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@mpvl @robpike @kevinburke @dsymonds
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// 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.
// Note: the file data_test.go that is generated should not be checked in.
//go:generate go run maketables.go triegen.go
//go:generate go test -tags test
// Package norm contains types and functions for normalizing Unicode strings.
package norm // import "golang.org/x/text/unicode/norm"
import (
"unicode/utf8"
"golang.org/x/text/transform"
)
// A Form denotes a canonical representation of Unicode code points.
// The Unicode-defined normalization and equivalence forms are:
//
// NFC Unicode Normalization Form C
// NFD Unicode Normalization Form D
// NFKC Unicode Normalization Form KC
// NFKD Unicode Normalization Form KD
//
// For a Form f, this documentation uses the notation f(x) to mean
// the bytes or string x converted to the given form.
// A position n in x is called a boundary if conversion to the form can
// proceed independently on both sides:
// f(x) == append(f(x[0:n]), f(x[n:])...)
//
// References: https://unicode.org/reports/tr15/ and
// https://unicode.org/notes/tn5/.
type Form int
const (
NFC Form = iota
NFD
NFKC
NFKD
)
// Bytes returns f(b). May return b if f(b) = b.
func (f Form) Bytes(b []byte) []byte {
src := inputBytes(b)
ft := formTable[f]
n, ok := ft.quickSpan(src, 0, len(b), true)
if ok {
return b
}
out := make([]byte, n, len(b))
copy(out, b[0:n])
rb := reorderBuffer{f: *ft, src: src, nsrc: len(b), out: out, flushF: appendFlush}
return doAppendInner(&rb, n)
}
// String returns f(s).
func (f Form) String(s string) string {
src := inputString(s)
ft := formTable[f]
n, ok := ft.quickSpan(src, 0, len(s), true)
if ok {
return s
}
out := make([]byte, n, len(s))
copy(out, s[0:n])
rb := reorderBuffer{f: *ft, src: src, nsrc: len(s), out: out, flushF: appendFlush}
return string(doAppendInner(&rb, n))
}
// IsNormal returns true if b == f(b).
func (f Form) IsNormal(b []byte) bool {
src := inputBytes(b)
ft := formTable[f]
bp, ok := ft.quickSpan(src, 0, len(b), true)
if ok {
return true
}
rb := reorderBuffer{f: *ft, src: src, nsrc: len(b)}
rb.setFlusher(nil, cmpNormalBytes)
for bp < len(b) {
rb.out = b[bp:]
if bp = decomposeSegment(&rb, bp, true); bp < 0 {
return false
}
bp, _ = rb.f.quickSpan(rb.src, bp, len(b), true)
}
return true
}
func cmpNormalBytes(rb *reorderBuffer) bool {
b := rb.out
for i := 0; i < rb.nrune; i++ {
info := rb.rune[i]
if int(info.size) > len(b) {
return false
}
p := info.pos
pe := p + info.size
for ; p < pe; p++ {
if b[0] != rb.byte[p] {
return false
}
b = b[1:]
}
}
return true
}
// IsNormalString returns true if s == f(s).
func (f Form) IsNormalString(s string) bool {
src := inputString(s)
ft := formTable[f]
bp, ok := ft.quickSpan(src, 0, len(s), true)
if ok {
return true
}
rb := reorderBuffer{f: *ft, src: src, nsrc: len(s)}
rb.setFlusher(nil, func(rb *reorderBuffer) bool {
for i := 0; i < rb.nrune; i++ {
info := rb.rune[i]
if bp+int(info.size) > len(s) {
return false
}
p := info.pos
pe := p + info.size
for ; p < pe; p++ {
if s[bp] != rb.byte[p] {
return false
}
bp++
}
}
return true
})
for bp < len(s) {
if bp = decomposeSegment(&rb, bp, true); bp < 0 {
return false
}
bp, _ = rb.f.quickSpan(rb.src, bp, len(s), true)
}
return true
}
// patchTail fixes a case where a rune may be incorrectly normalized
// if it is followed by illegal continuation bytes. It returns the
// patched buffer and whether the decomposition is still in progress.
func patchTail(rb *reorderBuffer) bool {
info, p := lastRuneStart(&rb.f, rb.out)
if p == -1 || info.size == 0 {
return true
}
end := p + int(info.size)
extra := len(rb.out) - end
if extra > 0 {
// Potentially allocating memory. However, this only
// happens with ill-formed UTF-8.
