resources/jquery/jquery.jStorage.js

   1 /*
   2  * ----------------------------- JSTORAGE -------------------------------------
   3  * Simple local storage wrapper to save data on the browser side, supporting
   4  * all major browsers - IE6+, Firefox2+, Safari4+, Chrome4+ and Opera 10.5+
   5  *
   6  * Copyright (c) 2010 - 2012 Andris Reinman, andris.reinman@gmail.com
   7  * Project homepage: www.jstorage.info
   8  *
   9  * Licensed under MIT-style license:
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a copy
  12  * of this software and associated documentation files (the "Software"), to deal
  13  * in the Software without restriction, including without limitation the rights
  14  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15  * copies of the Software, and to permit persons to whom the Software is
  16  * furnished to do so, subject to the following conditions:
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  24  * SOFTWARE.
  25  */
  26
  27  (function(){
  28     var
  29         /* jStorage version */
  30         JSTORAGE_VERSION = "0.3.0",
  31
  32         /* detect a dollar object or create one if not found */
  33         $ = window.jQuery || window.$ || (window.$ = {}),
  34
  35         /* check for a JSON handling support */
  36         JSON = {
  37             parse:
  38                 window.JSON && (window.JSON.parse || window.JSON.decode) ||
  39                 String.prototype.evalJSON && function(str){return String(str).evalJSON();} ||
  40                 $.parseJSON ||
  41                 $.evalJSON,
  42             stringify:
  43                 Object.toJSON ||
  44                 window.JSON && (window.JSON.stringify || window.JSON.encode) ||
  45                 $.toJSON
  46         };
  47
  48     // Break if no JSON support was found
  49     if(!JSON.parse || !JSON.stringify){
  50         throw new Error("No JSON support found, include //cdnjs.cloudflare.com/ajax/libs/json2/20110223/json2.js to page");
  51     }
  52
  53     var
  54         /* This is the object, that holds the cached values */
  55         _storage = {},
  56
  57         /* Actual browser storage (localStorage or globalStorage['domain']) */
  58         _storage_service = {jStorage:"{}"},
  59
  60         /* DOM element for older IE versions, holds userData behavior */
  61         _storage_elm = null,
  62
  63         /* How much space does the storage take */
  64         _storage_size = 0,
  65
  66         /* which backend is currently used */
  67         _backend = false,
  68
  69         /* onchange observers */
  70         _observers = {},
  71
  72         /* timeout to wait after onchange event */
  73         _observer_timeout = false,
  74
  75         /* last update time */
  76         _observer_update = 0,
  77
  78         /* pubsub observers */
  79         _pubsub_observers = {},
  80
  81         /* skip published items older than current timestamp */
  82         _pubsub_last = +new Date(),
  83
  84         /* Next check for TTL */
  85         _ttl_timeout,
  86
  87         /* crc32 table */
  88         _crc32Table = "00000000 77073096 EE0E612C 990951BA 076DC419 706AF48F E963A535 9E6495A3 "+
  89              "0EDB8832 79DCB8A4 E0D5E91E 97D2D988 09B64C2B 7EB17CBD E7B82D07 90BF1D91 1DB71064 "+
  90              "6AB020F2 F3B97148 84BE41DE 1ADAD47D 6DDDE4EB F4D4B551 83D385C7 136C9856 646BA8C0 "+
  91              "FD62F97A 8A65C9EC 14015C4F 63066CD9 FA0F3D63 8D080DF5 3B6E20C8 4C69105E D56041E4 "+
  92              "A2677172 3C03E4D1 4B04D447 D20D85FD A50AB56B 35B5A8FA 42B2986C DBBBC9D6 ACBCF940 "+
  93              "32D86CE3 45DF5C75 DCD60DCF ABD13D59 26D930AC 51DE003A C8D75180 BFD06116 21B4F4B5 "+
  94              "56B3C423 CFBA9599 B8BDA50F 2802B89E 5F058808 C60CD9B2 B10BE924 2F6F7C87 58684C11 "+
  95              "C1611DAB B6662D3D 76DC4190 01DB7106 98D220BC EFD5102A 71B18589 06B6B51F 9FBFE4A5 "+
  96              "E8B8D433 7807C9A2 0F00F934 9609A88E E10E9818 7F6A0DBB 086D3D2D 91646C97 E6635C01 "+
  97              "6B6B51F4 1C6C6162 856530D8 F262004E 6C0695ED 1B01A57B 8208F4C1 F50FC457 65B0D9C6 "+
  98              "12B7E950 8BBEB8EA FCB9887C 62DD1DDF 15DA2D49 8CD37CF3 FBD44C65 4DB26158 3AB551CE "+
  99              "A3BC0074 D4BB30E2 4ADFA541 3DD895D7 A4D1C46D D3D6F4FB 4369E96A 346ED9FC AD678846 "+
 100              "DA60B8D0 44042D73 33031DE5 AA0A4C5F DD0D7CC9 5005713C 270241AA BE0B1010 C90C2086 "+
