mirror of
https://github.com/superseriousbusiness/gotosocial.git
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672 lines
22 KiB
Go
672 lines
22 KiB
Go
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// Copyright 2017, 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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// Package cmp determines equality of values.
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//
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// This package is intended to be a more powerful and safer alternative to
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// [reflect.DeepEqual] for comparing whether two values are semantically equal.
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// It is intended to only be used in tests, as performance is not a goal and
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// it may panic if it cannot compare the values. Its propensity towards
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// panicking means that its unsuitable for production environments where a
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// spurious panic may be fatal.
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//
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// The primary features of cmp are:
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//
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// - When the default behavior of equality does not suit the test's needs,
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// custom equality functions can override the equality operation.
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// For example, an equality function may report floats as equal so long as
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// they are within some tolerance of each other.
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//
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// - Types with an Equal method (e.g., [time.Time.Equal]) may use that method
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// to determine equality. This allows package authors to determine
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// the equality operation for the types that they define.
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//
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// - If no custom equality functions are used and no Equal method is defined,
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// equality is determined by recursively comparing the primitive kinds on
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// both values, much like [reflect.DeepEqual]. Unlike [reflect.DeepEqual],
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// unexported fields are not compared by default; they result in panics
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// unless suppressed by using an [Ignore] option
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// (see [github.com/google/go-cmp/cmp/cmpopts.IgnoreUnexported])
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// or explicitly compared using the [Exporter] option.
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package cmp
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import (
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"fmt"
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"reflect"
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"strings"
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"github.com/google/go-cmp/cmp/internal/diff"
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"github.com/google/go-cmp/cmp/internal/function"
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"github.com/google/go-cmp/cmp/internal/value"
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)
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// TODO(≥go1.18): Use any instead of interface{}.
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// Equal reports whether x and y are equal by recursively applying the
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// following rules in the given order to x and y and all of their sub-values:
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//
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// - Let S be the set of all [Ignore], [Transformer], and [Comparer] options that
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// remain after applying all path filters, value filters, and type filters.
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// If at least one [Ignore] exists in S, then the comparison is ignored.
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// If the number of [Transformer] and [Comparer] options in S is non-zero,
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// then Equal panics because it is ambiguous which option to use.
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// If S contains a single [Transformer], then use that to transform
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// the current values and recursively call Equal on the output values.
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// If S contains a single [Comparer], then use that to compare the current values.
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// Otherwise, evaluation proceeds to the next rule.
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//
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// - If the values have an Equal method of the form "(T) Equal(T) bool" or
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// "(T) Equal(I) bool" where T is assignable to I, then use the result of
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// x.Equal(y) even if x or y is nil. Otherwise, no such method exists and
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// evaluation proceeds to the next rule.
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//
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// - Lastly, try to compare x and y based on their basic kinds.
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// Simple kinds like booleans, integers, floats, complex numbers, strings,
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// and channels are compared using the equivalent of the == operator in Go.
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// Functions are only equal if they are both nil, otherwise they are unequal.
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//
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// Structs are equal if recursively calling Equal on all fields report equal.
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// If a struct contains unexported fields, Equal panics unless an [Ignore] option
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// (e.g., [github.com/google/go-cmp/cmp/cmpopts.IgnoreUnexported]) ignores that field
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// or the [Exporter] option explicitly permits comparing the unexported field.
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//
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// Slices are equal if they are both nil or both non-nil, where recursively
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// calling Equal on all non-ignored slice or array elements report equal.
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// Empty non-nil slices and nil slices are not equal; to equate empty slices,
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// consider using [github.com/google/go-cmp/cmp/cmpopts.EquateEmpty].
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//
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// Maps are equal if they are both nil or both non-nil, where recursively
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// calling Equal on all non-ignored map entries report equal.
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// Map keys are equal according to the == operator.
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// To use custom comparisons for map keys, consider using
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// [github.com/google/go-cmp/cmp/cmpopts.SortMaps].
