--- /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 (
+ "fmt"
+ "reflect"
+
+ "github.com/google/go-cmp/cmp/internal/value"
+)
+
+// numContextRecords is the number of surrounding equal records to print.
+const numContextRecords = 2
+
+type diffMode byte
+
+const (
+ diffUnknown diffMode = 0
+ diffIdentical diffMode = ' '
+ diffRemoved diffMode = '-'
+ diffInserted diffMode = '+'
+)
+
+type typeMode int
+
+const (
+ // emitType always prints the type.
+ emitType typeMode = iota
+ // elideType never prints the type.
+ elideType
+ // autoType prints the type only for composite kinds
+ // (i.e., structs, slices, arrays, and maps).
+ autoType
+)
+
+type formatOptions struct {
+ // DiffMode controls the output mode of FormatDiff.
+ //
+ // If diffUnknown, then produce a diff of the x and y values.
+ // If diffIdentical, then emit values as if they were equal.
+ // If diffRemoved, then only emit x values (ignoring y values).
+ // If diffInserted, then only emit y values (ignoring x values).
+ DiffMode diffMode
+
+ // TypeMode controls whether to print the type for the current node.
+ //
+ // As a general rule of thumb, we always print the type of the next node
+ // after an interface, and always elide the type of the next node after
+ // a slice or map node.
+ TypeMode typeMode
+
+ // formatValueOptions are options specific to printing reflect.Values.
+ formatValueOptions
+}
+
+func (opts formatOptions) WithDiffMode(d diffMode) formatOptions {
+ opts.DiffMode = d
+ return opts
+}
+func (opts formatOptions) WithTypeMode(t typeMode) formatOptions {
+ opts.TypeMode = t
+ return opts
+}
+func (opts formatOptions) WithVerbosity(level int) formatOptions {
+ opts.VerbosityLevel = level
+ opts.LimitVerbosity = true
+ return opts
+}
+func (opts formatOptions) verbosity() uint {
+ switch {
+ case opts.VerbosityLevel < 0:
+ return 0
+ case opts.VerbosityLevel > 16:
+ return 16 // some reasonable maximum to avoid shift overflow
+ default:
+ return uint(opts.VerbosityLevel)
+ }
+}
+
+const maxVerbosityPreset = 3
+
+// verbosityPreset modifies the verbosity settings given an index
+// between 0 and maxVerbosityPreset, inclusive.
+func verbosityPreset(opts formatOptions, i int) formatOptions {
+ opts.VerbosityLevel = int(opts.verbosity()) + 2*i
+ if i > 0 {
+ opts.AvoidStringer = true
+ }
+ if i >= maxVerbosityPreset {
+ opts.PrintAddresses = true
+ opts.QualifiedNames = true
+ }
+ return opts
+}
+
+// FormatDiff converts a valueNode tree into a textNode tree, where the later
+// is a textual representation of the differences detected in the former.
+func (opts formatOptions) FormatDiff(v *valueNode, ptrs *pointerReferences) (out textNode) {
+ if opts.DiffMode == diffIdentical {
+ opts = opts.WithVerbosity(1)
+ } else {
+ opts = opts.WithVerbosity(3)
+ }
+
+ // Check whether we have specialized formatting for this node.
+ // This is not necessary, but helpful for producing more readable outputs.
+ if opts.CanFormatDiffSlice(v) {
+ return opts.FormatDiffSlice(v)
+ }
+
+ var parentKind reflect.Kind
+ if v.parent != nil && v.parent.TransformerName == "" {
+ parentKind = v.parent.Type.Kind()
+ }
+
+ // For leaf nodes, format the value based on the reflect.Values alone.
+ if v.MaxDepth == 0 {
+ switch opts.DiffMode {
+ case diffUnknown, diffIdentical:
+ // Format Equal.
