This repository has been archived on 2023-04-13. You can view files and clone it, but cannot push or open issues or pull requests.
go-discogs/vendor/github.com/google/go-cmp/cmp/report_slices.go
Artem Piskun 0191d5c84e
Methods moved to interface, vendors updated (#40)
* Move to interfaces

* update vendor

Co-authored-by: Artem Piskun <artem.piskun@myoffice.team>
2020-06-01 10:08:11 +03:00

336 lines
10 KiB
Go

// Copyright 2019, The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE.md file.
package cmp
import (
"bytes"
"fmt"
"reflect"
"strings"
"unicode"
"unicode/utf8"
"github.com/google/go-cmp/cmp/internal/diff"
)
// CanFormatDiffSlice reports whether we support custom formatting for nodes
// that are slices of primitive kinds or strings.
func (opts formatOptions) CanFormatDiffSlice(v *valueNode) bool {
switch {
case opts.DiffMode != diffUnknown:
return false // Must be formatting in diff mode
case v.NumDiff == 0:
return false // No differences detected
case v.NumIgnored+v.NumCompared+v.NumTransformed > 0:
// TODO: Handle the case where someone uses bytes.Equal on a large slice.
return false // Some custom option was used to determined equality
case !v.ValueX.IsValid() || !v.ValueY.IsValid():
return false // Both values must be valid
}
switch t := v.Type; t.Kind() {
case reflect.String:
case reflect.Array, reflect.Slice:
// Only slices of primitive types have specialized handling.
switch t.Elem().Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
reflect.Bool, reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
default:
return false
}
// If a sufficient number of elements already differ,
// use specialized formatting even if length requirement is not met.
if v.NumDiff > v.NumSame {
return true
}
default:
return false
}
// Use specialized string diffing for longer slices or strings.
const minLength = 64
return v.ValueX.Len() >= minLength && v.ValueY.Len() >= minLength
}
// FormatDiffSlice prints a diff for the slices (or strings) represented by v.
// This provides custom-tailored logic to make printing of differences in
// textual strings and slices of primitive kinds more readable.
func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
assert(opts.DiffMode == diffUnknown)
t, vx, vy := v.Type, v.ValueX, v.ValueY
// Auto-detect the type of the data.
var isLinedText, isText, isBinary bool
var sx, sy string
switch {
case t.Kind() == reflect.String:
sx, sy = vx.String(), vy.String()
isText = true // Initial estimate, verify later
case t.Kind() == reflect.Slice && t.Elem() == reflect.TypeOf(byte(0)):
sx, sy = string(vx.Bytes()), string(vy.Bytes())
isBinary = true // Initial estimate, verify later
case t.Kind() == reflect.Array:
// Arrays need to be addressable for slice operations to work.
vx2, vy2 := reflect.New(t).Elem(), reflect.New(t).Elem()
vx2.Set(vx)
vy2.Set(vy)
vx, vy = vx2, vy2
}
if isText || isBinary {
var numLines, lastLineIdx, maxLineLen int
isBinary = false
for i, r := range sx + sy {
if !(unicode.IsPrint(r) || unicode.IsSpace(r)) || r == utf8.RuneError {
isBinary = true
break
}
if r == '\n' {
if maxLineLen < i-lastLineIdx {
maxLineLen = i - lastLineIdx
}
lastLineIdx = i + 1
numLines++
}
}
isText = !isBinary
isLinedText = isText && numLines >= 4 && maxLineLen <= 256
}
// Format the string into printable records.
var list textList
var delim string
switch {
// If the text appears to be multi-lined text,
// then perform differencing across individual lines.
case isLinedText:
ssx := strings.Split(sx, "\n")
ssy := strings.Split(sy, "\n")
list = opts.formatDiffSlice(
reflect.ValueOf(ssx), reflect.ValueOf(ssy), 1, "line",
func(v reflect.Value, d diffMode) textRecord {
s := formatString(v.Index(0).String())
return textRecord{Diff: d, Value: textLine(s)}
},
)
delim = "\n"
// If the text appears to be single-lined text,
// then perform differencing in approximately fixed-sized chunks.