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// Empty non-nil maps and nil maps are not equal; to equate empty maps,
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// consider using [github.com/google/go-cmp/cmp/cmpopts.EquateEmpty].
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//
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// Pointers and interfaces are equal if they are both nil or both non-nil,
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// where they have the same underlying concrete type and recursively
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// calling Equal on the underlying values reports equal.
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//
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// Before recursing into a pointer, slice element, or map, the current path
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// is checked to detect whether the address has already been visited.
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// If there is a cycle, then the pointed at values are considered equal
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// only if both addresses were previously visited in the same path step.
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func Equal(x, y interface{}, opts ...Option) bool {
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s := newState(opts)
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s.compareAny(rootStep(x, y))
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return s.result.Equal()
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}
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// Diff returns a human-readable report of the differences between two values:
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// y - x. It returns an empty string if and only if Equal returns true for the
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// same input values and options.
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//
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// The output is displayed as a literal in pseudo-Go syntax.
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// At the start of each line, a "-" prefix indicates an element removed from x,
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// a "+" prefix to indicates an element added from y, and the lack of a prefix
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// indicates an element common to both x and y. If possible, the output
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// uses fmt.Stringer.String or error.Error methods to produce more humanly
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// readable outputs. In such cases, the string is prefixed with either an
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// 's' or 'e' character, respectively, to indicate that the method was called.
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//
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// Do not depend on this output being stable. If you need the ability to
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// programmatically interpret the difference, consider using a custom Reporter.
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func Diff(x, y interface{}, opts ...Option) string {
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s := newState(opts)
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// Optimization: If there are no other reporters, we can optimize for the
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// common case where the result is equal (and thus no reported difference).
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// This avoids the expensive construction of a difference tree.
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if len(s.reporters) == 0 {
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s.compareAny(rootStep(x, y))
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if s.result.Equal() {
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return ""
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}
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s.result = diff.Result{} // Reset results
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}
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r := new(defaultReporter)
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s.reporters = append(s.reporters, reporter{r})
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s.compareAny(rootStep(x, y))
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d := r.String()
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if (d == "") != s.result.Equal() {
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panic("inconsistent difference and equality results")
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}
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return d
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}
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// rootStep constructs the first path step. If x and y have differing types,
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// then they are stored within an empty interface type.
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func rootStep(x, y interface{}) PathStep {
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vx := reflect.ValueOf(x)
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vy := reflect.ValueOf(y)
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// If the inputs are different types, auto-wrap them in an empty interface
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// so that they have the same parent type.
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var t reflect.Type
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if !vx.IsValid() || !vy.IsValid() || vx.Type() != vy.Type() {
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t = anyType
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if vx.IsValid() {
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vvx := reflect.New(t).Elem()
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vvx.Set(vx)
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vx = vvx
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}
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if vy.IsValid() {
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vvy := reflect.New(t).Elem()
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vvy.Set(vy)
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vy = vvy
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}
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} else {
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t = vx.Type()
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}
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return &pathStep{t, vx, vy}
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}
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type state struct {
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// These fields represent the "comparison state".
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// Calling statelessCompare must not result in observable changes to these.
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result diff.Result // The current result of comparison
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curPath Path // The current path in the value tree
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curPtrs pointerPath // The current set of visited pointers
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reporters []reporter // Optional reporters
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// recChecker checks for infinite cycles applying the same set of
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// transformers upon the output of itself.
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recChecker recChecker
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// dynChecker triggers pseudo-random checks for option correctness.
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// It is safe for statelessCompare to mutate this value.
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dynChecker dynChecker
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// These fields, once set by processOption, will not change.
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exporters []exporter // List of exporters for structs with unexported fields
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opts Options // List of all fundamental and filter options
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}
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func newState(opts []Option) *state {
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// Always ensure a validator option exists to validate the inputs.
