input disabled="" type="checkbox"`)
+	}
+	if r.XHTML {
+		w.WriteString(" /> ")
+	} else {
+		w.WriteString("> ")
+	}
+	return gast.WalkContinue, nil
+}
+
+type taskList struct {
+}
+
+// TaskList is an extension that allow you to use GFM task lists.
+var TaskList = &taskList{}
+
+func (e *taskList) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithInlineParsers(
+		util.Prioritized(NewTaskCheckBoxParser(), 0),
+	))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewTaskCheckBoxHTMLRenderer(), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/typographer.go

@@ -0,0 +1,339 @@
+package extension
+
+import (
+	"unicode"
+
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var uncloseCounterKey = parser.NewContextKey()
+
+type unclosedCounter struct {
+	Single int
+	Double int
+}
+
+func (u *unclosedCounter) Reset() {
+	u.Single = 0
+	u.Double = 0
+}
+
+func getUnclosedCounter(pc parser.Context) *unclosedCounter {
+	v := pc.Get(uncloseCounterKey)
+	if v == nil {
+		v = &unclosedCounter{}
+		pc.Set(uncloseCounterKey, v)
+	}
+	return v.(*unclosedCounter)
+}
+
+// TypographicPunctuation is a key of the punctuations that can be replaced with
+// typographic entities.
+type TypographicPunctuation int
+
+const (
+	// LeftSingleQuote is '
+	LeftSingleQuote TypographicPunctuation = iota + 1
+	// RightSingleQuote is '
+	RightSingleQuote
+	// LeftDoubleQuote is "
+	LeftDoubleQuote
+	// RightDoubleQuote is "
+	RightDoubleQuote
+	// EnDash is --
+	EnDash
+	// EmDash is ---
+	EmDash
+	// Ellipsis is ...
+	Ellipsis
+	// LeftAngleQuote is <<
+	LeftAngleQuote
+	// RightAngleQuote is >>
+	RightAngleQuote
+	// Apostrophe is '
+	Apostrophe
+
+	typographicPunctuationMax
+)
+
+// An TypographerConfig struct is a data structure that holds configuration of the
+// Typographer extension.
+type TypographerConfig struct {
+	Substitutions [][]byte
+}
+
+func newDefaultSubstitutions() [][]byte {
+	replacements := make([][]byte, typographicPunctuationMax)
+	replacements[LeftSingleQuote] = []byte("&lsquo;")
+	replacements[RightSingleQuote] = []byte("&rsquo;")
+	replacements[LeftDoubleQuote] = []byte("&ldquo;")
+	replacements[RightDoubleQuote] = []byte("&rdquo;")
+	replacements[EnDash] = []byte("&ndash;")
+	replacements[EmDash] = []byte("&mdash;")
+	replacements[Ellipsis] = []byte("&hellip;")
+	replacements[LeftAngleQuote] = []byte("&laquo;")
+	replacements[RightAngleQuote] = []byte("&raquo;")
+	replacements[Apostrophe] = []byte("&rsquo;")
+
+	return replacements
+}
+
+// SetOption implements SetOptioner.
+func (b *TypographerConfig) SetOption(name parser.OptionName, value interface{}) {
+	switch name {
+	case optTypographicSubstitutions:
+		b.Substitutions = value.([][]byte)
+	}
+}
+
+// A TypographerOption interface sets options for the TypographerParser.
+type TypographerOption interface {
+	parser.Option
+	SetTypographerOption(*TypographerConfig)
+}
+
+const optTypographicSubstitutions parser.OptionName = "TypographicSubstitutions"
+
+// TypographicSubstitutions is a list of the substitutions for the Typographer extension.
+type TypographicSubstitutions map[TypographicPunctuation][]byte
+
+type withTypographicSubstitutions struct {
+	value [][]byte
+}
+
+func (o *withTypographicSubstitutions) SetParserOption(c *parser.Config) {
+	c.Options[optTypographicSubstitutions] = o.value
+}
+
+func (o *withTypographicSubstitutions) SetTypographerOption(p *TypographerConfig) {
+	p.Substitutions = o.value
+}
+
+// WithTypographicSubstitutions is a functional otpion that specify replacement text
+// for punctuations.
+func WithTypographicSubstitutions(values map[TypographicPunctuation][]byte) TypographerOption {
+	replacements := newDefaultSubstitutions()
+	for k, v := range values {
+		replacements[k] = v
+	}
+
+	return &withTypographicSubstitutions{replacements}
+}
+
+type typographerDelimiterProcessor struct {
+}
+
+func (p *typographerDelimiterProcessor) IsDelimiter(b byte) bool {
+	return b == '\'' || b == '"'
+}
+
+func (p *typographerDelimiterProcessor) CanOpenCloser(opener, closer *parser.Delimiter) bool {
+	return opener.Char == closer.Char
+}
+
+func (p *typographerDelimiterProcessor) OnMatch(consumes int) gast.Node {
+	return nil
+}
+
+var defaultTypographerDelimiterProcessor = &typographerDelimiterProcessor{}
+
+type typographerParser struct {
+	TypographerConfig
+}
+
+// NewTypographerParser return a new InlineParser that parses
+// typographer expressions.
+func NewTypographerParser(opts ...TypographerOption) parser.InlineParser {
+	p := &typographerParser{
+		TypographerConfig: TypographerConfig{
+			Substitutions: newDefaultSubstitutions(),
+		},
+	}
+	for _, o := range opts {
+		o.SetTypographerOption(&p.TypographerConfig)
+	}
+	return p
+}
+
+func (s *typographerParser) Trigger() []byte {
+	return []byte{'\'', '"', '-', '.', ',', '<', '>', '*', '['}
+}
+
+func (s *typographerParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+	line, _ := block.PeekLine()
+	c := line[0]
+	if len(line) > 2 {
+		if c == '-' {
+			if s.Substitutions[EmDash] != nil && line[1] == '-' && line[2] == '-' { // ---
+				node := gast.NewString(s.Substitutions[EmDash])
+				node.SetCode(true)
+				block.Advance(3)
+				return node
+			}
+		} else if c == '.' {
+			if s.Substitutions[Ellipsis] != nil && line[1] == '.' && line[2] == '.' { // ...
+				node := gast.NewString(s.Substitutions[Ellipsis])
+				node.SetCode(true)
+				block.Advance(3)
+				return node
+			}
+			return nil
+		}
+	}
+	if len(line) > 1 {
+		if c == '<' {
+			if s.Substitutions[LeftAngleQuote] != nil && line[1] == '<' { // <<
+				node := gast.NewString(s.Substitutions[LeftAngleQuote])
+				node.SetCode(true)
+				block.Advance(2)
+				return node
+			}
+			return nil
+		} else if c == '>' {
+			if s.Substitutions[RightAngleQuote] != nil && line[1] == '>' { // >>
+				node := gast.NewString(s.Substitutions[RightAngleQuote])
+				node.SetCode(true)
+				block.Advance(2)
+				return node
+			}
+			return nil
+		} else if s.Substitutions[EnDash] != nil && c == '-' && line[1] == '-' { // --
+			node := gast.NewString(s.Substitutions[EnDash])
+			node.SetCode(true)
+			block.Advance(2)
+			return node
+		}
+	}
+	if c == '\'' || c == '"' {
+		before := block.PrecendingCharacter()
+		d := parser.ScanDelimiter(line, before, 1, defaultTypographerDelimiterProcessor)
+		if d == nil {
+			return nil
+		}
+		counter := getUnclosedCounter(pc)
+		if c == '\'' {
+			if s.Substitutions[Apostrophe] != nil {
+				// Handle decade abbrevations such as '90s
+				if d.CanOpen && !d.CanClose && len(line) > 3 && util.IsNumeric(line[1]) && util.IsNumeric(line[2]) && line[3] == 's' {
+					after := rune(' ')
+					if len(line) > 4 {
+						after = util.ToRune(line, 4)
+					}
+					if len(line) == 3 || util.IsSpaceRune(after) || util.IsPunctRune(after) {
+						node := gast.NewString(s.Substitutions[Apostrophe])
+						node.SetCode(true)
+						block.Advance(1)
+						return node
+					}
+				}
+				// special cases: 'twas, 'em, 'net
+				if len(line) > 1 && (unicode.IsPunct(before) || unicode.IsSpace(before)) && (line[1] == 't' || line[1] == 'e' || line[1] == 'n' || line[1] == 'l') {
+					node := gast.NewString(s.Substitutions[Apostrophe])
+					node.SetCode(true)
+					block.Advance(1)
+					return node
+				}
+				// Convert normal apostrophes. This is probably more flexible than necessary but
+				// converts any apostrophe in between two alphanumerics.
+				if len(line) > 1 && (unicode.IsDigit(before) || unicode.IsLetter(before)) && (unicode.IsLetter(util.ToRune(line, 1))) {
+					node := gast.NewString(s.Substitutions[Apostrophe])
+					node.SetCode(true)
+					block.Advance(1)
+					return node
+				}
+			}
+			if s.Substitutions[LeftSingleQuote] != nil && d.CanOpen && !d.CanClose {
+				nt := LeftSingleQuote
+				// special cases: Alice's, I'm, Don't, You'd
+				if len(line) > 1 && (line[1] == 's' || line[1] == 'm' || line[1] == 't' || line[1] == 'd') && (len(line) < 3 || util.IsPunct(line[2]) || util.IsSpace(line[2])) {
+					nt = RightSingleQuote
+				}
+				// special cases: I've, I'll, You're
+				if len(line) > 2 && ((line[1] == 'v' && line[2] == 'e') || (line[1] == 'l' && line[2] == 'l') || (line[1] == 'r' && line[2] == 'e')) && (len(line) < 4 || util.IsPunct(line[3]) || util.IsSpace(line[3])) {
+					nt = RightSingleQuote
+				}
+				if nt == LeftSingleQuote {
+					counter.Single++
+				}
+
+				node := gast.NewString(s.Substitutions[nt])
+				node.SetCode(true)
+				block.Advance(1)
+				return node
+			}
+			if s.Substitutions[RightSingleQuote] != nil {
+				// plural possesives and abbreviations: Smiths', doin'
+				if len(line) > 1 && unicode.IsSpace(util.ToRune(line, 0)) || unicode.IsPunct(util.ToRune(line, 0)) && (len(line) > 2 && !unicode.IsDigit(util.ToRune(line, 1))) {
+					node := gast.NewString(s.Substitutions[RightSingleQuote])
+					node.SetCode(true)
+					block.Advance(1)
+					return node
+				}
+			}
+			if s.Substitutions[RightSingleQuote] != nil && counter.Single > 0 {
+				isClose := d.CanClose && !d.CanOpen
+				maybeClose := d.CanClose && d.CanOpen && len(line) > 1 && unicode.IsPunct(util.ToRune(line, 1)) && (len(line) == 2 || (len(line) > 2 && util.IsPunct(line[2]) || util.IsSpace(line[2])))
+				if isClose || maybeClose {
+					node := gast.NewString(s.Substitutions[RightSingleQuote])
+					node.SetCode(true)
+					block.Advance(1)
+					counter.Single--
+					return node
+				}
+			}
+		}
+		if c == '"' {
+			if s.Substitutions[LeftDoubleQuote] != nil && d.CanOpen && !d.CanClose {
+				node := gast.NewString(s.Substitutions[LeftDoubleQuote])
+				node.SetCode(true)
+				block.Advance(1)
+				counter.Double++
+				return node
+			}
+			if s.Substitutions[RightDoubleQuote] != nil && counter.Double > 0 {
+				isClose := d.CanClose && !d.CanOpen
+				maybeClose := d.CanClose && d.CanOpen && len(line) > 1 && (unicode.IsPunct(util.ToRune(line, 1))) && (len(line) == 2 || (len(line) > 2 && util.IsPunct(line[2]) || util.IsSpace(line[2])))
+				if isClose || maybeClose {
+					// special case: "Monitor 21""
+					if len(line) > 1 && line[1] == '"' && unicode.IsDigit(before) {
+						return nil
+					}
+					node := gast.NewString(s.Substitutions[RightDoubleQuote])
+					node.SetCode(true)
+					block.Advance(1)
+					counter.Double--
+					return node
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func (s *typographerParser) CloseBlock(parent gast.Node, pc parser.Context) {
+	getUnclosedCounter(pc).Reset()
+}
+
+type typographer struct {
+	options []TypographerOption
+}
+
+// Typographer is an extension that replaces punctuations with typographic entities.
+var Typographer = &typographer{}
+
+// NewTypographer returns a new Extender that replaces punctuations with typographic entities.
+func NewTypographer(opts ...TypographerOption) goldmark.Extender {
+	return &typographer{
+		options: opts,
+	}
+}
+
+func (e *typographer) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithInlineParsers(
+		util.Prioritized(NewTypographerParser(e.options...), 9999),
+	))
+}

vendor/github.com/yuin/goldmark/markdown.go

@@ -0,0 +1,140 @@
+// Package goldmark implements functions to convert markdown text to a desired format.
+package goldmark
+
+import (
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+	"io"
+)
+
+// DefaultParser returns a new Parser that is configured by default values.
+func DefaultParser() parser.Parser {
+	return parser.NewParser(parser.WithBlockParsers(parser.DefaultBlockParsers()...),
+		parser.WithInlineParsers(parser.DefaultInlineParsers()...),
+		parser.WithParagraphTransformers(parser.DefaultParagraphTransformers()...),
+	)
+}
+
+// DefaultRenderer returns a new Renderer that is configured by default values.
+func DefaultRenderer() renderer.Renderer {
+	return renderer.NewRenderer(renderer.WithNodeRenderers(util.Prioritized(html.NewRenderer(), 1000)))
+}
+
+var defaultMarkdown = New()
+
+// Convert interprets a UTF-8 bytes source in Markdown and
+// write rendered contents to a writer w.
+func Convert(source []byte, w io.Writer, opts ...parser.ParseOption) error {
+	return defaultMarkdown.Convert(source, w, opts...)
+}
+
+// A Markdown interface offers functions to convert Markdown text to
+// a desired format.
+type Markdown interface {
+	// Convert interprets a UTF-8 bytes source in Markdown and write rendered
+	// contents to a writer w.
+	Convert(source []byte, writer io.Writer, opts ...parser.ParseOption) error
+
+	// Parser returns a Parser that will be used for conversion.
+	Parser() parser.Parser
+
+	// SetParser sets a Parser to this object.
+	SetParser(parser.Parser)
+
+	// Parser returns a Renderer that will be used for conversion.
+	Renderer() renderer.Renderer
+
+	// SetRenderer sets a Renderer to this object.
+	SetRenderer(renderer.Renderer)
+}
+
+// Option is a functional option type for Markdown objects.
+type Option func(*markdown)
+
+// WithExtensions adds extensions.
+func WithExtensions(ext ...Extender) Option {
+	return func(m *markdown) {
+		m.extensions = append(m.extensions, ext...)
+	}
+}
+
+// WithParser allows you to override the default parser.
+func WithParser(p parser.Parser) Option {
+	return func(m *markdown) {
+		m.parser = p
+	}
+}
+
+// WithParserOptions applies options for the parser.
+func WithParserOptions(opts ...parser.Option) Option {
+	return func(m *markdown) {
+		m.parser.AddOptions(opts...)
+	}
+}
+
+// WithRenderer allows you to override the default renderer.
+func WithRenderer(r renderer.Renderer) Option {
+	return func(m *markdown) {
+		m.renderer = r
+	}
+}
+
+// WithRendererOptions applies options for the renderer.
+func WithRendererOptions(opts ...renderer.Option) Option {
+	return func(m *markdown) {
+		m.renderer.AddOptions(opts...)
+	}
+}
+
+type markdown struct {
+	parser     parser.Parser
+	renderer   renderer.Renderer
+	extensions []Extender
+}
+
+// New returns a new Markdown with given options.
+func New(options ...Option) Markdown {
+	md := &markdown{
+		parser:     DefaultParser(),
+		renderer:   DefaultRenderer(),
+		extensions: []Extender{},
+	}
+	for _, opt := range options {
+		opt(md)
+	}
+	for _, e := range md.extensions {
+		e.Extend(md)
+	}
+	return md
+}
+
+func (m *markdown) Convert(source []byte, writer io.Writer, opts ...parser.ParseOption) error {
+	reader := text.NewReader(source)
+	doc := m.parser.Parse(reader, opts...)
+	return m.renderer.Render(writer, source, doc)
+}
+
+func (m *markdown) Parser() parser.Parser {
+	return m.parser
+}
+
+func (m *markdown) SetParser(v parser.Parser) {
+	m.parser = v
+}
+
+func (m *markdown) Renderer() renderer.Renderer {
+	return m.renderer
+}
+
+func (m *markdown) SetRenderer(v renderer.Renderer) {
+	m.renderer = v
+}
+
+// An Extender interface is used for extending Markdown.
+type Extender interface {
+	// Extend extends the Markdown.
+	Extend(Markdown)
+}

vendor/github.com/yuin/goldmark/parser/attribute.go

@@ -0,0 +1,328 @@
+package parser
+
+import (
+	"bytes"
+	"io"
+	"strconv"
+
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var attrNameID = []byte("id")
+var attrNameClass = []byte("class")
+
+// An Attribute is an attribute of the markdown elements
+type Attribute struct {
+	Name  []byte
+	Value interface{}
+}
+
+// An Attributes is a collection of attributes.
+type Attributes []Attribute
+
+// Find returns a (value, true) if an attribute correspond with given name is found, otherwise (nil, false).
+func (as Attributes) Find(name []byte) (interface{}, bool) {
+	for _, a := range as {
+		if bytes.Equal(a.Name, name) {
+			return a.Value, true
+		}
+	}
+	return nil, false
+}
+
+func (as Attributes) findUpdate(name []byte, cb func(v interface{}) interface{}) bool {
+	for i, a := range as {
+		if bytes.Equal(a.Name, name) {
+			as[i].Value = cb(a.Value)
+			return true
+		}
+	}
+	return false
+}
+
+// ParseAttributes parses attributes into a map.
+// ParseAttributes returns a parsed attributes and true if could parse
+// attributes, otherwise nil and false.
+func ParseAttributes(reader text.Reader) (Attributes, bool) {
+	savedLine, savedPosition := reader.Position()
+	reader.SkipSpaces()
+	if reader.Peek() != '{' {
+		reader.SetPosition(savedLine, savedPosition)
+		return nil, false
+	}
+	reader.Advance(1)
+	attrs := Attributes{}
+	for {
+		if reader.Peek() == '}' {
+			reader.Advance(1)
+			return attrs, true
+		}
+		attr, ok := parseAttribute(reader)
+		if !ok {
+			reader.SetPosition(savedLine, savedPosition)
+			return nil, false
+		}
+		if bytes.Equal(attr.Name, attrNameClass) {
+			if !attrs.findUpdate(attrNameClass, func(v interface{}) interface{} {
+				ret := make([]byte, 0, len(v.([]byte))+1+len(attr.Value.([]byte)))
+				ret = append(ret, v.([]byte)...)
+				return append(append(ret, ' '), attr.Value.([]byte)...)
+			}) {
+				attrs = append(attrs, attr)
+			}
+		} else {
+			attrs = append(attrs, attr)
+		}
+		reader.SkipSpaces()
+		if reader.Peek() == ',' {
+			reader.Advance(1)
+			reader.SkipSpaces()
+		}
+	}
+}
+
+func parseAttribute(reader text.Reader) (Attribute, bool) {
+	reader.SkipSpaces()
+	c := reader.Peek()
+	if c == '#' || c == '.' {
+		reader.Advance(1)
+		line, _ := reader.PeekLine()
+		i := 0
+		// HTML5 allows any kind of characters as id, but XHTML restricts characters for id.
+		// CommonMark is basically defined for XHTML(even though it is legacy).
+		// So we restrict id characters.
+		for ; i < len(line) && !util.IsSpace(line[i]) &&
+			(!util.IsPunct(line[i]) || line[i] == '_' || line[i] == '-' || line[i] == ':' || line[i] == '.'); i++ {
+		}
+		name := attrNameClass
+		if c == '#' {
+			name = attrNameID
+		}
+		reader.Advance(i)
+		return Attribute{Name: name, Value: line[0:i]}, true
+	}
+	line, _ := reader.PeekLine()
+	if len(line) == 0 {
+		return Attribute{}, false
+	}
+	c = line[0]
+	if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+		c == '_' || c == ':') {
+		return Attribute{}, false
+	}
+	i := 0
+	for ; i < len(line); i++ {
+		c = line[i]
+		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+			(c >= '0' && c <= '9') ||
+			c == '_' || c == ':' || c == '.' || c == '-') {
+			break
+		}
+	}
+	name := line[:i]
+	reader.Advance(i)
+	reader.SkipSpaces()
+	c = reader.Peek()
+	if c != '=' {
+		return Attribute{}, false
+	}
+	reader.Advance(1)
+	reader.SkipSpaces()
+	value, ok := parseAttributeValue(reader)
+	if !ok {
+		return Attribute{}, false
+	}
+	if bytes.Equal(name, attrNameClass) {
+		if _, ok = value.([]byte); !ok {
+			return Attribute{}, false
+		}
+	}
+	return Attribute{Name: name, Value: value}, true
+}
+
+func parseAttributeValue(reader text.Reader) (interface{}, bool) {
+	reader.SkipSpaces()
+	c := reader.Peek()
+	var value interface{}
+	ok := false
+	switch c {
+	case text.EOF:
+		return Attribute{}, false
+	case '{':
+		value, ok = ParseAttributes(reader)
+	case '[':
+		value, ok = parseAttributeArray(reader)
+	case '"':
+		value, ok = parseAttributeString(reader)
+	default:
+		if c == '-' || c == '+' || util.IsNumeric(c) {
+			value, ok = parseAttributeNumber(reader)
+		} else {
+			value, ok = parseAttributeOthers(reader)
+		}
+	}
+	if !ok {
+		return nil, false
+	}
+	return value, true
+}
+
+func parseAttributeArray(reader text.Reader) ([]interface{}, bool) {
+	reader.Advance(1) // skip [
+	ret := []interface{}{}
+	for i := 0; ; i++ {
+		c := reader.Peek()
+		comma := false
+		if i != 0 && c == ',' {
+			reader.Advance(1)
+			comma = true
+		}
+		if c == ']' {
+			if !comma {
+				reader.Advance(1)
+				return ret, true
+			}
+			return nil, false
+		}
+		reader.SkipSpaces()
+		value, ok := parseAttributeValue(reader)
+		if !ok {
+			return nil, false
+		}
+		ret = append(ret, value)
+		reader.SkipSpaces()
+	}
+}
+
+func parseAttributeString(reader text.Reader) ([]byte, bool) {
+	reader.Advance(1) // skip "
+	line, _ := reader.PeekLine()
+	i := 0
+	l := len(line)
+	var buf bytes.Buffer
+	for i < l {
+		c := line[i]
+		if c == '\\' && i != l-1 {
+			n := line[i+1]
+			switch n {
+			case '"', '/', '\\':
+				buf.WriteByte(n)
+				i += 2
+			case 'b':
+				buf.WriteString("\b")
+				i += 2
+			case 'f':
+				buf.WriteString("\f")
+				i += 2
+			case 'n':
+				buf.WriteString("\n")
+				i += 2
+			case 'r':
+				buf.WriteString("\r")
+				i += 2
+			case 't':
+				buf.WriteString("\t")
+				i += 2
+			default:
+				buf.WriteByte('\\')
+				i++
+			}
+			continue
+		}
+		if c == '"' {
+			reader.Advance(i + 1)
+			return buf.Bytes(), true
+		}
+		buf.WriteByte(c)
+		i++
+	}
+	return nil, false
+}
+
+func scanAttributeDecimal(reader text.Reader, w io.ByteWriter) {
+	for {
+		c := reader.Peek()
+		if util.IsNumeric(c) {
+			w.WriteByte(c)
+		} else {
+			return
+		}
+		reader.Advance(1)
+	}
+}
+
+func parseAttributeNumber(reader text.Reader) (float64, bool) {
+	sign := 1
+	c := reader.Peek()
+	if c == '-' {
+		sign = -1
+		reader.Advance(1)
+	} else if c == '+' {
+		reader.Advance(1)
+	}
+	var buf bytes.Buffer
+	if !util.IsNumeric(reader.Peek()) {
+		return 0, false
+	}
+	scanAttributeDecimal(reader, &buf)
+	if buf.Len() == 0 {
+		return 0, false
+	}
+	c = reader.Peek()
+	if c == '.' {
+		buf.WriteByte(c)
+		reader.Advance(1)
+		scanAttributeDecimal(reader, &buf)
+	}
+	c = reader.Peek()
+	if c == 'e' || c == 'E' {
+		buf.WriteByte(c)
+		reader.Advance(1)
+		c = reader.Peek()
+		if c == '-' || c == '+' {
+			buf.WriteByte(c)
+			reader.Advance(1)
+		}
+		scanAttributeDecimal(reader, &buf)
+	}
+	f, err := strconv.ParseFloat(buf.String(), 10)
+	if err != nil {
+		return 0, false
+	}
+	return float64(sign) * f, true
+}
+
+var bytesTrue = []byte("true")
+var bytesFalse = []byte("false")
+var bytesNull = []byte("null")
+
+func parseAttributeOthers(reader text.Reader) (interface{}, bool) {
+	line, _ := reader.PeekLine()
+	c := line[0]
+	if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+		c == '_' || c == ':') {
+		return nil, false
+	}
+	i := 0
+	for ; i < len(line); i++ {
+		c := line[i]
+		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+			(c >= '0' && c <= '9') ||
+			c == '_' || c == ':' || c == '.' || c == '-') {
+			break
+		}
+	}
+	value := line[:i]
+	reader.Advance(i)
+	if bytes.Equal(value, bytesTrue) {
+		return true, true
+	}
+	if bytes.Equal(value, bytesFalse) {
+		return false, true
+	}
+	if bytes.Equal(value, bytesNull) {
+		return nil, true
+	}
+	return value, true
+}

