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Diffstat (limited to 'vendor/golang.org/x/text/unicode/norm/composition.go')
| -rw-r--r-- | vendor/golang.org/x/text/unicode/norm/composition.go | 512 |
1 files changed, 512 insertions, 0 deletions
diff --git a/vendor/golang.org/x/text/unicode/norm/composition.go b/vendor/golang.org/x/text/unicode/norm/composition.go new file mode 100644 index 0000000..e2087bc --- /dev/null +++ b/vendor/golang.org/x/text/unicode/norm/composition.go @@ -0,0 +1,512 @@ +// Copyright 2011 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 norm + +import "unicode/utf8" + +const ( + maxNonStarters = 30 + // The maximum number of characters needed for a buffer is + // maxNonStarters + 1 for the starter + 1 for the GCJ + maxBufferSize = maxNonStarters + 2 + maxNFCExpansion = 3 // NFC(0x1D160) + maxNFKCExpansion = 18 // NFKC(0xFDFA) + + maxByteBufferSize = utf8.UTFMax * maxBufferSize // 128 +) + +// ssState is used for reporting the segment state after inserting a rune. +// It is returned by streamSafe.next. +type ssState int + +const ( + // Indicates a rune was successfully added to the segment. + ssSuccess ssState = iota + // Indicates a rune starts a new segment and should not be added. + ssStarter + // Indicates a rune caused a segment overflow and a CGJ should be inserted. + ssOverflow +) + +// streamSafe implements the policy of when a CGJ should be inserted. +type streamSafe uint8 + +// first inserts the first rune of a segment. It is a faster version of next if +// it is known p represents the first rune in a segment. +func (ss *streamSafe) first(p Properties) { + *ss = streamSafe(p.nTrailingNonStarters()) +} + +// insert returns a ssState value to indicate whether a rune represented by p +// can be inserted. +func (ss *streamSafe) next(p Properties) ssState { + if *ss > maxNonStarters { + panic("streamSafe was not reset") + } + n := p.nLeadingNonStarters() + if *ss += streamSafe(n); *ss > maxNonStarters { + *ss = 0 + return ssOverflow + } + // The Stream-Safe Text Processing prescribes that the counting can stop + // as soon as a starter is encountered. However, there are some starters, + // like Jamo V and T, that can combine with other runes, leaving their + // successive non-starters appended to the previous, possibly causing an + // overflow. We will therefore consider any rune with a non-zero nLead to + // be a non-starter. Note that it always hold that if nLead > 0 then + // nLead == nTrail. + if n == 0 { + *ss = streamSafe(p.nTrailingNonStarters()) + return ssStarter + } + return ssSuccess +} + +// backwards is used for checking for overflow and segment starts +// when traversing a string backwards. Users do not need to call first +// for the first rune. The state of the streamSafe retains the count of +// the non-starters loaded. +func (ss *streamSafe) backwards(p Properties) ssState { + if *ss > maxNonStarters { + panic("streamSafe was not reset") + } + c := *ss + streamSafe(p.nTrailingNonStarters()) + if c > maxNonStarters { + return ssOverflow + } + *ss = c + if p.nLeadingNonStarters() == 0 { + return ssStarter + } + return ssSuccess +} + +func (ss streamSafe) isMax() bool { + return ss == maxNonStarters +} + +// GraphemeJoiner is inserted after maxNonStarters non-starter runes. +const GraphemeJoiner = "\u034F" + +// reorderBuffer is used to normalize a single segment. Characters inserted with +// insert are decomposed and reordered based on CCC. The compose method can +// be used to recombine characters. Note that the byte buffer does not hold +// the UTF-8 characters in order. Only the rune array is maintained in sorted +// order. flush writes the resulting segment to a byte array. +type reorderBuffer struct { + rune [maxBufferSize]Properties // Per