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- /**
- * 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;
- }
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