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s := &state{opts: Options{validator{}}}
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s.curPtrs.Init()
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s.processOption(Options(opts))
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return s
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}
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func (s *state) processOption(opt Option) {
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switch opt := opt.(type) {
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case nil:
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case Options:
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for _, o := range opt {
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s.processOption(o)
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}
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case coreOption:
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type filtered interface {
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isFiltered() bool
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}
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if fopt, ok := opt.(filtered); ok && !fopt.isFiltered() {
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panic(fmt.Sprintf("cannot use an unfiltered option: %v", opt))
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}
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s.opts = append(s.opts, opt)
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case exporter:
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s.exporters = append(s.exporters, opt)
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case reporter:
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s.reporters = append(s.reporters, opt)
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default:
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panic(fmt.Sprintf("unknown option %T", opt))
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}
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}
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// statelessCompare compares two values and returns the result.
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// This function is stateless in that it does not alter the current result,
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// or output to any registered reporters.
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func (s *state) statelessCompare(step PathStep) diff.Result {
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// We do not save and restore curPath and curPtrs because all of the
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// compareX methods should properly push and pop from them.
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// It is an implementation bug if the contents of the paths differ from
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// when calling this function to when returning from it.
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oldResult, oldReporters := s.result, s.reporters
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s.result = diff.Result{} // Reset result
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s.reporters = nil // Remove reporters to avoid spurious printouts
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s.compareAny(step)
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res := s.result
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s.result, s.reporters = oldResult, oldReporters
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return res
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}
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func (s *state) compareAny(step PathStep) {
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// Update the path stack.
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s.curPath.push(step)
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defer s.curPath.pop()
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for _, r := range s.reporters {
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r.PushStep(step)
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defer r.PopStep()
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}
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s.recChecker.Check(s.curPath)
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// Cycle-detection for slice elements (see NOTE in compareSlice).
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t := step.Type()
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vx, vy := step.Values()
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if si, ok := step.(SliceIndex); ok && si.isSlice && vx.IsValid() && vy.IsValid() {
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px, py := vx.Addr(), vy.Addr()
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if eq, visited := s.curPtrs.Push(px, py); visited {
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s.report(eq, reportByCycle)
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return
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}
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defer s.curPtrs.Pop(px, py)
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}
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// Rule 1: Check whether an option applies on this node in the value tree.
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if s.tryOptions(t, vx, vy) {
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return
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}
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// Rule 2: Check whether the type has a valid Equal method.
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if s.tryMethod(t, vx, vy) {
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return
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}
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// Rule 3: Compare based on the underlying kind.
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switch t.Kind() {
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case reflect.Bool:
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s.report(vx.Bool() == vy.Bool(), 0)
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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s.report(vx.Int() == vy.Int(), 0)
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
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s.report(vx.Uint() == vy.Uint(), 0)
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case reflect.Float32, reflect.Float64:
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s.report(vx.Float() == vy.Float(), 0)
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case reflect.Complex64, reflect.Complex128:
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s.report(vx.Complex() == vy.Complex(), 0)
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case reflect.String:
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s.report(vx.String() == vy.String(), 0)
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case reflect.Chan, reflect.UnsafePointer:
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s.report(vx.Pointer() == vy.Pointer(), 0)
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case reflect.Func:
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s.report(vx.IsNil() && vy.IsNil(), 0)
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case reflect.Struct:
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s.compareStruct(t, vx, vy)
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case reflect.Slice, reflect.Array:
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s.compareSlice(t, vx, vy)
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case reflect.Map:
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s.compareMap(t, vx, vy)
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case reflect.Ptr:
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s.comparePtr(t, vx, vy)
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case reflect.Interface:
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s.compareInterface(t, vx, vy)
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default:
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panic(fmt.Sprintf("%v kind not handled", t.Kind()))
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}
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}
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func (s *state) tryOptions(t reflect.Type, vx, vy reflect.Value) bool {
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// Evaluate all filters and apply the remaining options.
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if opt := s.opts.filter(s, t, vx, vy); opt != nil {
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opt.apply(s, vx, vy)
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return true
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}
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return false
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}
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func (s *state) tryMethod(t reflect.Type, vx, vy reflect.Value) bool {
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// Check if this type even has an Equal method.
