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- module.exports = preferredLanguages;
- preferredLanguages.preferredLanguages = preferredLanguages;
- function parseAcceptLanguage(accept) {
- return accept.split(',').map(function(e) {
- return parseLanguage(e.trim());
- }).filter(function(e) {
- return e;
- });
- }
- function parseLanguage(s) {
- var match = s.match(/^\s*(\S+?)(?:-(\S+?))?\s*(?:;(.*))?$/);
- if (!match) return null;
- var prefix = match[1],
- suffix = match[2],
- full = prefix;
- if (suffix) full += "-" + suffix;
- var q = 1;
- if (match[3]) {
- var params = match[3].split(';')
- for (var i = 0; i < params.length; i ++) {
- var p = params[i].split('=');
- if (p[0] === 'q') q = parseFloat(p[1]);
- }
- }
- return {
- prefix: prefix,
- suffix: suffix,
- q: q,
- full: full
- };
- }
- function getLanguagePriority(language, accepted) {
- return (accepted.map(function(a){
- return specify(language, 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(language, spec) {
- var p = parseLanguage(language)
- if (!p) return null;
- var s = 0;
- if(spec.full === p.full){
- s |= 4;
- } else if (spec.prefix === p.full) {
- s |= 2;
- } else if (spec.full === p.prefix) {
- s |= 1;
- } else if (spec.full !== '*' ) {
- return null
- }
- return {
- s: s,
- q: spec.q,
- }
- };
- function preferredLanguages(accept, provided) {
- // RFC 2616 sec 14.4: no header = *
- accept = parseAcceptLanguage(accept === undefined ? '*' : accept || '');
- if (provided) {
- var ret = provided.map(function(type) {
- return [type, getLanguagePriority(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];
- });
- return ret;
- } 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.full;
- });
- }
- }
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