 101              "5768B525 206F85B3 B966D409 CE61E49F 5EDEF90E 29D9C998 B0D09822 C7D7A8B4 59B33D17 "+
 102              "2EB40D81 B7BD5C3B C0BA6CAD EDB88320 9ABFB3B6 03B6E20C 74B1D29A EAD54739 9DD277AF "+
 103              "04DB2615 73DC1683 E3630B12 94643B84 0D6D6A3E 7A6A5AA8 E40ECF0B 9309FF9D 0A00AE27 "+
 104              "7D079EB1 F00F9344 8708A3D2 1E01F268 6906C2FE F762575D 806567CB 196C3671 6E6B06E7 "+
 105              "FED41B76 89D32BE0 10DA7A5A 67DD4ACC F9B9DF6F 8EBEEFF9 17B7BE43 60B08ED5 D6D6A3E8 "+
 106              "A1D1937E 38D8C2C4 4FDFF252 D1BB67F1 A6BC5767 3FB506DD 48B2364B D80D2BDA AF0A1B4C "+
 107              "36034AF6 41047A60 DF60EFC3 A867DF55 316E8EEF 4669BE79 CB61B38C BC66831A 256FD2A0 "+
 108              "5268E236 CC0C7795 BB0B4703 220216B9 5505262F C5BA3BBE B2BD0B28 2BB45A92 5CB36A04 "+
 109              "C2D7FFA7 B5D0CF31 2CD99E8B 5BDEAE1D 9B64C2B0 EC63F226 756AA39C 026D930A 9C0906A9 "+
 110              "EB0E363F 72076785 05005713 95BF4A82 E2B87A14 7BB12BAE 0CB61B38 92D28E9B E5D5BE0D "+
 111              "7CDCEFB7 0BDBDF21 86D3D2D4 F1D4E242 68DDB3F8 1FDA836E 81BE16CD F6B9265B 6FB077E1 "+
 112              "18B74777 88085AE6 FF0F6A70 66063BCA 11010B5C 8F659EFF F862AE69 616BFFD3 166CCF45 "+
 113              "A00AE278 D70DD2EE 4E048354 3903B3C2 A7672661 D06016F7 4969474D 3E6E77DB AED16A4A "+
 114              "D9D65ADC 40DF0B66 37D83BF0 A9BCAE53 DEBB9EC5 47B2CF7F 30B5FFE9 BDBDF21C CABAC28A "+
 115              "53B39330 24B4A3A6 BAD03605 CDD70693 54DE5729 23D967BF B3667A2E C4614AB8 5D681B02 "+
 116              "2A6F2B94 B40BBE37 C30C8EA1 5A05DF1B 2D02EF8D",
 117
 118         /**
 119          * XML encoding and decoding as XML nodes can't be JSON'ized
 120          * XML nodes are encoded and decoded if the node is the value to be saved
 121          * but not if it's as a property of another object
 122          * Eg. -
 123          *   $.jStorage.set("key", xmlNode);        // IS OK
 124          *   $.jStorage.set("key", {xml: xmlNode}); // NOT OK
 125          */
 126         _XMLService = {
 127
 128             /**
 129              * Validates a XML node to be XML
 130              * based on jQuery.isXML function
 131              */
 132             isXML: function(elm){
 133                 var documentElement = (elm ? elm.ownerDocument || elm : 0).documentElement;
 134                 return documentElement ? documentElement.nodeName !== "HTML" : false;
 135             },
 136
 137             /**
 138              * Encodes a XML node to string
 139              * based on http://www.mercurytide.co.uk/news/article/issues-when-working-ajax/
 140              */
 141             encode: function(xmlNode) {
 142                 if(!this.isXML(xmlNode)){
 143                     return false;
 144                 }
 145                 try{ // Mozilla, Webkit, Opera
 146                     return new XMLSerializer().serializeToString(xmlNode);
 147                 }catch(E1) {
 148                     try {  // IE
 149                         return xmlNode.xml;
 150                     }catch(E2){}
 151                 }
 152                 return false;
 153             },
 154
 155             /**
 156              * Decodes a XML node from string
 157              * loosely based on http://outwestmedia.com/jquery-plugins/xmldom/
 158              */
 159             decode: function(xmlString){
 160                 var dom_parser = ("DOMParser" in window && (new DOMParser()).parseFromString) ||
 161                         (window.ActiveXObject && function(_xmlString) {
 162                     var xml_doc = new ActiveXObject('Microsoft.XMLDOM');
 163                     xml_doc.async = 'false';
 164                     xml_doc.loadXML(_xmlString);
 165                     return xml_doc;
 166                 }),
 167                 resultXML;
 168                 if(!dom_parser){
 169                     return false;
 170                 }
 171                 resultXML = dom_parser.call("DOMParser" in window && (new DOMParser()) || window, xmlString, 'text/xml');
 172                 return this.isXML(resultXML)?resultXML:false;
 173             }
 174         },
 175
 176         _localStoragePolyfillSetKey = function(){};
 177
 178
 179     ////////////////////////// PRIVATE METHODS ////////////////////////
 180
 181     /**
 182      * Initialization function. Detects if the browser supports DOM Storage
 183      * or userData behavior and behaves accordingly.
