mirror of
https://github.com/go-gitea/gitea.git
synced 2024-12-04 14:46:57 -05:00
207 lines
5.7 KiB
Go
Vendored
207 lines
5.7 KiB
Go
Vendored
// Copyright 2016 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 bidi
|
|
|
|
import "unicode/utf8"
|
|
|
|
// Properties provides access to BiDi properties of runes.
|
|
type Properties struct {
|
|
entry uint8
|
|
last uint8
|
|
}
|
|
|
|
var trie = newBidiTrie(0)
|
|
|
|
// TODO: using this for bidirule reduces the running time by about 5%. Consider
|
|
// if this is worth exposing or if we can find a way to speed up the Class
|
|
// method.
|
|
//
|
|
// // CompactClass is like Class, but maps all of the BiDi control classes
|
|
// // (LRO, RLO, LRE, RLE, PDF, LRI, RLI, FSI, PDI) to the class Control.
|
|
// func (p Properties) CompactClass() Class {
|
|
// return Class(p.entry & 0x0F)
|
|
// }
|
|
|
|
// Class returns the Bidi class for p.
|
|
func (p Properties) Class() Class {
|
|
c := Class(p.entry & 0x0F)
|
|
if c == Control {
|
|
c = controlByteToClass[p.last&0xF]
|
|
}
|
|
return c
|
|
}
|
|
|
|
// IsBracket reports whether the rune is a bracket.
|
|
func (p Properties) IsBracket() bool { return p.entry&0xF0 != 0 }
|
|
|
|
// IsOpeningBracket reports whether the rune is an opening bracket.
|
|
// IsBracket must return true.
|
|
func (p Properties) IsOpeningBracket() bool { return p.entry&openMask != 0 }
|
|
|
|
// TODO: find a better API and expose.
|
|
func (p Properties) reverseBracket(r rune) rune {
|
|
return xorMasks[p.entry>>xorMaskShift] ^ r
|
|
}
|
|
|
|
var controlByteToClass = [16]Class{
|
|
0xD: LRO, // U+202D LeftToRightOverride,
|
|
0xE: RLO, // U+202E RightToLeftOverride,
|
|
0xA: LRE, // U+202A LeftToRightEmbedding,
|
|
0xB: RLE, // U+202B RightToLeftEmbedding,
|
|
0xC: PDF, // U+202C PopDirectionalFormat,
|
|
0x6: LRI, // U+2066 LeftToRightIsolate,
|
|
0x7: RLI, // U+2067 RightToLeftIsolate,
|
|
0x8: FSI, // U+2068 FirstStrongIsolate,
|
|
0x9: PDI, // U+2069 PopDirectionalIsolate,
|
|
}
|
|
|
|
// LookupRune returns properties for r.
|
|
func LookupRune(r rune) (p Properties, size int) {
|
|
var buf [4]byte
|
|
n := utf8.EncodeRune(buf[:], r)
|
|
return Lookup(buf[:n])
|
|
}
|
|
|
|
// TODO: these lookup methods are based on the generated trie code. The returned
|
|
// sizes have slightly different semantics from the generated code, in that it
|
|
// always returns size==1 for an illegal UTF-8 byte (instead of the length
|
|
// of the maximum invalid subsequence). Most Transformers, like unicode/norm,
|
|
// leave invalid UTF-8 untouched, in which case it has performance benefits to
|
|
// do so (without changing the semantics). Bidi requires the semantics used here
|
|
// for the bidirule implementation to be compatible with the Go semantics.
|
|
// They ultimately should perhaps be adopted by all trie implementations, for
|
|
// convenience sake.
|
|
// This unrolled code also boosts performance of the secure/bidirule package by
|
|
// about 30%.
|
|
// So, to remove this code:
|
|
// - add option to trie generator to define return type.
|
|
// - always return 1 byte size for ill-formed UTF-8 runes.
|
|
|
|
// Lookup returns properties for the first rune in s and the width in bytes of
|
|
// its encoding. The size will be 0 if s does not hold enough bytes to complete
|
|
// the encoding.
