deno.land / std@0.166.0 / encoding / ascii85.ts

نووسراو ببینە
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
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
/** * {@linkcode encode} and {@linkcode decode} for * [Ascii85/base85](https://en.wikipedia.org/wiki/Ascii85) encoding. * * This module is browser compatible. * * @module */
export type Ascii85Standard = "Adobe" | "btoa" | "RFC 1924" | "Z85";
/** * encoding/decoding options * @property standard - characterset and delimiter (if supported and used). Defaults to Adobe * @property delimiter - whether to use a delimiter (if supported) - "<~" and "~>" by default */export interface Ascii85Options { standard?: Ascii85Standard; delimiter?: boolean;}const rfc1924 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~";const Z85 = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-:+=^!/*?&<>()[]{}@%$#";/** * Encodes a given Uint8Array into ascii85, supports multiple standards * @param uint8 input to encode * @param [options] encoding options * @param [options.standard=Adobe] encoding standard (Adobe, btoa, RFC 1924 or Z85) * @param [options.delimiter] whether to use a delimiter, if supported by encoding standard */export function encode(uint8: Uint8Array, options?: Ascii85Options): string { const standard = options?.standard ?? "Adobe"; let output: string[] = [], v: number, n = 0, difference = 0; if (uint8.length % 4 !== 0) { const tmp = uint8; difference = 4 - (tmp.length % 4); uint8 = new Uint8Array(tmp.length + difference); uint8.set(tmp); } const view = new DataView(uint8.buffer); for (let i = 0, len = uint8.length; i < len; i += 4) { v = view.getUint32(i); // Adobe and btoa standards compress 4 zeroes to single "z" character if ( (standard === "Adobe" || standard === "btoa") && v === 0 && i < len - difference - 3 ) { output[n++] = "z"; continue; } // btoa compresses 4 spaces - that is, bytes equal to 32 - into single "y" character if (standard === "btoa" && v === 538976288) { output[n++] = "y"; continue; } for (let j = 4; j >= 0; j--) { output[n + j] = String.fromCharCode((v % 85) + 33); v = Math.trunc(v / 85); } n += 5; } switch (standard) { case "Adobe": if (options?.delimiter) { return `<~${output.slice(0, output.length - difference).join("")}~>`; } break; case "btoa": if (options?.delimiter) { return `xbtoa Begin\n${ output .slice(0, output.length - difference) .join("") }\nxbtoa End`; } break; case "RFC 1924": output = output.map((val) => rfc1924[val.charCodeAt(0) - 33]); break; case "Z85": output = output.map((val) => Z85[val.charCodeAt(0) - 33]); break; } return output.slice(0, output.length - difference).join("");}/** * Decodes a given ascii85 encoded string. * @param ascii85 input to decode * @param [options] decoding options * @param [options.standard=Adobe] encoding standard used in the input string (Adobe, btoa, RFC 1924 or Z85) */export function decode(ascii85: string, options?: Ascii85Options): Uint8Array { const encoding = options?.standard ?? "Adobe"; // translate all encodings to most basic adobe/btoa one and decompress some special characters ("z" and "y") switch (encoding) { case "Adobe": ascii85 = ascii85.replaceAll(/(<~|~>)/g, "").replaceAll("z", "!!!!!"); break; case "btoa": ascii85 = ascii85 .replaceAll(/(xbtoa Begin|xbtoa End|\n)/g, "") .replaceAll("z", "!!!!!") .replaceAll("y", "+<VdL"); break; case "RFC 1924": ascii85 = ascii85.replaceAll( /./g, (match) => String.fromCharCode(rfc1924.indexOf(match) + 33), ); break; case "Z85": ascii85 = ascii85.replaceAll( /./g, (match) => String.fromCharCode(Z85.indexOf(match) + 33), ); break; } //remove all invalid characters ascii85 = ascii85.replaceAll(/[^!-u]/g, ""); const len = ascii85.length, output = new Uint8Array(len + 4 - (len % 4)); const view = new DataView(output.buffer); let v = 0, n = 0, max = 0; for (let i = 0; i < len;) { for (max += 5; i < max; i++) { v = v * 85 + (i < len ? ascii85.charCodeAt(i) : 117) - 33; } view.setUint32(n, v); v = 0; n += 4; } return output.slice(0, Math.trunc(len * 0.8));}
std
Deno standard library
GitHub Repositorydenoland/deno_std
GitHub Stars
2447

Version Info

Tagged at
2 months ago