vendor/github.com/yuin/goldmark/parser/atx_heading.go

@@ -0,0 +1,246 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// A HeadingConfig struct is a data structure that holds configuration of the renderers related to headings.
+type HeadingConfig struct {
+	AutoHeadingID bool
+	Attribute     bool
+}
+
+// SetOption implements SetOptioner.
+func (b *HeadingConfig) SetOption(name OptionName, value interface{}) {
+	switch name {
+	case optAutoHeadingID:
+		b.AutoHeadingID = true
+	case optAttribute:
+		b.Attribute = true
+	}
+}
+
+// A HeadingOption interface sets options for heading parsers.
+type HeadingOption interface {
+	Option
+	SetHeadingOption(*HeadingConfig)
+}
+
+// AutoHeadingID is an option name that enables auto IDs for headings.
+const optAutoHeadingID OptionName = "AutoHeadingID"
+
+type withAutoHeadingID struct {
+}
+
+func (o *withAutoHeadingID) SetParserOption(c *Config) {
+	c.Options[optAutoHeadingID] = true
+}
+
+func (o *withAutoHeadingID) SetHeadingOption(p *HeadingConfig) {
+	p.AutoHeadingID = true
+}
+
+// WithAutoHeadingID is a functional option that enables custom heading ids and
+// auto generated heading ids.
+func WithAutoHeadingID() HeadingOption {
+	return &withAutoHeadingID{}
+}
+
+type withHeadingAttribute struct {
+	Option
+}
+
+func (o *withHeadingAttribute) SetHeadingOption(p *HeadingConfig) {
+	p.Attribute = true
+}
+
+// WithHeadingAttribute is a functional option that enables custom heading attributes.
+func WithHeadingAttribute() HeadingOption {
+	return &withHeadingAttribute{WithAttribute()}
+}
+
+type atxHeadingParser struct {
+	HeadingConfig
+}
+
+// NewATXHeadingParser return a new BlockParser that can parse ATX headings.
+func NewATXHeadingParser(opts ...HeadingOption) BlockParser {
+	p := &atxHeadingParser{}
+	for _, o := range opts {
+		o.SetHeadingOption(&p.HeadingConfig)
+	}
+	return p
+}
+
+func (b *atxHeadingParser) Trigger() []byte {
+	return []byte{'#'}
+}
+
+func (b *atxHeadingParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	line, segment := reader.PeekLine()
+	pos := pc.BlockOffset()
+	if pos < 0 {
+		return nil, NoChildren
+	}
+	i := pos
+	for ; i < len(line) && line[i] == '#'; i++ {
+	}
+	level := i - pos
+	if i == pos || level > 6 {
+		return nil, NoChildren
+	}
+	if i == len(line) { // alone '#' (without a new line character)
+		return ast.NewHeading(level), NoChildren
+	}
+	l := util.TrimLeftSpaceLength(line[i:])
+	if l == 0 {
+		return nil, NoChildren
+	}
+	start := i + l
+	if start >= len(line) {
+		start = len(line) - 1
+	}
+	origstart := start
+	stop := len(line) - util.TrimRightSpaceLength(line)
+
+	node := ast.NewHeading(level)
+	parsed := false
+	if b.Attribute { // handles special case like ### heading ### {#id}
+		start--
+		closureClose := -1
+		closureOpen := -1
+		for j := start; j < stop; {
+			c := line[j]
+			if util.IsEscapedPunctuation(line, j) {
+				j += 2
+			} else if util.IsSpace(c) && j < stop-1 && line[j+1] == '#' {
+				closureOpen = j + 1
+				k := j + 1
+				for ; k < stop && line[k] == '#'; k++ {
+				}
+				closureClose = k
+				break
+			} else {
+				j++
+			}
+		}
+		if closureClose > 0 {
+			reader.Advance(closureClose)
+			attrs, ok := ParseAttributes(reader)
+			rest, _ := reader.PeekLine()
+			parsed = ok && util.IsBlank(rest)
+			if parsed {
+				for _, attr := range attrs {
+					node.SetAttribute(attr.Name, attr.Value)
+				}
+				node.Lines().Append(text.NewSegment(segment.Start+start+1-segment.Padding, segment.Start+closureOpen-segment.Padding))
+			}
+		}
+	}
+	if !parsed {
+		start = origstart
+		stop := len(line) - util.TrimRightSpaceLength(line)
+		if stop <= start { // empty headings like '##[space]'
+			stop = start
+		} else {
+			i = stop - 1
+			for ; line[i] == '#' && i >= start; i-- {
+			}
+			if i != stop-1 && !util.IsSpace(line[i]) {
+				i = stop - 1
+			}
+			i++
+			stop = i
+		}
+
+		if len(util.TrimRight(line[start:stop], []byte{'#'})) != 0 { // empty heading like '### ###'
+			node.Lines().Append(text.NewSegment(segment.Start+start-segment.Padding, segment.Start+stop-segment.Padding))
+		}
+	}
+	return node, NoChildren
+}
+
+func (b *atxHeadingParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	return Close
+}
+
+func (b *atxHeadingParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	if b.Attribute {
+		_, ok := node.AttributeString("id")
+		if !ok {
+			parseLastLineAttributes(node, reader, pc)
+		}
+	}
+
+	if b.AutoHeadingID {
+		id, ok := node.AttributeString("id")
+		if !ok {
+			generateAutoHeadingID(node.(*ast.Heading), reader, pc)
+		} else {
+			pc.IDs().Put(id.([]byte))
+		}
+	}
+}
+
+func (b *atxHeadingParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *atxHeadingParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+func generateAutoHeadingID(node *ast.Heading, reader text.Reader, pc Context) {
+	var line []byte
+	lastIndex := node.Lines().Len() - 1
+	if lastIndex > -1 {
+		lastLine := node.Lines().At(lastIndex)
+		line = lastLine.Value(reader.Source())
+	}
+	headingID := pc.IDs().Generate(line, ast.KindHeading)
+	node.SetAttribute(attrNameID, headingID)
+}
+
+func parseLastLineAttributes(node ast.Node, reader text.Reader, pc Context) {
+	lastIndex := node.Lines().Len() - 1
+	if lastIndex < 0 { // empty headings
+		return
+	}
+	lastLine := node.Lines().At(lastIndex)
+	line := lastLine.Value(reader.Source())
+	lr := text.NewReader(line)
+	var attrs Attributes
+	var ok bool
+	var start text.Segment
+	var sl int
+	var end text.Segment
+	for {
+		c := lr.Peek()
+		if c == text.EOF {
+			break
+		}
+		if c == '\\' {
+			lr.Advance(1)
+			if lr.Peek() == '{' {
+				lr.Advance(1)
+			}
+			continue
+		}
+		if c == '{' {
+			sl, start = lr.Position()
+			attrs, ok = ParseAttributes(lr)
+			_, end = lr.Position()
+			lr.SetPosition(sl, start)
+		}
+		lr.Advance(1)
+	}
+	if ok && util.IsBlank(line[end.Start:]) {
+		for _, attr := range attrs {
+			node.SetAttribute(attr.Name, attr.Value)
+		}
+		lastLine.Stop = lastLine.Start + start.Start
+		node.Lines().Set(lastIndex, lastLine)
+	}
+}

vendor/github.com/yuin/goldmark/parser/auto_link.go

@@ -0,0 +1,42 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type autoLinkParser struct {
+}
+
+var defaultAutoLinkParser = &autoLinkParser{}
+
+// NewAutoLinkParser returns a new InlineParser that parses autolinks
+// surrounded by '<' and '>' .
+func NewAutoLinkParser() InlineParser {
+	return defaultAutoLinkParser
+}
+
+func (s *autoLinkParser) Trigger() []byte {
+	return []byte{'<'}
+}
+
+func (s *autoLinkParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	line, segment := block.PeekLine()
+	stop := util.FindEmailIndex(line[1:])
+	typ := ast.AutoLinkType(ast.AutoLinkEmail)
+	if stop < 0 {
+		stop = util.FindURLIndex(line[1:])
+		typ = ast.AutoLinkURL
+	}
+	if stop < 0 {
+		return nil
+	}
+	stop++
+	if stop >= len(line) || line[stop] != '>' {
+		return nil
+	}
+	value := ast.NewTextSegment(text.NewSegment(segment.Start+1, segment.Start+stop))
+	block.Advance(stop + 1)
+	return ast.NewAutoLink(typ, value)
+}

vendor/github.com/yuin/goldmark/parser/blockquote.go

@@ -0,0 +1,69 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type blockquoteParser struct {
+}
+
+var defaultBlockquoteParser = &blockquoteParser{}
+
+// NewBlockquoteParser returns a new BlockParser that
+// parses blockquotes.
+func NewBlockquoteParser() BlockParser {
+	return defaultBlockquoteParser
+}
+
+func (b *blockquoteParser) process(reader text.Reader) bool {
+	line, _ := reader.PeekLine()
+	w, pos := util.IndentWidth(line, reader.LineOffset())
+	if w > 3 || pos >= len(line) || line[pos] != '>' {
+		return false
+	}
+	pos++
+	if pos >= len(line) || line[pos] == '\n' {
+		reader.Advance(pos)
+		return true
+	}
+	if line[pos] == ' ' || line[pos] == '\t' {
+		pos++
+	}
+	reader.Advance(pos)
+	if line[pos-1] == '\t' {
+		reader.SetPadding(2)
+	}
+	return true
+}
+
+func (b *blockquoteParser) Trigger() []byte {
+	return []byte{'>'}
+}
+
+func (b *blockquoteParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	if b.process(reader) {
+		return ast.NewBlockquote(), HasChildren
+	}
+	return nil, NoChildren
+}
+
+func (b *blockquoteParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	if b.process(reader) {
+		return Continue | HasChildren
+	}
+	return Close
+}
+
+func (b *blockquoteParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// nothing to do
+}
+
+func (b *blockquoteParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *blockquoteParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/code_block.go

@@ -0,0 +1,100 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type codeBlockParser struct {
+}
+
+// CodeBlockParser is a BlockParser implementation that parses indented code blocks.
+var defaultCodeBlockParser = &codeBlockParser{}
+
+// NewCodeBlockParser returns a new BlockParser that
+// parses code blocks.
+func NewCodeBlockParser() BlockParser {
+	return defaultCodeBlockParser
+}
+
+func (b *codeBlockParser) Trigger() []byte {
+	return nil
+}
+
+func (b *codeBlockParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	line, segment := reader.PeekLine()
+	pos, padding := util.IndentPosition(line, reader.LineOffset(), 4)
+	if pos < 0 || util.IsBlank(line) {
+		return nil, NoChildren
+	}
+	node := ast.NewCodeBlock()
+	reader.AdvanceAndSetPadding(pos, padding)
+	_, segment = reader.PeekLine()
+	// if code block line starts with a tab, keep a tab as it is.
+	if segment.Padding != 0 {
+		preserveLeadingTabInCodeBlock(&segment, reader, 0)
+	}
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return node, NoChildren
+
+}
+
+func (b *codeBlockParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	line, segment := reader.PeekLine()
+	if util.IsBlank(line) {
+		node.Lines().Append(segment.TrimLeftSpaceWidth(4, reader.Source()))
+		return Continue | NoChildren
+	}
+	pos, padding := util.IndentPosition(line, reader.LineOffset(), 4)
+	if pos < 0 {
+		return Close
+	}
+	reader.AdvanceAndSetPadding(pos, padding)
+	_, segment = reader.PeekLine()
+
+	// if code block line starts with a tab, keep a tab as it is.
+	if segment.Padding != 0 {
+		preserveLeadingTabInCodeBlock(&segment, reader, 0)
+	}
+
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return Continue | NoChildren
+}
+
+func (b *codeBlockParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// trim trailing blank lines
+	lines := node.Lines()
+	length := lines.Len() - 1
+	source := reader.Source()
+	for length >= 0 {
+		line := lines.At(length)
+		if util.IsBlank(line.Value(source)) {
+			length--
+		} else {
+			break
+		}
+	}
+	lines.SetSliced(0, length+1)
+}
+
+func (b *codeBlockParser) CanInterruptParagraph() bool {
+	return false
+}
+
+func (b *codeBlockParser) CanAcceptIndentedLine() bool {
+	return true
+}
+
+func preserveLeadingTabInCodeBlock(segment *text.Segment, reader text.Reader, indent int) {
+	offsetWithPadding := reader.LineOffset() + indent
+	sl, ss := reader.Position()
+	reader.SetPosition(sl, text.NewSegment(ss.Start-1, ss.Stop))
+	if offsetWithPadding == reader.LineOffset() {
+		segment.Padding = 0
+		segment.Start--
+	}
+	reader.SetPosition(sl, ss)
+}

vendor/github.com/yuin/goldmark/parser/code_span.go

@@ -0,0 +1,84 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+)
+
+type codeSpanParser struct {
+}
+
+var defaultCodeSpanParser = &codeSpanParser{}
+
+// NewCodeSpanParser return a new InlineParser that parses inline codes
+// surrounded by '`' .
+func NewCodeSpanParser() InlineParser {
+	return defaultCodeSpanParser
+}
+
+func (s *codeSpanParser) Trigger() []byte {
+	return []byte{'`'}
+}
+
+func (s *codeSpanParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	line, startSegment := block.PeekLine()
+	opener := 0
+	for ; opener < len(line) && line[opener] == '`'; opener++ {
+	}
+	block.Advance(opener)
+	l, pos := block.Position()
+	node := ast.NewCodeSpan()
+	for {
+		line, segment := block.PeekLine()
+		if line == nil {
+			block.SetPosition(l, pos)
+			return ast.NewTextSegment(startSegment.WithStop(startSegment.Start + opener))
+		}
+		for i := 0; i < len(line); i++ {
+			c := line[i]
+			if c == '`' {
+				oldi := i
+				for ; i < len(line) && line[i] == '`'; i++ {
+				}
+				closure := i - oldi
+				if closure == opener && (i >= len(line) || line[i] != '`') {
+					segment = segment.WithStop(segment.Start + i - closure)
+					if !segment.IsEmpty() {
+						node.AppendChild(node, ast.NewRawTextSegment(segment))
+					}
+					block.Advance(i)
+					goto end
+				}
+			}
+		}
+		node.AppendChild(node, ast.NewRawTextSegment(segment))
+		block.AdvanceLine()
+	}
+end:
+	if !node.IsBlank(block.Source()) {
+		// trim first halfspace and last halfspace
+		segment := node.FirstChild().(*ast.Text).Segment
+		shouldTrimmed := true
+		if !(!segment.IsEmpty() && isSpaceOrNewline(block.Source()[segment.Start])) {
+			shouldTrimmed = false
+		}
+		segment = node.LastChild().(*ast.Text).Segment
+		if !(!segment.IsEmpty() && isSpaceOrNewline(block.Source()[segment.Stop-1])) {
+			shouldTrimmed = false
+		}
+		if shouldTrimmed {
+			t := node.FirstChild().(*ast.Text)
+			segment := t.Segment
+			t.Segment = segment.WithStart(segment.Start + 1)
+			t = node.LastChild().(*ast.Text)
+			segment = node.LastChild().(*ast.Text).Segment
+			t.Segment = segment.WithStop(segment.Stop - 1)
+		}
+
+	}
+	return node
+}
+
+func isSpaceOrNewline(c byte) bool {
+	return c == ' ' || c == '\n'
+}

vendor/github.com/yuin/goldmark/parser/delimiter.go

@@ -0,0 +1,238 @@
+package parser
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// A DelimiterProcessor interface provides a set of functions about
+// Delimiter nodes.
+type DelimiterProcessor interface {
+	// IsDelimiter returns true if given character is a delimiter, otherwise false.
+	IsDelimiter(byte) bool
+
+	// CanOpenCloser returns true if given opener can close given closer, otherwise false.
+	CanOpenCloser(opener, closer *Delimiter) bool
+
+	// OnMatch will be called when new matched delimiter found.
+	// OnMatch should return a new Node correspond to the matched delimiter.
+	OnMatch(consumes int) ast.Node
+}
+
+// A Delimiter struct represents a delimiter like '*' of the Markdown text.
+type Delimiter struct {
+	ast.BaseInline
+
+	Segment text.Segment
+
+	// CanOpen is set true if this delimiter can open a span for a new node.
+	// See https://spec.commonmark.org/0.30/#can-open-emphasis for details.
+	CanOpen bool
+
+	// CanClose is set true if this delimiter can close a span for a new node.
+	// See https://spec.commonmark.org/0.30/#can-open-emphasis for details.
+	CanClose bool
+
+	// Length is a remaining length of this delimiter.
+	Length int
+
+	// OriginalLength is a original length of this delimiter.
+	OriginalLength int
+
+	// Char is a character of this delimiter.
+	Char byte
+
+	// PreviousDelimiter is a previous sibling delimiter node of this delimiter.
+	PreviousDelimiter *Delimiter
+
+	// NextDelimiter is a next sibling delimiter node of this delimiter.
+	NextDelimiter *Delimiter
+
+	// Processor is a DelimiterProcessor associated with this delimiter.
+	Processor DelimiterProcessor
+}
+
+// Inline implements Inline.Inline.
+func (d *Delimiter) Inline() {}
+
+// Dump implements Node.Dump.
+func (d *Delimiter) Dump(source []byte, level int) {
+	fmt.Printf("%sDelimiter: \"%s\"\n", strings.Repeat("    ", level), string(d.Text(source)))
+}
+
+var kindDelimiter = ast.NewNodeKind("Delimiter")
+
+// Kind implements Node.Kind
+func (d *Delimiter) Kind() ast.NodeKind {
+	return kindDelimiter
+}
+
+// Text implements Node.Text
+func (d *Delimiter) Text(source []byte) []byte {
+	return d.Segment.Value(source)
+}
+
+// ConsumeCharacters consumes delimiters.
+func (d *Delimiter) ConsumeCharacters(n int) {
+	d.Length -= n
+	d.Segment = d.Segment.WithStop(d.Segment.Start + d.Length)
+}
+
+// CalcComsumption calculates how many characters should be used for opening
+// a new span correspond to given closer.
+func (d *Delimiter) CalcComsumption(closer *Delimiter) int {
+	if (d.CanClose || closer.CanOpen) && (d.OriginalLength+closer.OriginalLength)%3 == 0 && closer.OriginalLength%3 != 0 {
+		return 0
+	}
+	if d.Length >= 2 && closer.Length >= 2 {
+		return 2
+	}
+	return 1
+}
+
+// NewDelimiter returns a new Delimiter node.
+func NewDelimiter(canOpen, canClose bool, length int, char byte, processor DelimiterProcessor) *Delimiter {
+	c := &Delimiter{
+		BaseInline:        ast.BaseInline{},
+		CanOpen:           canOpen,
+		CanClose:          canClose,
+		Length:            length,
+		OriginalLength:    length,
+		Char:              char,
+		PreviousDelimiter: nil,
+		NextDelimiter:     nil,
+		Processor:         processor,
+	}
+	return c
+}
+
+// ScanDelimiter scans a delimiter by given DelimiterProcessor.
+func ScanDelimiter(line []byte, before rune, min int, processor DelimiterProcessor) *Delimiter {
+	i := 0
+	c := line[i]
+	j := i
+	if !processor.IsDelimiter(c) {
+		return nil
+	}
+	for ; j < len(line) && c == line[j]; j++ {
+	}
+	if (j - i) >= min {
+		after := rune(' ')
+		if j != len(line) {
+			after = util.ToRune(line, j)
+		}
+
+		canOpen, canClose := false, false
+		beforeIsPunctuation := util.IsPunctRune(before)
+		beforeIsWhitespace := util.IsSpaceRune(before)
+		afterIsPunctuation := util.IsPunctRune(after)
+		afterIsWhitespace := util.IsSpaceRune(after)
+
+		isLeft := !afterIsWhitespace &&
+			(!afterIsPunctuation || beforeIsWhitespace || beforeIsPunctuation)
+		isRight := !beforeIsWhitespace &&
+			(!beforeIsPunctuation || afterIsWhitespace || afterIsPunctuation)
+
+		if line[i] == '_' {
+			canOpen = isLeft && (!isRight || beforeIsPunctuation)
+			canClose = isRight && (!isLeft || afterIsPunctuation)
+		} else {
+			canOpen = isLeft
+			canClose = isRight
+		}
+		return NewDelimiter(canOpen, canClose, j-i, c, processor)
+	}
+	return nil
+}
+
+// ProcessDelimiters processes the delimiter list in the context.
+// Processing will be stop when reaching the bottom.
+//
+// If you implement an inline parser that can have other inline nodes as
+// children, you should call this function when nesting span has closed.
+func ProcessDelimiters(bottom ast.Node, pc Context) {
+	lastDelimiter := pc.LastDelimiter()
+	if lastDelimiter == nil {
+		return
+	}
+	var closer *Delimiter
+	if bottom != nil {
+		if bottom != lastDelimiter {
+			for c := lastDelimiter.PreviousSibling(); c != nil && c != bottom; {
+				if d, ok := c.(*Delimiter); ok {
+					closer = d
+				}
+				c = c.PreviousSibling()
+			}
+		}
+	} else {
+		closer = pc.FirstDelimiter()
+	}
+	if closer == nil {
+		pc.ClearDelimiters(bottom)
+		return
+	}
+	for closer != nil {
+		if !closer.CanClose {
+			closer = closer.NextDelimiter
+			continue
+		}
+		consume := 0
+		found := false
+		maybeOpener := false
+		var opener *Delimiter
+		for opener = closer.PreviousDelimiter; opener != nil && opener != bottom; opener = opener.PreviousDelimiter {
+			if opener.CanOpen && opener.Processor.CanOpenCloser(opener, closer) {
+				maybeOpener = true
+				consume = opener.CalcComsumption(closer)
+				if consume > 0 {
+					found = true
+					break
+				}
+			}
+		}
+		if !found {
+			next := closer.NextDelimiter
+			if !maybeOpener && !closer.CanOpen {
+				pc.RemoveDelimiter(closer)
+			}
+			closer = next
+			continue
+		}
+		opener.ConsumeCharacters(consume)
+		closer.ConsumeCharacters(consume)
+
+		node := opener.Processor.OnMatch(consume)
+
+		parent := opener.Parent()
+		child := opener.NextSibling()
+
+		for child != nil && child != closer {
+			next := child.NextSibling()
+			node.AppendChild(node, child)
+			child = next
+		}
+		parent.InsertAfter(parent, opener, node)
+
+		for c := opener.NextDelimiter; c != nil && c != closer; {
+			next := c.NextDelimiter
+			pc.RemoveDelimiter(c)
+			c = next
+		}
+
+		if opener.Length == 0 {
+			pc.RemoveDelimiter(opener)
+		}
+
+		if closer.Length == 0 {
+			next := closer.NextDelimiter
+			pc.RemoveDelimiter(closer)
+			closer = next
+		}
+	}
+	pc.ClearDelimiters(bottom)
+}

