1 YUI.add('cache-base', function (Y, NAME) {

     2 

     3 /**

     4  * The Cache utility provides a common configurable interface for components to

     5  * cache and retrieve data from a local JavaScript struct.

     6  *

     7  * @module cache

     8  * @main

     9  */

    10 

    11 /**

    12  * Provides the base class for the YUI Cache utility.

    13  *

    14  * @submodule cache-base

    15  */

    16 var LANG = Y.Lang,

    17     isDate = Y.Lang.isDate,

    18 

    19 /**

    20  * Base class for the YUI Cache utility.

    21  * @class Cache

    22  * @extends Base

    23  * @constructor

    24  */

    25 Cache = function() {

    26     Cache.superclass.constructor.apply(this, arguments);

    27 };

    28 

    29     /////////////////////////////////////////////////////////////////////////////

    30     //

    31     // Cache static properties

    32     //

    33     /////////////////////////////////////////////////////////////////////////////

    34 Y.mix(Cache, {

    35     /**

    36      * Class name.

    37      *

    38      * @property NAME

    39      * @type String

    40      * @static

    41      * @final

    42      * @value "cache"

    43      */

    44     NAME: "cache",

    45 

    46 

    47     ATTRS: {

    48         /////////////////////////////////////////////////////////////////////////////

    49         //

    50         // Cache Attributes

    51         //

    52         /////////////////////////////////////////////////////////////////////////////

    53 

    54         /**

    55         * @attribute max

    56         * @description Maximum number of entries the Cache can hold.

    57         * Set to 0 to turn off caching.

    58         * @type Number

    59         * @default 0

    60         */

    61         max: {

    62             value: 0,

    63             setter: "_setMax"

    64         },

    65 

    66         /**

    67         * @attribute size

    68         * @description Number of entries currently cached.

    69         * @type Number

    70         */

    71         size: {

    72             readOnly: true,

    73             getter: "_getSize"

    74         },

    75 

    76         /**

    77         * @attribute uniqueKeys

    78         * @description Validate uniqueness of stored keys. Default is false and

    79         * is more performant.

    80         * @type Boolean

    81         */

    82         uniqueKeys: {

    83             value: false

    84         },

    85 

    86         /**

    87         * @attribute expires

    88         * @description Absolute Date when data expires or

    89         * relative number of milliseconds. Zero disables expiration.

    90         * @type Date | Number

    91         * @default 0

    92         */

    93         expires: {

    94             value: 0,

    95             validator: function(v) {

    96                 return Y.Lang.isDate(v) || (Y.Lang.isNumber(v) && v >= 0);

    97             }

    98         },

    99 

   100         /**

   101          * @attribute entries

   102          * @description Cached entries.

   103          * @type Array

   104          */

   105         entries: {

   106             readOnly: true,

   107             getter: "_getEntries"

   108         }

   109     }

   110 });

   111 

   112 Y.extend(Cache, Y.Base, {

   113     /////////////////////////////////////////////////////////////////////////////

   114     //

   115     // Cache private properties

   116     //

   117     /////////////////////////////////////////////////////////////////////////////

   118 

   119     /**

   120      * Array of request/response objects indexed chronologically.

   121      *

   122      * @property _entries

   123      * @type Object[]

   124      * @private

   125      */

   126     _entries: null,

   127 

   128     /////////////////////////////////////////////////////////////////////////////

   129     //

   130     // Cache private methods

   131     //

   132     /////////////////////////////////////////////////////////////////////////////

   133 

   134     /**

   135     * @method initializer

   136     * @description Internal init() handler.

   137     * @param config {Object} Config object.

   138     * @private

   139     */

   140     initializer: function(config) {

   141 

   142         /**

   143         * @event add

   144         * @description Fired when an entry is added.

   145         * @param e {EventFacade} Event Facade with the following properties:

   146          * <dl>

   147          * <dt>entry (Object)</dt> <dd>The cached entry.</dd>

   148          * </dl>

   149         * @preventable _defAddFn

   150         */

   151         this.publish("add", {defaultFn: this._defAddFn});

   152 

   153         /**

   154         * @event flush

   155         * @description Fired when the cache is flushed.

