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author | Mura Li <typeless@users.noreply.github.com> | 2019-03-27 19:15:23 +0800 |
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committer | Lunny Xiao <xiaolunwen@gmail.com> | 2019-03-27 19:15:23 +0800 |
commit | d77176912bccf1dc0ad93366df55f00fee23b498 (patch) | |
tree | 309fc6350f77f4061360160b88343360d45d5d24 /vendor/github.com/sergi/go-diff/diffmatchpatch/match.go | |
parent | d578b71d61ee8131e8abf7f538b93d8c6cc6fe6d (diff) | |
download | gitea-d77176912bccf1dc0ad93366df55f00fee23b498.tar.gz gitea-d77176912bccf1dc0ad93366df55f00fee23b498.zip |
Use Go1.11 module (#5743)
* Migrate to go modules
* make vendor
* Update mvdan.cc/xurls
* make vendor
* Update code.gitea.io/git
* make fmt-check
* Update github.com/go-sql-driver/mysql
* make vendor
Diffstat (limited to 'vendor/github.com/sergi/go-diff/diffmatchpatch/match.go')
-rw-r--r-- | vendor/github.com/sergi/go-diff/diffmatchpatch/match.go | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/vendor/github.com/sergi/go-diff/diffmatchpatch/match.go b/vendor/github.com/sergi/go-diff/diffmatchpatch/match.go new file mode 100644 index 0000000000..17374e109f --- /dev/null +++ b/vendor/github.com/sergi/go-diff/diffmatchpatch/match.go @@ -0,0 +1,160 @@ +// 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 +} |