91 lines
1.9 KiB
JavaScript
Executable File
91 lines
1.9 KiB
JavaScript
Executable File
module.exports = preferredCharsets;
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preferredCharsets.preferredCharsets = preferredCharsets;
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function parseAcceptCharset(accept) {
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return accept.split(',').map(function(e) {
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return parseCharset(e.trim());
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}).filter(function(e) {
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return e;
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});
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}
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function parseCharset(s) {
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var match = s.match(/^\s*(\S+?)\s*(?:;(.*))?$/);
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if (!match) return null;
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var charset = match[1];
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var q = 1;
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if (match[2]) {
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var params = match[2].split(';')
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for (var i = 0; i < params.length; i ++) {
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var p = params[i].trim().split('=');
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if (p[0] === 'q') {
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q = parseFloat(p[1]);
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break;
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}
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}
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}
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return {
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charset: charset,
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q: q
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};
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}
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function getCharsetPriority(charset, accepted) {
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return (accepted.map(function(a) {
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return specify(charset, a);
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}).filter(Boolean).sort(function (a, b) {
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if(a.s == b.s) {
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return a.q > b.q ? -1 : 1;
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} else {
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return a.s > b.s ? -1 : 1;
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}
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})[0] || {s: 0, q:0});
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}
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function specify(charset, spec) {
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var s = 0;
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if(spec.charset === charset){
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s |= 1;
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} else if (spec.charset !== '*' ) {
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return null
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}
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return {
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s: s,
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q: spec.q,
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}
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}
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function preferredCharsets(accept, provided) {
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// RFC 2616 sec 14.2: no header = *
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accept = parseAcceptCharset(accept === undefined ? '*' : accept || '');
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if (provided) {
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return provided.map(function(type) {
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return [type, getCharsetPriority(type, accept)];
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}).filter(function(pair) {
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return pair[1].q > 0;
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}).sort(function(a, b) {
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var pa = a[1];
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var pb = b[1];
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if(pa.q == pb.q) {
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return pa.s < pb.s ? 1 : -1;
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} else {
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return pa.q < pb.q ? 1 : -1;
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}
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}).map(function(pair) {
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return pair[0];
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});
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} else {
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return accept.sort(function (a, b) {
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// revsort
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return a.q < b.q ? 1 : -1;
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}).filter(function(type) {
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return type.q > 0;
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}).map(function(type) {
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return type.charset;
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});
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}
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}
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