   156         * @param e {EventFacade} Event Facade object.

   157         * @preventable _defFlushFn

   158         */

   159         this.publish("flush", {defaultFn: this._defFlushFn});

   160 

   161         /**

   162         * @event request

   163         * @description Fired when an entry is requested from the cache.

   164         * @param e {EventFacade} Event Facade with the following properties:

   165         * <dl>

   166         * <dt>request (Object)</dt> <dd>The request object.</dd>

   167         * </dl>

   168         */

   169 

   170         /**

   171         * @event retrieve

   172         * @description Fired when an entry is retrieved from the cache.

   173         * @param e {EventFacade} Event Facade with the following properties:

   174         * <dl>

   175         * <dt>entry (Object)</dt> <dd>The retrieved entry.</dd>

   176         * </dl>

   177         */

   178 

   179         // Initialize internal values

   180         this._entries = [];

   181     },

   182 

   183     /**

   184     * @method destructor

   185     * @description Internal destroy() handler.

   186     * @private

   187     */

   188     destructor: function() {

   189         this._entries = [];

   190     },

   191 

   192     /////////////////////////////////////////////////////////////////////////////

   193     //

   194     // Cache protected methods

   195     //

   196     /////////////////////////////////////////////////////////////////////////////

   197 

   198     /**

   199      * Sets max.

   200      *

   201      * @method _setMax

   202      * @protected

   203      */

   204     _setMax: function(value) {

   205         // If the cache is full, make room by removing stalest element (index=0)

   206         var entries = this._entries;

   207         if(value > 0) {

   208             if(entries) {

   209                 while(entries.length > value) {

   210                     entries.shift();

   211                 }

   212             }

   213         }

   214         else {

   215             value = 0;

   216             this._entries = [];

   217         }

   218         return value;

   219     },

   220 

   221     /**

   222      * Gets size.

   223      *

   224      * @method _getSize

   225      * @protected

   226      */

   227     _getSize: function() {

   228         return this._entries.length;

   229     },

   230 

   231     /**

   232      * Gets all entries.

   233      *

   234      * @method _getEntries

   235      * @protected

   236      */

   237     _getEntries: function() {

   238         return this._entries;

   239     },

   240 

   241 

   242     /**

   243      * Adds entry to cache.

   244      *

   245      * @method _defAddFn

   246      * @param e {EventFacade} Event Facade with the following properties:

   247      * <dl>

   248      * <dt>entry (Object)</dt> <dd>The cached entry.</dd>

   249      * </dl>

   250      * @protected

   251      */

   252     _defAddFn: function(e) {

   253         var entries = this._entries,

   254             entry   = e.entry,

   255             max     = this.get("max"),

   256             pos;

   257 

   258         // If uniqueKeys is true and item exists with this key, then remove it.

   259         if (this.get("uniqueKeys")) {

   260             pos = this._position(e.entry.request);

   261             if (LANG.isValue(pos)) {

   262                 entries.splice(pos, 1);

   263             }

   264         }

   265 

   266         // If the cache at or over capacity, make room by removing stalest

   267         // element(s) starting at index-0.

   268         while (max && entries.length >= max) {

   269             entries.shift();

   270         }

   271 

   272         // Add entry to cache in the newest position, at the end of the array

   273         entries[entries.length] = entry;

   274     },

   275 

   276     /**

   277      * Flushes cache.

   278      *

   279      * @method _defFlushFn

   280      * @param e {EventFacade} Event Facade object.

   281      * @protected

   282      */

   283     _defFlushFn: function(e) {

   284         var entries = this._entries,

   285             details = e.details[0],

   286             pos;

   287 

   288         //passed an item, flush only that

   289         if(details && LANG.isValue(details.request)) {

   290             pos = this._position(details.request);

   291 

   292             if(LANG.isValue(pos)) {

   293                 entries.splice(pos,1);

   294 

   295             }

   296         }

   297         //no item, flush everything

   298         else {

   299             this._entries = [];

   300         }

   301     },

   302 

   303     /**

   304      * Default overridable method compares current request with given cache entry.