x := make([]byte, 0)
x = append(x, rb.out[len(rb.out)-extra:]...)
rb.out = rb.out[:end]
decomposeToLastBoundary(rb)
rb.doFlush()
rb.out = append(rb.out, x...)
return false
}
buf := rb.out[p:]
rb.out = rb.out[:p]
decomposeToLastBoundary(rb)
if s := rb.ss.next(info); s == ssStarter {
rb.doFlush()
rb.ss.first(info)
} else if s == ssOverflow {
rb.doFlush()
rb.insertCGJ()
rb.ss = 0
}
rb.insertUnsafe(inputBytes(buf), 0, info)
return true
}
func appendQuick(rb *reorderBuffer, i int) int {
if rb.nsrc == i {
return i
}
end, _ := rb.f.quickSpan(rb.src, i, rb.nsrc, true)
rb.out = rb.src.appendSlice(rb.out, i, end)
return end
}
// Append returns f(append(out, b...)).
// The buffer out must be nil, empty, or equal to f(out).
func (f Form) Append(out []byte, src ...byte) []byte {
return f.doAppend(out, inputBytes(src), len(src))
}
func (f Form) doAppend(out []byte, src input, n int) []byte {
if n == 0 {
return out
}
ft := formTable[f]
// Attempt to do a quickSpan first so we can avoid initializing the reorderBuffer.
if len(out) == 0 {
p, _ := ft.quickSpan(src, 0, n, true)
out = src.appendSlice(out, 0, p)
if p == n {
return out
}
rb := reorderBuffer{f: *ft, src: src, nsrc: n, out: out, flushF: appendFlush}
return doAppendInner(&rb, p)
}
rb := reorderBuffer{f: *ft, src: src, nsrc: n}
return doAppend(&rb, out, 0)
}
func doAppend(rb *reorderBuffer, out []byte, p int) []byte {
rb.setFlusher(out, appendFlush)
src, n := rb.src, rb.nsrc
doMerge := len(out) > 0
if q := src.skipContinuationBytes(p); q > p {
// Move leading non-starters to destination.
rb.out = src.appendSlice(rb.out, p, q)
p = q
doMerge = patchTail(rb)
}
fd := &rb.f
if doMerge {
var info Properties
if p < n {
info = fd.info(src, p)
if !info.BoundaryBefore() || info.nLeadingNonStarters() > 0 {
if p == 0 {
decomposeToLastBoundary(rb)
}
p = decomposeSegment(rb, p, true)
}
}
if info.size == 0 {
rb.doFlush()
// Append incomplete UTF-8 encoding.
return src.appendSlice(rb.out, p, n)
}
if rb.nrune > 0 {
return doAppendInner(rb, p)
}
}
p = appendQuick(rb, p)
return doAppendInner(rb, p)
}
func doAppendInner(rb *reorderBuffer, p int) []byte {
for n := rb.nsrc; p < n; {
p = decomposeSegment(rb, p, true)
p = appendQuick(rb, p)
}
return rb.out
}
// AppendString returns f(append(out, []byte(s))).
// The buffer out must be nil, empty, or equal to f(out).
func (f Form) AppendString(out []byte, src string) []byte {
return f.doAppend(out, inputString(src), len(src))
}
// QuickSpan returns a boundary n such that b[0:n] == f(b[0:n]).
// It is not guaranteed to return the largest such n.
func (f Form) QuickSpan(b []byte) int {
n, _ := formTable[f].quickSpan(inputBytes(b), 0, len(b), true)
return n
}
// Span implements transform.SpanningTransformer. It returns a boundary n such
// that b[0:n] == f(b[0:n]). It is not guaranteed to return the largest such n.
func (f Form) Span(b []byte, atEOF bool) (n int, err error) {
n, ok := formTable[f].quickSpan(inputBytes(b), 0, len(b), atEOF)
if n < len(b) {
if !ok {
err = transform.ErrEndOfSpan
} else {
err = transform.ErrShortSrc
}
}
return n, err
}
// SpanString returns a boundary n such that s[0:n] == f(s[0:n]).
