diff options
Diffstat (limited to 'libgo/go/utf8/utf8.go')
-rw-r--r-- | libgo/go/utf8/utf8.go | 391 |
1 files changed, 0 insertions, 391 deletions
diff --git a/libgo/go/utf8/utf8.go b/libgo/go/utf8/utf8.go deleted file mode 100644 index a5f9983..0000000 --- a/libgo/go/utf8/utf8.go +++ /dev/null @@ -1,391 +0,0 @@ -// Copyright 2009 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 utf8 implements functions and constants to support text encoded in -// UTF-8. This package calls a Unicode character a rune for brevity. -package utf8 - -import "unicode" // only needed for a couple of constants - -// Numbers fundamental to the encoding. -const ( - RuneError = unicode.ReplacementChar // the "error" Rune or "replacement character". - RuneSelf = 0x80 // characters below Runeself are represented as themselves in a single byte. - UTFMax = 4 // maximum number of bytes of a UTF-8 encoded Unicode character. -) - -const ( - t1 = 0x00 // 0000 0000 - tx = 0x80 // 1000 0000 - t2 = 0xC0 // 1100 0000 - t3 = 0xE0 // 1110 0000 - t4 = 0xF0 // 1111 0000 - t5 = 0xF8 // 1111 1000 - - maskx = 0x3F // 0011 1111 - mask2 = 0x1F // 0001 1111 - mask3 = 0x0F // 0000 1111 - mask4 = 0x07 // 0000 0111 - - rune1Max = 1<<7 - 1 - rune2Max = 1<<11 - 1 - rune3Max = 1<<16 - 1 - rune4Max = 1<<21 - 1 -) - -func decodeRuneInternal(p []byte) (r rune, size int, short bool) { - n := len(p) - if n < 1 { - return RuneError, 0, true - } - c0 := p[0] - - // 1-byte, 7-bit sequence? - if c0 < tx { - return rune(c0), 1, false - } - - // unexpected continuation byte? - if c0 < t2 { - return RuneError, 1, false - } - - // need first continuation byte - if n < 2 { - return RuneError, 1, true - } - c1 := p[1] - if c1 < tx || t2 <= c1 { - return RuneError, 1, false - } - - // 2-byte, 11-bit sequence? - if c0 < t3 { - r = rune(c0&mask2)<<6 | rune(c1&maskx) - if r <= rune1Max { - return RuneError, 1, false - } - return r, 2, false - } - - // need second continuation byte - if n < 3 { - return RuneError, 1, true - } - c2 := p[2] - if c2 < tx || t2 <= c2 { - return RuneError, 1, false - } - - // 3-byte, 16-bit sequence? - if c0 < t4 { - r = rune(c0&mask3)<<12 | rune(c1&maskx)<<6 | rune(c2&maskx) - if r <= rune2Max { - return RuneError, 1, false - } - return r, 3, false - } - - // need third continuation byte - if n < 4 { - return RuneError, 1, true - } - c3 := p[3] - if c3 < tx || t2 <= c3 { - return RuneError, 1, false - } - - // 4-byte, 21-bit sequence? - if c0 < t5 { - r = rune(c0&mask4)<<18 | rune(c1&maskx)<<12 | rune(c2&maskx)<<6 | rune(c3&maskx) - if r <= rune3Max { - return RuneError, 1, false - } - return r, 4, false - } - - // error - return RuneError, 1, false -} - -func decodeRuneInStringInternal(s string) (r rune, size int, short bool) { - n := len(s) - if n < 1 { - return RuneError, 0, true - } - c0 := s[0] - - // 1-byte, 7-bit sequence? - if c0 < tx { - return rune(c0), 1, false - } - - // unexpected continuation byte? - if c0 < t2 { - return RuneError, 1, false - } - - // need first continuation byte - if n < 2 { - return RuneError, 1, true - } - c1 := s[1] - if c1 < tx || t2 <= c1 { - return RuneError, 1, false - } - - // 2-byte, 11-bit sequence? - if c0 < t3 { - r = rune(c0&mask2)<<6 | rune(c1&maskx) - if r <= rune1Max { - return RuneError, 1, false - } - return r, 2, false - } - - // need second continuation byte - if n < 3 { - return RuneError, 1, true - } - c2 := s[2] - if c2 < tx || t2 <= c2 { - return RuneError, 1, false - } - - // 3-byte, 16-bit sequence? - if c0 < t4 { - r = rune(c0&mask3)<<12 | rune(c1&maskx)<<6 | rune(c2&maskx) - if r <= rune2Max { - return RuneError, 1, false - } - return r, 3, false - } - - // need third continuation byte - if n < 4 { - return RuneError, 1, true - } - c3 := s[3] - if c3 < tx || t2 <= c3 { - return RuneError, 1, false - } - - // 4-byte, 21-bit sequence? - if c0 < t5 { - r = rune(c0&mask4)<<18 | rune(c1&maskx)<<12 | rune(c2&maskx)<<6 | rune(c3&maskx) - if r <= rune3Max { - return RuneError, 1, false - } - return r, 4, false - } - - // error - return RuneError, 1, false -} - -// FullRune reports whether the bytes in p begin with a full UTF-8 encoding of a rune. -// An invalid encoding is considered a full Rune since it will convert as a width-1 error rune. -func FullRune(p []byte) bool { - _, _, short := decodeRuneInternal(p) - return !short -} - -// FullRuneInString is like FullRune but its input is a