 184      */
 185     function _init(){
 186         /* Check if browser supports localStorage */
 187         var localStorageReallyWorks = false;
 188         if("localStorage" in window){
 189             try {
 190                 window.localStorage.setItem('_tmptest', 'tmpval');
 191                 localStorageReallyWorks = true;
 192                 window.localStorage.removeItem('_tmptest');
 193             } catch(BogusQuotaExceededErrorOnIos5) {
 194                 // Thanks be to iOS5 Private Browsing mode which throws
 195                 // QUOTA_EXCEEDED_ERRROR DOM Exception 22.
 196             }
 197         }
 198
 199         if(localStorageReallyWorks){
 200             try {
 201                 if(window.localStorage) {
 202                     _storage_service = window.localStorage;
 203                     _backend = "localStorage";
 204                     _observer_update = _storage_service.jStorage_update;
 205                 }
 206             } catch(E3) {/* Firefox fails when touching localStorage and cookies are disabled */}
 207         }
 208         /* Check if browser supports globalStorage */
 209         else if("globalStorage" in window){
 210             try {
 211                 if(window.globalStorage) {
 212                     _storage_service = window.globalStorage[window.location.hostname];
 213                     _backend = "globalStorage";
 214                     _observer_update = _storage_service.jStorage_update;
 215                 }
 216             } catch(E4) {/* Firefox fails when touching localStorage and cookies are disabled */}
 217         }
 218         /* Check if browser supports userData behavior */
 219         else {
 220             _storage_elm = document.createElement('link');
 221             if(_storage_elm.addBehavior){
 222
 223                 /* Use a DOM element to act as userData storage */
 224                 _storage_elm.style.behavior = 'url(#default#userData)';
 225
 226                 /* userData element needs to be inserted into the DOM! */
 227                 document.getElementsByTagName('head')[0].appendChild(_storage_elm);
 228
 229                 try{
 230                     _storage_elm.load("jStorage");
 231                 }catch(E){
 232                     // try to reset cache
 233                     _storage_elm.setAttribute("jStorage", "{}");
 234                     _storage_elm.save("jStorage");
 235                     _storage_elm.load("jStorage");
 236                 }
 237
 238                 var data = "{}";
 239                 try{
 240                     data = _storage_elm.getAttribute("jStorage");
 241                 }catch(E5){}
 242
 243                 try{
 244                     _observer_update = _storage_elm.getAttribute("jStorage_update");
 245                 }catch(E6){}
 246
 247                 _storage_service.jStorage = data;
 248                 _backend = "userDataBehavior";
 249             }else{
 250                 _storage_elm = null;
 251                 return;
 252             }
 253         }
 254
 255         // Load data from storage
 256         _load_storage();
 257
 258         // remove dead keys
 259         _handleTTL();
 260
 261         // create localStorage and sessionStorage polyfills if needed
 262         _createPolyfillStorage("local");
 263         _createPolyfillStorage("session");
 264
 265         // start listening for changes
 266         _setupObserver();
 267
 268         // initialize publish-subscribe service
 269         _handlePubSub();
 270
 271         // handle cached navigation
 272         if("addEventListener" in window){
 273             window.addEventListener("pageshow", function(event){
 274                 if(event.persisted){
 275                     _storageObserver();
 276                 }
 277             }, false);
 278         }
 279     }
 280
 281     /**
 282      * Create a polyfill for localStorage (type="local") or sessionStorage (type="session")
 283      *
 284      * @param {String} type Either "local" or "session"
 285      * @param {Boolean} forceCreate If set to true, recreate the polyfill (needed with flush)
 286      */
 287     function _createPolyfillStorage(type, forceCreate){
 288         var _skipSave = false,
 289             _length = 0,
 290             i,
 291             storage,
 292             storage_source = {};
 293
 294             var rand = Math.random();
 295
 296         if(!forceCreate && typeof window[type+"Storage"] != "undefined"){
 297             return;
 298         }
 299
 300         // Use globalStorage for localStorage if available
 301         if(type == "local" && window.globalStorage){
 302             localStorage = window.globalStorage[window.location.hostname];
 303             return;
 304         }
 305
 306         // only IE6/7 from this point on
 307         if(_backend != "userDataBehavior"){
 308             return;
 309         }
 310
 311         // Remove existing storage element if available
 312         if(forceCreate && window[type+"Storage"] && window[type+"Storage"].parentNode){
 313             window[type+"Storage"].parentNode.removeChild(window[type+"Storage"]);
 314         }
 315
 316         storage = document.createElement("button");
 317         document.getElementsByTagName('head')[0].appendChild(storage);
 318
 319         if(type == "local"){
 320             storage_source = _storage;
 321         }else if(type == "session"){
 322             _sessionStoragePolyfillUpdate();
 323         }
 324
 325         for(i in storage_source){
 326
 327             if(storage_source.hasOwnProperty(i) && i != "__jstorage_meta" && i != "length" && typeof storage_source[i] != "undefined"){
 328                 if(!(i in storage)){
 329                     _length++;
 330                 }
 331                 storage[i] = storage_source[i];
 332             }
 333         }
 334
 335         // Polyfill API
 336
 337         /**