vendor/github.com/yuin/goldmark/parser/emphasis.go

@@ -0,0 +1,50 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+)
+
+type emphasisDelimiterProcessor struct {
+}
+
+func (p *emphasisDelimiterProcessor) IsDelimiter(b byte) bool {
+	return b == '*' || b == '_'
+}
+
+func (p *emphasisDelimiterProcessor) CanOpenCloser(opener, closer *Delimiter) bool {
+	return opener.Char == closer.Char
+}
+
+func (p *emphasisDelimiterProcessor) OnMatch(consumes int) ast.Node {
+	return ast.NewEmphasis(consumes)
+}
+
+var defaultEmphasisDelimiterProcessor = &emphasisDelimiterProcessor{}
+
+type emphasisParser struct {
+}
+
+var defaultEmphasisParser = &emphasisParser{}
+
+// NewEmphasisParser return a new InlineParser that parses emphasises.
+func NewEmphasisParser() InlineParser {
+	return defaultEmphasisParser
+}
+
+func (s *emphasisParser) Trigger() []byte {
+	return []byte{'*', '_'}
+}
+
+func (s *emphasisParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	before := block.PrecendingCharacter()
+	line, segment := block.PeekLine()
+	node := ScanDelimiter(line, before, 1, defaultEmphasisDelimiterProcessor)
+	if node == nil {
+		return nil
+	}
+	node.Segment = segment.WithStop(segment.Start + node.OriginalLength)
+	block.Advance(node.OriginalLength)
+	pc.PushDelimiter(node)
+	return node
+}

vendor/github.com/yuin/goldmark/parser/fcode_block.go

@@ -0,0 +1,121 @@
+package parser
+
+import (
+	"bytes"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type fencedCodeBlockParser struct {
+}
+
+var defaultFencedCodeBlockParser = &fencedCodeBlockParser{}
+
+// NewFencedCodeBlockParser returns a new BlockParser that
+// parses fenced code blocks.
+func NewFencedCodeBlockParser() BlockParser {
+	return defaultFencedCodeBlockParser
+}
+
+type fenceData struct {
+	char   byte
+	indent int
+	length int
+	node   ast.Node
+}
+
+var fencedCodeBlockInfoKey = NewContextKey()
+
+func (b *fencedCodeBlockParser) Trigger() []byte {
+	return []byte{'~', '`'}
+}
+
+func (b *fencedCodeBlockParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	line, segment := reader.PeekLine()
+	pos := pc.BlockOffset()
+	if pos < 0 || (line[pos] != '`' && line[pos] != '~') {
+		return nil, NoChildren
+	}
+	findent := pos
+	fenceChar := line[pos]
+	i := pos
+	for ; i < len(line) && line[i] == fenceChar; i++ {
+	}
+	oFenceLength := i - pos
+	if oFenceLength < 3 {
+		return nil, NoChildren
+	}
+	var info *ast.Text
+	if i < len(line)-1 {
+		rest := line[i:]
+		left := util.TrimLeftSpaceLength(rest)
+		right := util.TrimRightSpaceLength(rest)
+		if left < len(rest)-right {
+			infoStart, infoStop := segment.Start-segment.Padding+i+left, segment.Stop-right
+			value := rest[left : len(rest)-right]
+			if fenceChar == '`' && bytes.IndexByte(value, '`') > -1 {
+				return nil, NoChildren
+			} else if infoStart != infoStop {
+				info = ast.NewTextSegment(text.NewSegment(infoStart, infoStop))
+			}
+		}
+	}
+	node := ast.NewFencedCodeBlock(info)
+	pc.Set(fencedCodeBlockInfoKey, &fenceData{fenceChar, findent, oFenceLength, node})
+	return node, NoChildren
+
+}
+
+func (b *fencedCodeBlockParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	line, segment := reader.PeekLine()
+	fdata := pc.Get(fencedCodeBlockInfoKey).(*fenceData)
+
+	w, pos := util.IndentWidth(line, reader.LineOffset())
+	if w < 4 {
+		i := pos
+		for ; i < len(line) && line[i] == fdata.char; i++ {
+		}
+		length := i - pos
+		if length >= fdata.length && util.IsBlank(line[i:]) {
+			newline := 1
+			if line[len(line)-1] != '\n' {
+				newline = 0
+			}
+			reader.Advance(segment.Stop - segment.Start - newline + segment.Padding)
+			return Close
+		}
+	}
+	pos, padding := util.IndentPositionPadding(line, reader.LineOffset(), segment.Padding, fdata.indent)
+	if pos < 0 {
+		pos = util.FirstNonSpacePosition(line)
+		if pos < 0 {
+			pos = 0
+		}
+		padding = 0
+	}
+	seg := text.NewSegmentPadding(segment.Start+pos, segment.Stop, padding)
+	// if code block line starts with a tab, keep a tab as it is.
+	if padding != 0 {
+		preserveLeadingTabInCodeBlock(&seg, reader, fdata.indent)
+	}
+	node.Lines().Append(seg)
+	reader.AdvanceAndSetPadding(segment.Stop-segment.Start-pos-1, padding)
+	return Continue | NoChildren
+}
+
+func (b *fencedCodeBlockParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	fdata := pc.Get(fencedCodeBlockInfoKey).(*fenceData)
+	if fdata.node == node {
+		pc.Set(fencedCodeBlockInfoKey, nil)
+	}
+}
+
+func (b *fencedCodeBlockParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *fencedCodeBlockParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/html_block.go

@@ -0,0 +1,228 @@
+package parser
+
+import (
+	"bytes"
+	"regexp"
+	"strings"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var allowedBlockTags = map[string]bool{
+	"address":    true,
+	"article":    true,
+	"aside":      true,
+	"base":       true,
+	"basefont":   true,
+	"blockquote": true,
+	"body":       true,
+	"caption":    true,
+	"center":     true,
+	"col":        true,
+	"colgroup":   true,
+	"dd":         true,
+	"details":    true,
+	"dialog":     true,
+	"dir":        true,
+	"div":        true,
+	"dl":         true,
+	"dt":         true,
+	"fieldset":   true,
+	"figcaption": true,
+	"figure":     true,
+	"footer":     true,
+	"form":       true,
+	"frame":      true,
+	"frameset":   true,
+	"h1":         true,
+	"h2":         true,
+	"h3":         true,
+	"h4":         true,
+	"h5":         true,
+	"h6":         true,
+	"head":       true,
+	"header":     true,
+	"hr":         true,
+	"html":       true,
+	"iframe":     true,
+	"legend":     true,
+	"li":         true,
+	"link":       true,
+	"main":       true,
+	"menu":       true,
+	"menuitem":   true,
+	"meta":       true,
+	"nav":        true,
+	"noframes":   true,
+	"ol":         true,
+	"optgroup":   true,
+	"option":     true,
+	"p":          true,
+	"param":      true,
+	"section":    true,
+	"source":     true,
+	"summary":    true,
+	"table":      true,
+	"tbody":      true,
+	"td":         true,
+	"tfoot":      true,
+	"th":         true,
+	"thead":      true,
+	"title":      true,
+	"tr":         true,
+	"track":      true,
+	"ul":         true,
+}
+
+var htmlBlockType1OpenRegexp = regexp.MustCompile(`(?i)^[ ]{0,3}<(script|pre|style|textarea)(?:\s.*|>.*|/>.*|)(?:\r\n|\n)?$`)
+var htmlBlockType1CloseRegexp = regexp.MustCompile(`(?i)^.*</(?:script|pre|style|textarea)>.*`)
+
+var htmlBlockType2OpenRegexp = regexp.MustCompile(`^[ ]{0,3}<!\-\-`)
+var htmlBlockType2Close = []byte{'-', '-', '>'}
+
+var htmlBlockType3OpenRegexp = regexp.MustCompile(`^[ ]{0,3}<\?`)
+var htmlBlockType3Close = []byte{'?', '>'}
+
+var htmlBlockType4OpenRegexp = regexp.MustCompile(`^[ ]{0,3}<![A-Z]+.*(?:\r\n|\n)?$`)
+var htmlBlockType4Close = []byte{'>'}
+
+var htmlBlockType5OpenRegexp = regexp.MustCompile(`^[ ]{0,3}<\!\[CDATA\[`)
+var htmlBlockType5Close = []byte{']', ']', '>'}
+
+var htmlBlockType6Regexp = regexp.MustCompile(`^[ ]{0,3}<(?:/[ ]*)?([a-zA-Z]+[a-zA-Z0-9\-]*)(?:[ ].*|>.*|/>.*|)(?:\r\n|\n)?$`)
+
+var htmlBlockType7Regexp = regexp.MustCompile(`^[ ]{0,3}<(/[ ]*)?([a-zA-Z]+[a-zA-Z0-9\-]*)(` + attributePattern + `*)[ ]*(?:>|/>)[ ]*(?:\r\n|\n)?$`)
+
+type htmlBlockParser struct {
+}
+
+var defaultHTMLBlockParser = &htmlBlockParser{}
+
+// NewHTMLBlockParser return a new BlockParser that can parse html
+// blocks.
+func NewHTMLBlockParser() BlockParser {
+	return defaultHTMLBlockParser
+}
+
+func (b *htmlBlockParser) Trigger() []byte {
+	return []byte{'<'}
+}
+
+func (b *htmlBlockParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	var node *ast.HTMLBlock
+	line, segment := reader.PeekLine()
+	last := pc.LastOpenedBlock().Node
+	if pos := pc.BlockOffset(); pos < 0 || line[pos] != '<' {
+		return nil, NoChildren
+	}
+
+	if m := htmlBlockType1OpenRegexp.FindSubmatchIndex(line); m != nil {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType1)
+	} else if htmlBlockType2OpenRegexp.Match(line) {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType2)
+	} else if htmlBlockType3OpenRegexp.Match(line) {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType3)
+	} else if htmlBlockType4OpenRegexp.Match(line) {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType4)
+	} else if htmlBlockType5OpenRegexp.Match(line) {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType5)
+	} else if match := htmlBlockType7Regexp.FindSubmatchIndex(line); match != nil {
+		isCloseTag := match[2] > -1 && bytes.Equal(line[match[2]:match[3]], []byte("/"))
+		hasAttr := match[6] != match[7]
+		tagName := strings.ToLower(string(line[match[4]:match[5]]))
+		_, ok := allowedBlockTags[tagName]
+		if ok {
+			node = ast.NewHTMLBlock(ast.HTMLBlockType6)
+		} else if tagName != "script" && tagName != "style" && tagName != "pre" && !ast.IsParagraph(last) && !(isCloseTag && hasAttr) { // type 7 can not interrupt paragraph
+			node = ast.NewHTMLBlock(ast.HTMLBlockType7)
+		}
+	}
+	if node == nil {
+		if match := htmlBlockType6Regexp.FindSubmatchIndex(line); match != nil {
+			tagName := string(line[match[2]:match[3]])
+			_, ok := allowedBlockTags[strings.ToLower(tagName)]
+			if ok {
+				node = ast.NewHTMLBlock(ast.HTMLBlockType6)
+			}
+		}
+	}
+	if node != nil {
+		reader.Advance(segment.Len() - 1)
+		node.Lines().Append(segment)
+		return node, NoChildren
+	}
+	return nil, NoChildren
+}
+
+func (b *htmlBlockParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	htmlBlock := node.(*ast.HTMLBlock)
+	lines := htmlBlock.Lines()
+	line, segment := reader.PeekLine()
+	var closurePattern []byte
+
+	switch htmlBlock.HTMLBlockType {
+	case ast.HTMLBlockType1:
+		if lines.Len() == 1 {
+			firstLine := lines.At(0)
+			if htmlBlockType1CloseRegexp.Match(firstLine.Value(reader.Source())) {
+				return Close
+			}
+		}
+		if htmlBlockType1CloseRegexp.Match(line) {
+			htmlBlock.ClosureLine = segment
+			reader.Advance(segment.Len() - 1)
+			return Close
+		}
+	case ast.HTMLBlockType2:
+		closurePattern = htmlBlockType2Close
+		fallthrough
+	case ast.HTMLBlockType3:
+		if closurePattern == nil {
+			closurePattern = htmlBlockType3Close
+		}
+		fallthrough
+	case ast.HTMLBlockType4:
+		if closurePattern == nil {
+			closurePattern = htmlBlockType4Close
+		}
+		fallthrough
+	case ast.HTMLBlockType5:
+		if closurePattern == nil {
+			closurePattern = htmlBlockType5Close
+		}
+
+		if lines.Len() == 1 {
+			firstLine := lines.At(0)
+			if bytes.Contains(firstLine.Value(reader.Source()), closurePattern) {
+				return Close
+			}
+		}
+		if bytes.Contains(line, closurePattern) {
+			htmlBlock.ClosureLine = segment
+			reader.Advance(segment.Len())
+			return Close
+		}
+
+	case ast.HTMLBlockType6, ast.HTMLBlockType7:
+		if util.IsBlank(line) {
+			return Close
+		}
+	}
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return Continue | NoChildren
+}
+
+func (b *htmlBlockParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// nothing to do
+}
+
+func (b *htmlBlockParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *htmlBlockParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/link.go

@@ -0,0 +1,409 @@
+package parser
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var linkLabelStateKey = NewContextKey()
+
+type linkLabelState struct {
+	ast.BaseInline
+
+	Segment text.Segment
+
+	IsImage bool
+
+	Prev *linkLabelState
+
+	Next *linkLabelState
+
+	First *linkLabelState
+
+	Last *linkLabelState
+}
+
+func newLinkLabelState(segment text.Segment, isImage bool) *linkLabelState {
+	return &linkLabelState{
+		Segment: segment,
+		IsImage: isImage,
+	}
+}
+
+func (s *linkLabelState) Text(source []byte) []byte {
+	return s.Segment.Value(source)
+}
+
+func (s *linkLabelState) Dump(source []byte, level int) {
+	fmt.Printf("%slinkLabelState: \"%s\"\n", strings.Repeat("    ", level), s.Text(source))
+}
+
+var kindLinkLabelState = ast.NewNodeKind("LinkLabelState")
+
+func (s *linkLabelState) Kind() ast.NodeKind {
+	return kindLinkLabelState
+}
+
+func linkLabelStateLength(v *linkLabelState) int {
+	if v == nil || v.Last == nil || v.First == nil {
+		return 0
+	}
+	return v.Last.Segment.Stop - v.First.Segment.Start
+}
+
+func pushLinkLabelState(pc Context, v *linkLabelState) {
+	tlist := pc.Get(linkLabelStateKey)
+	var list *linkLabelState
+	if tlist == nil {
+		list = v
+		v.First = v
+		v.Last = v
+		pc.Set(linkLabelStateKey, list)
+	} else {
+		list = tlist.(*linkLabelState)
+		l := list.Last
+		list.Last = v
+		l.Next = v
+		v.Prev = l
+	}
+}
+
+func removeLinkLabelState(pc Context, d *linkLabelState) {
+	tlist := pc.Get(linkLabelStateKey)
+	var list *linkLabelState
+	if tlist == nil {
+		return
+	}
+	list = tlist.(*linkLabelState)
+
+	if d.Prev == nil {
+		list = d.Next
+		if list != nil {
+			list.First = d
+			list.Last = d.Last
+			list.Prev = nil
+			pc.Set(linkLabelStateKey, list)
+		} else {
+			pc.Set(linkLabelStateKey, nil)
+		}
+	} else {
+		d.Prev.Next = d.Next
+		if d.Next != nil {
+			d.Next.Prev = d.Prev
+		}
+	}
+	if list != nil && d.Next == nil {
+		list.Last = d.Prev
+	}
+	d.Next = nil
+	d.Prev = nil
+	d.First = nil
+	d.Last = nil
+}
+
+type linkParser struct {
+}
+
+var defaultLinkParser = &linkParser{}
+
+// NewLinkParser return a new InlineParser that parses links.
+func NewLinkParser() InlineParser {
+	return defaultLinkParser
+}
+
+func (s *linkParser) Trigger() []byte {
+	return []byte{'!', '[', ']'}
+}
+
+var linkBottom = NewContextKey()
+
+func (s *linkParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	line, segment := block.PeekLine()
+	if line[0] == '!' {
+		if len(line) > 1 && line[1] == '[' {
+			block.Advance(1)
+			pc.Set(linkBottom, pc.LastDelimiter())
+			return processLinkLabelOpen(block, segment.Start+1, true, pc)
+		}
+		return nil
+	}
+	if line[0] == '[' {
+		pc.Set(linkBottom, pc.LastDelimiter())
+		return processLinkLabelOpen(block, segment.Start, false, pc)
+	}
+
+	// line[0] == ']'
+	tlist := pc.Get(linkLabelStateKey)
+	if tlist == nil {
+		return nil
+	}
+	last := tlist.(*linkLabelState).Last
+	if last == nil {
+		return nil
+	}
+	block.Advance(1)
+	removeLinkLabelState(pc, last)
+	// CommonMark spec says:
+	//  > A link label can have at most 999 characters inside the square brackets.
+	if linkLabelStateLength(tlist.(*linkLabelState)) > 998 {
+		ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
+		return nil
+	}
+
+	if !last.IsImage && s.containsLink(last) { // a link in a link text is not allowed
+		ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
+		return nil
+	}
+
+	c := block.Peek()
+	l, pos := block.Position()
+	var link *ast.Link
+	var hasValue bool
+	if c == '(' { // normal link
+		link = s.parseLink(parent, last, block, pc)
+	} else if c == '[' { // reference link
+		link, hasValue = s.parseReferenceLink(parent, last, block, pc)
+		if link == nil && hasValue {
+			ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
+			return nil
+		}
+	}
+
+	if link == nil {
+		// maybe shortcut reference link
+		block.SetPosition(l, pos)
+		ssegment := text.NewSegment(last.Segment.Stop, segment.Start)
+		maybeReference := block.Value(ssegment)
+		// CommonMark spec says:
+		//  > A link label can have at most 999 characters inside the square brackets.
+		if len(maybeReference) > 999 {
+			ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
+			return nil
+		}
+
+		ref, ok := pc.Reference(util.ToLinkReference(maybeReference))
+		if !ok {
+			ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
+			return nil
+		}
+		link = ast.NewLink()
+		s.processLinkLabel(parent, link, last, pc)
+		link.Title = ref.Title()
+		link.Destination = ref.Destination()
+	}
+	if last.IsImage {
+		last.Parent().RemoveChild(last.Parent(), last)
+		return ast.NewImage(link)
+	}
+	last.Parent().RemoveChild(last.Parent(), last)
+	return link
+}
+
+func (s *linkParser) containsLink(n ast.Node) bool {
+	if n == nil {
+		return false
+	}
+	for c := n; c != nil; c = c.NextSibling() {
+		if _, ok := c.(*ast.Link); ok {
+			return true
+		}
+		if s.containsLink(c.FirstChild()) {
+			return true
+		}
+	}
+	return false
+}
+
+func processLinkLabelOpen(block text.Reader, pos int, isImage bool, pc Context) *linkLabelState {
+	start := pos
+	if isImage {
+		start--
+	}
+	state := newLinkLabelState(text.NewSegment(start, pos+1), isImage)
+	pushLinkLabelState(pc, state)
+	block.Advance(1)
+	return state
+}
+
+func (s *linkParser) processLinkLabel(parent ast.Node, link *ast.Link, last *linkLabelState, pc Context) {
+	var bottom ast.Node
+	if v := pc.Get(linkBottom); v != nil {
+		bottom = v.(ast.Node)
+	}
+	pc.Set(linkBottom, nil)
+	ProcessDelimiters(bottom, pc)
+	for c := last.NextSibling(); c != nil; {
+		next := c.NextSibling()
+		parent.RemoveChild(parent, c)
+		link.AppendChild(link, c)
+		c = next
+	}
+}
+
+var linkFindClosureOptions text.FindClosureOptions = text.FindClosureOptions{
+	Nesting: false,
+	Newline: true,
+	Advance: true,
+}
+
+func (s *linkParser) parseReferenceLink(parent ast.Node, last *linkLabelState, block text.Reader, pc Context) (*ast.Link, bool) {
+	_, orgpos := block.Position()
+	block.Advance(1) // skip '['
+	segments, found := block.FindClosure('[', ']', linkFindClosureOptions)
+	if !found {
+		return nil, false
+	}
+
+	var maybeReference []byte
+	if segments.Len() == 1 { // avoid allocate a new byte slice
+		maybeReference = block.Value(segments.At(0))
+	} else {
+		maybeReference = []byte{}
+		for i := 0; i < segments.Len(); i++ {
+			s := segments.At(i)
+			maybeReference = append(maybeReference, block.Value(s)...)
+		}
+	}
+	if util.IsBlank(maybeReference) { // collapsed reference link
+		s := text.NewSegment(last.Segment.Stop, orgpos.Start-1)
+		maybeReference = block.Value(s)
+	}
+	// CommonMark spec says:
+	//  > A link label can have at most 999 characters inside the square brackets.
+	if len(maybeReference) > 999 {
+		return nil, true
+	}
+
+	ref, ok := pc.Reference(util.ToLinkReference(maybeReference))
+	if !ok {
+		return nil, true
+	}
+
+	link := ast.NewLink()
+	s.processLinkLabel(parent, link, last, pc)
+	link.Title = ref.Title()
+	link.Destination = ref.Destination()
+	return link, true
+}
+
+func (s *linkParser) parseLink(parent ast.Node, last *linkLabelState, block text.Reader, pc Context) *ast.Link {
+	block.Advance(1) // skip '('
+	block.SkipSpaces()
+	var title []byte
+	var destination []byte
+	var ok bool
+	if block.Peek() == ')' { // empty link like '[link]()'
+		block.Advance(1)
+	} else {
+		destination, ok = parseLinkDestination(block)
+		if !ok {
+			return nil
+		}
+		block.SkipSpaces()
+		if block.Peek() == ')' {
+			block.Advance(1)
+		} else {
+			title, ok = parseLinkTitle(block)
+			if !ok {
+				return nil
+			}
+			block.SkipSpaces()
+			if block.Peek() == ')' {
+				block.Advance(1)
+			} else {
+				return nil
+			}
+		}
+	}
+
+	link := ast.NewLink()
+	s.processLinkLabel(parent, link, last, pc)
+	link.Destination = destination
+	link.Title = title
+	return link
+}
+
+func parseLinkDestination(block text.Reader) ([]byte, bool) {
+	block.SkipSpaces()
+	line, _ := block.PeekLine()
+	if block.Peek() == '<' {
+		i := 1
+		for i < len(line) {
+			c := line[i]
+			if c == '\\' && i < len(line)-1 && util.IsPunct(line[i+1]) {
+				i += 2
+				continue
+			} else if c == '>' {
+				block.Advance(i + 1)
+				return line[1:i], true
+			}
+			i++
+		}
+		return nil, false
+	}
+	opened := 0
+	i := 0
+	for i < len(line) {
+		c := line[i]
+		if c == '\\' && i < len(line)-1 && util.IsPunct(line[i+1]) {
+			i += 2
+			continue
+		} else if c == '(' {
+			opened++
+		} else if c == ')' {
+			opened--
+			if opened < 0 {
+				break
+			}
+		} else if util.IsSpace(c) {
+			break
+		}
+		i++
+	}
+	block.Advance(i)
+	return line[:i], len(line[:i]) != 0
+}
+
+func parseLinkTitle(block text.Reader) ([]byte, bool) {
+	block.SkipSpaces()
+	opener := block.Peek()
+	if opener != '"' && opener != '\'' && opener != '(' {
+		return nil, false
+	}
+	closer := opener
+	if opener == '(' {
+		closer = ')'
+	}
+	block.Advance(1)
+	segments, found := block.FindClosure(opener, closer, linkFindClosureOptions)
+	if found {
+		if segments.Len() == 1 {
+			return block.Value(segments.At(0)), true
+		}
+		var title []byte
+		for i := 0; i < segments.Len(); i++ {
+			s := segments.At(i)
+			title = append(title, block.Value(s)...)
+		}
+		return title, true
+	}
+	return nil, false
+}
+
+func (s *linkParser) CloseBlock(parent ast.Node, block text.Reader, pc Context) {
+	pc.Set(linkBottom, nil)
+	tlist := pc.Get(linkLabelStateKey)
+	if tlist == nil {
+		return
+	}
+	for s := tlist.(*linkLabelState); s != nil; {
+		next := s.Next
+		removeLinkLabelState(pc, s)
+		s.Parent().ReplaceChild(s.Parent(), s, ast.NewTextSegment(s.Segment))
+		s = next
+	}
+}