string. -func FullRuneInString(s string) bool { - _, _, short := decodeRuneInStringInternal(s) - return !short -} - -// DecodeRune unpacks the first UTF-8 encoding in p and returns the rune and its width in bytes. -func DecodeRune(p []byte) (r rune, size int) { - r, size, _ = decodeRuneInternal(p) - return -} - -// DecodeRuneInString is like DecodeRune but its input is a string. -func DecodeRuneInString(s string) (r rune, size int) { - r, size, _ = decodeRuneInStringInternal(s) - return -} - -// DecodeLastRune unpacks the last UTF-8 encoding in p -// and returns the rune and its width in bytes. -func DecodeLastRune(p []byte) (r rune, size int) { - end := len(p) - if end == 0 { - return RuneError, 0 - } - start := end - 1 - r = rune(p[start]) - if r < RuneSelf { - return r, 1 - } - // guard against O(n^2) behavior when traversing - // backwards through strings with long sequences of - // invalid UTF-8. - lim := end - UTFMax - if lim < 0 { - lim = 0 - } - for start--; start >= lim; start-- { - if RuneStart(p[start]) { - break - } - } - if start < 0 { - start = 0 - } - r, size = DecodeRune(p[start:end]) - if start+size != end { - return RuneError, 1 - } - return r, size -} - -// DecodeLastRuneInString is like DecodeLastRune but its input is a string. -func DecodeLastRuneInString(s string) (r rune, size int) { - end := len(s) - if end == 0 { - return RuneError, 0 - } - start := end - 1 - r = rune(s[start]) - if r < RuneSelf { - return r, 1 - } - // guard against O(n^2) behavior when traversing - // backwards through strings with long sequences of - // invalid UTF-8. - lim := end - UTFMax - if lim < 0 { - lim = 0 - } - for start--; start >= lim; start-- { - if RuneStart(s[start]) { - break - } - } - if start < 0 { - start = 0 - } - r, size = DecodeRuneInString(s[start:end]) - if start+size != end { - return RuneError, 1 - } - return r, size -} - -// RuneLen returns the number of bytes required to encode the rune. -func RuneLen(r rune) int { - switch { - case r <= rune1Max: - return 1 - case r <= rune2Max: - return 2 - case r <= rune3Max: - return 3 - case r <= rune4Max: - return 4 - } - return -1 -} - -// EncodeRune writes into p (which must be large enough) the UTF-8 encoding of the rune. -// It returns the number of bytes written. -func EncodeRune(p []byte, r rune) int { - // Negative values are erroneous. Making it unsigned addresses the problem. - if uint32(r) <= rune1Max { - p[0] = byte(r) - return 1 - } - - if uint32(r) <= rune2Max { - p[0] = t2 | byte(r>>6) - p[1] = tx | byte(r)&maskx - return 2 - } - - if uint32(r) > unicode.MaxRune { - r = RuneError - } - - if uint32(r) <= rune3Max { - p[0] = t3 | byte(r>>12) - p[1] = tx | byte(r>>6)&maskx - p[2] = tx | byte(r)&maskx - return 3 - } - - p[0] = t4 | byte(r>>18) - p[1] = tx | byte(r>>12)&maskx - p[2] = tx | byte(r>>6)&maskx - p[3] = tx | byte(r)&maskx - return 4 -} - -// RuneCount returns the number of runes in p. Erroneous and short -// encodings are treated as single runes of width 1 byte. -func RuneCount(p []byte) int { - i := 0 - var n int - for n = 0; i < len(p); n++ { - if p[i] < RuneSelf { - i++ - } else { - _, size := DecodeRune(p[i:]) - i += size - } - } - return n -} - -// RuneCountInString is like RuneCount but its input is a string. -func RuneCountInString(s string) (n int) { - for _ = range s { - n++ - } - return -} - -// RuneStart reports whether the byte could be the first byte of -// an encoded rune. Second and subsequent bytes always have the top -// two bits set to 10. -func RuneStart(b byte) bool { return b&0xC0 != 0x80 } - -// Valid reports whether p consists entirely of valid UTF-8-encoded runes. -func Valid(p []byte) bool { - i := 0 - for i < len(p) { - if p[i] < RuneSelf { - i++ - } else { - _, size := DecodeRune(p[i:]) - if size == 1 { - // All valid runes of size of 1 (those - // below RuneSelf) were handled above. - // This must be a RuneError. - return false - } - i += size - } - } - return true -} - -// ValidString reports whether s consists entirely of valid UTF-8-encoded runes. -func ValidString(s string) bool { - for i, r := range s { - if r == RuneError { - // The RuneError value can be an error - // sentinel value (if it's size 1) or the same - // value encoded properly. Decode it to see if - // it's the 1 byte sentinel value. - _, size := DecodeRuneInString(s[i:]) - if size == 1 { - return false - } - } - } - return true -} |