diff options
Diffstat (limited to 'vendor/github.com/google/go-cmp/cmp/report_slices.go')
-rw-r--r-- | vendor/github.com/google/go-cmp/cmp/report_slices.go | 465 |
1 files changed, 465 insertions, 0 deletions
diff --git a/vendor/github.com/google/go-cmp/cmp/report_slices.go b/vendor/github.com/google/go-cmp/cmp/report_slices.go new file mode 100644 index 000000000..168f92f3c --- /dev/null +++ b/vendor/github.com/google/go-cmp/cmp/report_slices.go @@ -0,0 +1,465 @@ +// 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 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.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 + } + + // Check whether this is an interface with the same concrete types. + t := v.Type + vx, vy := v.ValueX, v.ValueY + if t.Kind() == reflect.Interface && !vx.IsNil() && !vy.IsNil() && vx.Elem().Type() == vy.Elem().Type() { + vx, vy = vx.Elem(), vy.Elem() + t = vx.Type() + } + + // Check whether we provide specialized diffing for this type. + switch 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 + } + + // Both slice values have to be non-empty. + if t.Kind() == reflect.Slice && (vx.Len() == 0 || vy.Len() == 0) { + 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 vx.Len() >= minLength && vy.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 + if t.Kind() == reflect.Interface { + vx, vy = vx.Elem(), vy.Elem() + t = vx.Type() + opts = opts.WithTypeMode(emitType) + } + + // 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 +} |