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