--- /dev/null
+// Copyright (c) 2012-2016 The go-diff authors. All rights reserved.
+// https://github.com/sergi/go-diff
+// See the included LICENSE file for license details.
+//
+// go-diff is a Go implementation of Google's Diff, Match, and Patch library
+// Original library is Copyright (c) 2006 Google Inc.
+// http://code.google.com/p/google-diff-match-patch/
+
+package diffmatchpatch
+
+import (
+ "math"
+)
+
+// MatchMain locates the best instance of 'pattern' in 'text' near 'loc'.
+// Returns -1 if no match found.
+func (dmp *DiffMatchPatch) MatchMain(text, pattern string, loc int) int {
+ // Check for null inputs not needed since null can't be passed in C#.
+
+ loc = int(math.Max(0, math.Min(float64(loc), float64(len(text)))))
+ if text == pattern {
+ // Shortcut (potentially not guaranteed by the algorithm)
+ return 0
+ } else if len(text) == 0 {
+ // Nothing to match.
+ return -1
+ } else if loc+len(pattern) <= len(text) && text[loc:loc+len(pattern)] == pattern {
+ // Perfect match at the perfect spot! (Includes case of null pattern)
+ return loc
+ }
+ // Do a fuzzy compare.
+ return dmp.MatchBitap(text, pattern, loc)
+}
+
+// MatchBitap locates the best instance of 'pattern' in 'text' near 'loc' using the Bitap algorithm.
+// Returns -1 if no match was found.
+func (dmp *DiffMatchPatch) MatchBitap(text, pattern string, loc int) int {
+ // Initialise the alphabet.
+ s := dmp.MatchAlphabet(pattern)
+
+ // Highest score beyond which we give up.
+ scoreThreshold := dmp.MatchThreshold
+ // Is there a nearby exact match? (speedup)
+ bestLoc := indexOf(text, pattern, loc)
+ if bestLoc != -1 {
+ scoreThreshold = math.Min(dmp.matchBitapScore(0, bestLoc, loc,
+ pattern), scoreThreshold)
+ // What about in the other direction? (speedup)
+ bestLoc = lastIndexOf(text, pattern, loc+len(pattern))
+ if bestLoc != -1 {
+ scoreThreshold = math.Min(dmp.matchBitapScore(0, bestLoc, loc,
+ pattern), scoreThreshold)
+ }
+ }
+
+ // Initialise the bit arrays.
+ matchmask := 1 << uint((len(pattern) - 1))
+ bestLoc = -1
+
+ var binMin, binMid int
+ binMax := len(pattern) + len(text)
+ lastRd := []int{}
+ for d := 0; d < len(pattern); d++ {
+ // Scan for the best match; each iteration allows for one more error. Run a binary search to determine how far from 'loc' we can stray at this error level.
+ binMin = 0
+ binMid = binMax
+ for binMin < binMid {
+ if dmp.matchBitapScore(d, loc+binMid, loc, pattern) <= scoreThreshold {
+ binMin = binMid
+ } else {
+ binMax = binMid
+ }
+ binMid = (binMax-binMin)/2 + binMin
+ }
+ // Use the result from this iteration as the maximum for the next.
+ binMax = binMid
+ start := int(math.Max(1, float64(loc-binMid+1)))
+ finish := int(math.Min(float64(loc+binMid), float64(len(text))) + float64(len(pattern)))
+
+ rd := make([]int, finish+2)
+ rd[finish+1] = (1 << uint(d)) - 1
+
+ for j := finish; j >= start; j-- {
+ var charMatch int
+ if len(text) <= j-1 {
+ // Out of range.
+ charMatch = 0
+ } else if _, ok := s[text[j-1]]; !ok {
+ charMatch = 0
+ } else {
+ charMatch = s[text[j-1]]
+ }
+
+ if d == 0 {
+ // First pass: exact match.
+ rd[j] = ((rd[j+1] << 1) | 1) & charMatch
+ } else {
+ // Subsequent passes: fuzzy match.
+ rd[j] = ((rd[j+1]<<1)|1)&charMatch | (((lastRd[j+1] | lastRd[j]) << 1) | 1) | lastRd[j+1]
+ }
+ if (rd[j] & matchmask) != 0 {
+ score := dmp.matchBitapScore(d, j-1, loc, pattern)
+ // This match will almost certainly be better than any existing match. But check anyway.
+ if score <= scoreThreshold {
+ // Told you so.
+ scoreThreshold = score
+ bestLoc = j - 1
+ if bestLoc > loc {
+ // When passing loc, don't exceed our current distance from loc.
+ start = int(math.Max(1, float64(2*loc-bestLoc)))
+ } else {
+ // Already passed loc, downhill from here on in.
+ break
+ }
+ }
+ }
+ }
+ if dmp.matchBitapScore(d+1, loc, loc, pattern) > scoreThreshold {
+ // No hope for a (better) match at greater error levels.
+ break
+ }
+ lastRd = rd
+ }
+ return bestLoc
+}
+
+// matchBitapScore computes and returns the score for a match with e errors and x location.
+func (dmp *DiffMatchPatch) matchBitapScore(e, x, loc int, pattern string) float64 {
+ accuracy := float64(e) / float64(len(pattern))
+ proximity := math.Abs(float64(loc - x))
+ if dmp.MatchDistance == 0 {
+ // Dodge divide by zero error.
+ if proximity == 0 {
+ return accuracy
+ }
+
+ return 1.0
+ }
+ return accuracy + (proximity / float64(dmp.MatchDistance))
+}
+
+// MatchAlphabet initialises the alphabet for the Bitap algorithm.
+func (dmp *DiffMatchPatch) MatchAlphabet(pattern string) map[byte]int {
+ s := map[byte]int{}
+ charPattern := []byte(pattern)
+ for _, c := range charPattern {
+ _, ok := s[c]
+ if !ok {
+ s[c] = 0
+ }
+ }
+ i := 0
+
+ for _, c := range charPattern {
+ value := s[c] | int(uint(1)<<uint((len(pattern)-i-1)))
+ s[c] = value
+ i++
+ }
+ return s
+}
projects / dotfiles / .git / blobdiff