 338          * Indicates how many keys are stored in the storage
 339          */
 340         storage.length = _length;
 341
 342         /**
 343          * Returns the key of the nth stored value
 344          *
 345          * @param {Number} n Index position
 346          * @return {String} Key name of the nth stored value
 347          */
 348         storage.key = function(n){
 349             var count = 0, i;
 350             _sessionStoragePolyfillUpdate();
 351             for(i in storage_source){
 352                 if(storage_source.hasOwnProperty(i) && i != "__jstorage_meta" && i!="length" && typeof storage_source[i] != "undefined"){
 353                     if(count == n){
 354                         return i;
 355                     }
 356                     count++;
 357                 }
 358             }
 359         }
 360
 361         /**
 362          * Returns the current value associated with the given key
 363          *
 364          * @param {String} key key name
 365          * @return {Mixed} Stored value
 366          */
 367         storage.getItem = function(key){
 368             _sessionStoragePolyfillUpdate();
 369             if(type == "session"){
 370                 return storage_source[key];
 371             }
 372             return $.jStorage.get(key);
 373         }
 374
 375         /**
 376          * Sets or updates value for a give key
 377          *
 378          * @param {String} key Key name to be updated
 379          * @param {String} value String value to be stored
 380          */
 381         storage.setItem = function(key, value){
 382             if(typeof value == "undefined"){
 383                 return;
 384             }
 385             storage[key] = (value || "").toString();
 386         }
 387
 388         /**
 389          * Removes key from the storage
 390          *
 391          * @param {String} key Key name to be removed
 392          */
 393         storage.removeItem = function(key){
 394             if(type == "local"){
 395                 return $.jStorage.deleteKey(key);
 396             }
 397
 398             storage[key] = undefined;
 399
 400             _skipSave = true;
 401             if(key in storage){
 402                 storage.removeAttribute(key);
 403             }
 404             _skipSave = false;
 405         }
 406
 407         /**
 408          * Clear storage
 409          */
 410         storage.clear = function(){
 411             if(type == "session"){
 412                 window.name = "";
 413                 _createPolyfillStorage("session", true);
 414                 return;
 415             }
 416             $.jStorage.flush();
 417         }
 418
 419         if(type == "local"){
 420
 421             _localStoragePolyfillSetKey = function(key, value){
 422                 if(key == "length"){
 423                     return;
 424                 }
 425                 _skipSave = true;
 426                 if(typeof value == "undefined"){
 427                     if(key in storage){
 428                         _length--;
 429                         storage.removeAttribute(key);
 430                     }
 431                 }else{
 432                     if(!(key in storage)){
 433                         _length++;
 434                     }
 435                     storage[key] = (value || "").toString();
 436                 }
 437                 storage.length = _length;
 438                 _skipSave = false;
 439             }
 440         }
 441
 442         function _sessionStoragePolyfillUpdate(){
 443                 if(type != "session"){
 444                     return;
 445                 }
 446                 try{
 447                     storage_source = JSON.parse(window.name || "{}");
 448                 }catch(E){
 449                     storage_source = {};
 450                 }
 451             }
 452
 453         function _sessionStoragePolyfillSave(){
 454             if(type != "session"){
 455                 return;
 456             }
 457             window.name = JSON.stringify(storage_source);
 458         };
 459
 460         storage.attachEvent("onpropertychange", function(e){
 461             if(e.propertyName == "length"){
 462                 return;
 463             }
 464
 465             if(_skipSave || e.propertyName == "length"){
 466                 return;
 467             }
 468
 469             if(type == "local"){
 470                 if(!(e.propertyName in storage_source) && typeof storage[e.propertyName] != "undefined"){
 471                     _length ++;
 472                 }
 473             }else if(type == "session"){
 474                 _sessionStoragePolyfillUpdate();
 475                 if(typeof storage[e.propertyName] != "undefined" && !(e.propertyName in storage_source)){
 476                     storage_source[e.propertyName] = storage[e.propertyName];
 477                     _length++;
 478                 }else if(typeof storage[e.propertyName] == "undefined" && e.propertyName in storage_source){
 479                     delete storage_source[e.propertyName];
 480                     _length--;
 481                 }else{
 482                     storage_source[e.propertyName] = storage[e.propertyName];
 483                 }
 484
 485                 _sessionStoragePolyfillSave();
 486                 storage.length = _length;
 487                 return;
 488             }
 489
 490             $.jStorage.set(e.propertyName, storage[e.propertyName]);
 491             storage.length = _length;
 492         });
 493
 494         window[type+"Storage"] = storage;
 495     }
 496
 497     /**
 498      * Reload data from storage when needed
 499      */
 500     function _reloadData(){
 501         var data = "{}";
 502
 503         if(_backend == "userDataBehavior"){
 504             _storage_elm.load("jStorage");
 505
 506             try{
 507                 data = _storage_elm.getAttribute("jStorage");
