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// Copyright 2015 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 width
import (
"unicode/utf8"
"golang.org/x/text/transform"
)
type foldTransform struct {
transform.NopResetter
}
func (foldTransform) Span(src []byte, atEOF bool) (n int, err error) {
for n < len(src) {
if src[n] < utf8.RuneSelf {
// ASCII fast path.
for n++; n < len(src) && src[n] < utf8.RuneSelf; n++ {
}
continue
}
v, size := trie.lookup(src[n:])
if size == 0 { // incomplete UTF-8 encoding
if !atEOF {
err = transform.ErrShortSrc
} else {
n = len(src)
}
break
}
if elem(v)&tagNeedsFold != 0 {
err = transform.ErrEndOfSpan
break
}
n += size
}
return n, err
}
func (foldTransform) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
for nSrc < len(src) {
if src[nSrc] < utf8.RuneSelf {
// ASCII fast path.
start, end := nSrc, len(src)
if d := len(dst) - nDst; d < end-start {
end = nSrc + d
}
for nSrc++; nSrc < end && src[nSrc] < utf8.RuneSelf; nSrc++ {
}
n := copy(dst[nDst:], src[start:nSrc])
if nDst += n; nDst == len(dst) {
nSrc = start + n
if nSrc == len(src) {
return nDst, nSrc, nil
}
if src[nSrc] < utf8.RuneSelf {
return nDst, nSrc, transform.ErrShortDst
}
}
continue
}
v, size := trie.lookup(src[nSrc:])
if size == 0 { // incomplete UTF-8 encoding
if !atEOF {
return nDst, nSrc, transform.ErrShortSrc
}
size = 1 // gobble 1 byte
}
if elem(v)&tagNeedsFold == 0 {
if size != copy(dst[nDst:], src[nSrc:nSrc+size]) {
return nDst, nSrc, transform.ErrShortDst
}
nDst += size
} else {
data := inverseData[byte(v)]
if len(dst)-nDst < int(data[0]) {
return nDst, nSrc, transform.ErrShortDst
}
i := 1
for end := int(data[0]); i < end; i++ {
dst[nDst] = data[i]
nDst++
}
dst[nDst] = data[i] ^ src[nSrc+size-1]
nDst++
}
nSrc += size
}
return nDst, nSrc, nil
}
type narrowTransform struct {
transform.NopResetter
}
func (narrowTransform) Span(src []byte, atEOF bool) (n int, err error) {
for n < len(src) {
if src[n] < utf8.RuneSelf {
// ASCII fast path.
for n++; n < len(src) && src[n] < utf8.RuneSelf; n++ {
}
continue
}
v, size := trie.lookup(src[n:])
if size == 0 { // incomplete UTF-8 encoding
if !atEOF {
err = transform.ErrShortSrc
} else {
n = len(src)
}
break
}
if k := elem(v).kind(); byte(v) == 0 || k != EastAsianFullwidth && k != EastAsianWide && k != EastAsianAmbiguous {
} else {
err = transform.ErrEndOfSpan
break
}
n += size
}
return n, err
}
func (narrowTransform) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
for nSrc < len(src) {
if src[nSrc] < utf8.RuneSelf {
// ASCII fast path.
start, end := nSrc, len(src)
if d := len(dst) - nDst; d < end-start {
end = nSrc + d
}
for nSrc++; nSrc < end && src[nSrc] < utf8.RuneSelf; nSrc++ {
}
n := copy(dst[nDst:], src[start:nSrc])
if nDst += n; nDst == len(dst) {
nSrc = start + n
if nSrc == len(src) {
return nDst, nSrc, nil
}
if src[nSrc] < utf8.RuneSelf {
return nDst, nSrc, transform.ErrShortDst
}
}
continue
}
v, size := trie.lookup(src[nSrc:])
if size == 0 { // incomplete UTF-8 encoding
if !atEOF {
return nDst, nSrc, transform.ErrShortSrc
}
size = 1 // gobble 1 byte
}
if k := elem(v).kind(); byte(v) == 0 || k != EastAsianFullwidth && k != EastAsianWide && k != EastAsianAmbiguous {
if size != copy(dst[nDst:], src[nSrc:nSrc+size]) {
return nDst, nSrc, transform.ErrShortDst
}
nDst += size
} else {
data := inverseData[byte(v)]
if len(dst)-nDst < int(data[0]) {
return nDst, nSrc, transform.ErrShortDst
}
i := 1
for end := int(data[0]); i < end; i++ {
dst[nDst] = data[i]
nDst++
}
dst[nDst] = data[i] ^ src[nSrc+size-1]
nDst++
}
nSrc += size
}
return nDst, nSrc, nil
}
type wideTransform struct {
transform.NopResetter
}
func (wideTransform) Span(src []byte, atEOF bool) (n int, err error) {
for n < len(src) {
// TODO: Consider ASCII fast path. Special-casing ASCII handling can
// reduce the ns/op of BenchmarkWideASCII by about 30%. This is probably
// not enough to warrant the extra code and complexity.
v, size := trie.lookup(src[n:])
if size == 0 { // incomplete UTF-8 encoding
if !atEOF {
err = transform.ErrShortSrc
} else {
n = len(src)
}
break
}
if k := elem(v).kind(); byte(v) == 0 || k != EastAsianHalfwidth && k != EastAsianNarrow {
} else {
err = transform.ErrEndOfSpan
break
}
n += size
}
return n, err
}
func (wideTransform) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
for nSrc < len(src) {
// TODO: Consider ASCII fast path. Special-casing ASCII handling can
// reduce the ns/op of BenchmarkWideASCII by about 30%. This is probably
// not enough to warrant the extra code and complexity.
v, size := trie.lookup(src[nSrc:])
if size == 0 { // incomplete UTF-8 encoding
if !atEOF {
return nDst, nSrc, transform.ErrShortSrc
}
size = 1 // gobble 1 byte
}
if k := elem(v).kind(); byte(v) == 0 || k != EastAsianHalfwidth && k != EastAsianNarrow {
if size != copy(dst[nDst:], src[nSrc:nSrc+size]) {
return nDst, nSrc, transform.ErrShortDst
}
nDst += size
} else {
data := inverseData[byte(v)]
if len(dst)-nDst < int(data[0]) {
return nDst, nSrc, transform.ErrShortDst
}
i := 1
for end := int(data[0]); i < end; i++ {
dst[nDst] = data[i]
nDst++
}
dst[nDst] = data[i] ^ src[nSrc+size-1]
nDst++
}
nSrc += size
}
return nDst, nSrc, nil
}
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