+ if v.NumDiff == 0 {
+ outx := opts.FormatValue(v.ValueX, parentKind, ptrs)
+ outy := opts.FormatValue(v.ValueY, parentKind, ptrs)
+ if v.NumIgnored > 0 && v.NumSame == 0 {
+ return textEllipsis
+ } else if outx.Len() < outy.Len() {
+ return outx
+ } else {
+ return outy
+ }
+ }
+
+ // Format unequal.
+ assert(opts.DiffMode == diffUnknown)
+ var list textList
+ outx := opts.WithTypeMode(elideType).FormatValue(v.ValueX, parentKind, ptrs)
+ outy := opts.WithTypeMode(elideType).FormatValue(v.ValueY, parentKind, ptrs)
+ for i := 0; i <= maxVerbosityPreset && outx != nil && outy != nil && outx.Equal(outy); i++ {
+ opts2 := verbosityPreset(opts, i).WithTypeMode(elideType)
+ outx = opts2.FormatValue(v.ValueX, parentKind, ptrs)
+ outy = opts2.FormatValue(v.ValueY, parentKind, ptrs)
+ }
+ if outx != nil {
+ list = append(list, textRecord{Diff: '-', Value: outx})
+ }
+ if outy != nil {
+ list = append(list, textRecord{Diff: '+', Value: outy})
+ }
+ return opts.WithTypeMode(emitType).FormatType(v.Type, list)
+ case diffRemoved:
+ return opts.FormatValue(v.ValueX, parentKind, ptrs)
+ case diffInserted:
+ return opts.FormatValue(v.ValueY, parentKind, ptrs)
+ default:
+ panic("invalid diff mode")
+ }
+ }
+
+ // Register slice element to support cycle detection.
+ if parentKind == reflect.Slice {
+ ptrRefs := ptrs.PushPair(v.ValueX, v.ValueY, opts.DiffMode, true)
+ defer ptrs.Pop()
+ defer func() { out = wrapTrunkReferences(ptrRefs, out) }()
+ }
+
+ // Descend into the child value node.
+ if v.TransformerName != "" {
+ out := opts.WithTypeMode(emitType).FormatDiff(v.Value, ptrs)
+ out = &textWrap{Prefix: "Inverse(" + v.TransformerName + ", ", Value: out, Suffix: ")"}
+ return opts.FormatType(v.Type, out)
+ } else {
+ switch k := v.Type.Kind(); k {
+ case reflect.Struct, reflect.Array, reflect.Slice:
+ out = opts.formatDiffList(v.Records, k, ptrs)
+ out = opts.FormatType(v.Type, out)
+ case reflect.Map:
+ // Register map to support cycle detection.
+ ptrRefs := ptrs.PushPair(v.ValueX, v.ValueY, opts.DiffMode, false)
+ defer ptrs.Pop()
+
+ out = opts.formatDiffList(v.Records, k, ptrs)
+ out = wrapTrunkReferences(ptrRefs, out)
+ out = opts.FormatType(v.Type, out)
+ case reflect.Ptr:
+ // Register pointer to support cycle detection.
+ ptrRefs := ptrs.PushPair(v.ValueX, v.ValueY, opts.DiffMode, false)
+ defer ptrs.Pop()
+
+ out = opts.FormatDiff(v.Value, ptrs)
+ out = wrapTrunkReferences(ptrRefs, out)
+ out = &textWrap{Prefix: "&", Value: out}
+ case reflect.Interface:
+ out = opts.WithTypeMode(emitType).FormatDiff(v.Value, ptrs)
+ default:
+ panic(fmt.Sprintf("%v cannot have children", k))
+ }
+ return out
+ }
+}
+
+func (opts formatOptions) formatDiffList(recs []reportRecord, k reflect.Kind, ptrs *pointerReferences) textNode {
+ // Derive record name based on the data structure kind.
