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   1  /*
   2  YUI 3.17.2 (build 9c3c78e)
   3  Copyright 2014 Yahoo! Inc. All rights reserved.
   4  Licensed under the BSD License.
   5  http://yuilibrary.com/license/
   6  */
   7  
   8  YUI.add('cache-base', function (Y, NAME) {
   9  
  10  /**
  11   * The Cache utility provides a common configurable interface for components to
  12   * cache and retrieve data from a local JavaScript struct.
  13   *
  14   * @module cache
  15   * @main
  16   */
  17  
  18  /**
  19   * Provides the base class for the YUI Cache utility.
  20   *
  21   * @submodule cache-base
  22   */
  23  var LANG = Y.Lang,
  24      isDate = Y.Lang.isDate,
  25  
  26  /**
  27   * Base class for the YUI Cache utility.
  28   * @class Cache
  29   * @extends Base
  30   * @constructor
  31   */
  32  Cache = function() {
  33      Cache.superclass.constructor.apply(this, arguments);
  34  };
  35  
  36      /////////////////////////////////////////////////////////////////////////////
  37      //
  38      // Cache static properties
  39      //
  40      /////////////////////////////////////////////////////////////////////////////
  41  Y.mix(Cache, {
  42      /**
  43       * Class name.
  44       *
  45       * @property NAME
  46       * @type String
  47       * @static
  48       * @final
  49       * @value "cache"
  50       */
  51      NAME: "cache",
  52  
  53  
  54      ATTRS: {
  55          /////////////////////////////////////////////////////////////////////////////
  56          //
  57          // Cache Attributes
  58          //
  59          /////////////////////////////////////////////////////////////////////////////
  60  
  61          /**
  62          * @attribute max
  63          * @description Maximum number of entries the Cache can hold.
  64          * Set to 0 to turn off caching.
  65          * @type Number
  66          * @default 0
  67          */
  68          max: {
  69              value: 0,
  70              setter: "_setMax"
  71          },
  72  
  73          /**
  74          * @attribute size
  75          * @description Number of entries currently cached.
  76          * @type Number
  77          */
  78          size: {
  79              readOnly: true,
  80              getter: "_getSize"
  81          },
  82  
  83          /**
  84          * @attribute uniqueKeys
  85          * @description Validate uniqueness of stored keys. Default is false and
  86          * is more performant.
  87          * @type Boolean
  88          */
  89          uniqueKeys: {
  90              value: false
  91          },
  92  
  93          /**
  94          * @attribute expires
  95          * @description Absolute Date when data expires or
  96          * relative number of milliseconds. Zero disables expiration.
  97          * @type Date | Number
  98          * @default 0
  99          */
 100          expires: {
 101              value: 0,
 102              validator: function(v) {
 103                  return Y.Lang.isDate(v) || (Y.Lang.isNumber(v) && v >= 0);
 104              }
 105          },
 106  
 107          /**
 108           * @attribute entries
 109           * @description Cached entries.
 110           * @type Array
 111           */
 112          entries: {
 113              readOnly: true,
 114              getter: "_getEntries"
 115          }
 116      }
 117  });
 118  
 119  Y.extend(Cache, Y.Base, {
 120      /////////////////////////////////////////////////////////////////////////////
 121      //
 122      // Cache private properties
 123      //
 124      /////////////////////////////////////////////////////////////////////////////
 125  
 126      /**
 127       * Array of request/response objects indexed chronologically.
 128       *
 129       * @property _entries
 130       * @type Object[]
 131       * @private
 132       */
 133      _entries: null,
 134  
 135      /////////////////////////////////////////////////////////////////////////////
 136      //
 137      // Cache private methods
 138      //
 139      /////////////////////////////////////////////////////////////////////////////
 140  
 141      /**
 142      * @method initializer
 143      * @description Internal init() handler.
 144      * @param config {Object} Config object.
 145      * @private
 146      */
 147      initializer: function(config) {
 148  
 149          /**
 150          * @event add
 151          * @description Fired when an entry is added.