character info. + byte [maxByteBufferSize]byte // UTF-8 buffer. Referenced by runeInfo.pos. + nbyte uint8 // Number or bytes. + ss streamSafe // For limiting length of non-starter sequence. + nrune int // Number of runeInfos. + f formInfo + + src input + nsrc int + tmpBytes input + + out []byte + flushF func(*reorderBuffer) bool +} + +func (rb *reorderBuffer) init(f Form, src []byte) { + rb.f = *formTable[f] + rb.src.setBytes(src) + rb.nsrc = len(src) + rb.ss = 0 +} + +func (rb *reorderBuffer) initString(f Form, src string) { + rb.f = *formTable[f] + rb.src.setString(src) + rb.nsrc = len(src) + rb.ss = 0 +} + +func (rb *reorderBuffer) setFlusher(out []byte, f func(*reorderBuffer) bool) { + rb.out = out + rb.flushF = f +} + +// reset discards all characters from the buffer. +func (rb *reorderBuffer) reset() { + rb.nrune = 0 + rb.nbyte = 0 +} + +func (rb *reorderBuffer) doFlush() bool { + if rb.f.composing { + rb.compose() + } + res := rb.flushF(rb) + rb.reset() + return res +} + +// appendFlush appends the normalized segment to rb.out. +func appendFlush(rb *reorderBuffer) bool { + for i := 0; i < rb.nrune; i++ { + start := rb.rune[i].pos + end := start + rb.rune[i].size + rb.out = append(rb.out, rb.byte[start:end]...) + } + return true +} + +// flush appends the normalized segment to out and resets rb. +func (rb *reorderBuffer) flush(out []byte) []byte { + for i := 0; i < rb.nrune; i++ { + start := rb.rune[i].pos + end := start + rb.rune[i].size + out = append(out, rb.byte[start:end]...) + } + rb.reset() + return out +} + +// flushCopy copies the normalized segment to buf and resets rb. +// It returns the number of bytes written to buf. +func (rb *reorderBuffer) flushCopy(buf []byte) int { + p := 0 + for i := 0; i < rb.nrune; i++ { + runep := rb.rune[i] + p += copy(buf[p:], rb.byte[runep.pos:runep.pos+runep.size]) + } + rb.reset() + return p +} + +// insertOrdered inserts a rune in the buffer, ordered by Canonical Combining Class. +// It returns false if the buffer is not large enough to hold the rune. +// It is used internally by insert and insertString only. +func (rb *reorderBuffer) insertOrdered(info Properties) { + n := rb.nrune + b := rb.rune[:] + cc := info.ccc + if cc > 0 { + // Find insertion position + move elements to make room. + for ; n > 0; n-- { + if b[n-1].ccc <= cc { + break + } + b[n] = b[n-1] + } + } + rb.nrune += 1 + pos := uint8(rb.nbyte) + rb.nbyte += utf8.UTFMax + info.pos = pos + b[n] = info +} + +// insertErr is an error code returned by insert. Using this type instead +// of error improves performance up to 20% for many of the benchmarks. +type insertErr int + +const ( + iSuccess insertErr = -iota + iShortDst + iShortSrc +) + +// insertFlush inserts the given rune in the buffer ordered by CCC. +// If a decomposition with multiple segments are encountered, they leading +// ones are flushed. +// It returns a non-zero error code if the rune was not inserted. +func (rb *reorderBuffer) insertFlush(src input, i int, info Properties) insertErr { + if rune := src.hangul(i); rune != 0 { + rb.decomposeHangul(rune) + return iSuccess + } + if info.hasDecomposition() { + return rb.insertDecomposed(info.Decomposition()) + } + rb.insertSingle(src, i, info) + return iSuccess +} + +// insertUnsafe inserts the given rune in the buffer ordered by CCC. +// It is assumed there is sufficient space to hold the runes. It is the +// responsibility of the caller to ensure this. This can be done by checking +// the state returned by the streamSafe type. +func (rb *reorderBuffer) insertUnsafe(src input, i int, info Properties) { + if rune := src.hangul(i); rune != 0 { + rb.decomposeHangul(rune) + } + if info.hasDecomposition() { + // TODO: inline. + rb.insertDecomposed(info.Decomposition()) + } else { + rb.insertSingle(src, i, info) + } +} + +// insertDecomposed inserts an entry in to the reorderBuffer for each rune +// in dcomp. dcomp must be a sequence of decomposed UTF-8-encoded runes. +// It flushes the buffer on each new segment start. +func (rb *reorderBuffer) insertDecomposed(dcomp []byte) insertErr { + rb.tmpBytes.setBytes(dcomp) + // As the streamSafe accounting already handles the counting for modifiers, + // we don't have to call next. However, we do need to keep the accounting + // intact when flushing the buffer. + for i := 0; i < len(dcomp); { + info := rb.f.info(rb.tmpBytes, i) + if info.BoundaryBefore() && rb.nrune > 0 && !rb.doFlush() { + return iShortDst + } + i += copy(rb.byte[rb.nbyte:], dcomp[i:i+int(info.size)]) + rb.insertOrdered(info) + } + return iSuccess +} + +// insertSingle inserts an entry in the reorderBuffer for the rune at +// position i. info is the runeInfo for the rune at position i. +func (rb *reorderBuffer) insertSingle(src input, i int, info Properties) { + src.copySlice(rb.byte[rb.nbyte:], i, i+int(info.size)) + rb.insertOrdered(info) +} + +// insertCGJ inserts a Combining Grapheme Joiner (0x034f) into rb. +func (rb *reorderBuffer) insertCGJ() { + rb.insertSingle(input{str: GraphemeJoiner}, 0, Properties{size: uint8(len(GraphemeJoiner))}) +} + +// appendRune inserts a rune at the end of the buffer. It is used for Hangul. +func (rb *reorderBuffer) appendRune(r rune) { + bn := rb.nbyte + sz := utf8.EncodeRune(rb.byte[bn:], rune(r)) + rb.nbyte += utf8.UTFMax + rb.rune[rb.nrune] = Properties{pos: bn, size: uint8(sz)} + rb.nrune++ +} + +// assignRune sets a rune at position pos. It is used for Hangul and recomposition. +func (rb *reorderBuffer) assignRune(pos int, r rune) { + bn := rb.rune[pos].pos + sz := utf8.EncodeRune(rb.byte[bn:], rune(r)) + rb.rune[pos] = Properties{pos: bn, size: uint8(sz)} +} + +// runeAt returns the rune at position n. It is used for Hangul and recomposition. +func (rb *reorderBuffer) runeAt(n int) rune { + inf := rb.rune[n] + r, _ := utf8.DecodeRune(rb.byte[inf.pos : inf.pos+inf.size]) + return r +} + +// bytesAt returns the UTF-8 encoding of the rune at position n. +// It is used for Hangul and recomposition. +func (rb *reorderBuffer) bytesAt(n int) []byte { + inf := rb.rune[n] + return rb.byte[inf.pos : int(inf.pos)+int(inf.size)] +} + +// For Hangul we combine algorithmically, instead of using tables. +const ( + hangulBase = 0xAC00 // UTF-8(hangulBase) -> EA B0 80 + hangulBase0 = 0xEA + hangulBase1 = 0xB0 + hangulBase2 = 0x80 + + hangulEnd = hangulBase + jamoLVTCount // UTF-8(0xD7A4) -> ED 9E A4 + hangulEnd0 = 0xED + hangulEnd1 = 0x9E + hangulEnd2 = 0xA4 + + jamoLBase = 0x1100 // UTF-8(jamoLBase) -> E1 84 00 + jamoLBase0 = 0xE1 + jamoLBase1 = 0x84 + jamoLEnd = 0x1113 + jamoVBase = 0x1161 + jamoVEnd = 0x1176 + jamoTBase = 0x11A7 + jamoTEnd = 0x11C3 + + jamoTCount = 28 + jamoVCount = 21 + jamoVTCount = 21 * 28 + jamoLVTCount = 19 * 21 * 28 +) + +const hangulUTF8Size = 3 + +func isHangul(b []byte) bool { + if len(b) < hangulUTF8Size { + return false + } + b0 := b[0] + if b0 < hangulBase0 { + return false + } + b1 := b[1] + switch { + case b0 == hangulBase0: + return b1 >= hangulBase1 + case b0 < hangulEnd0: + return true + case b0 > hangulEnd0: + return false + case b1 < hangulEnd1: + return true + } + return b1 == hangulEnd1 && b[2] < hangulEnd2 +} + +func isHangulString(b string) bool { + if len(b) < hangulUTF8Size { + return false + } + b0 := b[0] + if b0 < hangulBase0 { + return false + } + b1 := b[1] + switch { + case b0 == hangulBase0: + return b1 >= hangulBase1 + case b0 < hangulEnd0: + return true + case b0 > hangulEnd0: + return false + case b1 < hangulEnd1: + return true + } + return b1 == hangulEnd1 && b[2] < hangulEnd2 +} + +// Caller