// The output is printed as quoted strings.
case isText:
list = opts.formatDiffSlice(
reflect.ValueOf(sx), reflect.ValueOf(sy), 64, "byte",
func(v reflect.Value, d diffMode) textRecord {
s := formatString(v.String())
return textRecord{Diff: d, Value: textLine(s)}
},
)
delim = ""
// If the text appears to be binary data,
// then perform differencing in approximately fixed-sized chunks.
// The output is inspired by hexdump.
case isBinary:
list = opts.formatDiffSlice(
reflect.ValueOf(sx), reflect.ValueOf(sy), 16, "byte",
func(v reflect.Value, d diffMode) textRecord {
var ss []string
for i := 0; i < v.Len(); i++ {
ss = append(ss, formatHex(v.Index(i).Uint()))
}
s := strings.Join(ss, ", ")
comment := commentString(fmt.Sprintf("%c|%v|", d, formatASCII(v.String())))
return textRecord{Diff: d, Value: textLine(s), Comment: comment}
},
)
// For all other slices of primitive types,
// then perform differencing in approximately fixed-sized chunks.
// The size of each chunk depends on the width of the element kind.
default:
var chunkSize int
if t.Elem().Kind() == reflect.Bool {
chunkSize = 16
} else {
switch t.Elem().Bits() {
case 8:
chunkSize = 16
case 16:
chunkSize = 12
case 32:
chunkSize = 8
default:
chunkSize = 8
}
}
list = opts.formatDiffSlice(
vx, vy, chunkSize, t.Elem().Kind().String(),
func(v reflect.Value, d diffMode) textRecord {
var ss []string
for i := 0; i < v.Len(); i++ {
switch t.Elem().Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
ss = append(ss, fmt.Sprint(v.Index(i).Int()))
case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
ss = append(ss, fmt.Sprint(v.Index(i).Uint()))
case reflect.Uint8, reflect.Uintptr:
ss = append(ss, formatHex(v.Index(i).Uint()))
case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
ss = append(ss, fmt.Sprint(v.Index(i).Interface()))
}
}
s := strings.Join(ss, ", ")
return textRecord{Diff: d, Value: textLine(s)}
},
)
}
// Wrap the output with appropriate type information.
var out textNode = textWrap{"{", list, "}"}
if !isText {
// The "{...}" byte-sequence literal is not valid Go syntax for strings.
// Emit the type for extra clarity (e.g. "string{...}").
if t.Kind() == reflect.String {
opts = opts.WithTypeMode(emitType)
}
return opts.FormatType(t, out)
}
switch t.Kind() {
case reflect.String:
out = textWrap{"strings.Join(", out, fmt.Sprintf(", %q)", delim)}
if t != reflect.TypeOf(string("")) {
out = opts.FormatType(t, out)
}
case reflect.Slice:
out = textWrap{"bytes.Join(", out, fmt.Sprintf(", %q)", delim)}
if t != reflect.TypeOf([]byte(nil)) {
out = opts.FormatType(t, out)
}
}
return out
}
// formatASCII formats s as an ASCII string.
// This is useful for printing binary strings in a semi-legible way.
func formatASCII(s string) string {
b := bytes.Repeat([]byte{'.'}, len(s))
for i := 0; i < len(s); i++ {
if ' ' <= s[i] && s[i] <= '~' {
b[i] = s[i]
}
}
return string(b)
}
func (opts formatOptions) formatDiffSlice(
vx, vy reflect.Value, chunkSize int, name string,
makeRec func(reflect.Value, diffMode) textRecord,
) (list textList) {
es := diff.Difference(vx.Len(), vy.Len(), func(ix int, iy int) diff.Result {
return diff.BoolResult(vx.Index(ix).Interface() == vy.Index(iy).Interface())
})
appendChunks := func(v reflect.Value, d diffMode) int {
n0 := v.Len()
for v.Len() > 0 {
n := chunkSize
if n > v.Len() {
n = v.Len()
}
list = append(list, makeRec(v.Slice(0, n), d))
v = v.Slice(n, v.Len())
}
return n0 - v.Len()
}
groups := coalesceAdjacentEdits(name, es)
groups = coalesceInterveningIdentical(groups, chunkSize/4)
for i, ds := range groups {
// Print equal.