 152          * @param e {EventFacade} Event Facade with the following properties:
 153           * <dl>
 154           * <dt>entry (Object)</dt> <dd>The cached entry.</dd>
 155           * </dl>
 156          * @preventable _defAddFn
 157          */
 158          this.publish("add", {defaultFn: this._defAddFn});
 159  
 160          /**
 161          * @event flush
 162          * @description Fired when the cache is flushed.
 163          * @param e {EventFacade} Event Facade object.
 164          * @preventable _defFlushFn
 165          */
 166          this.publish("flush", {defaultFn: this._defFlushFn});
 167  
 168          /**
 169          * @event request
 170          * @description Fired when an entry is requested from the cache.
 171          * @param e {EventFacade} Event Facade with the following properties:
 172          * <dl>
 173          * <dt>request (Object)</dt> <dd>The request object.</dd>
 174          * </dl>
 175          */
 176  
 177          /**
 178          * @event retrieve
 179          * @description Fired when an entry is retrieved from the cache.
 180          * @param e {EventFacade} Event Facade with the following properties:
 181          * <dl>
 182          * <dt>entry (Object)</dt> <dd>The retrieved entry.</dd>
 183          * </dl>
 184          */
 185  
 186          // Initialize internal values
 187          this._entries = [];
 188      },
 189  
 190      /**
 191      * @method destructor
 192      * @description Internal destroy() handler.
 193      * @private
 194      */
 195      destructor: function() {
 196          this._entries = [];
 197      },
 198  
 199      /////////////////////////////////////////////////////////////////////////////
 200      //
 201      // Cache protected methods
 202      //
 203      /////////////////////////////////////////////////////////////////////////////
 204  
 205      /**
 206       * Sets max.
 207       *
 208       * @method _setMax
 209       * @protected
 210       */
 211      _setMax: function(value) {
 212          // If the cache is full, make room by removing stalest element (index=0)
 213          var entries = this._entries;
 214          if(value > 0) {
 215              if(entries) {
 216                  while(entries.length > value) {
 217                      entries.shift();
 218                  }
 219              }
 220          }
 221          else {
 222              value = 0;
 223              this._entries = [];
 224          }
 225          return value;
 226      },
 227  
 228      /**
 229       * Gets size.
 230       *
 231       * @method _getSize
 232       * @protected
 233       */
 234      _getSize: function() {
 235          return this._entries.length;
 236      },
 237  
 238      /**
 239       * Gets all entries.
 240       *
 241       * @method _getEntries
 242       * @protected
 243       */
 244      _getEntries: function() {
 245          return this._entries;
 246      },
 247  
 248  
 249      /**
 250       * Adds entry to cache.
 251       *
 252       * @method _defAddFn
 253       * @param e {EventFacade} Event Facade with the following properties:
 254       * <dl>
 255       * <dt>entry (Object)</dt> <dd>The cached entry.</dd>
 256       * </dl>
 257       * @protected
 258       */
 259      _defAddFn: function(e) {
 260          var entries = this._entries,
 261              entry   = e.entry,
 262              max     = this.get("max"),
 263              pos;
 264  
 265          // If uniqueKeys is true and item exists with this key, then remove it.
 266          if (this.get("uniqueKeys")) {
 267              pos = this._position(e.entry.request);
 268              if (LANG.isValue(pos)) {
 269                  entries.splice(pos, 1);
 270              }
 271          }
 272  
 273          // If the cache at or over capacity, make room by removing stalest
 274          // element(s) starting at index-0.
 275          while (max && entries.length >= max) {
 276              entries.shift();
 277          }
 278  
 279          // Add entry to cache in the newest position, at the end of the array
 280          entries[entries.length] = entry;
 281      },
 282  
 283      /**
 284       * Flushes cache.
 285       *
 286       * @method _defFlushFn
 287       * @param e {EventFacade} Event Facade object.
 288       * @protected
 289       */
 290      _defFlushFn: function(e) {
 291          var entries = this._entries,
 292              details = e.details[0],
 293              pos;
 294  
 295          //passed an item, flush only that
 296          if(details && LANG.isValue(details.request)) {
 297              pos = this._position(details.request);
 298  
 299              if(LANG.isValue(pos)) {
 300                  entries.splice(pos,1);
 301  
 302              }
 303          }
 304          //no item, flush everything
 305          else {
 306              this._entries = [];
 307          }
 308      },
 309  
 310      /**
 311       * Default overridable method compares current request with given cache entry.
