557 lines
17 KiB
Go
557 lines
17 KiB
Go
// Copyright (c) 2012-2016 The go-diff authors. All rights reserved.
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// https://github.com/sergi/go-diff
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// See the included LICENSE file for license details.
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//
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// go-diff is a Go implementation of Google's Diff, Match, and Patch library
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// Original library is Copyright (c) 2006 Google Inc.
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// http://code.google.com/p/google-diff-match-patch/
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package diffmatchpatch
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import (
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"bytes"
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"errors"
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"math"
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"net/url"
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"regexp"
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"strconv"
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"strings"
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)
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// Patch represents one patch operation.
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type Patch struct {
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diffs []Diff
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Start1 int
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Start2 int
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Length1 int
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Length2 int
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}
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// String emulates GNU diff's format.
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// Header: @@ -382,8 +481,9 @@
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// Indices are printed as 1-based, not 0-based.
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func (p *Patch) String() string {
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var coords1, coords2 string
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if p.Length1 == 0 {
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coords1 = strconv.Itoa(p.Start1) + ",0"
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} else if p.Length1 == 1 {
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coords1 = strconv.Itoa(p.Start1 + 1)
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} else {
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coords1 = strconv.Itoa(p.Start1+1) + "," + strconv.Itoa(p.Length1)
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}
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if p.Length2 == 0 {
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coords2 = strconv.Itoa(p.Start2) + ",0"
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} else if p.Length2 == 1 {
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coords2 = strconv.Itoa(p.Start2 + 1)
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} else {
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coords2 = strconv.Itoa(p.Start2+1) + "," + strconv.Itoa(p.Length2)
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}
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var text bytes.Buffer
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_, _ = text.WriteString("@@ -" + coords1 + " +" + coords2 + " @@\n")
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// Escape the body of the patch with %xx notation.
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for _, aDiff := range p.diffs {
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switch aDiff.Type {
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case DiffInsert:
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_, _ = text.WriteString("+")
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case DiffDelete:
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_, _ = text.WriteString("-")
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case DiffEqual:
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_, _ = text.WriteString(" ")
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}
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_, _ = text.WriteString(strings.Replace(url.QueryEscape(aDiff.Text), "+", " ", -1))
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_, _ = text.WriteString("\n")
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}
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return unescaper.Replace(text.String())
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}
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// PatchAddContext increases the context until it is unique, but doesn't let the pattern expand beyond MatchMaxBits.
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func (dmp *DiffMatchPatch) PatchAddContext(patch Patch, text string) Patch {
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if len(text) == 0 {
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return patch
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}
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pattern := text[patch.Start2 : patch.Start2+patch.Length1]
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padding := 0
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// Look for the first and last matches of pattern in text. If two different matches are found, increase the pattern length.
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for strings.Index(text, pattern) != strings.LastIndex(text, pattern) &&
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len(pattern) < dmp.MatchMaxBits-2*dmp.PatchMargin {
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padding += dmp.PatchMargin
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maxStart := max(0, patch.Start2-padding)
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minEnd := min(len(text), patch.Start2+patch.Length1+padding)
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pattern = text[maxStart:minEnd]
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}
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// Add one chunk for good luck.
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padding += dmp.PatchMargin
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// Add the prefix.
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prefix := text[max(0, patch.Start2-padding):patch.Start2]
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if len(prefix) != 0 {
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patch.diffs = append([]Diff{Diff{DiffEqual, prefix}}, patch.diffs...)
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}
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// Add the suffix.
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suffix := text[patch.Start2+patch.Length1 : min(len(text), patch.Start2+patch.Length1+padding)]
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if len(suffix) != 0 {
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patch.diffs = append(patch.diffs, Diff{DiffEqual, suffix})
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}
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// Roll back the start points.
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patch.Start1 -= len(prefix)
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patch.Start2 -= len(prefix)
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// Extend the lengths.
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patch.Length1 += len(prefix) + len(suffix)
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patch.Length2 += len(prefix) + len(suffix)
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return patch
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}
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// PatchMake computes a list of patches.
