twitst4tz

mediaType.js (5358B)

---

 /**
  * 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 = preferredMediaTypes;
 module.exports.preferredMediaTypes = preferredMediaTypes;
 
 /**
  * Module variables.
  * @private
  */
 
 var simpleMediaTypeRegExp = /^\s*([^\s\/;]+)\/([^;\s]+)\s*(?:;(.*))?$/;
 
 /**
  * Parse the Accept header.
  * @private
  */
 
 function parseAccept(accept) {
   var accepts = splitMediaTypes(accept);
 
   for (var i = 0, j = 0; i < accepts.length; i++) {
     var mediaType = parseMediaType(accepts[i].trim(), i);
 
     if (mediaType) {
       accepts[j++] = mediaType;
     }
   }
 
   // trim accepts
   accepts.length = j;
 
   return accepts;
 }
 
 /**
  * Parse a media type from the Accept header.
  * @private
  */
 
 function parseMediaType(str, i) {
   var match = simpleMediaTypeRegExp.exec(str);
   if (!match) return null;
 
   var params = Object.create(null);
   var q = 1;
   var subtype = match[2];
   var type = match[1];
 
   if (match[3]) {
     var kvps = splitParameters(match[3]).map(splitKeyValuePair);
 
     for (var j = 0; j < kvps.length; j++) {
       var pair = kvps[j];
       var key = pair[0].toLowerCase();
       var val = pair[1];
 
       // get the value, unwrapping quotes
       var value = val && val[0] === '"' && val[val.length - 1] === '"'
         ? val.substr(1, val.length - 2)
         : val;
 
       if (key === 'q') {
         q = parseFloat(value);
         break;
       }
 
       // store parameter
       params[key] = value;
     }
   }
 
   return {
     type: type,
     subtype: subtype,
     params: params,
     q: q,
     i: i
   };
 }
 
 /**
  * Get the priority of a media type.
  * @private
  */
 
 function getMediaTypePriority(type, accepted, index) {
   var priority = {o: -1, q: 0, s: 0};
 
   for (var i = 0; i < accepted.length; i++) {
     var spec = specify(type, 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 media type.
  * @private
  */
 
 function specify(type, spec, index) {
   var p = parseMediaType(type);
   var s = 0;
 
   if (!p) {
     return null;
   }
 
   if(spec.type.toLowerCase() == p.type.toLowerCase()) {
     s |= 4
   } else if(spec.type != '*') {
     return null;
   }
 
   if(spec.subtype.toLowerCase() == p.subtype.toLowerCase()) {
     s |= 2
   } else if(spec.subtype != '*') {
     return null;
   }
 
   var keys = Object.keys(spec.params);
   if (keys.length > 0) {
     if (keys.every(function (k) {
       return spec.params[k] == '*' || (spec.params[k] || '').toLowerCase() == (p.params[k] || '').toLowerCase();
     })) {
       s |= 1
     } else {
       return null
     }
   }
 
   return {
     i: index,
     o: spec.i,
     q: spec.q,
     s: s,
   }
 }
 
 /**
  * Get the preferred media types from an Accept header.
  * @public
  */
 
 function preferredMediaTypes(accept, provided) {
   // RFC 2616 sec 14.2: no header = */*
   var accepts = parseAccept(accept === undefined ? '*/*' : accept || '');
 
   if (!provided) {
     // sorted list of all types
     return accepts
       .filter(isQuality)
       .sort(compareSpecs)
       .map(getFullType);
   }
 
   var priorities = provided.map(function getPriority(type, index) {
     return getMediaTypePriority(type, accepts, index);
   });
 
   // sorted list of accepted types
   return priorities.filter(isQuality).sort(compareSpecs).map(function getType(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 type string.
  * @private
  */
 
 function getFullType(spec) {
   return spec.type + '/' + spec.subtype;
 }
 
 /**
  * Check if a spec has any quality.
  * @private
  */
 
 function isQuality(spec) {
   return spec.q > 0;
 }
 
 /**
  * Count the number of quotes in a string.
  * @private
  */
 
 function quoteCount(string) {
   var count = 0;
   var index = 0;
 
   while ((index = string.indexOf('"', index)) !== -1) {
     count++;
     index++;
   }
 
   return count;
 }
 
 /**
  * Split a key value pair.
  * @private
  */
 
 function splitKeyValuePair(str) {
   var index = str.indexOf('=');
   var key;
   var val;
 
   if (index === -1) {
     key = str;
   } else {
     key = str.substr(0, index);
     val = str.substr(index + 1);
   }
 
   return [key, val];
 }
 
 /**
  * Split an Accept header into media types.
  * @private
  */
 
 function splitMediaTypes(accept) {
   var accepts = accept.split(',');
 
   for (var i = 1, j = 0; i < accepts.length; i++) {
     if (quoteCount(accepts[j]) % 2 == 0) {
       accepts[++j] = accepts[i];
     } else {
       accepts[j] += ',' + accepts[i];
     }
   }
 
   // trim accepts
   accepts.length = j + 1;
 
   return accepts;
 }
 
 /**
  * Split a string of parameters.
  * @private
  */
 
 function splitParameters(str) {
   var parameters = str.split(';');
 
   for (var i = 1, j = 0; i < parameters.length; i++) {
     if (quoteCount(parameters[j]) % 2 == 0) {
       parameters[++j] = parameters[i];
     } else {
       parameters[j] += ';' + parameters[i];
     }
   }
 
   // trim parameters
   parameters.length = j + 1;
 
   for (var i = 0; i < parameters.length; i++) {
     parameters[i] = parameters[i].trim();
   }
 
   return parameters;
 }