 508             }catch(E5){}
 509
 510             try{
 511                 _observer_update = _storage_elm.getAttribute("jStorage_update");
 512             }catch(E6){}
 513
 514             _storage_service.jStorage = data;
 515         }
 516
 517         _load_storage();
 518
 519         // remove dead keys
 520         _handleTTL();
 521
 522         _handlePubSub();
 523     }
 524
 525     /**
 526      * Sets up a storage change observer
 527      */
 528     function _setupObserver(){
 529         if(_backend == "localStorage" || _backend == "globalStorage"){
 530             if("addEventListener" in window){
 531                 window.addEventListener("storage", _storageObserver, false);
 532             }else{
 533                 document.attachEvent("onstorage", _storageObserver);
 534             }
 535         }else if(_backend == "userDataBehavior"){
 536             setInterval(_storageObserver, 1000);
 537         }
 538     }
 539
 540     /**
 541      * Fired on any kind of data change, needs to check if anything has
 542      * really been changed
 543      */
 544     function _storageObserver(){
 545         var updateTime;
 546         // cumulate change notifications with timeout
 547         clearTimeout(_observer_timeout);
 548         _observer_timeout = setTimeout(function(){
 549
 550             if(_backend == "localStorage" || _backend == "globalStorage"){
 551                 updateTime = _storage_service.jStorage_update;
 552             }else if(_backend == "userDataBehavior"){
 553                 _storage_elm.load("jStorage");
 554                 try{
 555                     updateTime = _storage_elm.getAttribute("jStorage_update");
 556                 }catch(E5){}
 557             }
 558
 559             if(updateTime && updateTime != _observer_update){
 560                 _observer_update = updateTime;
 561                 _checkUpdatedKeys();
 562             }
 563
 564         }, 25);
 565     }
 566
 567     /**
 568      * Reloads the data and checks if any keys are changed
 569      */
 570     function _checkUpdatedKeys(){
 571         var oldCrc32List = JSON.parse(JSON.stringify(_storage.__jstorage_meta.CRC32)),
 572             newCrc32List;
 573
 574         _reloadData();
 575         newCrc32List = JSON.parse(JSON.stringify(_storage.__jstorage_meta.CRC32));
 576
 577         var key,
 578             updated = [],
 579             removed = [];
 580
 581         for(key in oldCrc32List){
 582             if(oldCrc32List.hasOwnProperty(key)){
 583                 if(!newCrc32List[key]){
 584                     removed.push(key);
 585                     continue;
 586                 }
 587                 if(oldCrc32List[key] != newCrc32List[key]){
 588                     updated.push(key);
 589                 }
 590             }
 591         }
 592
 593         for(key in newCrc32List){
 594             if(newCrc32List.hasOwnProperty(key)){
 595                 if(!oldCrc32List[key]){
 596                     updated.push(key);
 597                 }
 598             }
 599         }
 600
 601         _fireObservers(updated, "updated");
 602         _fireObservers(removed, "deleted");
 603     }
 604
 605     /**
 606      * Fires observers for updated keys
 607      *
 608      * @param {Array|String} keys Array of key names or a key
 609      * @param {String} action What happened with the value (updated, deleted, flushed)
 610      */
 611     function _fireObservers(keys, action){
 612         keys = [].concat(keys || []);
 613         if(action == "flushed"){
 614             keys = [];
 615             for(var key in _observers){
 616                 if(_observers.hasOwnProperty(key)){
 617                     keys.push(key);
 618                 }
 619             }
 620             action = "deleted";
 621         }
 622         for(var i=0, len = keys.length; i<len; i++){
 623             if(_observers[keys[i]]){
 624                 for(var j=0, jlen = _observers[keys[i]].length; j<jlen; j++){
 625                     _observers[keys[i]][j](keys[i], action);
 626                 }
 627             }
 628         }
 629     }
 630
 631     /**
 632      * Publishes key change to listeners
 633      */
 634     function _publishChange(){
 635         var updateTime = (+new Date()).toString();
 636
 637         if(_backend == "localStorage" || _backend == "globalStorage"){
 638             _storage_service.jStorage_update = updateTime;
 639         }else if(_backend == "userDataBehavior"){
 640             _storage_elm.setAttribute("jStorage_update", updateTime);
 641             _storage_elm.save("jStorage");
 642         }
 643
 644         _storageObserver();
 645     }
 646
 647     /**
 648      * Loads the data from the storage based on the supported mechanism
 649      */
 650     function _load_storage(){
 651         /* if jStorage string is retrieved, then decode it */
 652         if(_storage_service.jStorage){
 653             try{
 654                 _storage = JSON.parse(String(_storage_service.jStorage));
 655             }catch(E6){_storage_service.jStorage = "{}";}
 656         }else{
 657             _storage_service.jStorage = "{}";
 658         }
 659         _storage_size = _storage_service.jStorage?String(_storage_service.jStorage).length:0;
 660
 661         if(!_storage.__jstorage_meta){
 662             _storage.__jstorage_meta = {};
 663         }
 664         if(!_storage.__jstorage_meta.CRC32){
 665             _storage.__jstorage_meta.CRC32 = {};
 666         }
 667     }
 668
 669     /**
 670      * This functions provides the "save" mechanism to store the jStorage object
 671      */
 672     function _save(){
 673         _dropOldEvents(); // remove expired events
 674         try{
 675             _storage_service.jStorage = JSON.stringify(_storage);
 676             // If userData is used as the storage engine, additional
 677             if(_storage_elm) {