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func (dmp *DiffMatchPatch) PatchMake(opt ...interface{}) []Patch {
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if len(opt) == 1 {
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diffs, _ := opt[0].([]Diff)
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text1 := dmp.DiffText1(diffs)
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return dmp.PatchMake(text1, diffs)
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} else if len(opt) == 2 {
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text1 := opt[0].(string)
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switch t := opt[1].(type) {
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case string:
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diffs := dmp.DiffMain(text1, t, true)
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if len(diffs) > 2 {
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diffs = dmp.DiffCleanupSemantic(diffs)
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diffs = dmp.DiffCleanupEfficiency(diffs)
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}
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return dmp.PatchMake(text1, diffs)
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case []Diff:
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return dmp.patchMake2(text1, t)
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}
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} else if len(opt) == 3 {
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return dmp.PatchMake(opt[0], opt[2])
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}
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return []Patch{}
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}
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// patchMake2 computes a list of patches to turn text1 into text2.
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// text2 is not provided, diffs are the delta between text1 and text2.
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func (dmp *DiffMatchPatch) patchMake2(text1 string, diffs []Diff) []Patch {
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// Check for null inputs not needed since null can't be passed in C#.
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patches := []Patch{}
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if len(diffs) == 0 {
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return patches // Get rid of the null case.
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}
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patch := Patch{}
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charCount1 := 0 // Number of characters into the text1 string.
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charCount2 := 0 // Number of characters into the text2 string.
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// Start with text1 (prepatchText) and apply the diffs until we arrive at text2 (postpatchText). We recreate the patches one by one to determine context info.
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prepatchText := text1
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postpatchText := text1
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for i, aDiff := range diffs {
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if len(patch.diffs) == 0 && aDiff.Type != DiffEqual {
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// A new patch starts here.
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patch.Start1 = charCount1
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patch.Start2 = charCount2
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}
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switch aDiff.Type {
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case DiffInsert:
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patch.diffs = append(patch.diffs, aDiff)
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patch.Length2 += len(aDiff.Text)
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postpatchText = postpatchText[:charCount2] +
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aDiff.Text + postpatchText[charCount2:]
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case DiffDelete:
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patch.Length1 += len(aDiff.Text)
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patch.diffs = append(patch.diffs, aDiff)
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postpatchText = postpatchText[:charCount2] + postpatchText[charCount2+len(aDiff.Text):]
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case DiffEqual:
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if len(aDiff.Text) <= 2*dmp.PatchMargin &&
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len(patch.diffs) != 0 && i != len(diffs)-1 {
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// Small equality inside a patch.
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patch.diffs = append(patch.diffs, aDiff)
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patch.Length1 += len(aDiff.Text)
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patch.Length2 += len(aDiff.Text)
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}
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if len(aDiff.Text) >= 2*dmp.PatchMargin {
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// Time for a new patch.
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if len(patch.diffs) != 0 {
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patch = dmp.PatchAddContext(patch, prepatchText)
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patches = append(patches, patch)
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patch = Patch{}
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// Unlike Unidiff, our patch lists have a rolling context. http://code.google.com/p/google-diff-match-patch/wiki/Unidiff Update prepatch text & pos to reflect the application of the just completed patch.
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prepatchText = postpatchText
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charCount1 = charCount2
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}
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}
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}
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// Update the current character count.
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if aDiff.Type != DiffInsert {
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charCount1 += len(aDiff.Text)
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}
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if aDiff.Type != DiffDelete {
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charCount2 += len(aDiff.Text)
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}
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}
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// Pick up the leftover patch if not empty.
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if len(patch.diffs) != 0 {
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patch = dmp.PatchAddContext(patch, prepatchText)
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patches = append(patches, patch)
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}
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return patches
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}
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// PatchDeepCopy returns an array that is identical to a given an array of patches.
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func (dmp *DiffMatchPatch) PatchDeepCopy(patches []Patch) []Patch {
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patchesCopy := []Patch{}
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for _, aPatch := range patches {
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patchCopy := Patch{}
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for _, aDiff := range aPatch.diffs {
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patchCopy.diffs = append(patchCopy.diffs, Diff{
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aDiff.Type,
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aDiff.Text,
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})
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}
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patchCopy.Start1 = aPatch.Start1
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patchCopy.Start2 = aPatch.Start2
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patchCopy.Length1 = aPatch.Length1
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patchCopy.Length2 = aPatch.Length2
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patchesCopy = append(patchesCopy, patchCopy)
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}
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return patchesCopy
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}
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// PatchApply merges a set of patches onto the text. Returns a patched text, as well as an array of true/false values indicating which patches were applied.
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func (dmp *DiffMatchPatch) PatchApply(patches []Patch, text string) (string, []bool) {
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if len(patches) == 0 {
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return text, []bool{}
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}
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// Deep copy the patches so that no changes are made to originals.