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m, ok := t.MethodByName("Equal")
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if !ok || !function.IsType(m.Type, function.EqualAssignable) {
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return false
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}
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eq := s.callTTBFunc(m.Func, vx, vy)
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s.report(eq, reportByMethod)
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return true
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}
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func (s *state) callTRFunc(f, v reflect.Value, step Transform) reflect.Value {
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if !s.dynChecker.Next() {
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return f.Call([]reflect.Value{v})[0]
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}
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// Run the function twice and ensure that we get the same results back.
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// We run in goroutines so that the race detector (if enabled) can detect
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// unsafe mutations to the input.
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c := make(chan reflect.Value)
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go detectRaces(c, f, v)
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got := <-c
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want := f.Call([]reflect.Value{v})[0]
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if step.vx, step.vy = got, want; !s.statelessCompare(step).Equal() {
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// To avoid false-positives with non-reflexive equality operations,
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// we sanity check whether a value is equal to itself.
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if step.vx, step.vy = want, want; !s.statelessCompare(step).Equal() {
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return want
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}
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panic(fmt.Sprintf("non-deterministic function detected: %s", function.NameOf(f)))
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}
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return want
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}
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func (s *state) callTTBFunc(f, x, y reflect.Value) bool {
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if !s.dynChecker.Next() {
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return f.Call([]reflect.Value{x, y})[0].Bool()
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}
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// Swapping the input arguments is sufficient to check that
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// f is symmetric and deterministic.
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// We run in goroutines so that the race detector (if enabled) can detect
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// unsafe mutations to the input.
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c := make(chan reflect.Value)
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go detectRaces(c, f, y, x)
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got := <-c
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want := f.Call([]reflect.Value{x, y})[0].Bool()
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if !got.IsValid() || got.Bool() != want {
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panic(fmt.Sprintf("non-deterministic or non-symmetric function detected: %s", function.NameOf(f)))
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}
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return want
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}
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func detectRaces(c chan<- reflect.Value, f reflect.Value, vs ...reflect.Value) {
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|
var ret reflect.Value
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defer func() {
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recover() // Ignore panics, let the other call to f panic instead
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c <- ret
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}()
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ret = f.Call(vs)[0]
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}
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func (s *state) compareStruct(t reflect.Type, vx, vy reflect.Value) {
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|
var addr bool
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var vax, vay reflect.Value // Addressable versions of vx and vy
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|
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var mayForce, mayForceInit bool
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step := StructField{&structField{}}
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for i := 0; i < t.NumField(); i++ {
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step.typ = t.Field(i).Type
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step.vx = vx.Field(i)
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step.vy = vy.Field(i)
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step.name = t.Field(i).Name
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step.idx = i
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step.unexported = !isExported(step.name)
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||
|
if step.unexported {
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||
|
if step.name == "_" {
|
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|
continue
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|
}
|
||
|
// Defer checking of unexported fields until later to give an
|
||
|
// Ignore a chance to ignore the field.
|
||
|
if !vax.IsValid() || !vay.IsValid() {
|
||
|
// For retrieveUnexportedField to work, the parent struct must
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|
// be addressable. Create a new copy of the values if
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||
|
// necessary to make them addressable.
|
||
|
addr = vx.CanAddr() || vy.CanAddr()
|
||
|
vax = makeAddressable(vx)
|
||
|
vay = makeAddressable(vy)
|
||
|
}
|
||
|
if !mayForceInit {
|
||
|
for _, xf := range s.exporters {
|
||
|
mayForce = mayForce || xf(t)
|
||
|
}
|
||
|
mayForceInit = true
|
||
|
}
|
||
|
step.mayForce = mayForce
|
||
|
step.paddr = addr
|
||
|
step.pvx = vax
|
||
|
step.pvy = vay
|
||
|
step.field = t.Field(i)
|
||
|
}
|
||
|
s.compareAny(step)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func (s *state) compareSlice(t reflect.Type, vx, vy reflect.Value) {
|
||
|
isSlice := t.Kind() == reflect.Slice
|
||
|
if isSlice && (vx.IsNil() || vy.IsNil()) {
|
||
|
s.report(vx.IsNil() && vy.IsNil(), 0)
|
||
|
return
|
||
|
}
|
||
|
|
||
|
// NOTE: It is incorrect to call curPtrs.Push on the slice header pointer
|
||
|
// since slices represents a list of pointers, rather than a single pointer.
