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package diff
import (
"bytes"
"strings"
"github.com/sergi/go-diff/diffmatchpatch"
)
func diff(a, b string) []diffmatchpatch.Diff {
dmp := diffmatchpatch.New()
diffs := dmp.DiffMain(a, b, true)
if len(diffs) > 2 {
diffs = dmp.DiffCleanupSemantic(diffs)
diffs = dmp.DiffCleanupEfficiency(diffs)
}
return diffs
}
// CharacterDiff returns an inline diff between the two strings, using (++added++) and (~~deleted~~) markup.
func CharacterDiff(a, b string) string {
return diffsToString(diff(a, b))
}
func diffsToString(diffs []diffmatchpatch.Diff) string {
var buff bytes.Buffer
for _, diff := range diffs {
text := diff.Text
switch diff.Type {
case diffmatchpatch.DiffInsert:
buff.WriteString("(++")
buff.WriteString(text)
buff.WriteString("++)")
case diffmatchpatch.DiffDelete:
buff.WriteString("(~~")
buff.WriteString(text)
buff.WriteString("~~)")
case diffmatchpatch.DiffEqual:
buff.WriteString(text)
}
}
return buff.String()
}
// LineDiff returns a normal linewise diff between the two given strings.
func LineDiff(a, b string) string {
return strings.Join(LineDiffAsLines(a, b), "\n")
}
// LineDiffAsLines returns the lines of a linewise diff between the two given strings.
func LineDiffAsLines(a, b string) []string {
return diffsToPatchLines(diff(a, b))
}
type patchBuilder struct {
output []string
oldLines []string
newLines []string
newLineBuffer bytes.Buffer
oldLineBuffer bytes.Buffer
}
func (b *patchBuilder) AddCharacters(text string, op diffmatchpatch.Operation) {
if op == diffmatchpatch.DiffInsert || op == diffmatchpatch.DiffEqual {
b.newLineBuffer.WriteString(text)
}
if op == diffmatchpatch.DiffDelete || op == diffmatchpatch.DiffEqual {
b.oldLineBuffer.WriteString(text)
}
}
func (b *patchBuilder) AddNewline(op diffmatchpatch.Operation) {
oldLine := b.oldLineBuffer.String()
newLine := b.newLineBuffer.String()
if op == diffmatchpatch.DiffEqual && (oldLine == newLine) {
b.FlushChunk()
b.output = append(b.output, " "+newLine)
b.oldLineBuffer.Reset()
b.newLineBuffer.Reset()
} else {
if op == diffmatchpatch.DiffDelete || op == diffmatchpatch.DiffEqual {
b.oldLines = append(b.oldLines, "-"+oldLine)
b.oldLineBuffer.Reset()
}
if op == diffmatchpatch.DiffInsert || op == diffmatchpatch.DiffEqual {
b.newLines = append(b.newLines, "+"+newLine)
b.newLineBuffer.Reset()
}
}
}
func (b *patchBuilder) FlushChunk() {
if b.oldLines != nil {
b.output = append(b.output, b.oldLines...)
b.oldLines = nil
}
if b.newLines != nil {
b.output = append(b.output, b.newLines...)
b.newLines = nil
}
}
func (b *patchBuilder) Flush() {
if b.oldLineBuffer.Len() > 0 && b.newLineBuffer.Len() > 0 {
b.AddNewline(diffmatchpatch.DiffEqual)
} else if b.oldLineBuffer.Len() > 0 {
b.AddNewline(diffmatchpatch.DiffDelete)
} else if b.newLineBuffer.Len() > 0 {
b.AddNewline(diffmatchpatch.DiffInsert)
}
b.FlushChunk()
}
func diffsToPatchLines(diffs []diffmatchpatch.Diff) []string {
b := new(patchBuilder)
b.output = make([]string, 0, len(diffs))
for _, diff := range diffs {
lines := strings.Split(diff.Text, "\n")
for idx, line := range lines {
if idx > 0 {
b.AddNewline(diff.Type)
}
b.AddCharacters(line, diff.Type)
}
}
b.Flush()
return b.output
}
|
