1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
// Copyright 2020 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package base52
import (
"fmt"
"strings"
)
const (
space = "0123456789bcdfghjkmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ"
base = len(space)
)
// Encode returns a string by encoding the id over a 51 characters space
func Encode(id int64) string {
var short []byte
for id > 0 {
i := id % int64(base)
short = append(short, space[i])
id /= int64(base)
}
for i, j := 0, len(short)-1; i < j; i, j = i+1, j-1 {
short[i], short[j] = short[j], short[i]
}
return string(short)
}
// Decode will decode the string and return the id
// The input string should be a valid one with only characters in the space
func Decode(encoded string) (int64, error) {
if len(encoded) != len([]rune(encoded)) {
return 0, fmt.Errorf("invalid encoded string: '%s'", encoded)
}
var id int64
for i := 0; i < len(encoded); i++ {
idx := strings.IndexByte(space, encoded[i])
if idx < 0 {
return 0, fmt.Errorf("invalid encoded string: '%s' contains invalid character", encoded)
}
id = id*int64(base) + int64(idx)
}
return id, nil
}
|