|
||
|
// The pointer checking logic must be handled on a per-element basis
|
||
|
// in compareAny.
|
||
|
//
|
||
|
// A slice header (see reflect.SliceHeader) in Go is a tuple of a starting
|
||
|
// pointer P, a length N, and a capacity C. Supposing each slice element has
|
||
|
// a memory size of M, then the slice is equivalent to the list of pointers:
|
||
|
// [P+i*M for i in range(N)]
|
||
|
//
|
||
|
// For example, v[:0] and v[:1] are slices with the same starting pointer,
|
||
|
// but they are clearly different values. Using the slice pointer alone
|
||
|
// violates the assumption that equal pointers implies equal values.
|
||
|
|
||
|
step := SliceIndex{&sliceIndex{pathStep: pathStep{typ: t.Elem()}, isSlice: isSlice}}
|
||
|
withIndexes := func(ix, iy int) SliceIndex {
|
||
|
if ix >= 0 {
|
||
|
step.vx, step.xkey = vx.Index(ix), ix
|
||
|
} else {
|
||
|
step.vx, step.xkey = reflect.Value{}, -1
|
||
|
}
|
||
|
if iy >= 0 {
|
||
|
step.vy, step.ykey = vy.Index(iy), iy
|
||
|
} else {
|
||
|
step.vy, step.ykey = reflect.Value{}, -1
|
||
|
}
|
||
|
return step
|
||
|
}
|
||
|
|
||
|
// Ignore options are able to ignore missing elements in a slice.
|
||
|
// However, detecting these reliably requires an optimal differencing
|
||
|
// algorithm, for which diff.Difference is not.
|
||
|
//
|
||
|
// Instead, we first iterate through both slices to detect which elements
|
||
|
// would be ignored if standing alone. The index of non-discarded elements
|
||
|
// are stored in a separate slice, which diffing is then performed on.
|
||
|
var indexesX, indexesY []int
|
||
|
var ignoredX, ignoredY []bool
|
||
|
for ix := 0; ix < vx.Len(); ix++ {
|
||
|
ignored := s.statelessCompare(withIndexes(ix, -1)).NumDiff == 0
|
||
|
if !ignored {
|
||
|
indexesX = append(indexesX, ix)
|
||
|
}
|
||
|
ignoredX = append(ignoredX, ignored)
|
||
|
}
|
||
|
for iy := 0; iy < vy.Len(); iy++ {
|
||
|
ignored := s.statelessCompare(withIndexes(-1, iy)).NumDiff == 0
|
||
|
if !ignored {
|
||
|
indexesY = append(indexesY, iy)
|
||
|
}
|
||
|
ignoredY = append(ignoredY, ignored)
|
||
|
}
|
||
|
|
||
|
// Compute an edit-script for slices vx and vy (excluding ignored elements).
|
||
|
edits := diff.Difference(len(indexesX), len(indexesY), func(ix, iy int) diff.Result {
|
||
|
return s.statelessCompare(withIndexes(indexesX[ix], indexesY[iy]))
|
||
|
})
|
||
|
|
||
|
// Replay the ignore-scripts and the edit-script.