vendor/github.com/yuin/goldmark/parser/link_ref.go

@@ -0,0 +1,152 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type linkReferenceParagraphTransformer struct {
+}
+
+// LinkReferenceParagraphTransformer is a ParagraphTransformer implementation
+// that parses and extracts link reference from paragraphs.
+var LinkReferenceParagraphTransformer = &linkReferenceParagraphTransformer{}
+
+func (p *linkReferenceParagraphTransformer) Transform(node *ast.Paragraph, reader text.Reader, pc Context) {
+	lines := node.Lines()
+	block := text.NewBlockReader(reader.Source(), lines)
+	removes := [][2]int{}
+	for {
+		start, end := parseLinkReferenceDefinition(block, pc)
+		if start > -1 {
+			if start == end {
+				end++
+			}
+			removes = append(removes, [2]int{start, end})
+			continue
+		}
+		break
+	}
+
+	offset := 0
+	for _, remove := range removes {
+		if lines.Len() == 0 {
+			break
+		}
+		s := lines.Sliced(remove[1]-offset, lines.Len())
+		lines.SetSliced(0, remove[0]-offset)
+		lines.AppendAll(s)
+		offset = remove[1]
+	}
+
+	if lines.Len() == 0 {
+		t := ast.NewTextBlock()
+		t.SetBlankPreviousLines(node.HasBlankPreviousLines())
+		node.Parent().ReplaceChild(node.Parent(), node, t)
+		return
+	}
+
+	node.SetLines(lines)
+}
+
+func parseLinkReferenceDefinition(block text.Reader, pc Context) (int, int) {
+	block.SkipSpaces()
+	line, _ := block.PeekLine()
+	if line == nil {
+		return -1, -1
+	}
+	startLine, _ := block.Position()
+	width, pos := util.IndentWidth(line, 0)
+	if width > 3 {
+		return -1, -1
+	}
+	if width != 0 {
+		pos++
+	}
+	if line[pos] != '[' {
+		return -1, -1
+	}
+	block.Advance(pos + 1)
+	segments, found := block.FindClosure('[', ']', linkFindClosureOptions)
+	if !found {
+		return -1, -1
+	}
+	var label []byte
+	if segments.Len() == 1 {
+		label = block.Value(segments.At(0))
+	} else {
+		for i := 0; i < segments.Len(); i++ {
+			s := segments.At(i)
+			label = append(label, block.Value(s)...)
+		}
+	}
+	if util.IsBlank(label) {
+		return -1, -1
+	}
+	if block.Peek() != ':' {
+		return -1, -1
+	}
+	block.Advance(1)
+	block.SkipSpaces()
+	destination, ok := parseLinkDestination(block)
+	if !ok {
+		return -1, -1
+	}
+	line, _ = block.PeekLine()
+	isNewLine := line == nil || util.IsBlank(line)
+
+	endLine, _ := block.Position()
+	_, spaces, _ := block.SkipSpaces()
+	opener := block.Peek()
+	if opener != '"' && opener != '\'' && opener != '(' {
+		if !isNewLine {
+			return -1, -1
+		}
+		ref := NewReference(label, destination, nil)
+		pc.AddReference(ref)
+		return startLine, endLine + 1
+	}
+	if spaces == 0 {
+		return -1, -1
+	}
+	block.Advance(1)
+	closer := opener
+	if opener == '(' {
+		closer = ')'
+	}
+	segments, found = block.FindClosure(opener, closer, linkFindClosureOptions)
+	if !found {
+		if !isNewLine {
+			return -1, -1
+		}
+		ref := NewReference(label, destination, nil)
+		pc.AddReference(ref)
+		block.AdvanceLine()
+		return startLine, endLine + 1
+	}
+	var title []byte
+	if segments.Len() == 1 {
+		title = block.Value(segments.At(0))
+	} else {
+		for i := 0; i < segments.Len(); i++ {
+			s := segments.At(i)
+			title = append(title, block.Value(s)...)
+		}
+	}
+
+	line, _ = block.PeekLine()
+	if line != nil && !util.IsBlank(line) {
+		if !isNewLine {
+			return -1, -1
+		}
+		ref := NewReference(label, destination, title)
+		pc.AddReference(ref)
+		return startLine, endLine
+	}
+
+	endLine, _ = block.Position()
+	ref := NewReference(label, destination, title)
+	pc.AddReference(ref)
+	return startLine, endLine + 1
+}

vendor/github.com/yuin/goldmark/parser/list.go

@@ -0,0 +1,287 @@
+package parser
+
+import (
+	"strconv"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type listItemType int
+
+const (
+	notList listItemType = iota
+	bulletList
+	orderedList
+)
+
+var skipListParserKey = NewContextKey()
+var emptyListItemWithBlankLines = NewContextKey()
+var listItemFlagValue interface{} = true
+
+// Same as
+// `^(([ ]*)([\-\*\+]))(\s+.*)?\n?$`.FindSubmatchIndex or
+// `^(([ ]*)(\d{1,9}[\.\)]))(\s+.*)?\n?$`.FindSubmatchIndex
+func parseListItem(line []byte) ([6]int, listItemType) {
+	i := 0
+	l := len(line)
+	ret := [6]int{}
+	for ; i < l && line[i] == ' '; i++ {
+		c := line[i]
+		if c == '\t' {
+			return ret, notList
+		}
+	}
+	if i > 3 {
+		return ret, notList
+	}
+	ret[0] = 0
+	ret[1] = i
+	ret[2] = i
+	var typ listItemType
+	if i < l && (line[i] == '-' || line[i] == '*' || line[i] == '+') {
+		i++
+		ret[3] = i
+		typ = bulletList
+	} else if i < l {
+		for ; i < l && util.IsNumeric(line[i]); i++ {
+		}
+		ret[3] = i
+		if ret[3] == ret[2] || ret[3]-ret[2] > 9 {
+			return ret, notList
+		}
+		if i < l && (line[i] == '.' || line[i] == ')') {
+			i++
+			ret[3] = i
+		} else {
+			return ret, notList
+		}
+		typ = orderedList
+	} else {
+		return ret, notList
+	}
+	if i < l && line[i] != '\n' {
+		w, _ := util.IndentWidth(line[i:], 0)
+		if w == 0 {
+			return ret, notList
+		}
+	}
+	if i >= l {
+		ret[4] = -1
+		ret[5] = -1
+		return ret, typ
+	}
+	ret[4] = i
+	ret[5] = len(line)
+	if line[ret[5]-1] == '\n' && line[i] != '\n' {
+		ret[5]--
+	}
+	return ret, typ
+}
+
+func matchesListItem(source []byte, strict bool) ([6]int, listItemType) {
+	m, typ := parseListItem(source)
+	if typ != notList && (!strict || strict && m[1] < 4) {
+		return m, typ
+	}
+	return m, notList
+}
+
+func calcListOffset(source []byte, match [6]int) int {
+	offset := 0
+	if match[4] < 0 || util.IsBlank(source[match[4]:]) { // list item starts with a blank line
+		offset = 1
+	} else {
+		offset, _ = util.IndentWidth(source[match[4]:], match[4])
+		if offset > 4 { // offseted codeblock
+			offset = 1
+		}
+	}
+	return offset
+}
+
+func lastOffset(node ast.Node) int {
+	lastChild := node.LastChild()
+	if lastChild != nil {
+		return lastChild.(*ast.ListItem).Offset
+	}
+	return 0
+}
+
+type listParser struct {
+}
+
+var defaultListParser = &listParser{}
+
+// NewListParser returns a new BlockParser that
+// parses lists.
+// This parser must take precedence over the ListItemParser.
+func NewListParser() BlockParser {
+	return defaultListParser
+}
+
+func (b *listParser) Trigger() []byte {
+	return []byte{'-', '+', '*', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}
+}
+
+func (b *listParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	last := pc.LastOpenedBlock().Node
+	if _, lok := last.(*ast.List); lok || pc.Get(skipListParserKey) != nil {
+		pc.Set(skipListParserKey, nil)
+		return nil, NoChildren
+	}
+	line, _ := reader.PeekLine()
+	match, typ := matchesListItem(line, true)
+	if typ == notList {
+		return nil, NoChildren
+	}
+	start := -1
+	if typ == orderedList {
+		number := line[match[2] : match[3]-1]
+		start, _ = strconv.Atoi(string(number))
+	}
+
+	if ast.IsParagraph(last) && last.Parent() == parent {
+		// we allow only lists starting with 1 to interrupt paragraphs.
+		if typ == orderedList && start != 1 {
+			return nil, NoChildren
+		}
+		//an empty list item cannot interrupt a paragraph:
+		if match[4] < 0 || util.IsBlank(line[match[4]:match[5]]) {
+			return nil, NoChildren
+		}
+	}
+
+	marker := line[match[3]-1]
+	node := ast.NewList(marker)
+	if start > -1 {
+		node.Start = start
+	}
+	pc.Set(emptyListItemWithBlankLines, nil)
+	return node, HasChildren
+}
+
+func (b *listParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	list := node.(*ast.List)
+	line, _ := reader.PeekLine()
+	if util.IsBlank(line) {
+		if node.LastChild().ChildCount() == 0 {
+			pc.Set(emptyListItemWithBlankLines, listItemFlagValue)
+		}
+		return Continue | HasChildren
+	}
+
+	// "offset" means a width that bar indicates.
+	//    -  aaaaaaaa
+	// |----|
+	//
+	// If the indent is less than the last offset like
+	// - a
+	//  - b          <--- current line
+	// it maybe a new child of the list.
+	//
+	// Empty list items can have multiple blanklines
+	//
+	// -             <--- 1st item is an empty thus "offset" is unknown
+	//
+	//
+	//   -           <--- current line
+	//
+	// -> 1 list with 2 blank items
+	//
+	// So if the last item is an empty, it maybe a new child of the list.
+	//
+	offset := lastOffset(node)
+	lastIsEmpty := node.LastChild().ChildCount() == 0
+	indent, _ := util.IndentWidth(line, reader.LineOffset())
+
+	if indent < offset || lastIsEmpty {
+		if indent < 4 {
+			match, typ := matchesListItem(line, false) // may have a leading spaces more than 3
+			if typ != notList && match[1]-offset < 4 {
+				marker := line[match[3]-1]
+				if !list.CanContinue(marker, typ == orderedList) {
+					return Close
+				}
+				// Thematic Breaks take precedence over lists
+				if isThematicBreak(line[match[3]-1:], 0) {
+					isHeading := false
+					last := pc.LastOpenedBlock().Node
+					if ast.IsParagraph(last) {
+						c, ok := matchesSetextHeadingBar(line[match[3]-1:])
+						if ok && c == '-' {
+							isHeading = true
+						}
+					}
+					if !isHeading {
+						return Close
+					}
+				}
+				return Continue | HasChildren
+			}
+		}
+		if !lastIsEmpty {
+			return Close
+		}
+	}
+
+	if lastIsEmpty && indent < offset {
+		return Close
+	}
+
+	// Non empty items can not exist next to an empty list item
+	// with blank lines. So we need to close the current list
+	//
+	// -
+	//
+	//   foo
+	//
+	// -> 1 list with 1 blank items and 1 paragraph
+	if pc.Get(emptyListItemWithBlankLines) != nil {
+		return Close
+	}
+	return Continue | HasChildren
+}
+
+func (b *listParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	list := node.(*ast.List)
+
+	for c := node.FirstChild(); c != nil && list.IsTight; c = c.NextSibling() {
+		if c.FirstChild() != nil && c.FirstChild() != c.LastChild() {
+			for c1 := c.FirstChild().NextSibling(); c1 != nil; c1 = c1.NextSibling() {
+				if bl, ok := c1.(ast.Node); ok && bl.HasBlankPreviousLines() {
+					list.IsTight = false
+					break
+				}
+			}
+		}
+		if c != node.FirstChild() {
+			if bl, ok := c.(ast.Node); ok && bl.HasBlankPreviousLines() {
+				list.IsTight = false
+			}
+		}
+	}
+
+	if list.IsTight {
+		for child := node.FirstChild(); child != nil; child = child.NextSibling() {
+			for gc := child.FirstChild(); gc != nil; {
+				paragraph, ok := gc.(*ast.Paragraph)
+				gc = gc.NextSibling()
+				if ok {
+					textBlock := ast.NewTextBlock()
+					textBlock.SetLines(paragraph.Lines())
+					child.ReplaceChild(child, paragraph, textBlock)
+				}
+			}
+		}
+	}
+}
+
+func (b *listParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *listParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/list_item.go

@@ -0,0 +1,90 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type listItemParser struct {
+}
+
+var defaultListItemParser = &listItemParser{}
+
+// NewListItemParser returns a new BlockParser that
+// parses list items.
+func NewListItemParser() BlockParser {
+	return defaultListItemParser
+}
+
+func (b *listItemParser) Trigger() []byte {
+	return []byte{'-', '+', '*', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}
+}
+
+func (b *listItemParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	list, lok := parent.(*ast.List)
+	if !lok { // list item must be a child of a list
+		return nil, NoChildren
+	}
+	offset := lastOffset(list)
+	line, _ := reader.PeekLine()
+	match, typ := matchesListItem(line, false)
+	if typ == notList {
+		return nil, NoChildren
+	}
+	if match[1]-offset > 3 {
+		return nil, NoChildren
+	}
+
+	pc.Set(emptyListItemWithBlankLines, nil)
+
+	itemOffset := calcListOffset(line, match)
+	node := ast.NewListItem(match[3] + itemOffset)
+	if match[4] < 0 || util.IsBlank(line[match[4]:match[5]]) {
+		return node, NoChildren
+	}
+
+	pos, padding := util.IndentPosition(line[match[4]:], match[4], itemOffset)
+	child := match[3] + pos
+	reader.AdvanceAndSetPadding(child, padding)
+	return node, HasChildren
+}
+
+func (b *listItemParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	line, _ := reader.PeekLine()
+	if util.IsBlank(line) {
+		reader.Advance(len(line) - 1)
+		return Continue | HasChildren
+	}
+
+	offset := lastOffset(node.Parent())
+	isEmpty := node.ChildCount() == 0
+	indent, _ := util.IndentWidth(line, reader.LineOffset())
+	if (isEmpty || indent < offset) && indent < 4 {
+		_, typ := matchesListItem(line, true)
+		// new list item found
+		if typ != notList {
+			pc.Set(skipListParserKey, listItemFlagValue)
+			return Close
+		}
+		if !isEmpty {
+			return Close
+		}
+	}
+	pos, padding := util.IndentPosition(line, reader.LineOffset(), offset)
+	reader.AdvanceAndSetPadding(pos, padding)
+
+	return Continue | HasChildren
+}
+
+func (b *listItemParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// nothing to do
+}
+
+func (b *listItemParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *listItemParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/paragraph.go

@@ -0,0 +1,72 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type paragraphParser struct {
+}
+
+var defaultParagraphParser = &paragraphParser{}
+
+// NewParagraphParser returns a new BlockParser that
+// parses paragraphs.
+func NewParagraphParser() BlockParser {
+	return defaultParagraphParser
+}
+
+func (b *paragraphParser) Trigger() []byte {
+	return nil
+}
+
+func (b *paragraphParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	_, segment := reader.PeekLine()
+	segment = segment.TrimLeftSpace(reader.Source())
+	if segment.IsEmpty() {
+		return nil, NoChildren
+	}
+	node := ast.NewParagraph()
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return node, NoChildren
+}
+
+func (b *paragraphParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	line, segment := reader.PeekLine()
+	if util.IsBlank(line) {
+		return Close
+	}
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return Continue | NoChildren
+}
+
+func (b *paragraphParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	lines := node.Lines()
+	if lines.Len() != 0 {
+		// trim leading spaces
+		for i := 0; i < lines.Len(); i++ {
+			l := lines.At(i)
+			lines.Set(i, l.TrimLeftSpace(reader.Source()))
+		}
+
+		// trim trailing spaces
+		length := lines.Len()
+		lastLine := node.Lines().At(length - 1)
+		node.Lines().Set(length-1, lastLine.TrimRightSpace(reader.Source()))
+	}
+	if lines.Len() == 0 {
+		node.Parent().RemoveChild(node.Parent(), node)
+		return
+	}
+}
+
+func (b *paragraphParser) CanInterruptParagraph() bool {
+	return false
+}
+
+func (b *paragraphParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/raw_html.go

@@ -0,0 +1,163 @@
+package parser
+
+import (
+	"bytes"
+	"regexp"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type rawHTMLParser struct {
+}
+
+var defaultRawHTMLParser = &rawHTMLParser{}
+
+// NewRawHTMLParser return a new InlineParser that can parse
+// inline htmls
+func NewRawHTMLParser() InlineParser {
+	return defaultRawHTMLParser
+}
+
+func (s *rawHTMLParser) Trigger() []byte {
+	return []byte{'<'}
+}
+
+func (s *rawHTMLParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	line, _ := block.PeekLine()
+	if len(line) > 1 && util.IsAlphaNumeric(line[1]) {
+		return s.parseMultiLineRegexp(openTagRegexp, block, pc)
+	}
+	if len(line) > 2 && line[1] == '/' && util.IsAlphaNumeric(line[2]) {
+		return s.parseMultiLineRegexp(closeTagRegexp, block, pc)
+	}
+	if bytes.HasPrefix(line, openComment) {
+		return s.parseComment(block, pc)
+	}
+	if bytes.HasPrefix(line, openProcessingInstruction) {
+		return s.parseUntil(block, closeProcessingInstruction, pc)
+	}
+	if len(line) > 2 && line[1] == '!' && line[2] >= 'A' && line[2] <= 'Z' {
+		return s.parseUntil(block, closeDecl, pc)
+	}
+	if bytes.HasPrefix(line, openCDATA) {
+		return s.parseUntil(block, closeCDATA, pc)
+	}
+	return nil
+}
+
+var tagnamePattern = `([A-Za-z][A-Za-z0-9-]*)`
+
+var attributePattern = `(?:[\r\n \t]+[a-zA-Z_:][a-zA-Z0-9:._-]*(?:[\r\n \t]*=[\r\n \t]*(?:[^\"'=<>` + "`" + `\x00-\x20]+|'[^']*'|"[^"]*"))?)`
+var openTagRegexp = regexp.MustCompile("^<" + tagnamePattern + attributePattern + `*[ \t]*/?>`)
+var closeTagRegexp = regexp.MustCompile("^</" + tagnamePattern + `\s*>`)
+
+var openProcessingInstruction = []byte("<?")
+var closeProcessingInstruction = []byte("?>")
+var openCDATA = []byte("<![CDATA[")
+var closeCDATA = []byte("]]>")
+var closeDecl = []byte(">")
+var emptyComment = []byte("<!---->")
+var invalidComment1 = []byte("<!-->")
+var invalidComment2 = []byte("<!--->")
+var openComment = []byte("<!--")
+var closeComment = []byte("-->")
+var doubleHyphen = []byte("--")
+
+func (s *rawHTMLParser) parseComment(block text.Reader, pc Context) ast.Node {
+	savedLine, savedSegment := block.Position()
+	node := ast.NewRawHTML()
+	line, segment := block.PeekLine()
+	if bytes.HasPrefix(line, emptyComment) {
+		node.Segments.Append(segment.WithStop(segment.Start + len(emptyComment)))
+		block.Advance(len(emptyComment))
+		return node
+	}
+	if bytes.HasPrefix(line, invalidComment1) || bytes.HasPrefix(line, invalidComment2) {
+		return nil
+	}
+	offset := len(openComment)
+	line = line[offset:]
+	for {
+		hindex := bytes.Index(line, doubleHyphen)
+		if hindex > -1 {
+			hindex += offset
+		}
+		index := bytes.Index(line, closeComment) + offset
+		if index > -1 && hindex == index {
+			if index == 0 || len(line) < 2 || line[index-offset-1] != '-' {
+				node.Segments.Append(segment.WithStop(segment.Start + index + len(closeComment)))
+				block.Advance(index + len(closeComment))
+				return node
+			}
+		}
+		if hindex > 0 {
+			break
+		}
+		node.Segments.Append(segment)
+		block.AdvanceLine()
+		line, segment = block.PeekLine()
+		offset = 0
+		if line == nil {
+			break
+		}
+	}
+	block.SetPosition(savedLine, savedSegment)
+	return nil
+}
+
+func (s *rawHTMLParser) parseUntil(block text.Reader, closer []byte, pc Context) ast.Node {
+	savedLine, savedSegment := block.Position()
+	node := ast.NewRawHTML()
+	for {
+		line, segment := block.PeekLine()
+		if line == nil {
+			break
+		}
+		index := bytes.Index(line, closer)
+		if index > -1 {
+			node.Segments.Append(segment.WithStop(segment.Start + index + len(closer)))
+			block.Advance(index + len(closer))
+			return node
+		}
+		node.Segments.Append(segment)
+		block.AdvanceLine()
+	}
+	block.SetPosition(savedLine, savedSegment)
+	return nil
+}
+
+func (s *rawHTMLParser) parseMultiLineRegexp(reg *regexp.Regexp, block text.Reader, pc Context) ast.Node {
+	sline, ssegment := block.Position()
+	if block.Match(reg) {
+		node := ast.NewRawHTML()
+		eline, esegment := block.Position()
+		block.SetPosition(sline, ssegment)
+		for {
+			line, segment := block.PeekLine()
+			if line == nil {
+				break
+			}
+			l, _ := block.Position()
+			start := segment.Start
+			if l == sline {
+				start = ssegment.Start
+			}
+			end := segment.Stop
+			if l == eline {
+				end = esegment.Start
+			}
+
+			node.Segments.Append(text.NewSegment(start, end))
+			if l == eline {
+				block.Advance(end - start)
+				break
+			} else {
+				block.AdvanceLine()
+			}
+		}
+		return node
+	}
+	return nil
+}