|
|
func Lookup(s []byte) (p Properties, sz int) {
|
|
c0 := s[0]
|
|
switch {
|
|
case c0 < 0x80: // is ASCII
|
|
return Properties{entry: bidiValues[c0]}, 1
|
|
case c0 < 0xC2:
|
|
return Properties{}, 1
|
|
case c0 < 0xE0: // 2-byte UTF-8
|
|
if len(s) < 2 {
|
|
return Properties{}, 0
|
|
}
|
|
i := bidiIndex[c0]
|
|
c1 := s[1]
|
|
if c1 < 0x80 || 0xC0 <= c1 {
|
|
return Properties{}, 1
|
|
}
|
|
return Properties{entry: trie.lookupValue(uint32(i), c1)}, 2
|
|
case c0 < 0xF0: // 3-byte UTF-8
|
|
if len(s) < 3 {
|
|
return Properties{}, 0
|
|
}
|
|
i := bidiIndex[c0]
|
|
c1 := s[1]
|
|
if c1 < 0x80 || 0xC0 <= c1 {
|
|
return Properties{}, 1
|
|
}
|
|
o := uint32(i)<<6 + uint32(c1)
|
|
i = bidiIndex[o]
|
|
c2 := s[2]
|
|
if c2 < 0x80 || 0xC0 <= c2 {
|
|
return Properties{}, 1
|
|
}
|
|
return Properties{entry: trie.lookupValue(uint32(i), c2), last: c2}, 3
|
|
case c0 < 0xF8: // 4-byte UTF-8
|
|
if len(s) < 4 {
|
|
return Properties{}, 0
|
|
}
|
|
i := bidiIndex[c0]
|
|
c1 := s[1]
|
|
if c1 < 0x80 || 0xC0 <= c1 {
|
|
return Properties{}, 1
|
|
}
|
|
o := uint32(i)<<6 + uint32(c1)
|
|
i = bidiIndex[o]
|
|
c2 := s[2]
|
|
if c2 < 0x80 || 0xC0 <= c2 {
|
|
return Properties{}, 1
|
|
}
|
|
o = uint32(i)<<6 + uint32(c2)
|
|
i = bidiIndex[o]
|
|
c3 := s[3]
|
|
if c3 < 0x80 || 0xC0 <= c3 {
|
|
return Properties{}, 1
|
|
}
|
|
return Properties{entry: trie.lookupValue(uint32(i), c3)}, 4
|
|
}
|
|
// Illegal rune
|
|
return Properties{}, 1
|
|
}
|
|
|
|
// LookupString returns properties for the first rune in s and the width in
|
|
// bytes of its encoding. The size will be 0 if s does not hold enough bytes to
|
|
// complete the encoding.
|
|
func LookupString(s string) (p Properties, sz int) {
|
|
c0 := s[0]
|
|
switch {
|
|
case c0 < 0x80: // is ASCII
|
|
return Properties{entry: bidiValues[c0]}, 1
|
|
case c0 < 0xC2:
|
|
return Properties{}, 1
|
|
case c0 < 0xE0: // 2-byte UTF-8
|
|
if len(s) < 2 {
|
|
return Properties{}, 0
|
|
}
|
|
i := bidiIndex[c0]
|
|
c1 := s[1]
|
|
if c1 < 0x80 || 0xC0 <= c1 {
|
|
return Properties{}, 1
|
|
}
|
|
return Properties{entry: trie.lookupValue(uint32(i), c1)}, 2
|
|
case c0 < 0xF0: // 3-byte UTF-8
|
|
if len(s) < 3 {
|
|
return Properties{}, 0
|
|
}
|
|
i := bidiIndex[c0]
|
|
c1 := s[1]
|
|
if c1 < 0x80 || 0xC0 <= c1 {
|
|
return Properties{}, 1
|
|
}
|
|
o := uint32(i)<<6 + uint32(c1)
|
|
i = bidiIndex[o]
|
|
c2 := s[2]
|
|
if c2 < 0x80 || 0xC0 <= c2 {
|
|
return Properties{}, 1
|
|
}
|
|
return Properties{entry: trie.lookupValue(uint32(i), c2), last: c2}, 3
|
|
case c0 < 0xF8: // 4-byte UTF-8
|
|
if len(s) < 4 {
|
|
return Properties{}, 0
|
|
}
|
|
i := bidiIndex[c0]
|
|
c1 := s[1]
|
|
if c1 < 0x80 || 0xC0 <= c1 {
|
|
return Properties{}, 1
|
|
}
|
|
o := uint32(i)<<6 + uint32(c1)
|
|
i = bidiIndex[o]
|
|
c2 := s[2]
|
|
if c2 < 0x80 || 0xC0 <= c2 {
|
|
return Properties{}, 1
|
|
}
|
|
o = uint32(i)<<6 + uint32(c2)
|
|
i = bidiIndex[o]
|
|
c3 := s[3]
|
|
if c3 < 0x80 || 0xC0 <= c3 {
|
|
return Properties{}, 1
|
|
}
|
|
return Properties{entry: trie.lookupValue(uint32(i), c3)}, 4
|
|
}
|
|
// Illegal rune
|
|
return Properties{}, 1
|
|
}
|