|
||
|
var ix, iy int
|
||
|
for ix < vx.Len() || iy < vy.Len() {
|
||
|
var e diff.EditType
|
||
|
switch {
|
||
|
case ix < len(ignoredX) && ignoredX[ix]:
|
||
|
e = diff.UniqueX
|
||
|
case iy < len(ignoredY) && ignoredY[iy]:
|
||
|
e = diff.UniqueY
|
||
|
default:
|
||
|
e, edits = edits[0], edits[1:]
|
||
|
}
|
||
|
switch e {
|
||
|
case diff.UniqueX:
|
||
|
s.compareAny(withIndexes(ix, -1))
|
||
|
ix++
|
||
|
case diff.UniqueY:
|
||
|
s.compareAny(withIndexes(-1, iy))
|
||
|
iy++
|
||
|
default:
|
||
|
s.compareAny(withIndexes(ix, iy))
|
||
|
ix++
|
||
|
iy++
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func (s *state) compareMap(t reflect.Type, vx, vy reflect.Value) {
|
||
|
if vx.IsNil() || vy.IsNil() {
|
||
|
s.report(vx.IsNil() && vy.IsNil(), 0)
|
||
|
return
|
||
|
}
|
||
|
|
||
|
// Cycle-detection for maps.
|
||
|
if eq, visited := s.curPtrs.Push(vx, vy); visited {
|
||
|
s.report(eq, reportByCycle)
|
||
|
return
|
||
|
}
|
||
|
defer s.curPtrs.Pop(vx, vy)
|
||
|
|
||
|
// We combine and sort the two map keys so that we can perform the
|
||
|
// comparisons in a deterministic order.
|
||
|
step := MapIndex{&mapIndex{pathStep: pathStep{typ: t.Elem()}}}
|
||
|
for _, k := range value.SortKeys(append(vx.MapKeys(), vy.MapKeys()...)) {
|
||
|
step.vx = vx.MapIndex(k)
|
||
|
step.vy = vy.MapIndex(k)
|
||
|
step.key = k
|
||
|
if !step.vx.IsValid() && !step.vy.IsValid() {
|
||
|
// It is possible for both vx and vy to be invalid if the
|
||
|
// key contained a NaN value in it.
|
||
|
//
|
||
|
// Even with the ability to retrieve NaN keys in Go 1.12,
|
||
|
// there still isn't a sensible way to compare the values since
|
||
|
// a NaN key may map to multiple unordered values.
|
||
|
// The most reasonable way to compare NaNs would be to compare the
|
||
|
// set of values. However, this is impossible to do efficiently
|
||
|
// since set equality is provably an O(n^2) operation given only
|
||
|
// an Equal function. If we had a Less function or Hash function,
|
||
|
// this could be done in O(n*log(n)) or O(n), respectively.
|
||
|
//
|
||
|
// Rather than adding complex logic to deal with NaNs, make it
|
||
|
// the user's responsibility to compare such obscure maps.
|
||
|
const help = "consider providing a Comparer to compare the map"
|
||
|
panic(fmt.Sprintf("%#v has map key with NaNs\n%s", s.curPath, help))
|
||
|
}
|
||
|
s.compareAny(step)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func (s *state) comparePtr(t reflect.Type, vx, vy reflect.Value) {
|
||
|
if vx.IsNil() || vy.IsNil() {
|
||
|
s.report(vx.IsNil() && vy.IsNil(), 0)
|
||
|
return
|
||
|
}
|
||
|
|
||
|
// Cycle-detection for pointers.
|
||
|
if eq, visited := s.curPtrs.Push(vx, vy); visited {
|
||
|
s.report(eq, reportByCycle)
|
||
|
return
|
||
|
}
|
||
|
defer s.curPtrs.Pop(vx, vy)
|
||
|
|
||
|
vx, vy = vx.Elem(), vy.Elem()
|
||
|
s.compareAny(Indirect{&indirect{pathStep{t.Elem(), vx, vy}}})
|
||
|
}
|
||
|
|
||
|
func (s *state) compareInterface(t reflect.Type, vx, vy reflect.Value) {
|
||
|
if vx.IsNil() || vy.IsNil() {
|
||
|
s.report(vx.IsNil() && vy.IsNil(), 0)
|
||
|
return
|
||
|
}
|
||
|
vx, vy = vx.Elem(), vy.Elem()
|
||
|
if vx.Type() != vy.Type() {
|
||
|
s.report(false, 0)
|
||
|
return
|
||
|
}
|
||
|
s.compareAny(TypeAssertion{&typeAssertion{pathStep{vx.Type(), vx, vy}}})
|
||
|
}
|
||
|
|
||
|
func (s *state) report(eq bool, rf resultFlags) {
|
||
|
if rf&reportByIgnore == 0 {
|
||
|
if eq {
|
||
|
s.result.NumSame++
|
||
|
rf |= reportEqual
|
||
|
} else {
|
||
|
s.result.NumDiff++
|
||
|
rf |= reportUnequal
|
||
|
}
|
||
|
}
|
||
|
for _, r := range s.reporters {
|
||
|
r.Report(Result{flags: rf})
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// recChecker tracks the state needed to periodically perform checks that
|
||
|
// user provided transformers are not stuck in an infinitely recursive cycle.