vendor/github.com/yuin/goldmark/parser/setext_headings.go

@@ -0,0 +1,126 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var temporaryParagraphKey = NewContextKey()
+
+type setextHeadingParser struct {
+	HeadingConfig
+}
+
+func matchesSetextHeadingBar(line []byte) (byte, bool) {
+	start := 0
+	end := len(line)
+	space := util.TrimLeftLength(line, []byte{' '})
+	if space > 3 {
+		return 0, false
+	}
+	start += space
+	level1 := util.TrimLeftLength(line[start:end], []byte{'='})
+	c := byte('=')
+	var level2 int
+	if level1 == 0 {
+		level2 = util.TrimLeftLength(line[start:end], []byte{'-'})
+		c = '-'
+	}
+	if util.IsSpace(line[end-1]) {
+		end -= util.TrimRightSpaceLength(line[start:end])
+	}
+	if !((level1 > 0 && start+level1 == end) || (level2 > 0 && start+level2 == end)) {
+		return 0, false
+	}
+	return c, true
+}
+
+// NewSetextHeadingParser return a new BlockParser that can parse Setext headings.
+func NewSetextHeadingParser(opts ...HeadingOption) BlockParser {
+	p := &setextHeadingParser{}
+	for _, o := range opts {
+		o.SetHeadingOption(&p.HeadingConfig)
+	}
+	return p
+}
+
+func (b *setextHeadingParser) Trigger() []byte {
+	return []byte{'-', '='}
+}
+
+func (b *setextHeadingParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	last := pc.LastOpenedBlock().Node
+	if last == nil {
+		return nil, NoChildren
+	}
+	paragraph, ok := last.(*ast.Paragraph)
+	if !ok || paragraph.Parent() != parent {
+		return nil, NoChildren
+	}
+	line, segment := reader.PeekLine()
+	c, ok := matchesSetextHeadingBar(line)
+	if !ok {
+		return nil, NoChildren
+	}
+	level := 1
+	if c == '-' {
+		level = 2
+	}
+	node := ast.NewHeading(level)
+	node.Lines().Append(segment)
+	pc.Set(temporaryParagraphKey, last)
+	return node, NoChildren | RequireParagraph
+}
+
+func (b *setextHeadingParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	return Close
+}
+
+func (b *setextHeadingParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	heading := node.(*ast.Heading)
+	segment := node.Lines().At(0)
+	heading.Lines().Clear()
+	tmp := pc.Get(temporaryParagraphKey).(*ast.Paragraph)
+	pc.Set(temporaryParagraphKey, nil)
+	if tmp.Lines().Len() == 0 {
+		next := heading.NextSibling()
+		segment = segment.TrimLeftSpace(reader.Source())
+		if next == nil || !ast.IsParagraph(next) {
+			para := ast.NewParagraph()
+			para.Lines().Append(segment)
+			heading.Parent().InsertAfter(heading.Parent(), heading, para)
+		} else {
+			next.(ast.Node).Lines().Unshift(segment)
+		}
+		heading.Parent().RemoveChild(heading.Parent(), heading)
+	} else {
+		heading.SetLines(tmp.Lines())
+		heading.SetBlankPreviousLines(tmp.HasBlankPreviousLines())
+		tp := tmp.Parent()
+		if tp != nil {
+			tp.RemoveChild(tp, tmp)
+		}
+	}
+
+	if b.Attribute {
+		parseLastLineAttributes(node, reader, pc)
+	}
+
+	if b.AutoHeadingID {
+		id, ok := node.AttributeString("id")
+		if !ok {
+			generateAutoHeadingID(heading, reader, pc)
+		} else {
+			pc.IDs().Put(id.([]byte))
+		}
+	}
+}
+
+func (b *setextHeadingParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *setextHeadingParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/thematic_break.go

@@ -0,0 +1,75 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type thematicBreakPraser struct {
+}
+
+var defaultThematicBreakPraser = &thematicBreakPraser{}
+
+// NewThematicBreakParser returns a new BlockParser that
+// parses thematic breaks.
+func NewThematicBreakParser() BlockParser {
+	return defaultThematicBreakPraser
+}
+
+func isThematicBreak(line []byte, offset int) bool {
+	w, pos := util.IndentWidth(line, offset)
+	if w > 3 {
+		return false
+	}
+	mark := byte(0)
+	count := 0
+	for i := pos; i < len(line); i++ {
+		c := line[i]
+		if util.IsSpace(c) {
+			continue
+		}
+		if mark == 0 {
+			mark = c
+			count = 1
+			if mark == '*' || mark == '-' || mark == '_' {
+				continue
+			}
+			return false
+		}
+		if c != mark {
+			return false
+		}
+		count++
+	}
+	return count > 2
+}
+
+func (b *thematicBreakPraser) Trigger() []byte {
+	return []byte{'-', '*', '_'}
+}
+
+func (b *thematicBreakPraser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	line, segment := reader.PeekLine()
+	if isThematicBreak(line, reader.LineOffset()) {
+		reader.Advance(segment.Len() - 1)
+		return ast.NewThematicBreak(), NoChildren
+	}
+	return nil, NoChildren
+}
+
+func (b *thematicBreakPraser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	return Close
+}
+
+func (b *thematicBreakPraser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// nothing to do
+}
+
+func (b *thematicBreakPraser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *thematicBreakPraser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/renderer/html/html.go

@@ -0,0 +1,931 @@
+package html
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+	"unicode/utf8"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/util"
+)
+
+// A Config struct has configurations for the HTML based renderers.
+type Config struct {
+	Writer              Writer
+	HardWraps           bool
+	EastAsianLineBreaks bool
+	XHTML               bool
+	Unsafe              bool
+}
+
+// NewConfig returns a new Config with defaults.
+func NewConfig() Config {
+	return Config{
+		Writer:              DefaultWriter,
+		HardWraps:           false,
+		EastAsianLineBreaks: false,
+		XHTML:               false,
+		Unsafe:              false,
+	}
+}
+
+// SetOption implements renderer.NodeRenderer.SetOption.
+func (c *Config) SetOption(name renderer.OptionName, value interface{}) {
+	switch name {
+	case optHardWraps:
+		c.HardWraps = value.(bool)
+	case optEastAsianLineBreaks:
+		c.EastAsianLineBreaks = value.(bool)
+	case optXHTML:
+		c.XHTML = value.(bool)
+	case optUnsafe:
+		c.Unsafe = value.(bool)
+	case optTextWriter:
+		c.Writer = value.(Writer)
+	}
+}
+
+// An Option interface sets options for HTML based renderers.
+type Option interface {
+	SetHTMLOption(*Config)
+}
+
+// TextWriter is an option name used in WithWriter.
+const optTextWriter renderer.OptionName = "Writer"
+
+type withWriter struct {
+	value Writer
+}
+
+func (o *withWriter) SetConfig(c *renderer.Config) {
+	c.Options[optTextWriter] = o.value
+}
+
+func (o *withWriter) SetHTMLOption(c *Config) {
+	c.Writer = o.value
+}
+
+// WithWriter is a functional option that allow you to set the given writer to
+// the renderer.
+func WithWriter(writer Writer) interface {
+	renderer.Option
+	Option
+} {
+	return &withWriter{writer}
+}
+
+// HardWraps is an option name used in WithHardWraps.
+const optHardWraps renderer.OptionName = "HardWraps"
+
+type withHardWraps struct {
+}
+
+func (o *withHardWraps) SetConfig(c *renderer.Config) {
+	c.Options[optHardWraps] = true
+}
+
+func (o *withHardWraps) SetHTMLOption(c *Config) {
+	c.HardWraps = true
+}
+
+// WithHardWraps is a functional option that indicates whether softline breaks
+// should be rendered as '<br>'.
+func WithHardWraps() interface {
+	renderer.Option
+	Option
+} {
+	return &withHardWraps{}
+}
+
+// EastAsianLineBreaks is an option name used in WithEastAsianLineBreaks.
+const optEastAsianLineBreaks renderer.OptionName = "EastAsianLineBreaks"
+
+type withEastAsianLineBreaks struct {
+}
+
+func (o *withEastAsianLineBreaks) SetConfig(c *renderer.Config) {
+	c.Options[optEastAsianLineBreaks] = true
+}
+
+func (o *withEastAsianLineBreaks) SetHTMLOption(c *Config) {
+	c.EastAsianLineBreaks = true
+}
+
+// WithEastAsianLineBreaks is a functional option that indicates whether softline breaks
+// between east asian wide characters should be ignored.
+func WithEastAsianLineBreaks() interface {
+	renderer.Option
+	Option
+} {
+	return &withEastAsianLineBreaks{}
+}
+
+// XHTML is an option name used in WithXHTML.
+const optXHTML renderer.OptionName = "XHTML"
+
+type withXHTML struct {
+}
+
+func (o *withXHTML) SetConfig(c *renderer.Config) {
+	c.Options[optXHTML] = true
+}
+
+func (o *withXHTML) SetHTMLOption(c *Config) {
+	c.XHTML = true
+}
+
+// WithXHTML is a functional option indicates that nodes should be rendered in
+// xhtml instead of HTML5.
+func WithXHTML() interface {
+	Option
+	renderer.Option
+} {
+	return &withXHTML{}
+}
+
+// Unsafe is an option name used in WithUnsafe.
+const optUnsafe renderer.OptionName = "Unsafe"
+
+type withUnsafe struct {
+}
+
+func (o *withUnsafe) SetConfig(c *renderer.Config) {
+	c.Options[optUnsafe] = true
+}
+
+func (o *withUnsafe) SetHTMLOption(c *Config) {
+	c.Unsafe = true
+}
+
+// WithUnsafe is a functional option that renders dangerous contents
+// (raw htmls and potentially dangerous links) as it is.
+func WithUnsafe() interface {
+	renderer.Option
+	Option
+} {
+	return &withUnsafe{}
+}
+
+// A Renderer struct is an implementation of renderer.NodeRenderer that renders
+// nodes as (X)HTML.
+type Renderer struct {
+	Config
+}
+
+// NewRenderer returns a new Renderer with given options.
+func NewRenderer(opts ...Option) renderer.NodeRenderer {
+	r := &Renderer{
+		Config: NewConfig(),
+	}
+
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+// RegisterFuncs implements NodeRenderer.RegisterFuncs .
+func (r *Renderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	// blocks
+
+	reg.Register(ast.KindDocument, r.renderDocument)
+	reg.Register(ast.KindHeading, r.renderHeading)
+	reg.Register(ast.KindBlockquote, r.renderBlockquote)
+	reg.Register(ast.KindCodeBlock, r.renderCodeBlock)
+	reg.Register(ast.KindFencedCodeBlock, r.renderFencedCodeBlock)
+	reg.Register(ast.KindHTMLBlock, r.renderHTMLBlock)
+	reg.Register(ast.KindList, r.renderList)
+	reg.Register(ast.KindListItem, r.renderListItem)
+	reg.Register(ast.KindParagraph, r.renderParagraph)
+	reg.Register(ast.KindTextBlock, r.renderTextBlock)
+	reg.Register(ast.KindThematicBreak, r.renderThematicBreak)
+
+	// inlines
+
+	reg.Register(ast.KindAutoLink, r.renderAutoLink)
+	reg.Register(ast.KindCodeSpan, r.renderCodeSpan)
+	reg.Register(ast.KindEmphasis, r.renderEmphasis)
+	reg.Register(ast.KindImage, r.renderImage)
+	reg.Register(ast.KindLink, r.renderLink)
+	reg.Register(ast.KindRawHTML, r.renderRawHTML)
+	reg.Register(ast.KindText, r.renderText)
+	reg.Register(ast.KindString, r.renderString)
+}
+
+func (r *Renderer) writeLines(w util.BufWriter, source []byte, n ast.Node) {
+	l := n.Lines().Len()
+	for i := 0; i < l; i++ {
+		line := n.Lines().At(i)
+		r.Writer.RawWrite(w, line.Value(source))
+	}
+}
+
+// GlobalAttributeFilter defines attribute names which any elements can have.
+var GlobalAttributeFilter = util.NewBytesFilter(
+	[]byte("accesskey"),
+	[]byte("autocapitalize"),
+	[]byte("autofocus"),
+	[]byte("class"),
+	[]byte("contenteditable"),
+	[]byte("dir"),
+	[]byte("draggable"),
+	[]byte("enterkeyhint"),
+	[]byte("hidden"),
+	[]byte("id"),
+	[]byte("inert"),
+	[]byte("inputmode"),
+	[]byte("is"),
+	[]byte("itemid"),
+	[]byte("itemprop"),
+	[]byte("itemref"),
+	[]byte("itemscope"),
+	[]byte("itemtype"),
+	[]byte("lang"),
+	[]byte("part"),
+	[]byte("slot"),
+	[]byte("spellcheck"),
+	[]byte("style"),
+	[]byte("tabindex"),
+	[]byte("title"),
+	[]byte("translate"),
+)
+
+func (r *Renderer) renderDocument(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	// nothing to do
+	return ast.WalkContinue, nil
+}
+
+// HeadingAttributeFilter defines attribute names which heading elements can have
+var HeadingAttributeFilter = GlobalAttributeFilter
+
+func (r *Renderer) renderHeading(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.Heading)
+	if entering {
+		_, _ = w.WriteString("<h")
+		_ = w.WriteByte("0123456"[n.Level])
+		if n.Attributes() != nil {
+			RenderAttributes(w, node, HeadingAttributeFilter)
+		}
+		_ = w.WriteByte('>')
+	} else {
+		_, _ = w.WriteString("</h")
+		_ = w.WriteByte("0123456"[n.Level])
+		_, _ = w.WriteString(">\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// BlockquoteAttributeFilter defines attribute names which blockquote elements can have
+var BlockquoteAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("cite"),
+)
+
+func (r *Renderer) renderBlockquote(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<blockquote")
+			RenderAttributes(w, n, BlockquoteAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<blockquote>\n")
+		}
+	} else {
+		_, _ = w.WriteString("</blockquote>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderCodeBlock(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		_, _ = w.WriteString("<pre><code>")
+		r.writeLines(w, source, n)
+	} else {
+		_, _ = w.WriteString("</code></pre>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderFencedCodeBlock(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.FencedCodeBlock)
+	if entering {
+		_, _ = w.WriteString("<pre><code")
+		language := n.Language(source)
+		if language != nil {
+			_, _ = w.WriteString(" class=\"language-")
+			r.Writer.Write(w, language)
+			_, _ = w.WriteString("\"")
+		}
+		_ = w.WriteByte('>')
+		r.writeLines(w, source, n)
+	} else {
+		_, _ = w.WriteString("</code></pre>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderHTMLBlock(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.HTMLBlock)
+	if entering {
+		if r.Unsafe {
+			l := n.Lines().Len()
+			for i := 0; i < l; i++ {
+				line := n.Lines().At(i)
+				r.Writer.SecureWrite(w, line.Value(source))
+			}
+		} else {
+			_, _ = w.WriteString("<!-- raw HTML omitted -->\n")
+		}
+	} else {
+		if n.HasClosure() {
+			if r.Unsafe {
+				closure := n.ClosureLine
+				r.Writer.SecureWrite(w, closure.Value(source))
+			} else {
+				_, _ = w.WriteString("<!-- raw HTML omitted -->\n")
+			}
+		}
+	}
+	return ast.WalkContinue, nil
+}
+
+// ListAttributeFilter defines attribute names which list elements can have.
+var ListAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("start"),
+	[]byte("reversed"),
+	[]byte("type"),
+)
+
+func (r *Renderer) renderList(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.List)
+	tag := "ul"
+	if n.IsOrdered() {
+		tag = "ol"
+	}
+	if entering {
+		_ = w.WriteByte('<')
+		_, _ = w.WriteString(tag)
+		if n.IsOrdered() && n.Start != 1 {
+			fmt.Fprintf(w, " start=\"%d\"", n.Start)
+		}
+		if n.Attributes() != nil {
+			RenderAttributes(w, n, ListAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+	} else {
+		_, _ = w.WriteString("</")
+		_, _ = w.WriteString(tag)
+		_, _ = w.WriteString(">\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// ListItemAttributeFilter defines attribute names which list item elements can have.
+var ListItemAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("value"),
+)
+
+func (r *Renderer) renderListItem(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<li")
+			RenderAttributes(w, n, ListItemAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<li>")
+		}
+		fc := n.FirstChild()
+		if fc != nil {
+			if _, ok := fc.(*ast.TextBlock); !ok {
+				_ = w.WriteByte('\n')
+			}
+		}
+	} else {
+		_, _ = w.WriteString("</li>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// ParagraphAttributeFilter defines attribute names which paragraph elements can have.
+var ParagraphAttributeFilter = GlobalAttributeFilter
+
+func (r *Renderer) renderParagraph(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<p")
+			RenderAttributes(w, n, ParagraphAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<p>")
+		}
+	} else {
+		_, _ = w.WriteString("</p>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderTextBlock(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		if _, ok := n.NextSibling().(ast.Node); ok && n.FirstChild() != nil {
+			_ = w.WriteByte('\n')
+		}
+	}
+	return ast.WalkContinue, nil
+}
+
+// ThematicAttributeFilter defines attribute names which hr elements can have.
+var ThematicAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("align"),   // [Deprecated]
+	[]byte("color"),   // [Not Standardized]
+	[]byte("noshade"), // [Deprecated]
+	[]byte("size"),    // [Deprecated]
+	[]byte("width"),   // [Deprecated]
+)
+
+func (r *Renderer) renderThematicBreak(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	_, _ = w.WriteString("<hr")
+	if n.Attributes() != nil {
+		RenderAttributes(w, n, ThematicAttributeFilter)
+	}
+	if r.XHTML {
+		_, _ = w.WriteString(" />\n")
+	} else {
+		_, _ = w.WriteString(">\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// LinkAttributeFilter defines attribute names which link elements can have.
+var LinkAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("download"),
+	// []byte("href"),
+	[]byte("hreflang"),
+	[]byte("media"),
+	[]byte("ping"),
+	[]byte("referrerpolicy"),
+	[]byte("rel"),
+	[]byte("shape"),
+	[]byte("target"),
+)
+
+func (r *Renderer) renderAutoLink(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.AutoLink)
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	_, _ = w.WriteString(`<a href="`)
+	url := n.URL(source)
+	label := n.Label(source)
+	if n.AutoLinkType == ast.AutoLinkEmail && !bytes.HasPrefix(bytes.ToLower(url), []byte("mailto:")) {
+		_, _ = w.WriteString("mailto:")
+	}
+	_, _ = w.Write(util.EscapeHTML(util.URLEscape(url, false)))
+	if n.Attributes() != nil {
+		_ = w.WriteByte('"')
+		RenderAttributes(w, n, LinkAttributeFilter)
+		_ = w.WriteByte('>')
+	} else {
+		_, _ = w.WriteString(`">`)
+	}
+	_, _ = w.Write(util.EscapeHTML(label))
+	_, _ = w.WriteString(`</a>`)
+	return ast.WalkContinue, nil
+}
+
+// CodeAttributeFilter defines attribute names which code elements can have.
+var CodeAttributeFilter = GlobalAttributeFilter
+
+func (r *Renderer) renderCodeSpan(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<code")
+			RenderAttributes(w, n, CodeAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<code>")
+		}
+		for c := n.FirstChild(); c != nil; c = c.NextSibling() {
+			segment := c.(*ast.Text).Segment
+			value := segment.Value(source)
+			if bytes.HasSuffix(value, []byte("\n")) {
+				r.Writer.RawWrite(w, value[:len(value)-1])
+				r.Writer.RawWrite(w, []byte(" "))
+			} else {
+				r.Writer.RawWrite(w, value)
+			}
+		}
+		return ast.WalkSkipChildren, nil
+	}
+	_, _ = w.WriteString("</code>")
+	return ast.WalkContinue, nil
+}
+
+// EmphasisAttributeFilter defines attribute names which emphasis elements can have.
+var EmphasisAttributeFilter = GlobalAttributeFilter
+
+func (r *Renderer) renderEmphasis(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.Emphasis)
+	tag := "em"
+	if n.Level == 2 {
+		tag = "strong"
+	}
+	if entering {
+		_ = w.WriteByte('<')
+		_, _ = w.WriteString(tag)
+		if n.Attributes() != nil {
+			RenderAttributes(w, n, EmphasisAttributeFilter)
+		}
+		_ = w.WriteByte('>')
+	} else {
+		_, _ = w.WriteString("</")
+		_, _ = w.WriteString(tag)
+		_ = w.WriteByte('>')
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderLink(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.Link)
+	if entering {
+		_, _ = w.WriteString("<a href=\"")
+		if r.Unsafe || !IsDangerousURL(n.Destination) {
+			_, _ = w.Write(util.EscapeHTML(util.URLEscape(n.Destination, true)))
+		}
+		_ = w.WriteByte('"')
+		if n.Title != nil {
+			_, _ = w.WriteString(` title="`)
+			r.Writer.Write(w, n.Title)
+			_ = w.WriteByte('"')
+		}
+		if n.Attributes() != nil {
+			RenderAttributes(w, n, LinkAttributeFilter)
+		}
+		_ = w.WriteByte('>')
+	} else {
+		_, _ = w.WriteString("</a>")
+	}
+	return ast.WalkContinue, nil
+}
+
+// ImageAttributeFilter defines attribute names which image elements can have.
+var ImageAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("align"),
+	[]byte("border"),
+	[]byte("crossorigin"),
+	[]byte("decoding"),
+	[]byte("height"),
+	[]byte("importance"),
+	[]byte("intrinsicsize"),
+	[]byte("ismap"),
+	[]byte("loading"),
+	[]byte("referrerpolicy"),
+	[]byte("sizes"),
+	[]byte("srcset"),
+	[]byte("usemap"),
+	[]byte("width"),
+)
+
+func (r *Renderer) renderImage(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	n := node.(*ast.Image)
+	_, _ = w.WriteString("<img src=\"")
+	if r.Unsafe || !IsDangerousURL(n.Destination) {
+		_, _ = w.Write(util.EscapeHTML(util.URLEscape(n.Destination, true)))
+	}
+	_, _ = w.WriteString(`" alt="`)
+	_, _ = w.Write(nodeToHTMLText(n, source))
+	_ = w.WriteByte('"')
+	if n.Title != nil {
+		_, _ = w.WriteString(` title="`)
+		r.Writer.Write(w, n.Title)
+		_ = w.WriteByte('"')
+	}
+	if n.Attributes() != nil {
+		RenderAttributes(w, n, ImageAttributeFilter)
+	}
+	if r.XHTML {
+		_, _ = w.WriteString(" />")
+	} else {
+		_, _ = w.WriteString(">")
+	}
+	return ast.WalkSkipChildren, nil
+}
+
+func (r *Renderer) renderRawHTML(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkSkipChildren, nil
+	}
+	if r.Unsafe {
+		n := node.(*ast.RawHTML)
+		l := n.Segments.Len()
+		for i := 0; i < l; i++ {
+			segment := n.Segments.At(i)
+			_, _ = w.Write(segment.Value(source))
+		}
+		return ast.WalkSkipChildren, nil
+	}
+	_, _ = w.WriteString("<!-- raw HTML omitted -->")
+	return ast.WalkSkipChildren, nil
+}
+
+func (r *Renderer) renderText(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	n := node.(*ast.Text)
+	segment := n.Segment
+	if n.IsRaw() {
+		r.Writer.RawWrite(w, segment.Value(source))
+	} else {
+		value := segment.Value(source)
+		r.Writer.Write(w, value)
+		if n.HardLineBreak() || (n.SoftLineBreak() && r.HardWraps) {
+			if r.XHTML {
+				_, _ = w.WriteString("<br />\n")
+			} else {
+				_, _ = w.WriteString("<br>\n")
+			}
+		} else if n.SoftLineBreak() {
+			if r.EastAsianLineBreaks && len(value) != 0 {
+				sibling := node.NextSibling()
+				if sibling != nil && sibling.Kind() == ast.KindText {
+					if siblingText := sibling.(*ast.Text).Text(source); len(siblingText) != 0 {
+						thisLastRune := util.ToRune(value, len(value)-1)
+						siblingFirstRune, _ := utf8.DecodeRune(siblingText)
+						if !(util.IsEastAsianWideRune(thisLastRune) &&
+							util.IsEastAsianWideRune(siblingFirstRune)) {
+							_ = w.WriteByte('\n')
+						}
+					}
+				}
+			} else {
+				_ = w.WriteByte('\n')
+			}
+		}
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderString(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	n := node.(*ast.String)
+	if n.IsCode() {
+		_, _ = w.Write(n.Value)
+	} else {
+		if n.IsRaw() {
+			r.Writer.RawWrite(w, n.Value)
+		} else {
+			r.Writer.Write(w, n.Value)
+		}
+	}
+	return ast.WalkContinue, nil
+}
+
+var dataPrefix = []byte("data-")
+
+// RenderAttributes renders given node's attributes.
+// You can specify attribute names to render by the filter.
+// If filter is nil, RenderAttributes renders all attributes.
+func RenderAttributes(w util.BufWriter, node ast.Node, filter util.BytesFilter) {
+	for _, attr := range node.Attributes() {
+		if filter != nil && !filter.Contains(attr.Name) {
+			if !bytes.HasPrefix(attr.Name, dataPrefix) {
+				continue
+			}
+		}
+		_, _ = w.WriteString(" ")
+		_, _ = w.Write(attr.Name)
+		_, _ = w.WriteString(`="`)
+		// TODO: convert numeric values to strings
+		_, _ = w.Write(util.EscapeHTML(attr.Value.([]byte)))
+		_ = w.WriteByte('"')
+	}
+}
+
+// A Writer interface writes textual contents to a writer.
+type Writer interface {
+	// Write writes the given source to writer with resolving references and unescaping
+	// backslash escaped characters.
+	Write(writer util.BufWriter, source []byte)
+
+	// RawWrite writes the given source to writer without resolving references and
+	// unescaping backslash escaped characters.
+	RawWrite(writer util.BufWriter, source []byte)
+
+	// SecureWrite writes the given source to writer with replacing insecure characters.
+	SecureWrite(writer util.BufWriter, source []byte)
+}
+
+var replacementCharacter = []byte("\ufffd")
+
+// A WriterConfig struct has configurations for the HTML based writers.
+type WriterConfig struct {
+	// EscapedSpace is an option that indicates that a '\' escaped half-space(0x20) should not be rendered.
+	EscapedSpace bool
+}
+
+// A WriterOption interface sets options for HTML based writers.
+type WriterOption func(*WriterConfig)
+
+// WithEscapedSpace is a WriterOption indicates that a '\' escaped half-space(0x20) should not be rendered.
+func WithEscapedSpace() WriterOption {
+	return func(c *WriterConfig) {
+		c.EscapedSpace = true
+	}
+}
+
+type defaultWriter struct {
+	WriterConfig
+}
+
+// NewWriter returns a new Writer.
+func NewWriter(opts ...WriterOption) Writer {
+	w := &defaultWriter{}
+	for _, opt := range opts {
+		opt(&w.WriterConfig)
+	}
+	return w
+}
+
+func escapeRune(writer util.BufWriter, r rune) {
+	if r < 256 {
+		v := util.EscapeHTMLByte(byte(r))
+		if v != nil {
+			_, _ = writer.Write(v)
+			return
+		}
+	}
+	_, _ = writer.WriteRune(util.ToValidRune(r))
+}
+
+func (d *defaultWriter) SecureWrite(writer util.BufWriter, source []byte) {
+	n := 0
+	l := len(source)
+	for i := 0; i < l; i++ {
+		if source[i] == '\u0000' {
+			_, _ = writer.Write(source[i-n : i])
+			n = 0
+			_, _ = writer.Write(replacementCharacter)
+			continue
+		}
+		n++
+	}
+	if n != 0 {
+		_, _ = writer.Write(source[l-n:])
+	}
+}
+
+func (d *defaultWriter) RawWrite(writer util.BufWriter, source []byte) {
+	n := 0
+	l := len(source)
+	for i := 0; i < l; i++ {
+		v := util.EscapeHTMLByte(source[i])
+		if v != nil {
+			_, _ = writer.Write(source[i-n : i])
+			n = 0
+			_, _ = writer.Write(v)
+			continue
+		}
+		n++
+	}
+	if n != 0 {
+		_, _ = writer.Write(source[l-n:])
+	}
+}
+
+func (d *defaultWriter) Write(writer util.BufWriter, source []byte) {
+	escaped := false
+	var ok bool
+	limit := len(source)
+	n := 0
+	for i := 0; i < limit; i++ {
+		c := source[i]
+		if escaped {
+			if util.IsPunct(c) {
+				d.RawWrite(writer, source[n:i-1])
+				n = i
+				escaped = false
+				continue
+			}
+			if d.EscapedSpace && c == ' ' {
+				d.RawWrite(writer, source[n:i-1])
+				n = i + 1
+				escaped = false
+				continue
+			}
+		}
+		if c == '\x00' {
+			d.RawWrite(writer, source[n:i])
+			d.RawWrite(writer, replacementCharacter)
+			n = i + 1
+			escaped = false
+			continue
+		}
+		if c == '&' {
+			pos := i
+			next := i + 1
+			if next < limit && source[next] == '#' {
+				nnext := next + 1
+				if nnext < limit {
+					nc := source[nnext]
+					// code point like #x22;
+					if nnext < limit && nc == 'x' || nc == 'X' {
+						start := nnext + 1
+						i, ok = util.ReadWhile(source, [2]int{start, limit}, util.IsHexDecimal)
+						if ok && i < limit && source[i] == ';' && i-start < 7 {
+							v, _ := strconv.ParseUint(util.BytesToReadOnlyString(source[start:i]), 16, 32)
+							d.RawWrite(writer, source[n:pos])
+							n = i + 1
+							escapeRune(writer, rune(v))
+							continue
+						}
+						// code point like #1234;
+					} else if nc >= '0' && nc <= '9' {
+						start := nnext
+						i, ok = util.ReadWhile(source, [2]int{start, limit}, util.IsNumeric)
+						if ok && i < limit && i-start < 8 && source[i] == ';' {
+							v, _ := strconv.ParseUint(util.BytesToReadOnlyString(source[start:i]), 10, 32)
+							d.RawWrite(writer, source[n:pos])
+							n = i + 1
+							escapeRune(writer, rune(v))
+							continue
+						}
+					}
+				}
+			} else {
+				start := next
+				i, ok = util.ReadWhile(source, [2]int{start, limit}, util.IsAlphaNumeric)
+				// entity reference
+				if ok && i < limit && source[i] == ';' {
+					name := util.BytesToReadOnlyString(source[start:i])
+					entity, ok := util.LookUpHTML5EntityByName(name)
+					if ok {
+						d.RawWrite(writer, source[n:pos])
+						n = i + 1
+						d.RawWrite(writer, entity.Characters)
+						continue
+					}
+				}
+			}
+			i = next - 1
+		}
+		if c == '\\' {
+			escaped = true
+			continue
+		}
+		escaped = false
+	}
+	d.RawWrite(writer, source[n:])
+}
+
+// DefaultWriter is a default instance of the Writer.
+var DefaultWriter = NewWriter()
+
+var bDataImage = []byte("data:image/")
+var bPng = []byte("png;")
+var bGif = []byte("gif;")
+var bJpeg = []byte("jpeg;")
+var bWebp = []byte("webp;")
+var bSvg = []byte("svg+xml;")
+var bJs = []byte("javascript:")
+var bVb = []byte("vbscript:")
+var bFile = []byte("file:")
+var bData = []byte("data:")
+
+// IsDangerousURL returns true if the given url seems a potentially dangerous url,
+// otherwise false.
+func IsDangerousURL(url []byte) bool {
+	if bytes.HasPrefix(url, bDataImage) && len(url) >= 11 {
+		v := url[11:]
+		if bytes.HasPrefix(v, bPng) || bytes.HasPrefix(v, bGif) ||
+			bytes.HasPrefix(v, bJpeg) || bytes.HasPrefix(v, bWebp) ||
+			bytes.HasPrefix(v, bSvg) {
+			return false
+		}
+		return true
+	}
+	return bytes.HasPrefix(url, bJs) || bytes.HasPrefix(url, bVb) ||
+		bytes.HasPrefix(url, bFile) || bytes.HasPrefix(url, bData)
+}
+
+func nodeToHTMLText(n ast.Node, source []byte) []byte {
+	var buf bytes.Buffer
+	for c := n.FirstChild(); c != nil; c = c.NextSibling() {
+		if s, ok := c.(*ast.String); ok && s.IsCode() {
+			buf.Write(s.Text(source))
+		} else if !c.HasChildren() {
+			buf.Write(util.EscapeHTML(c.Text(source)))
+		} else {
+			buf.Write(nodeToHTMLText(c, source))
+		}
+	}
+	return buf.Bytes()
+}

