peridot/vendor/github.com/google/go-cmp/cmp/report_compare.go

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2022-07-07 20:11:50 +00:00
// 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 (
"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 = 6
// 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 if opts.verbosity() < 3 {
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.
// As a special case, treat equal []byte as a leaf nodes.
isBytes := v.Type.Kind() == reflect.Slice && v.Type.Elem() == reflect.TypeOf(byte(0))
isEqualBytes := isBytes && v.NumDiff+v.NumIgnored+v.NumTransformed == 0
if v.MaxDepth == 0 || isEqualBytes {
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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
}