must ensure len(b) >= 2. +func isJamoVT(b []byte) bool { + // True if (rune & 0xff00) == jamoLBase + return b[0] == jamoLBase0 && (b[1]&0xFC) == jamoLBase1 +} + +func isHangulWithoutJamoT(b []byte) bool { + c, _ := utf8.DecodeRune(b) + c -= hangulBase + return c < jamoLVTCount && c%jamoTCount == 0 +} + +// decomposeHangul writes the decomposed Hangul to buf and returns the number +// of bytes written. len(buf) should be at least 9. +func decomposeHangul(buf []byte, r rune) int { + const JamoUTF8Len = 3 + r -= hangulBase + x := r % jamoTCount + r /= jamoTCount + utf8.EncodeRune(buf, jamoLBase+r/jamoVCount) + utf8.EncodeRune(buf[JamoUTF8Len:], jamoVBase+r%jamoVCount) + if x != 0 { + utf8.EncodeRune(buf[2*JamoUTF8Len:], jamoTBase+x) + return 3 * JamoUTF8Len + } + return 2 * JamoUTF8Len +} + +// decomposeHangul algorithmically decomposes a Hangul rune into +// its Jamo components. +// See https://unicode.org/reports/tr15/#Hangul for details on decomposing Hangul. +func (rb *reorderBuffer) decomposeHangul(r rune) { + r -= hangulBase + x := r % jamoTCount + r /= jamoTCount + rb.appendRune(jamoLBase + r/jamoVCount) + rb.appendRune(jamoVBase + r%jamoVCount) + if x != 0 { + rb.appendRune(jamoTBase + x) + } +} + +// combineHangul algorithmically combines Jamo character components into Hangul. +// See https://unicode.org/reports/tr15/#Hangul for details on combining Hangul. +func (rb *reorderBuffer) combineHangul(s, i, k int) { + b := rb.rune[:] + bn := rb.nrune + for ; i < bn; i++ { + cccB := b[k-1].ccc + cccC := b[i].ccc + if cccB == 0 { + s = k - 1 + } + if s != k-1 && cccB >= cccC { + // b[i] is blocked by greater-equal cccX below it + b[k] = b[i] + k++ + } else { + l := rb.runeAt(s) // also used to compare to hangulBase + v := rb.runeAt(i) // also used to compare to jamoT + switch { + case jamoLBase <= l && l < jamoLEnd && + jamoVBase <= v && v < jamoVEnd: + // 11xx plus 116x to LV + rb.assignRune(s, hangulBase+ + (l-jamoLBase)*jamoVTCount+(v-jamoVBase)*jamoTCount) + case hangulBase <= l && l < hangulEnd && + jamoTBase < v && v < jamoTEnd && + ((l-hangulBase)%jamoTCount) == 0: + // ACxx plus 11Ax to LVT + rb.assignRune(s, l+v-jamoTBase) + default: + b[k] = b[i] + k++ + } + } + } + rb.nrune = k +} + +// compose recombines the runes in the buffer. +// It should only be used to recompose a single segment, as it will not +// handle alternations between Hangul and non-Hangul characters correctly. +func (rb *reorderBuffer) compose() { + // Lazily load the map used by the combine func below, but do + // it outside of the loop. + recompMapOnce.Do(buildRecompMap) + + // UAX #15, section X5 , including Corrigendum #5 + // "In any character sequence beginning with starter S, a character C is + // blocked from S if and only if there is some character B between S + // and C, and either B is a starter or it has the same or higher + // combining class as C." + bn := rb.nrune + if bn == 0 { + return + } + k := 1 + b := rb.rune[:] + for s, i := 0, 1; i < bn; i++ { + if isJamoVT(rb.bytesAt(i)) { + // Redo from start in Hangul mode. Necessary to support + // U+320E..U+321E in NFKC mode. + rb.combineHangul(s, i, k) + return + } + ii := b[i] + // We can only use combineForward as a filter if we later + // get the info for the combined character. This is more + // expensive than using the filter. Using combinesBackward() + // is safe. + if ii.combinesBackward() { + cccB := b[k-1].ccc + cccC := ii.ccc + blocked := false // b[i] blocked by starter or greater or equal CCC? + if cccB == 0 { + s = k - 1 + } else { + blocked = s != k-1 && cccB >= cccC + } + if !blocked { + combined := combine(rb.runeAt(s), rb.runeAt(i)) + if combined != 0 { + rb.assignRune(s, combined) + continue + } + } + } + b[k] = b[i] + k++ + } + rb.nrune = k +} |