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2026-08-30 15:23:57 +02:00
commit dab5679098
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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';
+
+var contentType = require('content-type');
+var parseAccept = require('./accept');
+
+/**
+ * Module exports.
+ * @public
+ */
+
+module.exports = preferredLanguages;
+module.exports.preferredLanguages = preferredLanguages;
+
+/**
+ * Module variables.
+ * @private
+ */
+
+function parseAcceptLanguage(accept) {
+  var accepts = parseAccept(accept);
+
+  for (var i = 0, j = 0; i < accepts.length; i++) {
+    var language = formatLanguage(accepts[i], i);
+    if (language) accepts[j++] = language;
+  }
+
+  accepts.length = j;
+  return accepts;
+}
+
+/**
+ * Format a parsed language for negotiation.
+ * @private
+ */
+
+function formatLanguage(parsed, i) {
+  if (!parsed.type) return null;
+
+  var hyphen = parsed.type.indexOf('-');
+  var prefix = hyphen === -1 ? parsed.type : parsed.type.slice(0, hyphen);
+  var suffix = hyphen === -1 ? undefined : parsed.type.slice(hyphen + 1);
+
+  return {
+    prefix: prefix,
+    suffix: suffix,
+    q: parsed.parameters.q ? parseFloat(parsed.parameters.q) : 1,
+    i: i,
+    full: parsed.type
+  };
+}
+
+/**
+ * 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 = formatLanguage(contentType.parse(language), 0)
+  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;
+}