vendor/github.com/yuin/goldmark/renderer/renderer.go

@@ -0,0 +1,174 @@
+// Package renderer renders the given AST to certain formats.
+package renderer
+
+import (
+	"bufio"
+	"io"
+	"sync"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/util"
+)
+
+// A Config struct is a data structure that holds configuration of the Renderer.
+type Config struct {
+	Options       map[OptionName]interface{}
+	NodeRenderers util.PrioritizedSlice
+}
+
+// NewConfig returns a new Config
+func NewConfig() *Config {
+	return &Config{
+		Options:       map[OptionName]interface{}{},
+		NodeRenderers: util.PrioritizedSlice{},
+	}
+}
+
+// An OptionName is a name of the option.
+type OptionName string
+
+// An Option interface is a functional option type for the Renderer.
+type Option interface {
+	SetConfig(*Config)
+}
+
+type withNodeRenderers struct {
+	value []util.PrioritizedValue
+}
+
+func (o *withNodeRenderers) SetConfig(c *Config) {
+	c.NodeRenderers = append(c.NodeRenderers, o.value...)
+}
+
+// WithNodeRenderers is a functional option that allow you to add
+// NodeRenderers to the renderer.
+func WithNodeRenderers(ps ...util.PrioritizedValue) Option {
+	return &withNodeRenderers{ps}
+}
+
+type withOption struct {
+	name  OptionName
+	value interface{}
+}
+
+func (o *withOption) SetConfig(c *Config) {
+	c.Options[o.name] = o.value
+}
+
+// WithOption is a functional option that allow you to set
+// an arbitrary option to the parser.
+func WithOption(name OptionName, value interface{}) Option {
+	return &withOption{name, value}
+}
+
+// A SetOptioner interface sets given option to the object.
+type SetOptioner interface {
+	// SetOption sets given option to the object.
+	// Unacceptable options may be passed.
+	// Thus implementations must ignore unacceptable options.
+	SetOption(name OptionName, value interface{})
+}
+
+// NodeRendererFunc is a function that renders a given node.
+type NodeRendererFunc func(writer util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error)
+
+// A NodeRenderer interface offers NodeRendererFuncs.
+type NodeRenderer interface {
+	// RendererFuncs registers NodeRendererFuncs to given NodeRendererFuncRegisterer.
+	RegisterFuncs(NodeRendererFuncRegisterer)
+}
+
+// A NodeRendererFuncRegisterer registers
+type NodeRendererFuncRegisterer interface {
+	// Register registers given NodeRendererFunc to this object.
+	Register(ast.NodeKind, NodeRendererFunc)
+}
+
+// A Renderer interface renders given AST node to given
+// writer with given Renderer.
+type Renderer interface {
+	Render(w io.Writer, source []byte, n ast.Node) error
+
+	// AddOptions adds given option to this renderer.
+	AddOptions(...Option)
+}
+
+type renderer struct {
+	config               *Config
+	options              map[OptionName]interface{}
+	nodeRendererFuncsTmp map[ast.NodeKind]NodeRendererFunc
+	maxKind              int
+	nodeRendererFuncs    []NodeRendererFunc
+	initSync             sync.Once
+}
+
+// NewRenderer returns a new Renderer with given options.
+func NewRenderer(options ...Option) Renderer {
+	config := NewConfig()
+	for _, opt := range options {
+		opt.SetConfig(config)
+	}
+
+	r := &renderer{
+		options:              map[OptionName]interface{}{},
+		config:               config,
+		nodeRendererFuncsTmp: map[ast.NodeKind]NodeRendererFunc{},
+	}
+
+	return r
+}
+
+func (r *renderer) AddOptions(opts ...Option) {
+	for _, opt := range opts {
+		opt.SetConfig(r.config)
+	}
+}
+
+func (r *renderer) Register(kind ast.NodeKind, v NodeRendererFunc) {
+	r.nodeRendererFuncsTmp[kind] = v
+	if int(kind) > r.maxKind {
+		r.maxKind = int(kind)
+	}
+}
+
+// Render renders the given AST node to the given writer with the given Renderer.
+func (r *renderer) Render(w io.Writer, source []byte, n ast.Node) error {
+	r.initSync.Do(func() {
+		r.options = r.config.Options
+		r.config.NodeRenderers.Sort()
+		l := len(r.config.NodeRenderers)
+		for i := l - 1; i >= 0; i-- {
+			v := r.config.NodeRenderers[i]
+			nr, _ := v.Value.(NodeRenderer)
+			if se, ok := v.Value.(SetOptioner); ok {
+				for oname, ovalue := range r.options {
+					se.SetOption(oname, ovalue)
+				}
+			}
+			nr.RegisterFuncs(r)
+		}
+		r.nodeRendererFuncs = make([]NodeRendererFunc, r.maxKind+1)
+		for kind, nr := range r.nodeRendererFuncsTmp {
+			r.nodeRendererFuncs[kind] = nr
+		}
+		r.config = nil
+		r.nodeRendererFuncsTmp = nil
+	})
+	writer, ok := w.(util.BufWriter)
+	if !ok {
+		writer = bufio.NewWriter(w)
+	}
+	err := ast.Walk(n, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
+		s := ast.WalkStatus(ast.WalkContinue)
+		var err error
+		f := r.nodeRendererFuncs[n.Kind()]
+		if f != nil {
+			s, err = f(writer, source, n, entering)
+		}
+		return s, err
+	})
+	if err != nil {
+		return err
+	}
+	return writer.Flush()
+}