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patches = dmp.PatchDeepCopy(patches)
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nullPadding := dmp.PatchAddPadding(patches)
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text = nullPadding + text + nullPadding
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patches = dmp.PatchSplitMax(patches)
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x := 0
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// delta keeps track of the offset between the expected and actual location of the previous patch. If there are patches expected at positions 10 and 20, but the first patch was found at 12, delta is 2 and the second patch has an effective expected position of 22.
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delta := 0
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results := make([]bool, len(patches))
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for _, aPatch := range patches {
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expectedLoc := aPatch.Start2 + delta
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text1 := dmp.DiffText1(aPatch.diffs)
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var startLoc int
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endLoc := -1
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if len(text1) > dmp.MatchMaxBits {
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// PatchSplitMax will only provide an oversized pattern in the case of a monster delete.
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startLoc = dmp.MatchMain(text, text1[:dmp.MatchMaxBits], expectedLoc)
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if startLoc != -1 {
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endLoc = dmp.MatchMain(text,
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text1[len(text1)-dmp.MatchMaxBits:], expectedLoc+len(text1)-dmp.MatchMaxBits)
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if endLoc == -1 || startLoc >= endLoc {
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// Can't find valid trailing context. Drop this patch.
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startLoc = -1
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}
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}
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} else {
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startLoc = dmp.MatchMain(text, text1, expectedLoc)
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}
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if startLoc == -1 {
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// No match found. :(
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results[x] = false
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// Subtract the delta for this failed patch from subsequent patches.
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delta -= aPatch.Length2 - aPatch.Length1
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} else {
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// Found a match. :)
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results[x] = true
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delta = startLoc - expectedLoc
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var text2 string
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if endLoc == -1 {
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text2 = text[startLoc:int(math.Min(float64(startLoc+len(text1)), float64(len(text))))]
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} else {
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text2 = text[startLoc:int(math.Min(float64(endLoc+dmp.MatchMaxBits), float64(len(text))))]
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}
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if text1 == text2 {
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// Perfect match, just shove the Replacement text in.
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text = text[:startLoc] + dmp.DiffText2(aPatch.diffs) + text[startLoc+len(text1):]
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} else {
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// Imperfect match. Run a diff to get a framework of equivalent indices.
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diffs := dmp.DiffMain(text1, text2, false)
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if len(text1) > dmp.MatchMaxBits && float64(dmp.DiffLevenshtein(diffs))/float64(len(text1)) > dmp.PatchDeleteThreshold {
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// The end points match, but the content is unacceptably bad.
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results[x] = false
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} else {
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diffs = dmp.DiffCleanupSemanticLossless(diffs)
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index1 := 0
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for _, aDiff := range aPatch.diffs {
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if aDiff.Type != DiffEqual {
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index2 := dmp.DiffXIndex(diffs, index1)
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if aDiff.Type == DiffInsert {
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// Insertion
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text = text[:startLoc+index2] + aDiff.Text + text[startLoc+index2:]
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} else if aDiff.Type == DiffDelete {
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// Deletion
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startIndex := startLoc + index2
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text = text[:startIndex] +
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text[startIndex+dmp.DiffXIndex(diffs, index1+len(aDiff.Text))-index2:]
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}
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}
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if aDiff.Type != DiffDelete {
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index1 += len(aDiff.Text)
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}
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}
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}
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}
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}
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x++
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}
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// Strip the padding off.
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text = text[len(nullPadding) : len(nullPadding)+(len(text)-2*len(nullPadding))]
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return text, results
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}
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// PatchAddPadding adds some padding on text start and end so that edges can match something.
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// Intended to be called only from within patchApply.
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func (dmp *DiffMatchPatch) PatchAddPadding(patches []Patch) string {
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paddingLength := dmp.PatchMargin
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nullPadding := ""
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for x := 1; x <= paddingLength; x++ {
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nullPadding += string(rune(x))
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}
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// Bump all the patches forward.
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for i := range patches {
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patches[i].Start1 += paddingLength
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patches[i].Start2 += paddingLength
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}
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// Add some padding on start of first diff.
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if len(patches[0].diffs) == 0 || patches[0].diffs[0].Type != DiffEqual {
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// Add nullPadding equality.
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patches[0].diffs = append([]Diff{Diff{DiffEqual, nullPadding}}, patches[0].diffs...)
