--- /dev/null
+// 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"
+ "strconv"
+ "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.ValueX.IsValid() || !v.ValueY.IsValid():
+ return false // Both values must be valid
+ case v.Type.Kind() == reflect.Slice && (v.ValueX.Len() == 0 || v.ValueY.Len() == 0):
+ return false // Both slice values have to be non-empty
+ case v.NumIgnored > 0:
+ return false // Some ignore option was used
+ case v.NumTransformed > 0:
+ return false // Some transform option was used
+ case v.NumCompared > 1:
+ return false // More than one comparison was used
+ case v.NumCompared == 1 && v.Type.Name() != "":
+ // The need for cmp to check applicability of options on every element
+ // in a slice is a significant performance detriment for large []byte.
+ // The workaround is to specify Comparer(bytes.Equal),
+ // which enables cmp to compare []byte more efficiently.
+ // If they differ, we still want to provide batched diffing.
+ // The logic disallows named types since they tend to have their own
+ // String method, with nicer formatting than what this provides.
+ return false
+ }
+
+ 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 = !utf8.ValidString(sx) || !utf8.ValidString(sy)
+ 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 <= 1024
+ }
+
+ // 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 possible, use a custom triple-quote (""") syntax for printing
+ // differences in a string literal. This format is more readable,
+ // but has edge-cases where differences are visually indistinguishable.
+ // This format is avoided under the following conditions:
+ // • A line starts with `"""`
+ // • A line starts with "..."
+ // • A line contains non-printable characters
+ // • Adjacent different lines differ only by whitespace
+ //
+ // For example:
+ // """
+ // ... // 3 identical lines
+ // foo
+ // bar
+ // - baz
+ // + BAZ
+ // """
+ isTripleQuoted := true
+ prevRemoveLines := map[string]bool{}
+ prevInsertLines := map[string]bool{}
+ var list2 textList
+ list2 = append(list2, textRecord{Value: textLine(`"""`), ElideComma: true})
+ for _, r := range list {
+ if !r.Value.Equal(textEllipsis) {
+ line, _ := strconv.Unquote(string(r.Value.(textLine)))
+ line = strings.TrimPrefix(strings.TrimSuffix(line, "\r"), "\r") // trim leading/trailing carriage returns for legacy Windows endline support
+ normLine := strings.Map(func(r rune) rune {
+ if unicode.IsSpace(r) {
+ return -1 // drop whitespace to avoid visually indistinguishable output
+ }
+ return r
+ }, line)
+ isPrintable := func(r rune) bool {
+ return unicode.IsPrint(r) || r == '\t' // specially treat tab as printable
+ }
+ isTripleQuoted = !strings.HasPrefix(line, `"""`) && !strings.HasPrefix(line, "...") && strings.TrimFunc(line, isPrintable) == ""
+ switch r.Diff {
+ case diffRemoved:
+ isTripleQuoted = isTripleQuoted && !prevInsertLines[normLine]
+ prevRemoveLines[normLine] = true
+ case diffInserted:
+ isTripleQuoted = isTripleQuoted && !prevRemoveLines[normLine]
+ prevInsertLines[normLine] = true
+ }
+ if !isTripleQuoted {
+ break
+ }
+ r.Value = textLine(line)
+ r.ElideComma = true
+ }
+ if !(r.Diff == diffRemoved || r.Diff == diffInserted) { // start a new non-adjacent difference group
+ prevRemoveLines = map[string]bool{}
+ prevInsertLines = map[string]bool{}
+ }
+ list2 = append(list2, r)
+ }
+ if r := list2[len(list2)-1]; r.Diff == diffIdentical && len(r.Value.(textLine)) == 0 {
+ list2 = list2[:len(list2)-1] // elide single empty line at the end
+ }
+ list2 = append(list2, textRecord{Value: textLine(`"""`), ElideComma: true})
+ if isTripleQuoted {
+ var out textNode = &textWrap{Prefix: "(", Value: list2, Suffix: ")"}
+ switch t.Kind() {
+ case reflect.String:
+ if t != reflect.TypeOf(string("")) {
+ out = opts.FormatType(t, out)
+ }
+ case reflect.Slice:
+ // Always emit type for slices since the triple-quote syntax
+ // looks like a string (not a slice).
+ opts = opts.WithTypeMode(emitType)
+ out = opts.FormatType(t, out)
+ }
+ return out
+ }
+
+ // 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{Prefix: "{", Value: list, Suffix: "}"}
+ 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{Prefix: "strings.Join(", Value: out, Suffix: fmt.Sprintf(", %q)", delim)}
+ if t != reflect.TypeOf(string("")) {
+ out = opts.FormatType(t, out)
+ }
+ case reflect.Slice:
+ out = &textWrap{Prefix: "bytes.Join(", Value: out, Suffix: 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()
+ }
+
+ var numDiffs int
+ maxLen := -1
+ if opts.LimitVerbosity {
+ maxLen = (1 << opts.verbosity()) << 2 // 4, 8, 16, 32, 64, etc...
+ opts.VerbosityLevel--
+ }
+
+ groups := coalesceAdjacentEdits(name, es)
+ groups = coalesceInterveningIdentical(groups, chunkSize/4)
+ maxGroup := diffStats{Name: name}
+ for i, ds := range groups {
+ if maxLen >= 0 && numDiffs >= maxLen {
+ maxGroup = maxGroup.Append(ds)
+ continue
+ }
+
+ // 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.
+ len0 := len(list)
+ 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())
+ numDiffs += len(list) - len0
+ }
+ if maxGroup.IsZero() {
+ assert(vx.Len() == 0 && vy.Len() == 0)
+ } else {
+ list.AppendEllipsis(maxGroup)
+ }
+ 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
+}
projects / dotfiles / .git / blobdiff