+ var name string
+ var formatKey func(reflect.Value) string
+ switch k {
+ case reflect.Struct:
+ name = "field"
+ opts = opts.WithTypeMode(autoType)
+ formatKey = func(v reflect.Value) string { return v.String() }
+ case reflect.Slice, reflect.Array:
+ name = "element"
+ opts = opts.WithTypeMode(elideType)
+ formatKey = func(reflect.Value) string { return "" }
+ case reflect.Map:
+ name = "entry"
+ opts = opts.WithTypeMode(elideType)
+ formatKey = func(v reflect.Value) string { return formatMapKey(v, false, ptrs) }
+ }
+
+ maxLen := -1
+ if opts.LimitVerbosity {
+ if opts.DiffMode == diffIdentical {
+ maxLen = ((1 << opts.verbosity()) >> 1) << 2 // 0, 4, 8, 16, 32, etc...
+ } else {
+ maxLen = (1 << opts.verbosity()) << 1 // 2, 4, 8, 16, 32, 64, etc...
+ }
+ opts.VerbosityLevel--
+ }
+
+ // Handle unification.
+ switch opts.DiffMode {
+ case diffIdentical, diffRemoved, diffInserted:
+ var list textList
+ var deferredEllipsis bool // Add final "..." to indicate records were dropped
+ for _, r := range recs {
+ if len(list) == maxLen {
+ deferredEllipsis = true
+ break
+ }
+
+ // Elide struct fields that are zero value.
+ if k == reflect.Struct {
+ var isZero bool
+ switch opts.DiffMode {
+ case diffIdentical:
+ isZero = value.IsZero(r.Value.ValueX) || value.IsZero(r.Value.ValueY)
+ case diffRemoved:
+ isZero = value.IsZero(r.Value.ValueX)
+ case diffInserted:
+ isZero = value.IsZero(r.Value.ValueY)
+ }
+ if isZero {
+ continue
+ }
+ }
+ // Elide ignored nodes.
+ if r.Value.NumIgnored > 0 && r.Value.NumSame+r.Value.NumDiff == 0 {
+ deferredEllipsis = !(k == reflect.Slice || k == reflect.Array)
+ if !deferredEllipsis {
+ list.AppendEllipsis(diffStats{})
+ }
+ continue
+ }
+ if out := opts.FormatDiff(r.Value, ptrs); out != nil {
+ list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
+ }
+ }
+ if deferredEllipsis {
+ list.AppendEllipsis(diffStats{})
+ }
+ return &textWrap{Prefix: "{", Value: list, Suffix: "}"}
+ case diffUnknown:
+ default:
+ panic("invalid diff mode")
+ }
+
+ // Handle differencing.
+ var numDiffs int
+ var list textList
+ var keys []reflect.Value // invariant: len(list) == len(keys)
+ groups := coalesceAdjacentRecords(name, recs)
+ maxGroup := diffStats{Name: name}
+ for i, ds := range groups {
+ if maxLen >= 0 && numDiffs >= maxLen {
+ maxGroup = maxGroup.Append(ds)
+ continue
+ }
+
+ // Handle equal records.
+ if ds.NumDiff() == 0 {
+ // Compute the number of leading and trailing records to print.
+ var numLo, numHi int
+ numEqual := ds.NumIgnored + ds.NumIdentical
+ for numLo < numContextRecords && numLo+numHi < numEqual && i != 0 {
+ if r := recs[numLo].Value; r.NumIgnored > 0 && r.NumSame+r.NumDiff == 0 {
+ break
+ }
+ numLo++
+ }
+ for numHi < numContextRecords && numLo+numHi < numEqual && i != len(groups)-1 {
+ if r := recs[numEqual-numHi-1].Value; r.NumIgnored > 0 && r.NumSame+r.NumDiff == 0 {
+ break
+ }
+ numHi++
+ }
+ if numEqual-(numLo+numHi) == 1 && ds.NumIgnored == 0 {
+ numHi++ // Avoid pointless coalescing of a single equal record
+ }
+
+ // Format the equal values.