 678                 _storage_elm.setAttribute("jStorage",_storage_service.jStorage);
 679                 _storage_elm.save("jStorage");
 680             }
 681             _storage_size = _storage_service.jStorage?String(_storage_service.jStorage).length:0;
 682         }catch(E7){/* probably cache is full, nothing is saved this way*/}
 683     }
 684
 685     /**
 686      * Function checks if a key is set and is string or numberic
 687      *
 688      * @param {String} key Key name
 689      */
 690     function _checkKey(key){
 691         if(!key || (typeof key != "string" && typeof key != "number")){
 692             throw new TypeError('Key name must be string or numeric');
 693         }
 694         if(key == "__jstorage_meta"){
 695             throw new TypeError('Reserved key name');
 696         }
 697         return true;
 698     }
 699
 700     /**
 701      * Removes expired keys
 702      */
 703     function _handleTTL(){
 704         var curtime, i, TTL, CRC32, nextExpire = Infinity, changed = false, deleted = [];
 705
 706         clearTimeout(_ttl_timeout);
 707
 708         if(!_storage.__jstorage_meta || typeof _storage.__jstorage_meta.TTL != "object"){
 709             // nothing to do here
 710             return;
 711         }
 712
 713         curtime = +new Date();
 714         TTL = _storage.__jstorage_meta.TTL;
 715
 716         CRC32 = _storage.__jstorage_meta.CRC32;
 717         for(i in TTL){
 718             if(TTL.hasOwnProperty(i)){
 719                 if(TTL[i] <= curtime){
 720                     delete TTL[i];
 721                     delete CRC32[i];
 722                     delete _storage[i];
 723                     changed = true;
 724                     deleted.push(i);
 725                 }else if(TTL[i] < nextExpire){
 726                     nextExpire = TTL[i];
 727                 }
 728             }
 729         }
 730
 731         // set next check
 732         if(nextExpire != Infinity){
 733             _ttl_timeout = setTimeout(_handleTTL, nextExpire - curtime);
 734         }
 735
 736         // save changes
 737         if(changed){
 738             _save();
 739             _publishChange();
 740             _fireObservers(deleted, "deleted");
 741         }
 742     }
 743
 744     /**
 745      * Checks if there's any events on hold to be fired to listeners
 746      */
 747     function _handlePubSub(){
 748         if(!_storage.__jstorage_meta.PubSub){
 749             return;
 750         }
 751         var pubelm,
 752             _pubsubCurrent = _pubsub_last;
 753
 754         for(var i=len=_storage.__jstorage_meta.PubSub.length-1; i>=0; i--){
 755             pubelm = _storage.__jstorage_meta.PubSub[i];
 756             if(pubelm[0] > _pubsub_last){
 757                 _pubsubCurrent = pubelm[0];
 758                 _fireSubscribers(pubelm[1], pubelm[2]);
 759             }
 760         }
 761
 762         _pubsub_last = _pubsubCurrent;
 763     }
 764
 765     /**
 766      * Fires all subscriber listeners for a pubsub channel
 767      *
 768      * @param {String} channel Channel name
 769      * @param {Mixed} payload Payload data to deliver
 770      */
 771     function _fireSubscribers(channel, payload){
 772         if(_pubsub_observers[channel]){
 773             for(var i=0, len = _pubsub_observers[channel].length; i<len; i++){
 774                 // send immutable data that can't be modified by listeners
 775                 _pubsub_observers[channel][i](channel, JSON.parse(JSON.stringify(payload)));
 776             }
 777         }
 778     }
 779
 780     /**
 781      * Remove old events from the publish stream (at least 2sec old)
 782      */
 783     function _dropOldEvents(){
 784         if(!_storage.__jstorage_meta.PubSub){
 785             return;
 786         }
 787
 788         var retire = +new Date() - 2000;
 789
 790         for(var i=0, len = _storage.__jstorage_meta.PubSub.length; i<len; i++){
 791             if(_storage.__jstorage_meta.PubSub[i][0] <= retire){
 792                 // deleteCount is needed for IE6
 793                 _storage.__jstorage_meta.PubSub.splice(i, _storage.__jstorage_meta.PubSub.length - i);
 794                 break;
 795             }
 796         }
 797
 798         if(!_storage.__jstorage_meta.PubSub.length){
 799             delete _storage.__jstorage_meta.PubSub;
 800         }
 801
 802     }
 803
 804     /**
 805      * Publish payload to a channel
 806      *
 807      * @param {String} channel Channel name
 808      * @param {Mixed} payload Payload to send to the subscribers
 809      */
 810     function _publish(channel, payload){
 811         if(!_storage.__jstorage_meta){
 812             _storage.__jstorage_meta = {};
 813         }
 814         if(!_storage.__jstorage_meta.PubSub){
 815             _storage.__jstorage_meta.PubSub = [];
 816         }
 817
 818         _storage.__jstorage_meta.PubSub.unshift([+new Date, channel, payload]);
 819
 820         _save();
 821         _publishChange();
 822     }
 823
 824     /**
 825      * CRC32 calculation based on http://noteslog.com/post/crc32-for-javascript/
 826      *
 827      * @param {String} str String to be hashed
 828      * @param {Number} [crc] Last crc value in case of streams
 829      */
 830     function _crc32(str, crc){
 831         crc = crc || 0;
 832
 833         var n = 0, //a number between 0 and 255
 834             x = 0; //an hex number
 835
 836         crc = crc ^ (-1);
 837         for(var i = 0, len = str.length; i < len; i++){
 838             n = (crc ^ str.charCodeAt(i)) & 0xFF;
 839             x = "0x" + _crc32Table.substr(n * 9, 8);
 840             crc = (crc >>> 8)^x;
 841         }
 842         return crc^(-1);
 843     }
 844
 845     ////////////////////////// PUBLIC INTERFACE /////////////////////////
 846
 847     $.jStorage = {
 848         /* Version number */
 849         version: JSTORAGE_VERSION,
 850
 851         /**
 852          * Sets a key's value.