// It is not guaranteed to return the largest such n.
func (f Form) SpanString(s string, atEOF bool) (n int, err error) {
n, ok := formTable[f].quickSpan(inputString(s), 0, len(s), atEOF)
if n < len(s) {
if !ok {
err = transform.ErrEndOfSpan
} else {
err = transform.ErrShortSrc
}
}
return n, err
}
// quickSpan returns a boundary n such that src[0:n] == f(src[0:n]) and
// whether any non-normalized parts were found. If atEOF is false, n will
// not point past the last segment if this segment might be become
// non-normalized by appending other runes.
func (f *formInfo) quickSpan(src input, i, end int, atEOF bool) (n int, ok bool) {
var lastCC uint8
ss := streamSafe(0)
lastSegStart := i
for n = end; i < n; {
if j := src.skipASCII(i, n); i != j {
i = j
lastSegStart = i - 1
lastCC = 0
ss = 0
continue
}
info := f.info(src, i)
if info.size == 0 {
if atEOF {
// include incomplete runes
return n, true
}
return lastSegStart, true
}
// This block needs to be before the next, because it is possible to
// have an overflow for runes that are starters (e.g. with U+FF9E).
switch ss.next(info) {
case ssStarter:
lastSegStart = i
case ssOverflow:
return lastSegStart, false
case ssSuccess:
if lastCC > info.ccc {
return lastSegStart, false
}
}
if f.composing {
if !info.isYesC() {
break
}
} else {
if !info.isYesD() {
break
}
}
lastCC = info.ccc
i += int(info.size)
}
if i == n {
if !atEOF {
n = lastSegStart
}
return n, true
}
return lastSegStart, false
}
// QuickSpanString returns a boundary n such that s[0:n] == f(s[0:n]).
// It is not guaranteed to return the largest such n.
func (f Form) QuickSpanString(s string) int {
n, _ := formTable[f].quickSpan(inputString(s), 0, len(s), true)
return n
}
// FirstBoundary returns the position i of the first boundary in b
// or -1 if b contains no boundary.
func (f Form) FirstBoundary(b []byte) int {
return f.firstBoundary(inputBytes(b), len(b))
}
func (f Form) firstBoundary(src input, nsrc int) int {
i := src.skipContinuationBytes(0)
if i >= nsrc {
return -1
}
fd := formTable[f]
ss := streamSafe(0)
// We should call ss.first here, but we can't as the first rune is
// skipped already. This means FirstBoundary can't really determine
// CGJ insertion points correctly. Luckily it doesn't have to.
for {
info := fd.info(src, i)
if info.size == 0 {
return -1
}
if s := ss.next(info); s != ssSuccess {
return i
}
i += int(info.size)
if i >= nsrc {
if !info.BoundaryAfter() && !ss.isMax() {
return -1
}
return nsrc
}
}
}
// FirstBoundaryInString returns the position i of the first boundary in s
// or -1 if s contains no boundary.
func (f Form) FirstBoundaryInString(s string) int {
return f.firstBoundary(inputString(s), len(s))
}
// NextBoundary reports the index of the boundary between the first and next
// segment in b or -1 if atEOF is false and there are not enough bytes to
// determine this boundary.
func (f Form) NextBoundary(b []byte, atEOF bool) int {
return f.nextBoundary(inputBytes(b), len(b), atEOF)
}
// NextBoundaryInString reports the index of the boundary between the first and
// next segment in b or -1 if atEOF is false and there are not enough bytes to
// determine this boundary.
func (f Form) NextBoundaryInString(s string, atEOF bool) int {
return f.nextBoundary(inputString(s), len(s), atEOF)
}
func (f Form) nextBoundary(src input, nsrc int, atEOF bool) int {
if nsrc == 0 {
if atEOF {
return 0
}
return -1
}
fd := formTable[f]
info := fd.info(src, 0)
if info.size == 0 {
if atEOF {
return 1
}
return -1
}
ss := streamSafe(0)
ss.first(info)
for i := int(info.size); i < nsrc; i += int(info.size) {
info = fd.info(src, i)
if info.size == 0 {
if atEOF {
return i
}
return -1
}
// TODO: Using streamSafe to determine the boundary isn't the same as
// using BoundaryBefore. Determine which should be used.
if s := ss.next(info); s != ssSuccess {
return i
}
}
if !atEOF && !info.BoundaryAfter() && !ss.isMax() {
return -1
}
return nsrc
}
// LastBoundary returns the position i of the last boundary in b
// or -1 if b contains no boundary.