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patches[0].Start1 -= paddingLength // Should be 0.
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patches[0].Start2 -= paddingLength // Should be 0.
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patches[0].Length1 += paddingLength
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patches[0].Length2 += paddingLength
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} else if paddingLength > len(patches[0].diffs[0].Text) {
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// Grow first equality.
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extraLength := paddingLength - len(patches[0].diffs[0].Text)
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patches[0].diffs[0].Text = nullPadding[len(patches[0].diffs[0].Text):] + patches[0].diffs[0].Text
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patches[0].Start1 -= extraLength
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patches[0].Start2 -= extraLength
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patches[0].Length1 += extraLength
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patches[0].Length2 += extraLength
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}
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// Add some padding on end of last diff.
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last := len(patches) - 1
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if len(patches[last].diffs) == 0 || patches[last].diffs[len(patches[last].diffs)-1].Type != DiffEqual {
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// Add nullPadding equality.
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patches[last].diffs = append(patches[last].diffs, Diff{DiffEqual, nullPadding})
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patches[last].Length1 += paddingLength
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patches[last].Length2 += paddingLength
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} else if paddingLength > len(patches[last].diffs[len(patches[last].diffs)-1].Text) {
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// Grow last equality.
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lastDiff := patches[last].diffs[len(patches[last].diffs)-1]
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extraLength := paddingLength - len(lastDiff.Text)
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patches[last].diffs[len(patches[last].diffs)-1].Text += nullPadding[:extraLength]
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patches[last].Length1 += extraLength
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patches[last].Length2 += extraLength
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}
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return nullPadding
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}
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// PatchSplitMax looks through the patches and breaks up any which are longer than the maximum limit of the match algorithm.
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// Intended to be called only from within patchApply.
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func (dmp *DiffMatchPatch) PatchSplitMax(patches []Patch) []Patch {
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patchSize := dmp.MatchMaxBits
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for x := 0; x < len(patches); x++ {
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if patches[x].Length1 <= patchSize {
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continue
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}
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bigpatch := patches[x]
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// Remove the big old patch.
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patches = append(patches[:x], patches[x+1:]...)
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x--
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Start1 := bigpatch.Start1
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Start2 := bigpatch.Start2
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precontext := ""
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for len(bigpatch.diffs) != 0 {
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// Create one of several smaller patches.
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patch := Patch{}
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empty := true
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patch.Start1 = Start1 - len(precontext)
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patch.Start2 = Start2 - len(precontext)
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if len(precontext) != 0 {
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patch.Length1 = len(precontext)
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patch.Length2 = len(precontext)
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patch.diffs = append(patch.diffs, Diff{DiffEqual, precontext})
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}
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for len(bigpatch.diffs) != 0 && patch.Length1 < patchSize-dmp.PatchMargin {
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diffType := bigpatch.diffs[0].Type
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diffText := bigpatch.diffs[0].Text
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if diffType == DiffInsert {
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// Insertions are harmless.
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patch.Length2 += len(diffText)
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Start2 += len(diffText)
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patch.diffs = append(patch.diffs, bigpatch.diffs[0])
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bigpatch.diffs = bigpatch.diffs[1:]
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empty = false
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} else if diffType == DiffDelete && len(patch.diffs) == 1 && patch.diffs[0].Type == DiffEqual && len(diffText) > 2*patchSize {
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// This is a large deletion. Let it pass in one chunk.
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patch.Length1 += len(diffText)
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Start1 += len(diffText)
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empty = false
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patch.diffs = append(patch.diffs, Diff{diffType, diffText})
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bigpatch.diffs = bigpatch.diffs[1:]
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} else {
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// Deletion or equality. Only take as much as we can stomach.
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diffText = diffText[:min(len(diffText), patchSize-patch.Length1-dmp.PatchMargin)]
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patch.Length1 += len(diffText)
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Start1 += len(diffText)
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if diffType == DiffEqual {
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patch.Length2 += len(diffText)
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Start2 += len(diffText)
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} else {
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empty = false
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}
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patch.diffs = append(patch.diffs, Diff{diffType, diffText})
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if diffText == bigpatch.diffs[0].Text {
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bigpatch.diffs = bigpatch.diffs[1:]
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} else {
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bigpatch.diffs[0].Text =
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bigpatch.diffs[0].Text[len(diffText):]
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}
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}
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}
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// Compute the head context for the next patch.
