tidb gbk_chinese_ci 源码
tidb gbk_chinese_ci 代码
文件路径：/util/collate/gbk_chinese_ci.go
// Copyright 2021 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package collate
import "github.com/pingcap/tidb/util/stringutil"
type gbkChineseCICollator struct {
}
// Compare implements Collator interface.
func (*gbkChineseCICollator) Compare(a, b string) int {
a = truncateTailingSpace(a)
b = truncateTailingSpace(b)
r1, r2 := rune(0), rune(0)
ai, bi := 0, 0
for ai < len(a) && bi < len(b) {
r1, ai = decodeRune(a, ai)
r2, bi = decodeRune(b, bi)
cmp := int(gbkChineseCISortKey(r1)) - int(gbkChineseCISortKey(r2))
if cmp != 0 {
return sign(cmp)
}
}
return sign((len(a) - ai) - (len(b) - bi))
}
// Key implements Collator interface.
func (g *gbkChineseCICollator) Key(str string) []byte {
return g.KeyWithoutTrimRightSpace(truncateTailingSpace(str))
}
// KeyWithoutTrimRightSpace implement Collator interface.
func (*gbkChineseCICollator) KeyWithoutTrimRightSpace(str string) []byte {
buf := make([]byte, 0, len(str)*2)
i := 0
r := rune(0)
for i < len(str) {
r, i = decodeRune(str, i)
u16 := gbkChineseCISortKey(r)
if u16 > 0xFF {
buf = append(buf, byte(u16>>8))
}
buf = append(buf, byte(u16))
}
return buf
}
// Pattern implements Collator interface.
func (*gbkChineseCICollator) Pattern() WildcardPattern {
return &gbkChineseCIPattern{}
}
type gbkChineseCIPattern struct {
patChars []rune
patTypes []byte
}
// Compile implements WildcardPattern interface.
func (p *gbkChineseCIPattern) Compile(patternStr string, escape byte) {
p.patChars, p.patTypes = stringutil.CompilePatternInner(patternStr, escape)
}
// DoMatch implements WildcardPattern interface.
func (p *gbkChineseCIPattern) DoMatch(str string) bool {
return stringutil.DoMatchInner(str, p.patChars, p.patTypes, func(a, b rune) bool {
return gbkChineseCISortKey(a) == gbkChineseCISortKey(b)
})
}
func gbkChineseCISortKey(r rune) uint16 {
if r > 0xFFFF {
return 0x3F
}
return gbkChineseCISortKeyTable[r]
}
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