|
||
|
type recChecker struct{ next int }
|
||
|
|
||
|
// Check scans the Path for any recursive transformers and panics when any
|
||
|
// recursive transformers are detected. Note that the presence of a
|
||
|
// recursive Transformer does not necessarily imply an infinite cycle.
|
||
|
// As such, this check only activates after some minimal number of path steps.
|
||
|
func (rc *recChecker) Check(p Path) {
|
||
|
const minLen = 1 << 16
|
||
|
if rc.next == 0 {
|
||
|
rc.next = minLen
|
||
|
}
|
||
|
if len(p) < rc.next {
|
||
|
return
|
||
|
}
|
||
|
rc.next <<= 1
|
||
|
|
||
|
// Check whether the same transformer has appeared at least twice.
|
||
|
var ss []string
|
||
|
m := map[Option]int{}
|
||
|
for _, ps := range p {
|
||
|
if t, ok := ps.(Transform); ok {
|
||
|
t := t.Option()
|
||
|
if m[t] == 1 { // Transformer was used exactly once before
|
||
|
tf := t.(*transformer).fnc.Type()
|
||
|
ss = append(ss, fmt.Sprintf("%v: %v => %v", t, tf.In(0), tf.Out(0)))
|
||
|
}
|
||
|
m[t]++
|
||
|
}
|
||
|
}
|
||
|
if len(ss) > 0 {
|
||
|
const warning = "recursive set of Transformers detected"
|
||
|
const help = "consider using cmpopts.AcyclicTransformer"
|
||
|
set := strings.Join(ss, "\n\t")
|
||
|
panic(fmt.Sprintf("%s:\n\t%s\n%s", warning, set, help))
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// dynChecker tracks the state needed to periodically perform checks that
|
||
|
// user provided functions are symmetric and deterministic.
|
||
|
// The zero value is safe for immediate use.
|
||
|
type dynChecker struct{ curr, next int }
|
||
|
|
||
|
// Next increments the state and reports whether a check should be performed.
|
||
|
//
|
||
|
// Checks occur every Nth function call, where N is a triangular number:
|
||
|
//
|
||
|
// 0 1 3 6 10 15 21 28 36 45 55 66 78 91 105 120 136 153 171 190 ...
|
||
|
//
|
||
|
// See https://en.wikipedia.org/wiki/Triangular_number
|
||
|
//
|
||
|
// This sequence ensures that the cost of checks drops significantly as
|
||
|
// the number of functions calls grows larger.
|
||
|
func (dc *dynChecker) Next() bool {
|
||
|
ok := dc.curr == dc.next
|
||
|
if ok {
|
||
|
dc.curr = 0
|
||
|
dc.next++
|
||
|
}
|
||
|
dc.curr++
|
||
|
return ok
|
||
|
}
|
||
|
|
||
|
// makeAddressable returns a value that is always addressable.
|
||
|
// It returns the input verbatim if it is already addressable,
|
||
|
// otherwise it creates a new value and returns an addressable copy.
|
||
|
func makeAddressable(v reflect.Value) reflect.Value {
|
||
|
if v.CanAddr() {
|
||
|
return v
|
||
|
}
|
||
|
vc := reflect.New(v.Type()).Elem()
|
||
|
vc.Set(v)
|
||
|
return vc
|
||
|
}
|