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precontext = dmp.DiffText2(patch.diffs)
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precontext = precontext[max(0, len(precontext)-dmp.PatchMargin):]
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postcontext := ""
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// Append the end context for this patch.
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if len(dmp.DiffText1(bigpatch.diffs)) > dmp.PatchMargin {
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postcontext = dmp.DiffText1(bigpatch.diffs)[:dmp.PatchMargin]
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} else {
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postcontext = dmp.DiffText1(bigpatch.diffs)
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}
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if len(postcontext) != 0 {
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patch.Length1 += len(postcontext)
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patch.Length2 += len(postcontext)
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if len(patch.diffs) != 0 && patch.diffs[len(patch.diffs)-1].Type == DiffEqual {
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patch.diffs[len(patch.diffs)-1].Text += postcontext
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} else {
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patch.diffs = append(patch.diffs, Diff{DiffEqual, postcontext})
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}
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}
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if !empty {
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x++
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patches = append(patches[:x], append([]Patch{patch}, patches[x:]...)...)
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}
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}
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}
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return patches
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}
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// PatchToText takes a list of patches and returns a textual representation.
|
|
func (dmp *DiffMatchPatch) PatchToText(patches []Patch) string {
|
|
var text bytes.Buffer
|
|
for _, aPatch := range patches {
|
|
_, _ = text.WriteString(aPatch.String())
|
|
}
|
|
return text.String()
|
|
}
|
|
|
|
// PatchFromText parses a textual representation of patches and returns a List of Patch objects.
|
|
func (dmp *DiffMatchPatch) PatchFromText(textline string) ([]Patch, error) {
|
|
patches := []Patch{}
|
|
if len(textline) == 0 {
|
|
return patches, nil
|
|
}
|
|
text := strings.Split(textline, "\n")
|
|
textPointer := 0
|
|
patchHeader := regexp.MustCompile("^@@ -(\\d+),?(\\d*) \\+(\\d+),?(\\d*) @@$")
|
|
|
|
var patch Patch
|
|
var sign uint8
|
|
var line string
|
|
for textPointer < len(text) {
|
|
|
|
if !patchHeader.MatchString(text[textPointer]) {
|
|
return patches, errors.New("Invalid patch string: " + text[textPointer])
|
|
}
|
|
|
|
patch = Patch{}
|
|
m := patchHeader.FindStringSubmatch(text[textPointer])
|
|
|
|
patch.Start1, _ = strconv.Atoi(m[1])
|
|
if len(m[2]) == 0 {
|
|
patch.Start1--
|
|
patch.Length1 = 1
|
|
} else if m[2] == "0" {
|
|
patch.Length1 = 0
|
|
} else {
|
|
patch.Start1--
|
|
patch.Length1, _ = strconv.Atoi(m[2])
|
|
}
|
|
|
|
patch.Start2, _ = strconv.Atoi(m[3])
|
|
|
|
if len(m[4]) == 0 {
|
|
patch.Start2--
|
|
patch.Length2 = 1
|
|
} else if m[4] == "0" {
|
|
patch.Length2 = 0
|
|
} else {
|
|
patch.Start2--
|
|
patch.Length2, _ = strconv.Atoi(m[4])
|
|
}
|
|
textPointer++
|
|
|
|
for textPointer < len(text) {
|
|
if len(text[textPointer]) > 0 {
|
|
sign = text[textPointer][0]
|
|
} else {
|
|
textPointer++
|
|
continue
|
|
}
|
|
|
|
line = text[textPointer][1:]
|
|
line = strings.Replace(line, "+", "%2b", -1)
|
|
line, _ = url.QueryUnescape(line)
|
|
if sign == '-' {
|
|
// Deletion.
|
|
patch.diffs = append(patch.diffs, Diff{DiffDelete, line})
|
|
} else if sign == '+' {
|
|
// Insertion.
|
|
patch.diffs = append(patch.diffs, Diff{DiffInsert, line})
|
|
} else if sign == ' ' {
|
|
// Minor equality.
|
|
patch.diffs = append(patch.diffs, Diff{DiffEqual, line})
|
|
} else if sign == '@' {
|
|
// Start of next patch.
|
|
break
|
|
} else {
|
|
// WTF?
|
|
return patches, errors.New("Invalid patch mode '" + string(sign) + "' in: " + string(line))
|
|
}
|
|
textPointer++
|
|
}
|
|
|
|
patches = append(patches, patch)
|
|
}
|
|
return patches, nil
|
|
}
|