vitess.io/vitess@v0.16.2/go/mysql/collations/internal/charset/eightbit/8bit.go (about) 1 /* 2 Copyright 2021 The Vitess Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package eightbit 18 19 import ( 20 "unicode/utf8" 21 22 "vitess.io/vitess/go/mysql/collations/internal/charset/types" 23 ) 24 25 type UnicodeMapping struct { 26 From, To uint16 27 Range []byte `json:"Tab"` 28 } 29 30 type Charset_8bit struct { 31 Name_ string 32 ToUnicode *[256]uint16 33 FromUnicode []UnicodeMapping 34 } 35 36 func (e *Charset_8bit) Name() string { 37 return e.Name_ 38 } 39 40 func (e *Charset_8bit) IsSuperset(other types.Charset) bool { 41 switch other := other.(type) { 42 case *Charset_8bit: 43 return e.Name_ == other.Name_ 44 default: 45 return false 46 } 47 } 48 49 func (e *Charset_8bit) SupportsSupplementaryChars() bool { 50 return false 51 } 52 53 func (e *Charset_8bit) DecodeRune(bytes []byte) (rune, int) { 54 if len(bytes) < 1 { 55 return utf8.RuneError, 0 56 } 57 return rune(e.ToUnicode[bytes[0]]), 1 58 } 59 60 func (e *Charset_8bit) EncodeRune(dst []byte, r rune) int { 61 if r > 0xFFFF { 62 return -1 63 } 64 cp := uint16(r) 65 for _, mapping := range e.FromUnicode { 66 if cp >= mapping.From && cp <= mapping.To { 67 dst[0] = mapping.Range[cp-mapping.From] 68 if dst[0] == 0 && cp != 0 { 69 return -1 70 } 71 return 1 72 } 73 } 74 return -1 75 } 76 77 func (Charset_8bit) Length(src []byte) int { 78 return len(src) 79 }