vendor/github.com/yuin/goldmark/text/reader.go

@@ -0,0 +1,653 @@
+package text
+
+import (
+	"io"
+	"regexp"
+	"unicode/utf8"
+
+	"github.com/yuin/goldmark/util"
+)
+
+const invalidValue = -1
+
+// EOF indicates the end of file.
+const EOF = byte(0xff)
+
+// A Reader interface provides abstracted method for reading text.
+type Reader interface {
+	io.RuneReader
+
+	// Source returns a source of the reader.
+	Source() []byte
+
+	// ResetPosition resets positions.
+	ResetPosition()
+
+	// Peek returns a byte at current position without advancing the internal pointer.
+	Peek() byte
+
+	// PeekLine returns the current line without advancing the internal pointer.
+	PeekLine() ([]byte, Segment)
+
+	// PrecendingCharacter returns a character just before current internal pointer.
+	PrecendingCharacter() rune
+
+	// Value returns a value of the given segment.
+	Value(Segment) []byte
+
+	// LineOffset returns a distance from the line head to current position.
+	LineOffset() int
+
+	// Position returns current line number and position.
+	Position() (int, Segment)
+
+	// SetPosition sets current line number and position.
+	SetPosition(int, Segment)
+
+	// SetPadding sets padding to the reader.
+	SetPadding(int)
+
+	// Advance advances the internal pointer.
+	Advance(int)
+
+	// AdvanceAndSetPadding advances the internal pointer and add padding to the
+	// reader.
+	AdvanceAndSetPadding(int, int)
+
+	// AdvanceLine advances the internal pointer to the next line head.
+	AdvanceLine()
+
+	// SkipSpaces skips space characters and returns a non-blank line.
+	// If it reaches EOF, returns false.
+	SkipSpaces() (Segment, int, bool)
+
+	// SkipSpaces skips blank lines and returns a non-blank line.
+	// If it reaches EOF, returns false.
+	SkipBlankLines() (Segment, int, bool)
+
+	// Match performs regular expression matching to current line.
+	Match(reg *regexp.Regexp) bool
+
+	// Match performs regular expression searching to current line.
+	FindSubMatch(reg *regexp.Regexp) [][]byte
+
+	// FindClosure finds corresponding closure.
+	FindClosure(opener, closer byte, options FindClosureOptions) (*Segments, bool)
+}
+
+// FindClosureOptions is options for Reader.FindClosure
+type FindClosureOptions struct {
+	// CodeSpan is a flag for the FindClosure. If this is set to true,
+	// FindClosure ignores closers in codespans.
+	CodeSpan bool
+
+	// Nesting is a flag for the FindClosure. If this is set to true,
+	// FindClosure allows nesting.
+	Nesting bool
+
+	// Newline is a flag for the FindClosure. If this is set to true,
+	// FindClosure searches for a closer over multiple lines.
+	Newline bool
+
+	// Advance is a flag for the FindClosure. If this is set to true,
+	// FindClosure advances pointers when closer is found.
+	Advance bool
+}
+
+type reader struct {
+	source       []byte
+	sourceLength int
+	line         int
+	peekedLine   []byte
+	pos          Segment
+	head         int
+	lineOffset   int
+}
+
+// NewReader return a new Reader that can read UTF-8 bytes .
+func NewReader(source []byte) Reader {
+	r := &reader{
+		source:       source,
+		sourceLength: len(source),
+	}
+	r.ResetPosition()
+	return r
+}
+
+func (r *reader) FindClosure(opener, closer byte, options FindClosureOptions) (*Segments, bool) {
+	return findClosureReader(r, opener, closer, options)
+}
+
+func (r *reader) ResetPosition() {
+	r.line = -1
+	r.head = 0
+	r.lineOffset = -1
+	r.AdvanceLine()
+}
+
+func (r *reader) Source() []byte {
+	return r.source
+}
+
+func (r *reader) Value(seg Segment) []byte {
+	return seg.Value(r.source)
+}
+
+func (r *reader) Peek() byte {
+	if r.pos.Start >= 0 && r.pos.Start < r.sourceLength {
+		if r.pos.Padding != 0 {
+			return space[0]
+		}
+		return r.source[r.pos.Start]
+	}
+	return EOF
+}
+
+func (r *reader) PeekLine() ([]byte, Segment) {
+	if r.pos.Start >= 0 && r.pos.Start < r.sourceLength {
+		if r.peekedLine == nil {
+			r.peekedLine = r.pos.Value(r.Source())
+		}
+		return r.peekedLine, r.pos
+	}
+	return nil, r.pos
+}
+
+// io.RuneReader interface
+func (r *reader) ReadRune() (rune, int, error) {
+	return readRuneReader(r)
+}
+
+func (r *reader) LineOffset() int {
+	if r.lineOffset < 0 {
+		v := 0
+		for i := r.head; i < r.pos.Start; i++ {
+			if r.source[i] == '\t' {
+				v += util.TabWidth(v)
+			} else {
+				v++
+			}
+		}
+		r.lineOffset = v - r.pos.Padding
+	}
+	return r.lineOffset
+}
+
+func (r *reader) PrecendingCharacter() rune {
+	if r.pos.Start <= 0 {
+		if r.pos.Padding != 0 {
+			return rune(' ')
+		}
+		return rune('\n')
+	}
+	i := r.pos.Start - 1
+	for ; i >= 0; i-- {
+		if utf8.RuneStart(r.source[i]) {
+			break
+		}
+	}
+	rn, _ := utf8.DecodeRune(r.source[i:])
+	return rn
+}
+
+func (r *reader) Advance(n int) {
+	r.lineOffset = -1
+	if n < len(r.peekedLine) && r.pos.Padding == 0 {
+		r.pos.Start += n
+		r.peekedLine = nil
+		return
+	}
+	r.peekedLine = nil
+	l := r.sourceLength
+	for ; n > 0 && r.pos.Start < l; n-- {
+		if r.pos.Padding != 0 {
+			r.pos.Padding--
+			continue
+		}
+		if r.source[r.pos.Start] == '\n' {
+			r.AdvanceLine()
+			continue
+		}
+		r.pos.Start++
+	}
+}
+
+func (r *reader) AdvanceAndSetPadding(n, padding int) {
+	r.Advance(n)
+	if padding > r.pos.Padding {
+		r.SetPadding(padding)
+	}
+}
+
+func (r *reader) AdvanceLine() {
+	r.lineOffset = -1
+	r.peekedLine = nil
+	r.pos.Start = r.pos.Stop
+	r.head = r.pos.Start
+	if r.pos.Start < 0 {
+		return
+	}
+	r.pos.Stop = r.sourceLength
+	for i := r.pos.Start; i < r.sourceLength; i++ {
+		c := r.source[i]
+		if c == '\n' {
+			r.pos.Stop = i + 1
+			break
+		}
+	}
+	r.line++
+	r.pos.Padding = 0
+}
+
+func (r *reader) Position() (int, Segment) {
+	return r.line, r.pos
+}
+
+func (r *reader) SetPosition(line int, pos Segment) {
+	r.lineOffset = -1
+	r.line = line
+	r.pos = pos
+}
+
+func (r *reader) SetPadding(v int) {
+	r.pos.Padding = v
+}
+
+func (r *reader) SkipSpaces() (Segment, int, bool) {
+	return skipSpacesReader(r)
+}
+
+func (r *reader) SkipBlankLines() (Segment, int, bool) {
+	return skipBlankLinesReader(r)
+}
+
+func (r *reader) Match(reg *regexp.Regexp) bool {
+	return matchReader(r, reg)
+}
+
+func (r *reader) FindSubMatch(reg *regexp.Regexp) [][]byte {
+	return findSubMatchReader(r, reg)
+}
+
+// A BlockReader interface is a reader that is optimized for Blocks.
+type BlockReader interface {
+	Reader
+	// Reset resets current state and sets new segments to the reader.
+	Reset(segment *Segments)
+}
+
+type blockReader struct {
+	source         []byte
+	segments       *Segments
+	segmentsLength int
+	line           int
+	pos            Segment
+	head           int
+	last           int
+	lineOffset     int
+}
+
+// NewBlockReader returns a new BlockReader.
+func NewBlockReader(source []byte, segments *Segments) BlockReader {
+	r := &blockReader{
+		source: source,
+	}
+	if segments != nil {
+		r.Reset(segments)
+	}
+	return r
+}
+
+func (r *blockReader) FindClosure(opener, closer byte, options FindClosureOptions) (*Segments, bool) {
+	return findClosureReader(r, opener, closer, options)
+}
+
+func (r *blockReader) ResetPosition() {
+	r.line = -1
+	r.head = 0
+	r.last = 0
+	r.lineOffset = -1
+	r.pos.Start = -1
+	r.pos.Stop = -1
+	r.pos.Padding = 0
+	if r.segmentsLength > 0 {
+		last := r.segments.At(r.segmentsLength - 1)
+		r.last = last.Stop
+	}
+	r.AdvanceLine()
+}
+
+func (r *blockReader) Reset(segments *Segments) {
+	r.segments = segments
+	r.segmentsLength = segments.Len()
+	r.ResetPosition()
+}
+
+func (r *blockReader) Source() []byte {
+	return r.source
+}
+
+func (r *blockReader) Value(seg Segment) []byte {
+	line := r.segmentsLength - 1
+	ret := make([]byte, 0, seg.Stop-seg.Start+1)
+	for ; line >= 0; line-- {
+		if seg.Start >= r.segments.At(line).Start {
+			break
+		}
+	}
+	i := seg.Start
+	for ; line < r.segmentsLength; line++ {
+		s := r.segments.At(line)
+		if i < 0 {
+			i = s.Start
+		}
+		ret = s.ConcatPadding(ret)
+		for ; i < seg.Stop && i < s.Stop; i++ {
+			ret = append(ret, r.source[i])
+		}
+		i = -1
+		if s.Stop > seg.Stop {
+			break
+		}
+	}
+	return ret
+}
+
+// io.RuneReader interface
+func (r *blockReader) ReadRune() (rune, int, error) {
+	return readRuneReader(r)
+}
+
+func (r *blockReader) PrecendingCharacter() rune {
+	if r.pos.Padding != 0 {
+		return rune(' ')
+	}
+	if r.segments.Len() < 1 {
+		return rune('\n')
+	}
+	firstSegment := r.segments.At(0)
+	if r.line == 0 && r.pos.Start <= firstSegment.Start {
+		return rune('\n')
+	}
+	l := len(r.source)
+	i := r.pos.Start - 1
+	for ; i < l && i >= 0; i-- {
+		if utf8.RuneStart(r.source[i]) {
+			break
+		}
+	}
+	if i < 0 || i >= l {
+		return rune('\n')
+	}
+	rn, _ := utf8.DecodeRune(r.source[i:])
+	return rn
+}
+
+func (r *blockReader) LineOffset() int {
+	if r.lineOffset < 0 {
+		v := 0
+		for i := r.head; i < r.pos.Start; i++ {
+			if r.source[i] == '\t' {
+				v += util.TabWidth(v)
+			} else {
+				v++
+			}
+		}
+		r.lineOffset = v - r.pos.Padding
+	}
+	return r.lineOffset
+}
+
+func (r *blockReader) Peek() byte {
+	if r.line < r.segmentsLength && r.pos.Start >= 0 && r.pos.Start < r.last {
+		if r.pos.Padding != 0 {
+			return space[0]
+		}
+		return r.source[r.pos.Start]
+	}
+	return EOF
+}
+
+func (r *blockReader) PeekLine() ([]byte, Segment) {
+	if r.line < r.segmentsLength && r.pos.Start >= 0 && r.pos.Start < r.last {
+		return r.pos.Value(r.source), r.pos
+	}
+	return nil, r.pos
+}
+
+func (r *blockReader) Advance(n int) {
+	r.lineOffset = -1
+
+	if n < r.pos.Stop-r.pos.Start && r.pos.Padding == 0 {
+		r.pos.Start += n
+		return
+	}
+
+	for ; n > 0; n-- {
+		if r.pos.Padding != 0 {
+			r.pos.Padding--
+			continue
+		}
+		if r.pos.Start >= r.pos.Stop-1 && r.pos.Stop < r.last {
+			r.AdvanceLine()
+			continue
+		}
+		r.pos.Start++
+	}
+}
+
+func (r *blockReader) AdvanceAndSetPadding(n, padding int) {
+	r.Advance(n)
+	if padding > r.pos.Padding {
+		r.SetPadding(padding)
+	}
+}
+
+func (r *blockReader) AdvanceLine() {
+	r.SetPosition(r.line+1, NewSegment(invalidValue, invalidValue))
+	r.head = r.pos.Start
+}
+
+func (r *blockReader) Position() (int, Segment) {
+	return r.line, r.pos
+}
+
+func (r *blockReader) SetPosition(line int, pos Segment) {
+	r.lineOffset = -1
+	r.line = line
+	if pos.Start == invalidValue {
+		if r.line < r.segmentsLength {
+			s := r.segments.At(line)
+			r.head = s.Start
+			r.pos = s
+		}
+	} else {
+		r.pos = pos
+		if r.line < r.segmentsLength {
+			s := r.segments.At(line)
+			r.head = s.Start
+		}
+	}
+}
+
+func (r *blockReader) SetPadding(v int) {
+	r.lineOffset = -1
+	r.pos.Padding = v
+}
+
+func (r *blockReader) SkipSpaces() (Segment, int, bool) {
+	return skipSpacesReader(r)
+}
+
+func (r *blockReader) SkipBlankLines() (Segment, int, bool) {
+	return skipBlankLinesReader(r)
+}
+
+func (r *blockReader) Match(reg *regexp.Regexp) bool {
+	return matchReader(r, reg)
+}
+
+func (r *blockReader) FindSubMatch(reg *regexp.Regexp) [][]byte {
+	return findSubMatchReader(r, reg)
+}
+
+func skipBlankLinesReader(r Reader) (Segment, int, bool) {
+	lines := 0
+	for {
+		line, seg := r.PeekLine()
+		if line == nil {
+			return seg, lines, false
+		}
+		if util.IsBlank(line) {
+			lines++
+			r.AdvanceLine()
+		} else {
+			return seg, lines, true
+		}
+	}
+}
+
+func skipSpacesReader(r Reader) (Segment, int, bool) {
+	chars := 0
+	for {
+		line, segment := r.PeekLine()
+		if line == nil {
+			return segment, chars, false
+		}
+		for i, c := range line {
+			if util.IsSpace(c) {
+				chars++
+				r.Advance(1)
+				continue
+			}
+			return segment.WithStart(segment.Start + i + 1), chars, true
+		}
+	}
+}
+
+func matchReader(r Reader, reg *regexp.Regexp) bool {
+	oldline, oldseg := r.Position()
+	match := reg.FindReaderSubmatchIndex(r)
+	r.SetPosition(oldline, oldseg)
+	if match == nil {
+		return false
+	}
+	r.Advance(match[1] - match[0])
+	return true
+}
+
+func findSubMatchReader(r Reader, reg *regexp.Regexp) [][]byte {
+	oldline, oldseg := r.Position()
+	match := reg.FindReaderSubmatchIndex(r)
+	r.SetPosition(oldline, oldseg)
+	if match == nil {
+		return nil
+	}
+	runes := make([]rune, 0, match[1]-match[0])
+	for i := 0; i < match[1]; {
+		r, size, _ := readRuneReader(r)
+		i += size
+		runes = append(runes, r)
+	}
+	result := [][]byte{}
+	for i := 0; i < len(match); i += 2 {
+		result = append(result, []byte(string(runes[match[i]:match[i+1]])))
+	}
+
+	r.SetPosition(oldline, oldseg)
+	r.Advance(match[1] - match[0])
+	return result
+}
+
+func readRuneReader(r Reader) (rune, int, error) {
+	line, _ := r.PeekLine()
+	if line == nil {
+		return 0, 0, io.EOF
+	}
+	rn, size := utf8.DecodeRune(line)
+	if rn == utf8.RuneError {
+		return 0, 0, io.EOF
+	}
+	r.Advance(size)
+	return rn, size, nil
+}
+
+func findClosureReader(r Reader, opener, closer byte, opts FindClosureOptions) (*Segments, bool) {
+	opened := 1
+	codeSpanOpener := 0
+	closed := false
+	orgline, orgpos := r.Position()
+	var ret *Segments
+
+	for {
+		bs, seg := r.PeekLine()
+		if bs == nil {
+			goto end
+		}
+		i := 0
+		for i < len(bs) {
+			c := bs[i]
+			if opts.CodeSpan && codeSpanOpener != 0 && c == '`' {
+				codeSpanCloser := 0
+				for ; i < len(bs); i++ {
+					if bs[i] == '`' {
+						codeSpanCloser++
+					} else {
+						i--
+						break
+					}
+				}
+				if codeSpanCloser == codeSpanOpener {
+					codeSpanOpener = 0
+				}
+			} else if codeSpanOpener == 0 && c == '\\' && i < len(bs)-1 && util.IsPunct(bs[i+1]) {
+				i += 2
+				continue
+			} else if opts.CodeSpan && codeSpanOpener == 0 && c == '`' {
+				for ; i < len(bs); i++ {
+					if bs[i] == '`' {
+						codeSpanOpener++
+					} else {
+						i--
+						break
+					}
+				}
+			} else if (opts.CodeSpan && codeSpanOpener == 0) || !opts.CodeSpan {
+				if c == closer {
+					opened--
+					if opened == 0 {
+						if ret == nil {
+							ret = NewSegments()
+						}
+						ret.Append(seg.WithStop(seg.Start + i))
+						r.Advance(i + 1)
+						closed = true
+						goto end
+					}
+				} else if c == opener {
+					if !opts.Nesting {
+						goto end
+					}
+					opened++
+				}
+			}
+			i++
+		}
+		if !opts.Newline {
+			goto end
+		}
+		r.AdvanceLine()
+		if ret == nil {
+			ret = NewSegments()
+		}
+		ret.Append(seg)
+	}
+end:
+	if !opts.Advance {
+		r.SetPosition(orgline, orgpos)
+	}
+	if closed {
+		return ret, true
+	}
+	return nil, false
+}

vendor/github.com/yuin/goldmark/text/segment.go

@@ -0,0 +1,209 @@
+package text
+
+import (
+	"bytes"
+	"github.com/yuin/goldmark/util"
+)
+
+var space = []byte(" ")
+
+// A Segment struct holds information about source positions.
+type Segment struct {
+	// Start is a start position of the segment.
+	Start int
+
+	// Stop is a stop position of the segment.
+	// This value should be excluded.
+	Stop int
+
+	// Padding is a padding length of the segment.
+	Padding int
+}
+
+// NewSegment return a new Segment.
+func NewSegment(start, stop int) Segment {
+	return Segment{
+		Start:   start,
+		Stop:    stop,
+		Padding: 0,
+	}
+}
+
+// NewSegmentPadding returns a new Segment with the given padding.
+func NewSegmentPadding(start, stop, n int) Segment {
+	return Segment{
+		Start:   start,
+		Stop:    stop,
+		Padding: n,
+	}
+}
+
+// Value returns a value of the segment.
+func (t *Segment) Value(buffer []byte) []byte {
+	if t.Padding == 0 {
+		return buffer[t.Start:t.Stop]
+	}
+	result := make([]byte, 0, t.Padding+t.Stop-t.Start+1)
+	result = append(result, bytes.Repeat(space, t.Padding)...)
+	return append(result, buffer[t.Start:t.Stop]...)
+}
+
+// Len returns a length of the segment.
+func (t *Segment) Len() int {
+	return t.Stop - t.Start + t.Padding
+}
+
+// Between returns a segment between this segment and the given segment.
+func (t *Segment) Between(other Segment) Segment {
+	if t.Stop != other.Stop {
+		panic("invalid state")
+	}
+	return NewSegmentPadding(
+		t.Start,
+		other.Start,
+		t.Padding-other.Padding,
+	)
+}
+
+// IsEmpty returns true if this segment is empty, otherwise false.
+func (t *Segment) IsEmpty() bool {
+	return t.Start >= t.Stop && t.Padding == 0
+}
+
+// TrimRightSpace returns a new segment by slicing off all trailing
+// space characters.
+func (t *Segment) TrimRightSpace(buffer []byte) Segment {
+	v := buffer[t.Start:t.Stop]
+	l := util.TrimRightSpaceLength(v)
+	if l == len(v) {
+		return NewSegment(t.Start, t.Start)
+	}
+	return NewSegmentPadding(t.Start, t.Stop-l, t.Padding)
+}
+
+// TrimLeftSpace returns a new segment by slicing off all leading
+// space characters including padding.
+func (t *Segment) TrimLeftSpace(buffer []byte) Segment {
+	v := buffer[t.Start:t.Stop]
+	l := util.TrimLeftSpaceLength(v)
+	return NewSegment(t.Start+l, t.Stop)
+}
+
+// TrimLeftSpaceWidth returns a new segment by slicing off leading space
+// characters until the given width.
+func (t *Segment) TrimLeftSpaceWidth(width int, buffer []byte) Segment {
+	padding := t.Padding
+	for ; width > 0; width-- {
+		if padding == 0 {
+			break
+		}
+		padding--
+	}
+	if width == 0 {
+		return NewSegmentPadding(t.Start, t.Stop, padding)
+	}
+	text := buffer[t.Start:t.Stop]
+	start := t.Start
+	for _, c := range text {
+		if start >= t.Stop-1 || width <= 0 {
+			break
+		}
+		if c == ' ' {
+			width--
+		} else if c == '\t' {
+			width -= 4
+		} else {
+			break
+		}
+		start++
+	}
+	if width < 0 {
+		padding = width * -1
+	}
+	return NewSegmentPadding(start, t.Stop, padding)
+}
+
+// WithStart returns a new Segment with same value except Start.
+func (t *Segment) WithStart(v int) Segment {
+	return NewSegmentPadding(v, t.Stop, t.Padding)
+}
+
+// WithStop returns a new Segment with same value except Stop.
+func (t *Segment) WithStop(v int) Segment {
+	return NewSegmentPadding(t.Start, v, t.Padding)
+}
+
+// ConcatPadding concats the padding to the given slice.
+func (t *Segment) ConcatPadding(v []byte) []byte {
+	if t.Padding > 0 {
+		return append(v, bytes.Repeat(space, t.Padding)...)
+	}
+	return v
+}
+
+// Segments is a collection of the Segment.
+type Segments struct {
+	values []Segment
+}
+
+// NewSegments return a new Segments.
+func NewSegments() *Segments {
+	return &Segments{
+		values: nil,
+	}
+}
+
+// Append appends the given segment after the tail of the collection.
+func (s *Segments) Append(t Segment) {
+	if s.values == nil {
+		s.values = make([]Segment, 0, 20)
+	}
+	s.values = append(s.values, t)
+}
+
+// AppendAll appends all elements of given segments after the tail of the collection.
+func (s *Segments) AppendAll(t []Segment) {
+	if s.values == nil {
+		s.values = make([]Segment, 0, 20)
+	}
+	s.values = append(s.values, t...)
+}
+
+// Len returns the length of the collection.
+func (s *Segments) Len() int {
+	if s.values == nil {
+		return 0
+	}
+	return len(s.values)
+}
+
+// At returns a segment at the given index.
+func (s *Segments) At(i int) Segment {
+	return s.values[i]
+}
+
+// Set sets the given Segment.
+func (s *Segments) Set(i int, v Segment) {
+	s.values[i] = v
+}
+
+// SetSliced replace the collection with a subsliced value.
+func (s *Segments) SetSliced(lo, hi int) {
+	s.values = s.values[lo:hi]
+}
+
+// Sliced returns a subslice of the collection.
+func (s *Segments) Sliced(lo, hi int) []Segment {
+	return s.values[lo:hi]
+}
+
+// Clear delete all element of the collection.
+func (s *Segments) Clear() {
+	s.values = nil
+}
+
+// Unshift insert the given Segment to head of the collection.
+func (s *Segments) Unshift(v Segment) {
+	s.values = append(s.values[0:1], s.values[0:]...)
+	s.values[0] = v
+}

