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- /*
- Copyright (c) 2010, Yahoo! Inc. All rights reserved.
- Code licensed under the BSD License:
- http://developer.yahoo.com/yui/license.html
- version: 3.4.0
- build: nightly
- */
- YUI.add('cache-base', function(Y) {
-
- /**
- * The Cache utility provides a common configurable interface for components to
- * cache and retrieve data from a local JavaScript struct.
- *
- * @module cache
- * @main
- */
-
- /**
- * Provides the base class for the YUI Cache utility.
- *
- * @submodule cache-base
- */
- var LANG = Y.Lang,
- isDate = Y.Lang.isDate,
-
- /**
- * Base class for the YUI Cache utility.
- * @class Cache
- * @extends Base
- * @constructor
- */
- Cache = function() {
- Cache.superclass.constructor.apply(this, arguments);
- };
-
- /////////////////////////////////////////////////////////////////////////////
- //
- // Cache static properties
- //
- /////////////////////////////////////////////////////////////////////////////
- Y.mix(Cache, {
- /**
- * Class name.
- *
- * @property NAME
- * @type String
- * @static
- * @final
- * @value "cache"
- */
- NAME: "cache",
-
-
- ATTRS: {
- /////////////////////////////////////////////////////////////////////////////
- //
- // Cache Attributes
- //
- /////////////////////////////////////////////////////////////////////////////
-
- /**
- * @attribute max
- * @description Maximum number of entries the Cache can hold.
- * Set to 0 to turn off caching.
- * @type Number
- * @default 0
- */
- max: {
- value: 0,
- setter: "_setMax"
- },
-
- /**
- * @attribute size
- * @description Number of entries currently cached.
- * @type Number
- */
- size: {
- readOnly: true,
- getter: "_getSize"
- },
-
- /**
- * @attribute uniqueKeys
- * @description Validate uniqueness of stored keys. Default is false and
- * is more performant.
- * @type Boolean
- */
- uniqueKeys: {
- value: false
- },
-
- /**
- * @attribute expires
- * @description Absolute Date when data expires or
- * relative number of milliseconds. Zero disables expiration.
- * @type Date | Number
- * @default 0
- */
- expires: {
- value: 0,
- validator: function(v) {
- return Y.Lang.isDate(v) || (Y.Lang.isNumber(v) && v >= 0);
- }
- },
-
- /**
- * @attribute entries
- * @description Cached entries.
- * @type Array
- */
- entries: {
- readOnly: true,
- getter: "_getEntries"
- }
- }
- });
-
- Y.extend(Cache, Y.Base, {
- /////////////////////////////////////////////////////////////////////////////
- //
- // Cache private properties
- //
- /////////////////////////////////////////////////////////////////////////////
-
- /**
- * Array of request/response objects indexed chronologically.
- *
- * @property _entries
- * @type Object[]
- * @private
- */
- _entries: null,
-
- /////////////////////////////////////////////////////////////////////////////
- //
- // Cache private methods
- //
- /////////////////////////////////////////////////////////////////////////////
-
- /**
- * @method initializer
- * @description Internal init() handler.
- * @param config {Object} Config object.
- * @private
- */
- initializer: function(config) {
-
- /**
- * @event add
- * @description Fired when an entry is added.
- * @param e {Event.Facade} Event Facade with the following properties:
- * <dl>
- * <dt>entry (Object)</dt> <dd>The cached entry.</dd>
- * </dl>
- * @preventable _defAddFn
- */
- this.publish("add", {defaultFn: this._defAddFn});
-
- /**
- * @event flush
- * @description Fired when the cache is flushed.
- * @param e {Event.Facade} Event Facade object.
- * @preventable _defFlushFn
- */
- this.publish("flush", {defaultFn: this._defFlushFn});
-
- /**
- * @event request
- * @description Fired when an entry is requested from the cache.
- * @param e {Event.Facade} Event Facade with the following properties:
- * <dl>
- * <dt>request (Object)</dt> <dd>The request object.</dd>
- * </dl>
- */
-
- /**
- * @event retrieve
- * @description Fired when an entry is retrieved from the cache.
- * @param e {Event.Facade} Event Facade with the following properties:
- * <dl>
- * <dt>entry (Object)</dt> <dd>The retrieved entry.</dd>
- * </dl>
- */
-
- // Initialize internal values
- this._entries = [];
- Y.log("Cache initialized", "info", "cache");
- },
-
- /**
- * @method destructor
- * @description Internal destroy() handler.
- * @private
- */
- destructor: function() {
- this._entries = [];
- Y.log("Cache destroyed", "info", "cache");
- },
-
- /////////////////////////////////////////////////////////////////////////////
- //
- // Cache protected methods
- //
- /////////////////////////////////////////////////////////////////////////////
-
- /**
- * Sets max.
- *
- * @method _setMax
- * @protected
- */
- _setMax: function(value) {
- // If the cache is full, make room by removing stalest element (index=0)
- var entries = this._entries;
- if(value > 0) {
- if(entries) {
- while(entries.length > value) {
- entries.shift();
- }
- }
- }
- else {
- value = 0;
- this._entries = [];
- }
- return value;
- },
-
- /**
- * Gets size.
- *
- * @method _getSize
- * @protected
- */
- _getSize: function() {
- return this._entries.length;
- },
-
- /**
- * Gets all entries.
