mirror of
https://github.com/superseriousbusiness/gotosocial.git
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173 lines
4.2 KiB
Go
173 lines
4.2 KiB
Go
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// Copyright 2023 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This is a fork of internal/gover for use by x/tools until
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// go1.21 and earlier are no longer supported by x/tools.
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package versions
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import "strings"
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// A gover is a parsed Go gover: major[.Minor[.Patch]][kind[pre]]
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// The numbers are the original decimal strings to avoid integer overflows
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// and since there is very little actual math. (Probably overflow doesn't matter in practice,
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// but at the time this code was written, there was an existing test that used
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// go1.99999999999, which does not fit in an int on 32-bit platforms.
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// The "big decimal" representation avoids the problem entirely.)
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type gover struct {
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major string // decimal
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minor string // decimal or ""
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patch string // decimal or ""
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kind string // "", "alpha", "beta", "rc"
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pre string // decimal or ""
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}
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// compare returns -1, 0, or +1 depending on whether
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// x < y, x == y, or x > y, interpreted as toolchain versions.
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// The versions x and y must not begin with a "go" prefix: just "1.21" not "go1.21".
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// Malformed versions compare less than well-formed versions and equal to each other.
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// The language version "1.21" compares less than the release candidate and eventual releases "1.21rc1" and "1.21.0".
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func compare(x, y string) int {
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vx := parse(x)
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vy := parse(y)
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if c := cmpInt(vx.major, vy.major); c != 0 {
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return c
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}
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if c := cmpInt(vx.minor, vy.minor); c != 0 {
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return c
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}
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if c := cmpInt(vx.patch, vy.patch); c != 0 {
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return c
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}
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if c := strings.Compare(vx.kind, vy.kind); c != 0 { // "" < alpha < beta < rc
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return c
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}
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if c := cmpInt(vx.pre, vy.pre); c != 0 {
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return c
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}
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return 0
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}
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// lang returns the Go language version. For example, lang("1.2.3") == "1.2".
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func lang(x string) string {
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v := parse(x)
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if v.minor == "" || v.major == "1" && v.minor == "0" {
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return v.major
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}
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return v.major + "." + v.minor
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}
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// isValid reports whether the version x is valid.
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func isValid(x string) bool {
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return parse(x) != gover{}
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}
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// parse parses the Go version string x into a version.
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// It returns the zero version if x is malformed.
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func parse(x string) gover {
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var v gover
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// Parse major version.
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var ok bool
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v.major, x, ok = cutInt(x)
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if !ok {
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return gover{}
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}
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if x == "" {
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// Interpret "1" as "1.0.0".
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v.minor = "0"
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v.patch = "0"
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return v
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}
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// Parse . before minor version.
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if x[0] != '.' {
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return gover{}
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}
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// Parse minor version.
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v.minor, x, ok = cutInt(x[1:])
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if !ok {
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return gover{}
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}
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if x == "" {
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// Patch missing is same as "0" for older versions.
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// Starting in Go 1.21, patch missing is different from explicit .0.
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if cmpInt(v.minor, "21") < 0 {
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v.patch = "0"
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}
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return v
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}
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// Parse patch if present.
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if x[0] == '.' {
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v.patch, x, ok = cutInt(x[1:])
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if !ok || x != "" {
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// Note that we are disallowing prereleases (alpha, beta, rc) for patch releases here (x != "").
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// Allowing them would be a bit confusing because we already have:
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// 1.21 < 1.21rc1
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// But a prerelease of a patch would have the opposite effect:
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// 1.21.3rc1 < 1.21.3
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// We've never needed them before, so let's not start now.
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return gover{}
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}
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return v
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}
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// Parse prerelease.
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i := 0
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for i < len(x) && (x[i] < '0' || '9' < x[i]) {
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if x[i] < 'a' || 'z' < x[i] {
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return gover{}
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}
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i++
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}
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if i == 0 {
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return gover{}
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}
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v.kind, x = x[:i], x[i:]
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if x == "" {
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return v
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}
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v.pre, x, ok = cutInt(x)
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if !ok || x != "" {
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return gover{}
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}
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return v
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}
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// cutInt scans the leading decimal number at the start of x to an integer
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// and returns that value and the rest of the string.
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func cutInt(x string) (n, rest string, ok bool) {
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i := 0
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for i < len(x) && '0' <= x[i] && x[i] <= '9' {
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i++
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}
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if i == 0 || x[0] == '0' && i != 1 { // no digits or unnecessary leading zero
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return "", "", false
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}
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return x[:i], x[i:], true
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}
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// cmpInt returns cmp.Compare(x, y) interpreting x and y as decimal numbers.
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// (Copied from golang.org/x/mod/semver's compareInt.)
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func cmpInt(x, y string) int {
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if x == y {
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return 0
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}
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if len(x) < len(y) {
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return -1
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}
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if len(x) > len(y) {
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return +1
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}
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if x < y {
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return -1
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} else {
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return +1
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}
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}
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