vendor/github.com/yuin/goldmark/util/util.go

@@ -0,0 +1,989 @@
+// Package util provides utility functions for the goldmark.
+package util
+
+import (
+	"bytes"
+	"io"
+	"net/url"
+	"regexp"
+	"sort"
+	"strconv"
+	"unicode"
+	"unicode/utf8"
+)
+
+// A CopyOnWriteBuffer is a byte buffer that copies buffer when
+// it need to be changed.
+type CopyOnWriteBuffer struct {
+	buffer []byte
+	copied bool
+}
+
+// NewCopyOnWriteBuffer returns a new CopyOnWriteBuffer.
+func NewCopyOnWriteBuffer(buffer []byte) CopyOnWriteBuffer {
+	return CopyOnWriteBuffer{
+		buffer: buffer,
+		copied: false,
+	}
+}
+
+// Write writes given bytes to the buffer.
+// Write allocate new buffer and clears it at the first time.
+func (b *CopyOnWriteBuffer) Write(value []byte) {
+	if !b.copied {
+		b.buffer = make([]byte, 0, len(b.buffer)+20)
+		b.copied = true
+	}
+	b.buffer = append(b.buffer, value...)
+}
+
+// WriteString writes given string to the buffer.
+// WriteString allocate new buffer and clears it at the first time.
+func (b *CopyOnWriteBuffer) WriteString(value string) {
+	b.Write(StringToReadOnlyBytes(value))
+}
+
+// Append appends given bytes to the buffer.
+// Append copy buffer at the first time.
+func (b *CopyOnWriteBuffer) Append(value []byte) {
+	if !b.copied {
+		tmp := make([]byte, len(b.buffer), len(b.buffer)+20)
+		copy(tmp, b.buffer)
+		b.buffer = tmp
+		b.copied = true
+	}
+	b.buffer = append(b.buffer, value...)
+}
+
+// AppendString appends given string to the buffer.
+// AppendString copy buffer at the first time.
+func (b *CopyOnWriteBuffer) AppendString(value string) {
+	b.Append(StringToReadOnlyBytes(value))
+}
+
+// WriteByte writes the given byte to the buffer.
+// WriteByte allocate new buffer and clears it at the first time.
+func (b *CopyOnWriteBuffer) WriteByte(c byte) {
+	if !b.copied {
+		b.buffer = make([]byte, 0, len(b.buffer)+20)
+		b.copied = true
+	}
+	b.buffer = append(b.buffer, c)
+}
+
+// AppendByte appends given bytes to the buffer.
+// AppendByte copy buffer at the first time.
+func (b *CopyOnWriteBuffer) AppendByte(c byte) {
+	if !b.copied {
+		tmp := make([]byte, len(b.buffer), len(b.buffer)+20)
+		copy(tmp, b.buffer)
+		b.buffer = tmp
+		b.copied = true
+	}
+	b.buffer = append(b.buffer, c)
+}
+
+// Bytes returns bytes of this buffer.
+func (b *CopyOnWriteBuffer) Bytes() []byte {
+	return b.buffer
+}
+
+// IsCopied returns true if buffer has been copied, otherwise false.
+func (b *CopyOnWriteBuffer) IsCopied() bool {
+	return b.copied
+}
+
+// IsEscapedPunctuation returns true if character at a given index i
+// is an escaped punctuation, otherwise false.
+func IsEscapedPunctuation(source []byte, i int) bool {
+	return source[i] == '\\' && i < len(source)-1 && IsPunct(source[i+1])
+}
+
+// ReadWhile read the given source while pred is true.
+func ReadWhile(source []byte, index [2]int, pred func(byte) bool) (int, bool) {
+	j := index[0]
+	ok := false
+	for ; j < index[1]; j++ {
+		c1 := source[j]
+		if pred(c1) {
+			ok = true
+			continue
+		}
+		break
+	}
+	return j, ok
+}
+
+// IsBlank returns true if the given string is all space characters.
+func IsBlank(bs []byte) bool {
+	for _, b := range bs {
+		if !IsSpace(b) {
+			return false
+		}
+	}
+	return true
+}
+
+// VisualizeSpaces visualize invisible space characters.
+func VisualizeSpaces(bs []byte) []byte {
+	bs = bytes.Replace(bs, []byte(" "), []byte("[SPACE]"), -1)
+	bs = bytes.Replace(bs, []byte("\t"), []byte("[TAB]"), -1)
+	bs = bytes.Replace(bs, []byte("\n"), []byte("[NEWLINE]\n"), -1)
+	bs = bytes.Replace(bs, []byte("\r"), []byte("[CR]"), -1)
+	bs = bytes.Replace(bs, []byte("\v"), []byte("[VTAB]"), -1)
+	bs = bytes.Replace(bs, []byte("\x00"), []byte("[NUL]"), -1)
+	bs = bytes.Replace(bs, []byte("\ufffd"), []byte("[U+FFFD]"), -1)
+	return bs
+}
+
+// TabWidth calculates actual width of a tab at the given position.
+func TabWidth(currentPos int) int {
+	return 4 - currentPos%4
+}
+
+// IndentPosition searches an indent position with the given width for the given line.
+// If the line contains tab characters, paddings may be not zero.
+// currentPos==0 and width==2:
+//
+//     position: 0    1
+//               [TAB]aaaa
+//     width:    1234 5678
+//
+// width=2 is in the tab character. In this case, IndentPosition returns
+// (pos=1, padding=2)
+func IndentPosition(bs []byte, currentPos, width int) (pos, padding int) {
+	return IndentPositionPadding(bs, currentPos, 0, width)
+}
+
+// IndentPositionPadding searches an indent position with the given width for the given line.
+// This function is mostly same as IndentPosition except this function
+// takes account into additional paddings.
+func IndentPositionPadding(bs []byte, currentPos, paddingv, width int) (pos, padding int) {
+	if width == 0 {
+		return 0, paddingv
+	}
+	w := 0
+	i := 0
+	l := len(bs)
+	for ; i < l; i++ {
+		if bs[i] == '\t' && w < width {
+			w += TabWidth(currentPos + w)
+		} else if bs[i] == ' ' && w < width {
+			w++
+		} else {
+			break
+		}
+	}
+	if w >= width {
+		return i - paddingv, w - width
+	}
+	return -1, -1
+}
+
+// DedentPosition dedents lines by the given width.
+//
+// Deprecated: This function has bugs. Use util.IndentPositionPadding and util.FirstNonSpacePosition.
+func DedentPosition(bs []byte, currentPos, width int) (pos, padding int) {
+	if width == 0 {
+		return 0, 0
+	}
+	w := 0
+	l := len(bs)
+	i := 0
+	for ; i < l; i++ {
+		if bs[i] == '\t' {
+			w += TabWidth(currentPos + w)
+		} else if bs[i] == ' ' {
+			w++
+		} else {
+			break
+		}
+	}
+	if w >= width {
+		return i, w - width
+	}
+	return i, 0
+}
+
+// DedentPositionPadding dedents lines by the given width.
+// This function is mostly same as DedentPosition except this function
+// takes account into additional paddings.
+//
+// Deprecated: This function has bugs. Use util.IndentPositionPadding and util.FirstNonSpacePosition.
+func DedentPositionPadding(bs []byte, currentPos, paddingv, width int) (pos, padding int) {
+	if width == 0 {
+		return 0, paddingv
+	}
+
+	w := 0
+	i := 0
+	l := len(bs)
+	for ; i < l; i++ {
+		if bs[i] == '\t' {
+			w += TabWidth(currentPos + w)
+		} else if bs[i] == ' ' {
+			w++
+		} else {
+			break
+		}
+	}
+	if w >= width {
+		return i - paddingv, w - width
+	}
+	return i - paddingv, 0
+}
+
+// IndentWidth calculate an indent width for the given line.
+func IndentWidth(bs []byte, currentPos int) (width, pos int) {
+	l := len(bs)
+	for i := 0; i < l; i++ {
+		b := bs[i]
+		if b == ' ' {
+			width++
+			pos++
+		} else if b == '\t' {
+			width += TabWidth(currentPos + width)
+			pos++
+		} else {
+			break
+		}
+	}
+	return
+}
+
+// FirstNonSpacePosition returns a position line that is a first nonspace
+// character.
+func FirstNonSpacePosition(bs []byte) int {
+	i := 0
+	for ; i < len(bs); i++ {
+		c := bs[i]
+		if c == ' ' || c == '\t' {
+			continue
+		}
+		if c == '\n' {
+			return -1
+		}
+		return i
+	}
+	return -1
+}
+
+// FindClosure returns a position that closes the given opener.
+// If codeSpan is set true, it ignores characters in code spans.
+// If allowNesting is set true, closures correspond to nested opener will be
+// ignored.
+//
+// Deprecated: This function can not handle newlines. Many elements
+// can be existed over multiple lines(e.g. link labels).
+// Use text.Reader.FindClosure.
+func FindClosure(bs []byte, opener, closure byte, codeSpan, allowNesting bool) int {
+	i := 0
+	opened := 1
+	codeSpanOpener := 0
+	for i < len(bs) {
+		c := bs[i]
+		if codeSpan && codeSpanOpener != 0 && c == '`' {
+			codeSpanCloser := 0
+			for ; i < len(bs); i++ {
+				if bs[i] == '`' {
+					codeSpanCloser++
+				} else {
+					i--
+					break
+				}
+			}
+			if codeSpanCloser == codeSpanOpener {
+				codeSpanOpener = 0
+			}
+		} else if codeSpanOpener == 0 && c == '\\' && i < len(bs)-1 && IsPunct(bs[i+1]) {
+			i += 2
+			continue
+		} else if codeSpan && codeSpanOpener == 0 && c == '`' {
+			for ; i < len(bs); i++ {
+				if bs[i] == '`' {
+					codeSpanOpener++
+				} else {
+					i--
+					break
+				}
+			}
+		} else if (codeSpan && codeSpanOpener == 0) || !codeSpan {
+			if c == closure {
+				opened--
+				if opened == 0 {
+					return i
+				}
+			} else if c == opener {
+				if !allowNesting {
+					return -1
+				}
+				opened++
+			}
+		}
+		i++
+	}
+	return -1
+}
+
+// TrimLeft trims characters in the given s from head of the source.
+// bytes.TrimLeft offers same functionalities, but bytes.TrimLeft
+// allocates new buffer for the result.
+func TrimLeft(source, b []byte) []byte {
+	i := 0
+	for ; i < len(source); i++ {
+		c := source[i]
+		found := false
+		for j := 0; j < len(b); j++ {
+			if c == b[j] {
+				found = true
+				break
+			}
+		}
+		if !found {
+			break
+		}
+	}
+	return source[i:]
+}
+
+// TrimRight trims characters in the given s from tail of the source.
+func TrimRight(source, b []byte) []byte {
+	i := len(source) - 1
+	for ; i >= 0; i-- {
+		c := source[i]
+		found := false
+		for j := 0; j < len(b); j++ {
+			if c == b[j] {
+				found = true
+				break
+			}
+		}
+		if !found {
+			break
+		}
+	}
+	return source[:i+1]
+}
+
+// TrimLeftLength returns a length of leading specified characters.
+func TrimLeftLength(source, s []byte) int {
+	return len(source) - len(TrimLeft(source, s))
+}
+
+// TrimRightLength returns a length of trailing specified characters.
+func TrimRightLength(source, s []byte) int {
+	return len(source) - len(TrimRight(source, s))
+}
+
+// TrimLeftSpaceLength returns a length of leading space characters.
+func TrimLeftSpaceLength(source []byte) int {
+	i := 0
+	for ; i < len(source); i++ {
+		if !IsSpace(source[i]) {
+			break
+		}
+	}
+	return i
+}
+
+// TrimRightSpaceLength returns a length of trailing space characters.
+func TrimRightSpaceLength(source []byte) int {
+	l := len(source)
+	i := l - 1
+	for ; i >= 0; i-- {
+		if !IsSpace(source[i]) {
+			break
+		}
+	}
+	if i < 0 {
+		return l
+	}
+	return l - 1 - i
+}
+
+// TrimLeftSpace returns a subslice of the given string by slicing off all leading
+// space characters.
+func TrimLeftSpace(source []byte) []byte {
+	return TrimLeft(source, spaces)
+}
+
+// TrimRightSpace returns a subslice of the given string by slicing off all trailing
+// space characters.
+func TrimRightSpace(source []byte) []byte {
+	return TrimRight(source, spaces)
+}
+
+// DoFullUnicodeCaseFolding performs full unicode case folding to given bytes.
+func DoFullUnicodeCaseFolding(v []byte) []byte {
+	var rbuf []byte
+	cob := NewCopyOnWriteBuffer(v)
+	n := 0
+	for i := 0; i < len(v); i++ {
+		c := v[i]
+		if c < 0xb5 {
+			if c >= 0x41 && c <= 0x5a {
+				// A-Z to a-z
+				cob.Write(v[n:i])
+				cob.WriteByte(c + 32)
+				n = i + 1
+			}
+			continue
+		}
+
+		if !utf8.RuneStart(c) {
+			continue
+		}
+		r, length := utf8.DecodeRune(v[i:])
+		if r == utf8.RuneError {
+			continue
+		}
+		folded, ok := unicodeCaseFoldings[r]
+		if !ok {
+			continue
+		}
+
+		cob.Write(v[n:i])
+		if rbuf == nil {
+			rbuf = make([]byte, 4)
+		}
+		for _, f := range folded {
+			l := utf8.EncodeRune(rbuf, f)
+			cob.Write(rbuf[:l])
+		}
+		i += length - 1
+		n = i + 1
+	}
+	if cob.IsCopied() {
+		cob.Write(v[n:])
+	}
+	return cob.Bytes()
+}
+
+// ReplaceSpaces replaces sequence of spaces with the given repl.
+func ReplaceSpaces(source []byte, repl byte) []byte {
+	var ret []byte
+	start := -1
+	for i, c := range source {
+		iss := IsSpace(c)
+		if start < 0 && iss {
+			start = i
+			continue
+		} else if start >= 0 && iss {
+			continue
+		} else if start >= 0 {
+			if ret == nil {
+				ret = make([]byte, 0, len(source))
+				ret = append(ret, source[:start]...)
+			}
+			ret = append(ret, repl)
+			start = -1
+		}
+		if ret != nil {
+			ret = append(ret, c)
+		}
+	}
+	if start >= 0 && ret != nil {
+		ret = append(ret, repl)
+	}
+	if ret == nil {
+		return source
+	}
+	return ret
+}
+
+// ToRune decode given bytes start at pos and returns a rune.
+func ToRune(source []byte, pos int) rune {
+	i := pos
+	for ; i >= 0; i-- {
+		if utf8.RuneStart(source[i]) {
+			break
+		}
+	}
+	r, _ := utf8.DecodeRune(source[i:])
+	return r
+}
+
+// ToValidRune returns 0xFFFD if the given rune is invalid, otherwise v.
+func ToValidRune(v rune) rune {
+	if v == 0 || !utf8.ValidRune(v) {
+		return rune(0xFFFD)
+	}
+	return v
+}
+
+// ToLinkReference converts given bytes into a valid link reference string.
+// ToLinkReference performs unicode case folding, trims leading and trailing spaces,  converts into lower
+// case and replace spaces with a single space character.
+func ToLinkReference(v []byte) string {
+	v = TrimLeftSpace(v)
+	v = TrimRightSpace(v)
+	v = DoFullUnicodeCaseFolding(v)
+	return string(ReplaceSpaces(v, ' '))
+}
+
+var htmlEscapeTable = [256][]byte{nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, []byte("&quot;"), nil, nil, nil, []byte("&amp;"), nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, []byte("&lt;"), nil, []byte("&gt;"), nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil}
+
+// EscapeHTMLByte returns HTML escaped bytes if the given byte should be escaped,
+// otherwise nil.
+func EscapeHTMLByte(b byte) []byte {
+	return htmlEscapeTable[b]
+}
+
+// EscapeHTML escapes characters that should be escaped in HTML text.
+func EscapeHTML(v []byte) []byte {
+	cob := NewCopyOnWriteBuffer(v)
+	n := 0
+	for i := 0; i < len(v); i++ {
+		c := v[i]
+		escaped := htmlEscapeTable[c]
+		if escaped != nil {
+			cob.Write(v[n:i])
+			cob.Write(escaped)
+			n = i + 1
+		}
+	}
+	if cob.IsCopied() {
+		cob.Write(v[n:])
+	}
+	return cob.Bytes()
+}
+
+// UnescapePunctuations unescapes blackslash escaped punctuations.
+func UnescapePunctuations(source []byte) []byte {
+	cob := NewCopyOnWriteBuffer(source)
+	limit := len(source)
+	n := 0
+	for i := 0; i < limit; {
+		c := source[i]
+		if i < limit-1 && c == '\\' && IsPunct(source[i+1]) {
+			cob.Write(source[n:i])
+			cob.WriteByte(source[i+1])
+			i += 2
+			n = i
+			continue
+		}
+		i++
+	}
+	if cob.IsCopied() {
+		cob.Write(source[n:])
+	}
+	return cob.Bytes()
+}
+
+// ResolveNumericReferences resolve numeric references like '&#1234;" .
+func ResolveNumericReferences(source []byte) []byte {
+	cob := NewCopyOnWriteBuffer(source)
+	buf := make([]byte, 6, 6)
+	limit := len(source)
+	ok := false
+	n := 0
+	for i := 0; i < limit; i++ {
+		if source[i] == '&' {
+			pos := i
+			next := i + 1
+			if next < limit && source[next] == '#' {
+				nnext := next + 1
+				if nnext < limit {
+					nc := source[nnext]
+					// code point like #x22;
+					if nnext < limit && nc == 'x' || nc == 'X' {
+						start := nnext + 1
+						i, ok = ReadWhile(source, [2]int{start, limit}, IsHexDecimal)
+						if ok && i < limit && source[i] == ';' {
+							v, _ := strconv.ParseUint(BytesToReadOnlyString(source[start:i]), 16, 32)
+							cob.Write(source[n:pos])
+							n = i + 1
+							runeSize := utf8.EncodeRune(buf, ToValidRune(rune(v)))
+							cob.Write(buf[:runeSize])
+							continue
+						}
+						// code point like #1234;
+					} else if nc >= '0' && nc <= '9' {
+						start := nnext
+						i, ok = ReadWhile(source, [2]int{start, limit}, IsNumeric)
+						if ok && i < limit && i-start < 8 && source[i] == ';' {
+							v, _ := strconv.ParseUint(BytesToReadOnlyString(source[start:i]), 0, 32)
+							cob.Write(source[n:pos])
+							n = i + 1
+							runeSize := utf8.EncodeRune(buf, ToValidRune(rune(v)))
+							cob.Write(buf[:runeSize])
+							continue
+						}
+					}
+				}
+			}
+			i = next - 1
+		}
+	}
+	if cob.IsCopied() {
+		cob.Write(source[n:])
+	}
+	return cob.Bytes()
+}
+
+// ResolveEntityNames resolve entity references like '&ouml;" .
+func ResolveEntityNames(source []byte) []byte {
+	cob := NewCopyOnWriteBuffer(source)
+	limit := len(source)
+	ok := false
+	n := 0
+	for i := 0; i < limit; i++ {
+		if source[i] == '&' {
+			pos := i
+			next := i + 1
+			if !(next < limit && source[next] == '#') {
+				start := next
+				i, ok = ReadWhile(source, [2]int{start, limit}, IsAlphaNumeric)
+				if ok && i < limit && source[i] == ';' {
+					name := BytesToReadOnlyString(source[start:i])
+					entity, ok := LookUpHTML5EntityByName(name)
+					if ok {
+						cob.Write(source[n:pos])
+						n = i + 1
+						cob.Write(entity.Characters)
+						continue
+					}
+				}
+			}
+			i = next - 1
+		}
+	}
+	if cob.IsCopied() {
+		cob.Write(source[n:])
+	}
+	return cob.Bytes()
+}
+
+var htmlSpace = []byte("%20")
+
+// URLEscape escape the given URL.
+// If resolveReference is set true:
+//   1. unescape punctuations
+//   2. resolve numeric references
+//   3. resolve entity references
+//
+// URL encoded values (%xx) are kept as is.
+func URLEscape(v []byte, resolveReference bool) []byte {
+	if resolveReference {
+		v = UnescapePunctuations(v)
+		v = ResolveNumericReferences(v)
+		v = ResolveEntityNames(v)
+	}
+	cob := NewCopyOnWriteBuffer(v)
+	limit := len(v)
+	n := 0
+
+	for i := 0; i < limit; {
+		c := v[i]
+		if urlEscapeTable[c] == 1 {
+			i++
+			continue
+		}
+		if c == '%' && i+2 < limit && IsHexDecimal(v[i+1]) && IsHexDecimal(v[i+1]) {
+			i += 3
+			continue
+		}
+		u8len := utf8lenTable[c]
+		if u8len == 99 { // invalid utf8 leading byte, skip it
+			i++
+			continue
+		}
+		if c == ' ' {
+			cob.Write(v[n:i])
+			cob.Write(htmlSpace)
+			i++
+			n = i
+			continue
+		}
+		if int(u8len) > len(v) {
+			u8len = int8(len(v) - 1)
+		}
+		if u8len == 0 {
+			i++
+			n = i
+			continue
+		}
+		cob.Write(v[n:i])
+		stop := i + int(u8len)
+		if stop > len(v) {
+			i++
+			n = i
+			continue
+		}
+		cob.Write(StringToReadOnlyBytes(url.QueryEscape(string(v[i:stop]))))
+		i += int(u8len)
+		n = i
+	}
+	if cob.IsCopied() && n < limit {
+		cob.Write(v[n:])
+	}
+	return cob.Bytes()
+}
+
+// FindURLIndex returns a stop index value if the given bytes seem an URL.
+// This function is equivalent to [A-Za-z][A-Za-z0-9.+-]{1,31}:[^<>\x00-\x20]* .
+func FindURLIndex(b []byte) int {
+	i := 0
+	if !(len(b) > 0 && urlTable[b[i]]&7 == 7) {
+		return -1
+	}
+	i++
+	for ; i < len(b); i++ {
+		c := b[i]
+		if urlTable[c]&4 != 4 {
+			break
+		}
+	}
+	if i == 1 || i > 33 || i >= len(b) {
+		return -1
+	}
+	if b[i] != ':' {
+		return -1
+	}
+	i++
+	for ; i < len(b); i++ {
+		c := b[i]
+		if urlTable[c]&1 != 1 {
+			break
+		}
+	}
+	return i
+}
+
+var emailDomainRegexp = regexp.MustCompile(`^[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*`)
+
+// FindEmailIndex returns a stop index value if the given bytes seem an email address.
+func FindEmailIndex(b []byte) int {
+	// TODO: eliminate regexps
+	i := 0
+	for ; i < len(b); i++ {
+		c := b[i]
+		if emailTable[c]&1 != 1 {
+			break
+		}
+	}
+	if i == 0 {
+		return -1
+	}
+	if i >= len(b) || b[i] != '@' {
+		return -1
+	}
+	i++
+	if i >= len(b) {
+		return -1
+	}
+	match := emailDomainRegexp.FindSubmatchIndex(b[i:])
+	if match == nil {
+		return -1
+	}
+	return i + match[1]
+}
+
+var spaces = []byte(" \t\n\x0b\x0c\x0d")
+
+var spaceTable = [256]int8{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+var punctTable = [256]int8{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+// a-zA-Z0-9, ;/?:@&=+$,-_.!~*'()#
+var urlEscapeTable = [256]int8{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+var utf8lenTable = [256]int8{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 99, 99, 99, 99, 99, 99, 99, 99}
+
+var urlTable = [256]uint8{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 5, 5, 1, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 1, 1, 0, 1, 0, 1, 1, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 1, 1, 1, 1, 1, 1, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
+
+var emailTable = [256]uint8{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+// UTF8Len returns a byte length of the utf-8 character.
+func UTF8Len(b byte) int8 {
+	return utf8lenTable[b]
+}
+
+// IsPunct returns true if the given character is a punctuation, otherwise false.
+func IsPunct(c byte) bool {
+	return punctTable[c] == 1
+}
+
+// IsPunctRune returns true if the given rune is a punctuation, otherwise false.
+func IsPunctRune(r rune) bool {
+	return int32(r) <= 256 && IsPunct(byte(r)) || unicode.IsPunct(r)
+}
+
+// IsSpace returns true if the given character is a space, otherwise false.
+func IsSpace(c byte) bool {
+	return spaceTable[c] == 1
+}
+
+// IsSpaceRune returns true if the given rune is a space, otherwise false.
+func IsSpaceRune(r rune) bool {
+	return int32(r) <= 256 && IsSpace(byte(r)) || unicode.IsSpace(r)
+}
+
+// IsNumeric returns true if the given character is a numeric, otherwise false.
+func IsNumeric(c byte) bool {
+	return c >= '0' && c <= '9'
+}
+
+// IsHexDecimal returns true if the given character is a hexdecimal, otherwise false.
+func IsHexDecimal(c byte) bool {
+	return c >= '0' && c <= '9' || c >= 'a' && c <= 'f' || c >= 'A' && c <= 'F'
+}
+
+// IsAlphaNumeric returns true if the given character is a alphabet or a numeric, otherwise false.
+func IsAlphaNumeric(c byte) bool {
+	return c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9'
+}
+
+// IsEastAsianWideRune returns trhe if the given rune is an east asian wide character, otherwise false.
+func IsEastAsianWideRune(r rune) bool {
+	return unicode.Is(unicode.Hiragana, r) ||
+		unicode.Is(unicode.Katakana, r) ||
+		unicode.Is(unicode.Han, r) ||
+		unicode.Is(unicode.Lm, r) ||
+		unicode.Is(unicode.Hangul, r)
+}
+
+// A BufWriter is a subset of the bufio.Writer .
+type BufWriter interface {
+	io.Writer
+	Available() int
+	Buffered() int
+	Flush() error
+	WriteByte(c byte) error
+	WriteRune(r rune) (size int, err error)
+	WriteString(s string) (int, error)
+}
+
+// A PrioritizedValue struct holds pair of an arbitrary value and a priority.
+type PrioritizedValue struct {
+	// Value is an arbitrary value that you want to prioritize.
+	Value interface{}
+	// Priority is a priority of the value.
+	Priority int
+}
+
+// PrioritizedSlice is a slice of the PrioritizedValues
+type PrioritizedSlice []PrioritizedValue
+
+// Sort sorts the PrioritizedSlice in ascending order.
+func (s PrioritizedSlice) Sort() {
+	sort.Slice(s, func(i, j int) bool {
+		return s[i].Priority < s[j].Priority
+	})
+}
+
+// Remove removes the given value from this slice.
+func (s PrioritizedSlice) Remove(v interface{}) PrioritizedSlice {
+	i := 0
+	found := false
+	for ; i < len(s); i++ {
+		if s[i].Value == v {
+			found = true
+			break
+		}
+	}
+	if !found {
+		return s
+	}
+	return append(s[:i], s[i+1:]...)
+}
+
+// Prioritized returns a new PrioritizedValue.
+func Prioritized(v interface{}, priority int) PrioritizedValue {
+	return PrioritizedValue{v, priority}
+}
+
+func bytesHash(b []byte) uint64 {
+	var hash uint64 = 5381
+	for _, c := range b {
+		hash = ((hash << 5) + hash) + uint64(c)
+	}
+	return hash
+}
+
+// BytesFilter is a efficient data structure for checking whether bytes exist or not.
+// BytesFilter is thread-safe.
+type BytesFilter interface {
+	// Add adds given bytes to this set.
+	Add([]byte)
+
+	// Contains return true if this set contains given bytes, otherwise false.
+	Contains([]byte) bool
+
+	// Extend copies this filter and adds given bytes to new filter.
+	Extend(...[]byte) BytesFilter
+}
+
+type bytesFilter struct {
+	chars     [256]uint8
+	threshold int
+	slots     [][][]byte
+}
+
+// NewBytesFilter returns a new BytesFilter.
+func NewBytesFilter(elements ...[]byte) BytesFilter {
+	s := &bytesFilter{
+		threshold: 3,
+		slots:     make([][][]byte, 64),
+	}
+	for _, element := range elements {
+		s.Add(element)
+	}
+	return s
+}
+
+func (s *bytesFilter) Add(b []byte) {
+	l := len(b)
+	m := s.threshold
+	if l < s.threshold {
+		m = l
+	}
+	for i := 0; i < m; i++ {
+		s.chars[b[i]] |= 1 << uint8(i)
+	}
+	h := bytesHash(b) % uint64(len(s.slots))
+	slot := s.slots[h]
+	if slot == nil {
+		slot = [][]byte{}
+	}
+	s.slots[h] = append(slot, b)
+}
+
+func (s *bytesFilter) Extend(bs ...[]byte) BytesFilter {
+	newFilter := NewBytesFilter().(*bytesFilter)
+	newFilter.chars = s.chars
+	newFilter.threshold = s.threshold
+	for k, v := range s.slots {
+		newSlot := make([][]byte, len(v))
+		copy(newSlot, v)
+		newFilter.slots[k] = v
+	}
+	for _, b := range bs {
+		newFilter.Add(b)
+	}
+	return newFilter
+}
+
+func (s *bytesFilter) Contains(b []byte) bool {
+	l := len(b)
+	m := s.threshold
+	if l < s.threshold {
+		m = l
+	}
+	for i := 0; i < m; i++ {
+		if (s.chars[b[i]] & (1 << uint8(i))) == 0 {
+			return false
+		}
+	}
+	h := bytesHash(b) % uint64(len(s.slots))
+	slot := s.slots[h]
+	if slot == nil || len(slot) == 0 {
+		return false
+	}
+	for _, element := range slot {
+		if bytes.Equal(element, b) {
+			return true
+		}
+	}
+	return false
+}

vendor/github.com/yuin/goldmark/util/util_safe.go

@@ -0,0 +1,13 @@
+// +build appengine js
+
+package util
+
+// BytesToReadOnlyString returns a string converted from given bytes.
+func BytesToReadOnlyString(b []byte) string {
+	return string(b)
+}
+
+// StringToReadOnlyBytes returns bytes converted from given string.
+func StringToReadOnlyBytes(s string) []byte {
+	return []byte(s)
+}

vendor/github.com/yuin/goldmark/util/util_unsafe.go

@@ -0,0 +1,23 @@
+// +build !appengine,!js
+
+package util
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+// BytesToReadOnlyString returns a string converted from given bytes.
+func BytesToReadOnlyString(b []byte) string {
+	return *(*string)(unsafe.Pointer(&b))
+}
+
+// StringToReadOnlyBytes returns bytes converted from given string.
+func StringToReadOnlyBytes(s string) (bs []byte) {
+	sh := (*reflect.StringHeader)(unsafe.Pointer(&s))
+	bh := (*reflect.SliceHeader)(unsafe.Pointer(&bs))
+	bh.Data = sh.Data
+	bh.Cap = sh.Len
+	bh.Len = sh.Len
+	return
+}

vendor/modules.txt

@@ -342,9 +342,6 @@ github.com/robfig/cron/v3
 # github.com/rs/xid v1.4.0
 ## explicit; go 1.12
 github.com/rs/xid
-# github.com/russross/blackfriday/v2 v2.1.0
-## explicit
-github.com/russross/blackfriday/v2
 # github.com/sirupsen/logrus v1.9.0
 ## explicit; go 1.13
 github.com/sirupsen/logrus
@@ -636,6 +633,17 @@ github.com/vmihailenco/tagparser/v2/internal/parser
 # github.com/wagslane/go-password-validator v0.3.0
 ## explicit; go 1.16
 github.com/wagslane/go-password-validator
+# github.com/yuin/goldmark v1.5.3
+## explicit; go 1.18
+github.com/yuin/goldmark
+github.com/yuin/goldmark/ast
+github.com/yuin/goldmark/extension
+github.com/yuin/goldmark/extension/ast
+github.com/yuin/goldmark/parser
+github.com/yuin/goldmark/renderer
+github.com/yuin/goldmark/renderer/html
+github.com/yuin/goldmark/text
+github.com/yuin/goldmark/util
 # golang.org/x/crypto v0.0.0-20220829220503-c86fa9a7ed90
 ## explicit; go 1.17
 golang.org/x/crypto/acme