if ds.NumDiff() == 0 {
// Compute the number of leading and trailing equal bytes to print.
var numLo, numHi int
numEqual := ds.NumIgnored + ds.NumIdentical
for numLo < chunkSize*numContextRecords && numLo+numHi < numEqual && i != 0 {
numLo++
}
for numHi < chunkSize*numContextRecords && numLo+numHi < numEqual && i != len(groups)-1 {
numHi++
}
if numEqual-(numLo+numHi) <= chunkSize && ds.NumIgnored == 0 {
numHi = numEqual - numLo // Avoid pointless coalescing of single equal row
}
// Print the equal bytes.
appendChunks(vx.Slice(0, numLo), diffIdentical)
if numEqual > numLo+numHi {
ds.NumIdentical -= numLo + numHi
list.AppendEllipsis(ds)
}
appendChunks(vx.Slice(numEqual-numHi, numEqual), diffIdentical)
vx = vx.Slice(numEqual, vx.Len())
vy = vy.Slice(numEqual, vy.Len())
continue
}
// Print unequal.
nx := appendChunks(vx.Slice(0, ds.NumIdentical+ds.NumRemoved+ds.NumModified), diffRemoved)
vx = vx.Slice(nx, vx.Len())
ny := appendChunks(vy.Slice(0, ds.NumIdentical+ds.NumInserted+ds.NumModified), diffInserted)
vy = vy.Slice(ny, vy.Len())
}
assert(vx.Len() == 0 && vy.Len() == 0)
return list
}
// coalesceAdjacentEdits coalesces the list of edits into groups of adjacent
// equal or unequal counts.
func coalesceAdjacentEdits(name string, es diff.EditScript) (groups []diffStats) {
var prevCase int // Arbitrary index into which case last occurred
lastStats := func(i int) *diffStats {
if prevCase != i {
groups = append(groups, diffStats{Name: name})
prevCase = i
}
return &groups[len(groups)-1]
}
for _, e := range es {
switch e {
case diff.Identity:
lastStats(1).NumIdentical++
case diff.UniqueX:
lastStats(2).NumRemoved++
case diff.UniqueY:
lastStats(2).NumInserted++
case diff.Modified:
lastStats(2).NumModified++
}
}
return groups
}
// coalesceInterveningIdentical coalesces sufficiently short (<= windowSize)
// equal groups into adjacent unequal groups that currently result in a
// dual inserted/removed printout. This acts as a high-pass filter to smooth
// out high-frequency changes within the windowSize.
func coalesceInterveningIdentical(groups []diffStats, windowSize int) []diffStats {
groups, groupsOrig := groups[:0], groups
for i, ds := range groupsOrig {
if len(groups) >= 2 && ds.NumDiff() > 0 {
prev := &groups[len(groups)-2] // Unequal group
curr := &groups[len(groups)-1] // Equal group
next := &groupsOrig[i] // Unequal group
hadX, hadY := prev.NumRemoved > 0, prev.NumInserted > 0
hasX, hasY := next.NumRemoved > 0, next.NumInserted > 0
if ((hadX || hasX) && (hadY || hasY)) && curr.NumIdentical <= windowSize {
*prev = prev.Append(*curr).Append(*next)
groups = groups[:len(groups)-1] // Truncate off equal group
continue
}
}
groups = append(groups, ds)
}
return groups
}