 312       * Returns true if current request matches the cached request, otherwise
 313       * false. Implementers should override this method to customize the
 314       * cache-matching algorithm.
 315       *
 316       * @method _isMatch
 317       * @param request {Object} Request object.
 318       * @param entry {Object} Cached entry.
 319       * @return {Boolean} True if current request matches given cached request, false otherwise.
 320       * @protected
 321       */
 322      _isMatch: function(request, entry) {
 323          if(!entry.expires || new Date() < entry.expires) {
 324              return (request === entry.request);
 325          }
 326          return false;
 327      },
 328  
 329      /**
 330       * Returns position of a request in the entries array, otherwise null.
 331       *
 332       * @method _position
 333       * @param request {Object} Request object.
 334       * @return {Number} Array position if found, null otherwise.
 335       * @protected
 336       */
 337      _position: function(request) {
 338          // If cache is enabled...
 339          var entries = this._entries,
 340              length = entries.length,
 341              i = length-1;
 342  
 343          if((this.get("max") === null) || this.get("max") > 0) {
 344              // Loop through each cached entry starting from the newest
 345              for(; i >= 0; i--) {
 346                  // Execute matching function
 347                  if(this._isMatch(request, entries[i])) {
 348                      return i;
 349                  }
 350              }
 351          }
 352  
 353          return null;
 354      },
 355  
 356      /////////////////////////////////////////////////////////////////////////////
 357      //
 358      // Cache public methods
 359      //
 360      /////////////////////////////////////////////////////////////////////////////
 361  
 362      /**
 363       * Adds a new entry to the cache of the format
 364       * {request:request, response:response, cached:cached, expires:expires}.
 365       * If cache is full, evicts the stalest entry before adding the new one.
 366       *
 367       * @method add
 368       * @param request {Object} Request value.
 369       * @param response {Object} Response value.
 370       */
 371      add: function(request, response) {
 372          var expires = this.get("expires");
 373          if(this.get("initialized") && ((this.get("max") === null) || this.get("max") > 0) &&
 374                  (LANG.isValue(request) || LANG.isNull(request) || LANG.isUndefined(request))) {
 375              this.fire("add", {entry: {
 376                  request:request,
 377                  response:response,
 378                  cached: new Date(),
 379                  expires: isDate(expires) ? expires :
 380              (expires ? new Date(new Date().getTime() + this.get("expires")) : null)
 381              }});
 382          }
 383          else {
 384          }
 385      },
 386  
 387      /**
 388       * Flushes cache.
 389       *
 390       * @method flush
 391       */
 392      flush: function(request) {
 393          this.fire("flush", { request: (LANG.isValue(request) ? request : null) });
 394      },
 395  
 396      /**
 397       * Retrieves cached object for given request, if available, and refreshes
 398       * entry in the cache. Returns null if there is no cache match.
 399       *
 400       * @method retrieve
 401       * @param request {Object} Request object.
 402       * @return {Object} Cached object with the properties request and response, or null.
 403       */
 404      retrieve: function(request) {
 405          // If cache is enabled...
 406          var entries = this._entries,
 407              length = entries.length,
 408              entry = null,
 409              pos;
 410  
 411          if((length > 0) && ((this.get("max") === null) || (this.get("max") > 0))) {
 412              this.fire("request", {request: request});
 413  
 414              pos = this._position(request);
 415  
 416              if(LANG.isValue(pos)) {
 417                  entry = entries[pos];
 418  
 419                  this.fire("retrieve", {entry: entry});
 420  
 421                  // Refresh the position of the cache hit
 422                  if(pos < length-1) {
 423                      // Remove element from its original location
 424                      entries.splice(pos,1);
 425                      // Add as newest
 426                      entries[entries.length] = entry;
 427                  }
 428  
 429                  return entry;
 430              }
 431          }
 432          return null;
 433      }
 434  });
 435  
 436  Y.Cache = Cache;
 437  
 438  
 439  }, '3.17.2', {"requires": ["base"]});