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/**
* The StorageManager class is a singleton that registers DataStorage objects and returns instances of those objects.
* @class StorageManager
* @namespace YAHOO.util
* @static
*/
(function() {
// internal shorthand
var Y = YAHOO.util,
YL = YAHOO.lang,
// private variables
_locationEngineMap = {}, // cached engines
_registeredEngineSet = [], // set of available engines
_registeredEngineMap = {}, // map of available engines
/**
* Fetches a storage constructor if it is available, otherwise returns NULL.
* @method _getClass
* @param klass {Function} Required. The storage constructor to test.
* @return {Function} An available storage constructor or NULL.
* @private
*/
_getClass = function(klass) {
return (klass && klass.isAvailable()) ? klass : null;
},
/**
* Fetches the storage engine from the cache, or creates and caches it.
* @method _getStorageEngine
* @param location {String} Required. The location to store.
* @param klass {Function} Required. A pointer to the engineType Class.
* @param conf {Object} Optional. Additional configuration for the data source engine.
* @private
*/
_getStorageEngine = function(location, klass, conf) {
var engine = _locationEngineMap[location + klass.ENGINE_NAME];
if (! engine) {
engine = new klass(location, conf);
_locationEngineMap[location + klass.ENGINE_NAME] = engine;
}
return engine;
},
/**
* Ensures that the location is valid before returning it or a default value.
* @method _getValidLocation
* @param location {String} Required. The location to evaluate.
* @private
*/
_getValidLocation = function(location) {
switch (location) {
case Y.StorageManager.LOCATION_LOCAL:
case Y.StorageManager.LOCATION_SESSION:
return location;
default: return Y.StorageManager.LOCATION_SESSION;
}
};
// public namespace
Y.StorageManager = {
/**
* The storage location - session; data cleared at the end of a user's session.
* @property LOCATION_SESSION
* @type {String}
* @static
*/
LOCATION_SESSION: 'sessionStorage',
/**
* The storage location - local; data cleared on demand.
* @property LOCATION_LOCAL
* @type {String}
* @static
*/
LOCATION_LOCAL: 'localStorage',
/**
* Fetches the desired engine type or first available engine type.
* @method get
* @param engineType {String} Optional. The engine type, see engines.
* @param location {String} Optional. The storage location - LOCATION_SESSION & LOCATION_LOCAL; default is LOCAL.
* @param conf {Object} Optional. Additional configuration for the getting the storage engine.
* {
* engine: {Object} configuration parameters for the desired engine
* order: {Array} an array of storage engine names; the desired order to try engines}
* }
* @static
*/
get: function(engineType, location, conf) {
var _cfg = YL.isObject(conf) ? conf : {},
klass = _getClass(_registeredEngineMap[engineType]);
if (! klass && ! _cfg.force) {
var i, j;
if (_cfg.order) {
j = _cfg.order.length;
for (i = 0; i < j && ! klass; i += 1) {
klass = _getClass(_cfg.order[i]);
}
}
if (! klass) {
j = _registeredEngineSet.length;
for (i = 0; i < j && ! klass; i += 1) {
klass = _getClass(_registeredEngineSet[i]);
}
}
}
if (klass) {
return _getStorageEngine(_getValidLocation(location), klass, _cfg.engine);
}
throw('YAHOO.util.StorageManager.get - No engine available, please include an engine before calling this function.');
},
/*
* Estimates the size of the string using 1 byte for each alpha-numeric character and 3 for each non-alpha-numeric character.
* @method getByteSize
* @param s {String} Required. The string to evaulate.
* @return {Number} The estimated string size.
* @private
*/
getByteSize: function(s) {
return encodeURIComponent('' + s).length;
},
/**
* Registers a engineType Class with the StorageManager singleton; first in is the first out.
* @method register
* @param engineConstructor {Function} Required. The engine constructor function, see engines.
* @return {Boolean} When successfully registered.
* @static
*/
register: function(engineConstructor) {
if (YL.isFunction(engineConstructor) && YL.isFunction(engineConstructor.isAvailable) && YL.isString(engineConstructor.ENGINE_NAME)) {
_registeredEngineMap[engineConstructor.ENGINE_NAME] = engineConstructor;
_registeredEngineSet.push(engineConstructor);
return true;
}
return false;
}
};
YAHOO.register("StorageManager", Y.SWFStore, {version: "@VERSION@", build: "@BUILD@"});
}());