 853          *
 854          * @param {String} key Key to set. If this value is not set or not
 855          *              a string an exception is raised.
 856          * @param {Mixed} value Value to set. This can be any value that is JSON
 857          *              compatible (Numbers, Strings, Objects etc.).
 858          * @param {Object} [options] - possible options to use
 859          * @param {Number} [options.TTL] - optional TTL value
 860          * @return {Mixed} the used value
 861          */
 862         set: function(key, value, options){
 863             _checkKey(key);
 864
 865             options = options || {};
 866
 867             // undefined values are deleted automatically
 868             if(typeof value == "undefined"){
 869                 this.deleteKey(key);
 870                 return value;
 871             }
 872
 873             if(_XMLService.isXML(value)){
 874                 value = {_is_xml:true,xml:_XMLService.encode(value)};
 875             }else if(typeof value == "function"){
 876                 return undefined; // functions can't be saved!
 877             }else if(value && typeof value == "object"){
 878                 // clone the object before saving to _storage tree
 879                 value = JSON.parse(JSON.stringify(value));
 880             }
 881
 882             _storage[key] = value;
 883
 884             _storage.__jstorage_meta.CRC32[key] = _crc32(JSON.stringify(value));
 885
 886             this.setTTL(key, options.TTL || 0); // also handles saving and _publishChange
 887
 888             _localStoragePolyfillSetKey(key, value);
 889
 890             _fireObservers(key, "updated");
 891             return value;
 892         },
 893
 894         /**
 895          * Looks up a key in cache
 896          *
 897          * @param {String} key - Key to look up.
 898          * @param {mixed} def - Default value to return, if key didn't exist.
 899          * @return {Mixed} the key value, default value or null
 900          */
 901         get: function(key, def){
 902             _checkKey(key);
 903             if(key in _storage){
 904                 if(_storage[key] && typeof _storage[key] == "object" &&
 905                         _storage[key]._is_xml &&
 906                             _storage[key]._is_xml){
 907                     return _XMLService.decode(_storage[key].xml);
 908                 }else{
 909                     return _storage[key];
 910                 }
 911             }
 912             return typeof(def) == 'undefined' ? null : def;
 913         },
 914
 915         /**
 916          * Deletes a key from cache.
 917          *
 918          * @param {String} key - Key to delete.
 919          * @return {Boolean} true if key existed or false if it didn't
 920          */
 921         deleteKey: function(key){
 922             _checkKey(key);
 923             if(key in _storage){
 924                 delete _storage[key];
 925                 // remove from TTL list
 926                 if(typeof _storage.__jstorage_meta.TTL == "object" &&
 927                   key in _storage.__jstorage_meta.TTL){
 928                     delete _storage.__jstorage_meta.TTL[key];
 929                 }
 930
 931                 delete _storage.__jstorage_meta.CRC32[key];
 932                 _localStoragePolyfillSetKey(key, undefined);
 933
 934                 _save();
 935                 _publishChange();
 936                 _fireObservers(key, "deleted");
 937                 return true;
 938             }
 939             return false;
 940         },
 941
 942         /**
 943          * Sets a TTL for a key, or remove it if ttl value is 0 or below
 944          *
 945          * @param {String} key - key to set the TTL for
 946          * @param {Number} ttl - TTL timeout in milliseconds
 947          * @return {Boolean} true if key existed or false if it didn't
 948          */
 949         setTTL: function(key, ttl){
 950             var curtime = +new Date();
 951             _checkKey(key);
 952             ttl = Number(ttl) || 0;
 953             if(key in _storage){
 954
 955                 if(!_storage.__jstorage_meta.TTL){
 956                     _storage.__jstorage_meta.TTL = {};
 957                 }
 958
 959                 // Set TTL value for the key
 960                 if(ttl>0){
 961                     _storage.__jstorage_meta.TTL[key] = curtime + ttl;
 962                 }else{
 963                     delete _storage.__jstorage_meta.TTL[key];
 964                 }
 965
 966                 _save();
 967
 968                 _handleTTL();
 969
 970                 _publishChange();
 971                 return true;
 972             }
 973             return false;
 974         },
 975
 976         /**
 977          * Gets remaining TTL (in milliseconds) for a key or 0 when no TTL has been set
 978          *
 979          * @param {String} key Key to check
 980          * @return {Number} Remaining TTL in milliseconds
 981          */
 982         getTTL: function(key){
 983             var curtime = +new Date(), ttl;
 984             _checkKey(key);
 985             if(key in _storage && _storage.__jstorage_meta.TTL && _storage.__jstorage_meta.TTL[key]){
 986                 ttl = _storage.__jstorage_meta.TTL[key] - curtime;
 987                 return ttl || 0;
 988             }
 989             return 0;
 990         },
 991
 992         /**
 993          * Deletes everything in cache.
