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1 /* |
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2 Copyright (c) 2009, Yahoo! Inc. All rights reserved. |
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3 Code licensed under the BSD License: |
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4 http://developer.yahoo.net/yui/license.txt |
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5 version: 3.0.0 |
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6 build: 1549 |
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7 */ |
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8 YUI.add('cache', function(Y) { |
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9 |
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10 /** |
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11 * The Cache utility provides a common configurable interface for components to |
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12 * cache and retrieve data from a local JavaScript struct. |
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13 * |
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14 * @module cache |
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15 */ |
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16 var LANG = Y.Lang, |
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17 |
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18 /** |
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19 * Base class for the YUI Cache utility. |
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20 * @class Cache |
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21 * @extends Plugin.Base |
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22 * @constructor |
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23 */ |
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24 Cache = function() { |
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25 Cache.superclass.constructor.apply(this, arguments); |
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26 }; |
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27 |
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28 ///////////////////////////////////////////////////////////////////////////// |
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29 // |
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30 // Cache static properties |
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31 // |
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32 ///////////////////////////////////////////////////////////////////////////// |
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33 Y.mix(Cache, { |
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34 /** |
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35 * The namespace for the plugin. This will be the property on the host which |
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36 * references the plugin instance. |
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37 * |
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38 * @property NS |
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39 * @type String |
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40 * @static |
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41 * @final |
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42 * @value "cache" |
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43 */ |
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44 NS: "cache", |
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45 |
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46 |
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47 /** |
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48 * Class name. |
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49 * |
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50 * @property NAME |
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51 * @type String |
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52 * @static |
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53 * @final |
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54 * @value "cache" |
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55 */ |
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56 NAME: "cache", |
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57 |
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58 |
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59 ATTRS: { |
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60 ///////////////////////////////////////////////////////////////////////////// |
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61 // |
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62 // Cache Attributes |
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63 // |
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64 ///////////////////////////////////////////////////////////////////////////// |
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65 |
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66 /** |
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67 * @attribute max |
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68 * @description Maximum number of entries the Cache can hold. |
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69 * Set to 0 to turn off caching. |
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70 * @type Number |
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71 * @default 0 |
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72 */ |
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73 max: { |
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74 value: 0, |
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75 validator: function(value) { |
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76 return (LANG.isNumber(value)); |
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77 }, |
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78 setter: function(value) { |
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79 // If the cache is full, make room by removing stalest element (index=0) |
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80 var entries = this._entries; |
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81 if(value > 0) { |
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82 if(entries) { |
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83 while(entries.length > value) { |
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84 entries.shift(); |
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85 } |
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86 } |
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87 } |
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88 else { |
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89 this._entries = []; |
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90 } |
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91 return value; |
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92 } |
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93 }, |
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94 |
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95 /** |
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96 * @attribute size |
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97 * @description Number of entries currently cached. |
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98 * @type Number |
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99 */ |
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100 size: { |
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101 readOnly: true, |
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102 getter: function() { |
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103 return this._entries.length; |
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104 } |
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105 }, |
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106 |
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107 /** |
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108 * @attribute uniqueKeys |
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109 * @description Validate uniqueness of stored keys. Default is false and |
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110 * is more performant. |
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111 * @type Number |
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112 */ |
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113 uniqueKeys: { |
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114 value: false, |
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115 validator: function(value) { |
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116 return (LANG.isBoolean(value)); |
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117 } |
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118 }, |
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119 |
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120 /** |
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121 * @attribute entries |
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122 * @description Cached entries. |
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123 * @type Array |
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124 */ |
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125 entries: { |
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126 readOnly: true, |
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127 getter: function() { |
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128 return this._entries; |
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129 } |
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130 } |
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131 } |
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132 }); |
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133 |
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134 Y.extend(Cache, Y.Plugin.Base, { |
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135 ///////////////////////////////////////////////////////////////////////////// |
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136 // |
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137 // Cache private properties |
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138 // |
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139 ///////////////////////////////////////////////////////////////////////////// |
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140 |
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141 /** |
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142 * Array of request/response objects indexed chronologically. |
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143 * |
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144 * @property _entries |
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145 * @type Object[] |
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146 * @private |
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147 */ |
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148 _entries: null, |
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149 |
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150 ///////////////////////////////////////////////////////////////////////////// |
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151 // |
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152 // Cache private methods |
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153 // |
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154 ///////////////////////////////////////////////////////////////////////////// |
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155 |
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156 /** |
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157 * @method initializer |
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158 * @description Internal init() handler. |
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159 * @param config {Object} Config object. |
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160 * @private |
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161 */ |
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162 initializer: function(config) { |
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163 |
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164 /** |
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165 * @event add |
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166 * @description Fired when an entry is added. |
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167 * @param e {Event.Facade} Event Facade with the following properties: |
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168 * <dl> |
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169 * <dt>entry (Object)</dt> <dd>The cached entry.</dd> |
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170 * </dl> |
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171 * @preventable _defAddFn |
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172 */ |
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173 this.publish("add", {defaultFn: this._defAddFn}); |
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174 |
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175 /** |
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176 * @event flush |
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177 * @description Fired when the cache is flushed. |
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178 * @param e {Event.Facade} Event Facade object. |
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179 * @preventable _defFlushFn |
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180 */ |
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181 this.publish("flush", {defaultFn: this._defFlushFn}); |
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182 |
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183 /** |
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184 * @event request |