- *
- * @method _getEntries
- * @protected
- */
- _getEntries: function() {
- return this._entries;
- },
-
-
- /**
- * Adds entry to cache.
- *
- * @method _defAddFn
- * @param e {Event.Facade} Event Facade with the following properties:
- * <dl>
- * <dt>entry (Object)</dt> <dd>The cached entry.</dd>
- * </dl>
- * @protected
- */
- _defAddFn: function(e) {
- var entries = this._entries,
- max = this.get("max"),
- entry = e.entry;
-
- if(this.get("uniqueKeys") && (this.retrieve(e.entry.request))) {
- entries.shift();
- }
-
-
- // If the cache at or over capacity, make room by removing stalest element (index=0)
- while(max && entries.length>=max) {
- entries.shift();
- }
-
- // Add entry to cache in the newest position, at the end of the array
- entries[entries.length] = entry;
- Y.log("Cached entry: " + Y.dump(entry), "info", "cache");
- },
-
- /**
- * Flushes cache.
- *
- * @method _defFlushFn
- * @param e {Event.Facade} Event Facade object.
- * @protected
- */
- _defFlushFn: function(e) {
- var entries = this._entries,
- details = e.details[0],
- pos;
-
- //passed an item, flush only that
- if(details && LANG.isValue(details.request)) {
- pos = this._position(details.request);
-
- if(LANG.isValue(pos)) {
- entries.splice(pos,1);
-
- Y.log("Flushed cache item " + Y.dump(details.request), "info", "cache");
- }
- }
- //no item, flush everything
- else {
- this._entries = [];
- Y.log("Cache flushed", "info", "cache");
- }
- },
-
- /**
- * Default overridable method compares current request with given cache entry.
- * Returns true if current request matches the cached request, otherwise
- * false. Implementers should override this method to customize the
- * cache-matching algorithm.
- *
- * @method _isMatch
- * @param request {Object} Request object.
- * @param entry {Object} Cached entry.
- * @return {Boolean} True if current request matches given cached request, false otherwise.
- * @protected
- */
- _isMatch: function(request, entry) {
- if(!entry.expires || new Date() < entry.expires) {
- return (request === entry.request);
- }
- return false;
- },
-
- /**
- * Returns position of a request in the entries array, otherwise null.
- *
- * @method _position
- * @param request {Object} Request object.
- * @return {Number} Array position if found, null otherwise.
- * @protected
- */
- _position: function(request) {
- // If cache is enabled...
- var entries = this._entries,
- length = entries.length,
- i = length-1;
-
- if((this.get("max") === null) || this.get("max") > 0) {
- // Loop through each cached entry starting from the newest
- for(; i >= 0; i--) {
- // Execute matching function
- if(this._isMatch(request, entries[i])) {
- return i;
- }
- }
- }
-
- return null;
- },
-
- /////////////////////////////////////////////////////////////////////////////
- //
- // Cache public methods
- //
- /////////////////////////////////////////////////////////////////////////////
-
- /**
- * Adds a new entry to the cache of the format
- * {request:request, response:response, cached:cached, expires:expires}.
- * If cache is full, evicts the stalest entry before adding the new one.
- *
- * @method add
- * @param request {Object} Request value.
- * @param response {Object} Response value.
- */
- add: function(request, response) {
- var expires = this.get("expires");
- if(this.get("initialized") && ((this.get("max") === null) || this.get("max") > 0) &&
- (LANG.isValue(request) || LANG.isNull(request) || LANG.isUndefined(request))) {
- this.fire("add", {entry: {
- request:request,
- response:response,
- cached: new Date(),
- expires: isDate(expires) ? expires :
- (expires ? new Date(new Date().getTime() + this.get("expires")) : null)
- }});
- }
- else {
- Y.log("Could not add " + Y.dump(response) + " to cache for " + Y.dump(request), "info", "cache");
- }
- },
-
- /**
- * Flushes cache.
- *
- * @method flush
- */
- flush: function(request) {
- this.fire("flush", { request: (LANG.isValue(request) ? request : null) });
- },
-
- /**
- * Retrieves cached object for given request, if available, and refreshes
- * entry in the cache. Returns null if there is no cache match.
- *
- * @method retrieve
- * @param request {Object} Request object.
- * @return {Object} Cached object with the properties request and response, or null.
- */
- retrieve: function(request) {
- // If cache is enabled...
- var entries = this._entries,
- length = entries.length,
- entry = null,
- pos;
-
- if((length > 0) && ((this.get("max") === null) || (this.get("max") > 0))) {
- this.fire("request", {request: request});
-
- pos = this._position(request);
-
- if(LANG.isValue(pos)) {
- entry = entries[pos];
-
- this.fire("retrieve", {entry: entry});
-
- // Refresh the position of the cache hit
- if(pos < length-1) {
- // Remove element from its original location
- entries.splice(pos,1);
- // Add as newest
- entries[entries.length] = entry;
- Y.log("Refreshed cache entry: " + Y.dump(entry) +
- " for request: " + Y.dump(request), "info", "cache");
- }
-
- Y.log("Retrieved cached response: " + Y.dump(entry) +
- " for request: " + Y.dump(request), "info", "cache");
- return entry;
- }
- }
- return null;
- }
- });
-
- Y.Cache = Cache;
-
-
- }, '3.4.0' ,{requires:['base']});
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