 994          *
 995          * @return {Boolean} Always true
 996          */
 997         flush: function(){
 998             _storage = {__jstorage_meta:{CRC32:{}}};
 999             _createPolyfillStorage("local", true);
1000             _save();
1001             _publishChange();
1002             _fireObservers(null, "flushed");
1003             return true;
1004         },
1005
1006         /**
1007          * Returns a read-only copy of _storage
1008          *
1009          * @return {Object} Read-only copy of _storage
1010         */
1011         storageObj: function(){
1012             function F() {}
1013             F.prototype = _storage;
1014             return new F();
1015         },
1016
1017         /**
1018          * Returns an index of all used keys as an array
1019          * ['key1', 'key2',..'keyN']
1020          *
1021          * @return {Array} Used keys
1022         */
1023         index: function(){
1024             var index = [], i;
1025             for(i in _storage){
1026                 if(_storage.hasOwnProperty(i) && i != "__jstorage_meta"){
1027                     index.push(i);
1028                 }
1029             }
1030             return index;
1031         },
1032
1033         /**
1034          * How much space in bytes does the storage take?
1035          *
1036          * @return {Number} Storage size in chars (not the same as in bytes,
1037          *                  since some chars may take several bytes)
1038          */
1039         storageSize: function(){
1040             return _storage_size;
1041         },
1042
1043         /**
1044          * Which backend is currently in use?
1045          *
1046          * @return {String} Backend name
1047          */
1048         currentBackend: function(){
1049             return _backend;
1050         },
1051
1052         /**
1053          * Test if storage is available
1054          *
1055          * @return {Boolean} True if storage can be used
1056          */
1057         storageAvailable: function(){
1058             return !!_backend;
1059         },
1060
1061         /**
1062          * Register change listeners
1063          *
1064          * @param {String} key Key name
1065          * @param {Function} callback Function to run when the key changes
1066          */
1067         listenKeyChange: function(key, callback){
1068             _checkKey(key);
1069             if(!_observers[key]){
1070                 _observers[key] = [];
1071             }
1072             _observers[key].push(callback);
1073         },
1074
1075         /**
1076          * Remove change listeners
1077          *
1078          * @param {String} key Key name to unregister listeners against
1079          * @param {Function} [callback] If set, unregister the callback, if not - unregister all
1080          */
1081         stopListening: function(key, callback){
1082             _checkKey(key);
1083
1084             if(!_observers[key]){
1085                 return;
1086             }
1087
1088             if(!callback){
1089                 delete _observers[key];
1090                 return;
1091             }
1092
1093             for(var i = _observers[key].length - 1; i>=0; i--){
1094                 if(_observers[key][i] == callback){
1095                     _observers[key].splice(i,1);
1096                 }
1097             }
1098         },
1099
1100         /**
1101          * Subscribe to a Publish/Subscribe event stream
1102          *
1103          * @param {String} channel Channel name
1104          * @param {Function} callback Function to run when the something is published to the channel
1105          */
1106         subscribe: function(channel, callback){
1107             channel = (channel || "").toString();
1108             if(!channel){
1109                 throw new TypeError('Channel not defined');
1110             }
1111             if(!_pubsub_observers[channel]){
1112                 _pubsub_observers[channel] = [];
1113             }
1114             _pubsub_observers[channel].push(callback);
1115         },
1116
1117         /**
1118          * Publish data to an event stream
1119          *
1120          * @param {String} channel Channel name
1121          * @param {Mixed} payload Payload to deliver
1122          */
1123         publish: function(channel, payload){
1124             channel = (channel || "").toString();
1125             if(!channel){
1126                 throw new TypeError('Channel not defined');
1127             }
1128
1129             _publish(channel, payload);
1130         },
1131
1132         /**
1133          * Reloads the data from browser storage
1134          */
1135         reInit: function(){
1136             _reloadData();
1137         }
1138     };
1139
1140     // Initialize jStorage
1141     _init();
1142
1143 })();