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185 * @description Fired when an entry is requested from the cache. |
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186 * @param e {Event.Facade} Event Facade with the following properties: |
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187 * <dl> |
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188 * <dt>request (Object)</dt> <dd>The request object.</dd> |
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189 * </dl> |
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190 */ |
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191 |
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192 /** |
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193 * @event retrieve |
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194 * @description Fired when an entry is retrieved from the cache. |
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195 * @param e {Event.Facade} Event Facade with the following properties: |
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196 * <dl> |
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197 * <dt>entry (Object)</dt> <dd>The retrieved entry.</dd> |
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198 * </dl> |
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199 */ |
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200 |
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201 // Initialize internal values |
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202 this._entries = []; |
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203 }, |
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204 |
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205 /** |
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206 * @method destructor |
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207 * @description Internal destroy() handler. |
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208 * @private |
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209 */ |
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210 destructor: function() { |
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211 this._entries = null; |
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212 }, |
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213 |
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214 ///////////////////////////////////////////////////////////////////////////// |
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215 // |
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216 // Cache protected methods |
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217 // |
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218 ///////////////////////////////////////////////////////////////////////////// |
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219 |
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220 /** |
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221 * Adds entry to cache. |
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222 * |
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223 * @method _defAddFn |
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224 * @param e {Event.Facade} Event Facade with the following properties: |
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225 * <dl> |
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226 * <dt>entry (Object)</dt> <dd>The cached entry.</dd> |
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227 * </dl> |
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228 * @protected |
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229 */ |
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230 _defAddFn: function(e) { |
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231 var entries = this._entries, |
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232 max = this.get("max"), |
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233 entry = e.entry; |
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234 |
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235 if(this.get("uniqueKeys") && (this.retrieve(e.entry.request))) { |
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236 entries.shift(); |
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237 } |
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238 |
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239 |
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240 // If the cache at or over capacity, make room by removing stalest element (index=0) |
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241 while(entries.length>=max) { |
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242 entries.shift(); |
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243 } |
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244 |
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245 // Add entry to cache in the newest position, at the end of the array |
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246 entries[entries.length] = entry; |
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247 }, |
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248 |
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249 /** |
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250 * Flushes cache. |
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251 * |
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252 * @method _defFlushFn |
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253 * @param e {Event.Facade} Event Facade object. |
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254 * @protected |
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255 */ |
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256 _defFlushFn: function(e) { |
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257 this._entries = []; |
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258 }, |
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259 |
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260 /** |
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261 * Default overridable method compares current request with given cache entry. |
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262 * Returns true if current request matches the cached request, otherwise |
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263 * false. Implementers should override this method to customize the |
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264 * cache-matching algorithm. |
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265 * |
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266 * @method _isMatch |
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267 * @param request {Object} Request object. |
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268 * @param entry {Object} Cached entry. |
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269 * @return {Boolean} True if current request matches given cached request, false otherwise. |
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270 * @protected |
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271 */ |
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272 _isMatch: function(request, entry) { |
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273 return (request === entry.request); |
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274 }, |
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275 |
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276 ///////////////////////////////////////////////////////////////////////////// |
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277 // |
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278 // Cache public methods |
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279 // |
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280 ///////////////////////////////////////////////////////////////////////////// |
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281 |
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282 /** |
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283 * Adds a new entry to the cache of the format |
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284 * {request:request, response:response, payload:payload}. |
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285 * If cache is full, evicts the stalest entry before adding the new one. |
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286 * |
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287 * @method add |
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288 * @param request {Object} Request value. |
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289 * @param response {Object} Response value. |
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290 * @param payload {Object} (optional) Arbitrary data payload. |
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291 */ |
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292 add: function(request, response, payload) { |
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293 if(this.get("entries") && (this.get("max")>0) && |
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294 (LANG.isValue(request) || LANG.isNull(request) || LANG.isUndefined(request))) { |
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295 this.fire("add", {entry: {request:request, response:response, payload:payload}}); |
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296 } |
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297 else { |
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298 } |
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299 }, |
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300 |
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301 /** |
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302 * Flushes cache. |
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303 * |
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304 * @method flush |
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305 */ |
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306 flush: function() { |
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307 this.fire("flush"); |
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308 }, |
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309 |
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310 /** |
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311 * Retrieves cached entry for given request, if available, and refreshes |
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312 * entry in the cache. Returns null if there is no cache match. |
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313 * |
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314 * @method retrieve |
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315 * @param request {Object} Request object. |
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316 * @return {Object} Cached entry object with the properties request, response, and payload, or null. |
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317 */ |
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318 retrieve: function(request) { |
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319 // If cache is enabled... |
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320 var entries = this._entries, |
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321 length = entries.length, |
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322 entry = null, |
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323 i = length-1; |
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324 |
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325 if((this.get("max") > 0) && (length > 0)) { |
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326 this.fire("request", {request: request}); |
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327 |
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328 // Loop through each cached entry starting from the newest |
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329 for(; i >= 0; i--) { |
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330 entry = entries[i]; |
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331 |
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332 // Execute matching function |
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333 if(this._isMatch(request, entry)) { |
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334 this.fire("retrieve", {entry: entry}); |
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335 |
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336 // Refresh the position of the cache hit |
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337 if(i < length-1) { |
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338 // Remove element from its original location |
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339 entries.splice(i,1); |
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340 // Add as newest |
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341 entries[entries.length] = entry; |
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342 } |
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343 |
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344 return entry; |
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345 } |
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346 } |
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347 } |
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348 return null; |
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349 } |
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350 }); |
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351 |
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352 Y.Cache = Cache; |
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353 |
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354 |
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355 |
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356 |
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357 }, '3.0.0' ,{requires:['plugin']}); |