   305      * Returns true if current request matches the cached request, otherwise

   306      * false. Implementers should override this method to customize the

   307      * cache-matching algorithm.

   308      *

   309      * @method _isMatch

   310      * @param request {Object} Request object.

   311      * @param entry {Object} Cached entry.

   312      * @return {Boolean} True if current request matches given cached request, false otherwise.

   313      * @protected

   314      */

   315     _isMatch: function(request, entry) {

   316         if(!entry.expires || new Date() < entry.expires) {

   317             return (request === entry.request);

   318         }

   319         return false;

   320     },

   321 

   322     /**

   323      * Returns position of a request in the entries array, otherwise null.

   324      *

   325      * @method _position

   326      * @param request {Object} Request object.

   327      * @return {Number} Array position if found, null otherwise.

   328      * @protected

   329      */

   330     _position: function(request) {

   331         // If cache is enabled...

   332         var entries = this._entries,

   333             length = entries.length,

   334             i = length-1;

   335 

   336         if((this.get("max") === null) || this.get("max") > 0) {

   337             // Loop through each cached entry starting from the newest

   338             for(; i >= 0; i--) {

   339                 // Execute matching function

   340                 if(this._isMatch(request, entries[i])) {

   341                     return i;

   342                 }

   343             }

   344         }

   345 

   346         return null;

   347     },

   348 

   349     /////////////////////////////////////////////////////////////////////////////

   350     //

   351     // Cache public methods

   352     //

   353     /////////////////////////////////////////////////////////////////////////////

   354 

   355     /**

   356      * Adds a new entry to the cache of the format

   357      * {request:request, response:response, cached:cached, expires:expires}.

   358      * If cache is full, evicts the stalest entry before adding the new one.

   359      *

   360      * @method add

   361      * @param request {Object} Request value.

   362      * @param response {Object} Response value.

   363      */

   364     add: function(request, response) {

   365         var expires = this.get("expires");

   366         if(this.get("initialized") && ((this.get("max") === null) || this.get("max") > 0) &&

   367                 (LANG.isValue(request) || LANG.isNull(request) || LANG.isUndefined(request))) {

   368             this.fire("add", {entry: {

   369                 request:request,

   370                 response:response,

   371                 cached: new Date(),

   372                 expires: isDate(expires) ? expires :

   373             (expires ? new Date(new Date().getTime() + this.get("expires")) : null)

   374             }});

   375         }

   376         else {

   377         }

   378     },

   379 

   380     /**

   381      * Flushes cache.

   382      *

   383      * @method flush

   384      */

   385     flush: function(request) {

   386         this.fire("flush", { request: (LANG.isValue(request) ? request : null) });

   387     },

   388 

   389     /**

   390      * Retrieves cached object for given request, if available, and refreshes

   391      * entry in the cache. Returns null if there is no cache match.

   392      *

   393      * @method retrieve

   394      * @param request {Object} Request object.

   395      * @return {Object} Cached object with the properties request and response, or null.

   396      */

   397     retrieve: function(request) {

   398         // If cache is enabled...

   399         var entries = this._entries,

   400             length = entries.length,

   401             entry = null,

   402             pos;

   403 

   404         if((length > 0) && ((this.get("max") === null) || (this.get("max") > 0))) {

   405             this.fire("request", {request: request});

   406 

   407             pos = this._position(request);

   408 

   409             if(LANG.isValue(pos)) {

   410                 entry = entries[pos];

   411 

   412                 this.fire("retrieve", {entry: entry});

   413 

   414                 // Refresh the position of the cache hit

   415                 if(pos < length-1) {

   416                     // Remove element from its original location

   417                     entries.splice(pos,1);

   418                     // Add as newest

   419                     entries[entries.length] = entry;

   420                 }

   421 

   422                 return entry;

   423             }

   424         }

   425         return null;

   426     }

   427 });

   428 

   429 Y.Cache = Cache;

   430 

   431 

   432 }, '@VERSION@', {"requires": ["base"]});