cache-offline.js revision 594beada864561d88596137e07159a806aabed66
/**
* Extends Cache utility with offline functionality.
* @class CacheOffline
* @extends Cache
* @constructor
*/
function CacheOffline() {
CacheOffline.superclass.constructor.apply(this, arguments);
}
/////////////////////////////////////////////////////////////////////////////
//
// CacheOffline static properties
//
/////////////////////////////////////////////////////////////////////////////
Y.mix(CacheOffline, {
/**
* Class name.
*
* @property NAME
* @type String
* @static
* @final
* @value "cacheOffline"
*/
NAME: "cacheOffline",
ATTRS: {
/////////////////////////////////////////////////////////////////////////////
//
// CacheOffline Attributes
//
/////////////////////////////////////////////////////////////////////////////
/**
* @attribute expires
* @description Absolute Date when data expires or
* relative number of milliseconds. Zero disables expiration.
* @type Date | Number
* @default 0
*/
expires: {
value: 86400000, //one day
validator: function(v) {
return Y.Lang.isNumber(v) && v >= 0;
}
},
/**
* @attribute max
* @description Disabled.
* @readonly
* @default null
*/
max: {
value: null,
readonly: true,
setter: function() {
return null;
}
},
/**
* @attribute uniqueKeys
* @description Always true for CacheOffline.
* @readonly
* @default true
*/
uniqueKeys: {
value: true,
readonly: true,
setter: function() {
return true;
}
}
}
});
var localStorage = Y.config.win.localStorage,
isDate = Y.Lang.isDate,
JSON = Y.JSON,
cacheOfflinePrototype = localStorage ? {
/////////////////////////////////////////////////////////////////////////////
//
// CacheOffline protected methods
//
/////////////////////////////////////////////////////////////////////////////
/**
* Sets max.
*
* @method _setMax
* @protected
*/
//_setMax: function(value) {
//return null;
//},
/**
* Gets size.
*
* @method _getSize
* @protected
*/
_getSize: function() {
return localStorage.length;
},
/**
* Gets all entries.
*
* @method _getEntries
* @protected
*/
_getEntries: function() {
var entries = this._entries,
i=0,
l=this._getSize();
if(entries) { // Could be null if instance was destroyed
for(; i<l; ++i) {
entries[i] = JSON.parse(localStorage.key(i));
}
}
return 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 entry = e.entry,
request = entry.request,
expires = this.get("expires");
entry.expires = isDate(expires) ? expires :
(expires ? new Date().getTime() + expires : null);
localStorage.setItem(JSON.stringify({"request":request}), JSON.stringify(entry));
Y.log("Cached offline entry: " + Y.dump(entry), "info", "cache");
},
/**
* Flushes cache.
*
* @method _defFlushFn
* @param e {Event.Facade} Event Facade object.
* @protected
*/
_defFlushFn: function(e) {
var store = localStorage, key;
if(store) {
if(store.clear) {
store.clear();
}
// FF2.x and FF3.0.x
else {
for (key in store) {
if (store.hasOwnProperty(key)) {
store.removeItem(key);
delete store[key];
}
}
}
}
Y.log("OfflineCache flushed", "info", "cache");
},
/**
* Adds a new entry to the cache of the format
* {request:request, response:response, expires: expires}.
*
* @method add
* @param request {Object} Request value must be a String or JSON.
* @param response {Object} Response value must be a String or JSON.
*/
/**
* Retrieves cached object for given request, if available.
* Returns null if there is no cache match.
*
* @method retrieve
* @param request {Object} Request object.
* @return {Object} Cached object with the properties request, response,
* and expires, or null.
*/
retrieve: function(request) {
this.fire("request", {request: request});
var entry, expires, cached;
try {
request = JSON.stringify({"request":request});
try {
entry = JSON.parse(localStorage.getItem(request));
}
catch(e) {
}
}
catch(e2) {
}
if(entry) {
cached = entry.cached;
entry.cached = cached ? new Date(cached) : cached;
expires = entry.expires;
if(!expires || new Date() < expires) {
this.fire("retrieve", {entry: entry});
Y.log("Retrieved offlinecached response: " + Y.dump(entry) +
" for request: " + Y.dump(request), "info", "cache");
return entry;
}
}
return null;
}
} : {
/**
* Adds entry to cache with an expires property.
*
* @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 expires = this.get("expires");
e.entry.expires = isDate(expires) ? expires :
(expires ? new Date().getTime() + this.get("expires") : null);
Y.log("Added expires property: " + Y.dump(e.entry), "info", "cache");
CacheOffline.superclass._defAddFn.call(this, e);
},
/**
* Overrides the default method to check for expired 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
* and entry has not expired, false otherwise.
* @protected
*/
_isMatch: function(request, entry) {
if(!entry.expires || new Date() < entry.expires) {
return (request === entry.request);
}
return false;
}
};
Y.extend(CacheOffline, Y.Cache, cacheOfflinePrototype);
Y.CacheOffline = CacheOffline;