func (f Form) LastBoundary(b []byte) int {
return lastBoundary(formTable[f], b)
}
func lastBoundary(fd *formInfo, b []byte) int {
i := len(b)
info, p := lastRuneStart(fd, b)
if p == -1 {
return -1
}
if info.size == 0 { // ends with incomplete rune
if p == 0 { // starts with incomplete rune
return -1
}
i = p
info, p = lastRuneStart(fd, b[:i])
if p == -1 { // incomplete UTF-8 encoding or non-starter bytes without a starter
return i
}
}
if p+int(info.size) != i { // trailing non-starter bytes: illegal UTF-8
return i
}
if info.BoundaryAfter() {
return i
}
ss := streamSafe(0)
v := ss.backwards(info)
for i = p; i >= 0 && v != ssStarter; i = p {
info, p = lastRuneStart(fd, b[:i])
if v = ss.backwards(info); v == ssOverflow {
break
}
if p+int(info.size) != i {
if p == -1 { // no boundary found
return -1
}
return i // boundary after an illegal UTF-8 encoding
}
}
return i
}
// decomposeSegment scans the first segment in src into rb. It inserts 0x034f
// (Grapheme Joiner) when it encounters a sequence of more than 30 non-starters
// and returns the number of bytes consumed from src or iShortDst or iShortSrc.
func decomposeSegment(rb *reorderBuffer, sp int, atEOF bool) int {
// Force one character to be consumed.
info := rb.f.info(rb.src, sp)
if info.size == 0 {
return 0
}
if s := rb.ss.next(info); s == ssStarter {
// TODO: this could be removed if we don't support merging.
if rb.nrune > 0 {
goto end
}
} else if s == ssOverflow {
rb.insertCGJ()
goto end
}
if err := rb.insertFlush(rb.src, sp, info); err != iSuccess {
return int(err)
}
for {
sp += int(info.size)
if sp >= rb.nsrc {
if !atEOF && !info.BoundaryAfter() {
return int(iShortSrc)
}
break
}
info = rb.f.info(rb.src, sp)
if info.size == 0 {
if !atEOF {
return int(iShortSrc)
}
break
}
if s := rb.ss.next(info); s == ssStarter {
break
} else if s == ssOverflow {
rb.insertCGJ()
break
}
if err := rb.insertFlush(rb.src, sp, info); err != iSuccess {
return int(err)
}
}
end:
if !rb.doFlush() {
return int(iShortDst)
}
return sp
}
// lastRuneStart returns the runeInfo and position of the last
// rune in buf or the zero runeInfo and -1 if no rune was found.
func lastRuneStart(fd *formInfo, buf []byte) (Properties, int) {
p := len(buf) - 1
for ; p >= 0 && !utf8.RuneStart(buf[p]); p-- {
}
if p < 0 {
return Properties{}, -1
}
return fd.info(inputBytes(buf), p), p
}
// decomposeToLastBoundary finds an open segment at the end of the buffer
// and scans it into rb. Returns the buffer minus the last segment.
func decomposeToLastBoundary(rb *reorderBuffer) {
fd := &rb.f
info, i := lastRuneStart(fd, rb.out)
if int(info.size) != len(rb.out)-i {
// illegal trailing continuation bytes
return
}
if info.BoundaryAfter() {
return
}
var add [maxNonStarters + 1]Properties // stores runeInfo in reverse order
padd := 0
ss := streamSafe(0)
p := len(rb.out)
for {
add[padd] = info
v := ss.backwards(info)
if v == ssOverflow {
// Note that if we have an overflow, it the string we are appending to
// is not correctly normalized. In this case the behavior is undefined.
break
}
padd++
p -= int(info.size)
if v == ssStarter || p < 0 {
break
}
info, i = lastRuneStart(fd, rb.out[:p])
if int(info.size) != p-i {
break
}
}
rb.ss = ss
// Copy bytes for insertion as we may need to overwrite rb.out.
var buf [maxBufferSize * utf8.UTFMax]byte
cp := buf[:copy(buf[:], rb.out[p:])]
rb.out = rb.out[:p]
for padd--; padd >= 0; padd-- {
info = add[padd]
rb.insertUnsafe(inputBytes(cp), 0, info)
cp = cp[info.size:]
}
}
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