179 lines
3.3 KiB
JavaScript
179 lines
3.3 KiB
JavaScript
/**
|
|
* 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 = preferredLanguages;
|
|
module.exports.preferredLanguages = preferredLanguages;
|
|
|
|
/**
|
|
* Module variables.
|
|
* @private
|
|
*/
|
|
|
|
var simpleLanguageRegExp = /^\s*([^\s\-;]+)(?:-([^\s;]+))?\s*(?:;(.*))?$/;
|
|
|
|
/**
|
|
* Parse the Accept-Language header.
|
|
* @private
|
|
*/
|
|
|
|
function parseAcceptLanguage(accept) {
|
|
var accepts = accept.split(',');
|
|
|
|
for (var i = 0, j = 0; i < accepts.length; i++) {
|
|
var language = parseLanguage(accepts[i].trim(), i);
|
|
|
|
if (language) {
|
|
accepts[j++] = language;
|
|
}
|
|
}
|
|
|
|
// trim accepts
|
|
accepts.length = j;
|
|
|
|
return accepts;
|
|
}
|
|
|
|
/**
|
|
* Parse a language from the Accept-Language header.
|
|
* @private
|
|
*/
|
|
|
|
function parseLanguage(str, i) {
|
|
var match = simpleLanguageRegExp.exec(str);
|
|
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 j = 0; j < params.length; j++) {
|
|
var p = params[j].split('=');
|
|
if (p[0] === 'q') q = parseFloat(p[1]);
|
|
}
|
|
}
|
|
|
|
return {
|
|
prefix: prefix,
|
|
suffix: suffix,
|
|
q: q,
|
|
i: i,
|
|
full: full
|
|
};
|
|
}
|
|
|
|
/**
|
|
* Get the priority of a language.
|
|
* @private
|
|
*/
|
|
|
|
function getLanguagePriority(language, accepted, index) {
|
|
var priority = {o: -1, q: 0, s: 0};
|
|
|
|
for (var i = 0; i < accepted.length; i++) {
|
|
var spec = specify(language, 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 language.
|
|
* @private
|
|
*/
|
|
|
|
function specify(language, spec, index) {
|
|
var p = parseLanguage(language)
|
|
if (!p) return null;
|
|
var s = 0;
|
|
if(spec.full.toLowerCase() === p.full.toLowerCase()){
|
|
s |= 4;
|
|
} else if (spec.prefix.toLowerCase() === p.full.toLowerCase()) {
|
|
s |= 2;
|
|
} else if (spec.full.toLowerCase() === p.prefix.toLowerCase()) {
|
|
s |= 1;
|
|
} else if (spec.full !== '*' ) {
|
|
return null
|
|
}
|
|
|
|
return {
|
|
i: index,
|
|
o: spec.i,
|
|
q: spec.q,
|
|
s: s
|
|
}
|
|
};
|
|
|
|
/**
|
|
* Get the preferred languages from an Accept-Language header.
|
|
* @public
|
|
*/
|
|
|
|
function preferredLanguages(accept, provided) {
|
|
// RFC 2616 sec 14.4: no header = *
|
|
var accepts = parseAcceptLanguage(accept === undefined ? '*' : accept || '');
|
|
|
|
if (!provided) {
|
|
// sorted list of all languages
|
|
return accepts
|
|
.filter(isQuality)
|
|
.sort(compareSpecs)
|
|
.map(getFullLanguage);
|
|
}
|
|
|
|
var priorities = provided.map(function getPriority(type, index) {
|
|
return getLanguagePriority(type, accepts, index);
|
|
});
|
|
|
|
// sorted list of accepted languages
|
|
return priorities.filter(isQuality).sort(compareSpecs).map(function getLanguage(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 language string.
|
|
* @private
|
|
*/
|
|
|
|
function getFullLanguage(spec) {
|
|
return spec.full;
|
|
}
|
|
|
|
/**
|
|
* Check if a spec has any quality.
|
|
* @private
|
|
*/
|
|
|
|
function isQuality(spec) {
|
|
return spec.q > 0;
|
|
}
|