+ for _, r := range recs[:numLo] {
+ out := opts.WithDiffMode(diffIdentical).FormatDiff(r.Value, ptrs)
+ list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
+ keys = append(keys, r.Key)
+ }
+ if numEqual > numLo+numHi {
+ ds.NumIdentical -= numLo + numHi
+ list.AppendEllipsis(ds)
+ for len(keys) < len(list) {
+ keys = append(keys, reflect.Value{})
+ }
+ }
+ for _, r := range recs[numEqual-numHi : numEqual] {
+ out := opts.WithDiffMode(diffIdentical).FormatDiff(r.Value, ptrs)
+ list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
+ keys = append(keys, r.Key)
+ }
+ recs = recs[numEqual:]
+ continue
+ }
+
+ // Handle unequal records.
+ for _, r := range recs[:ds.NumDiff()] {
+ switch {
+ case opts.CanFormatDiffSlice(r.Value):
+ out := opts.FormatDiffSlice(r.Value)
+ list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
+ keys = append(keys, r.Key)
+ case r.Value.NumChildren == r.Value.MaxDepth:
+ outx := opts.WithDiffMode(diffRemoved).FormatDiff(r.Value, ptrs)
+ outy := opts.WithDiffMode(diffInserted).FormatDiff(r.Value, ptrs)
+ for i := 0; i <= maxVerbosityPreset && outx != nil && outy != nil && outx.Equal(outy); i++ {
+ opts2 := verbosityPreset(opts, i)
+ outx = opts2.WithDiffMode(diffRemoved).FormatDiff(r.Value, ptrs)
+ outy = opts2.WithDiffMode(diffInserted).FormatDiff(r.Value, ptrs)
+ }
+ if outx != nil {
+ list = append(list, textRecord{Diff: diffRemoved, Key: formatKey(r.Key), Value: outx})
+ keys = append(keys, r.Key)
+ }
+ if outy != nil {
+ list = append(list, textRecord{Diff: diffInserted, Key: formatKey(r.Key), Value: outy})
+ keys = append(keys, r.Key)
+ }
+ default:
+ out := opts.FormatDiff(r.Value, ptrs)
+ list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
+ keys = append(keys, r.Key)
+ }
+ }
+ recs = recs[ds.NumDiff():]
+ numDiffs += ds.NumDiff()
+ }
+ if maxGroup.IsZero() {
+ assert(len(recs) == 0)
+ } else {
+ list.AppendEllipsis(maxGroup)
+ for len(keys) < len(list) {
+ keys = append(keys, reflect.Value{})
+ }
+ }
+ assert(len(list) == len(keys))
+
+ // For maps, the default formatting logic uses fmt.Stringer which may
+ // produce ambiguous output. Avoid calling String to disambiguate.
+ if k == reflect.Map {
+ var ambiguous bool
+ seenKeys := map[string]reflect.Value{}
+ for i, currKey := range keys {
+ if currKey.IsValid() {
+ strKey := list[i].Key
+ prevKey, seen := seenKeys[strKey]
+ if seen && prevKey.CanInterface() && currKey.CanInterface() {
+ ambiguous = prevKey.Interface() != currKey.Interface()
+ if ambiguous {
+ break
+ }
+ }
+ seenKeys[strKey] = currKey
+ }
+ }
+ if ambiguous {
+ for i, k := range keys {
+ if k.IsValid() {
+ list[i].Key = formatMapKey(k, true, ptrs)
+ }
+ }
+ }
+ }
+
+ return &textWrap{Prefix: "{", Value: list, Suffix: "}"}
+}
+
+// coalesceAdjacentRecords coalesces the list of records into groups of
+// adjacent equal, or unequal counts.
+func coalesceAdjacentRecords(name string, recs []reportRecord) (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 _, r := range recs {
+ switch rv := r.Value; {
+ case rv.NumIgnored > 0 && rv.NumSame+rv.NumDiff == 0:
+ lastStats(1).NumIgnored++
+ case rv.NumDiff == 0:
+ lastStats(1).NumIdentical++
+ case rv.NumDiff > 0 && !rv.ValueY.IsValid():
+ lastStats(2).NumRemoved++
+ case rv.NumDiff > 0 && !rv.ValueX.IsValid():
+ lastStats(2).NumInserted++
+ default:
+ lastStats(2).NumModified++
+ }
+ }
+ return groups
+}
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