File: charset.js

package info (click to toggle)
node-negotiator 0.6.2-1
  • links: PTS, VCS
  • area: main
  • in suites: bookworm, bullseye, sid
  • size: 208 kB
  • sloc: makefile: 2
file content (169 lines) | stat: -rw-r--r-- 3,081 bytes parent folder | download | duplicates (4)
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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
/**
 * negotiator
 * Copyright(c) 2012 Isaac Z. Schlueter
 * Copyright(c) 2014 Federico Romero
 * Copyright(c) 2014-2015 Douglas Christopher Wilson
 * MIT Licensed
 */

'use strict';

/**
 * Module exports.
 * @public
 */

module.exports = preferredCharsets;
module.exports.preferredCharsets = preferredCharsets;

/**
 * Module variables.
 * @private
 */

var simpleCharsetRegExp = /^\s*([^\s;]+)\s*(?:;(.*))?$/;

/**
 * Parse the Accept-Charset header.
 * @private
 */

function parseAcceptCharset(accept) {
  var accepts = accept.split(',');

  for (var i = 0, j = 0; i < accepts.length; i++) {
    var charset = parseCharset(accepts[i].trim(), i);

    if (charset) {
      accepts[j++] = charset;
    }
  }

  // trim accepts
  accepts.length = j;

  return accepts;
}

/**
 * Parse a charset from the Accept-Charset header.
 * @private
 */

function parseCharset(str, i) {
  var match = simpleCharsetRegExp.exec(str);
  if (!match) return null;

  var charset = match[1];
  var q = 1;
  if (match[2]) {
    var params = match[2].split(';')
    for (var j = 0; j < params.length; j++) {
      var p = params[j].trim().split('=');
      if (p[0] === 'q') {
        q = parseFloat(p[1]);
        break;
      }
    }
  }

  return {
    charset: charset,
    q: q,
    i: i
  };
}

/**
 * Get the priority of a charset.
 * @private
 */

function getCharsetPriority(charset, accepted, index) {
  var priority = {o: -1, q: 0, s: 0};

  for (var i = 0; i < accepted.length; i++) {
    var spec = specify(charset, accepted[i], index);

    if (spec && (priority.s - spec.s || priority.q - spec.q || priority.o - spec.o) < 0) {
      priority = spec;
    }
  }

  return priority;
}

/**
 * Get the specificity of the charset.
 * @private
 */

function specify(charset, spec, index) {
  var s = 0;
  if(spec.charset.toLowerCase() === charset.toLowerCase()){
    s |= 1;
  } else if (spec.charset !== '*' ) {
    return null
  }

  return {
    i: index,
    o: spec.i,
    q: spec.q,
    s: s
  }
}

/**
 * Get the preferred charsets from an Accept-Charset header.
 * @public
 */

function preferredCharsets(accept, provided) {
  // RFC 2616 sec 14.2: no header = *
  var accepts = parseAcceptCharset(accept === undefined ? '*' : accept || '');

  if (!provided) {
    // sorted list of all charsets
    return accepts
      .filter(isQuality)
      .sort(compareSpecs)
      .map(getFullCharset);
  }

  var priorities = provided.map(function getPriority(type, index) {
    return getCharsetPriority(type, accepts, index);
  });

  // sorted list of accepted charsets
  return priorities.filter(isQuality).sort(compareSpecs).map(function getCharset(priority) {
    return provided[priorities.indexOf(priority)];
  });
}

/**
 * Compare two specs.
 * @private
 */

function compareSpecs(a, b) {
  return (b.q - a.q) || (b.s - a.s) || (a.o - b.o) || (a.i - b.i) || 0;
}

/**
 * Get full charset string.
 * @private
 */

function getFullCharset(spec) {
  return spec.charset;
}

/**
 * Check if a spec has any quality.
 * @private
 */

function isQuality(spec) {
  return spec.q > 0;
}