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Diffstat (limited to 'vendor/golang.org/x/text/width/transform.go')
| -rw-r--r-- | vendor/golang.org/x/text/width/transform.go | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/vendor/golang.org/x/text/width/transform.go b/vendor/golang.org/x/text/width/transform.go new file mode 100644 index 0000000..0049f70 --- /dev/null +++ b/vendor/golang.org/x/text/width/transform.go @@ -0,0 +1,239 @@ +// 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 +} |