source: Dev/trunk/src/client/dojox/storage/Provider.js

dojo.provide("dojox.storage.Provider");

dojo.declare("dojox.storage.Provider", null, {
        // summary:
        //              A singleton for working with dojox.storage.
        // description:
        //              dojox.storage exposes the current available storage provider on this
        //              platform. It gives you methods such as dojox.storage.put(),
        //              dojox.storage.get(), etc.
        //
        //              For more details on dojox.storage, see the primary documentation
        //              page at http://manual.dojotoolkit.org/storage.html.
        //
        //              Note for storage provider developers who are creating subclasses-
        //              This is the base class for all storage providers Specific kinds of
        //              Storage Providers should subclass this and implement these methods.
        //              You should avoid initialization in storage provider subclass's
        //              constructor; instead, perform initialization in your initialize()
        //              method.

        constructor: function(){
        },
        
        // SUCCESS: String
        //              Flag that indicates a put() call to a
        //              storage provider was successful.
        SUCCESS: "success",
        
        // FAILED: String
        //              Flag that indicates a put() call to
        //              a storage provider failed.
        FAILED: "failed",
        
        // PENDING: String
        //              Flag that indicates a put() call to a
        //              storage provider is pending user approval.
        PENDING: "pending",
        
        // SIZE_NOT_AVAILABLE: String
        //              Returned by getMaximumSize() if this storage provider can not determine
        //              the maximum amount of data it can support.
        SIZE_NOT_AVAILABLE: "Size not available",
        
        // SIZE_NO_LIMIT: String
        //              Returned by getMaximumSize() if this storage provider has no theoretical
        //              limit on the amount of data it can store.
        SIZE_NO_LIMIT: "No size limit",

        // DEFAULT_NAMESPACE: String
        //              The namespace for all storage operations. This is useful if several
        //              applications want access to the storage system from the same domain but
        //              want different storage silos.
        DEFAULT_NAMESPACE: "default",
        
        // onHideSettingsUI: Function
        //              If a function is assigned to this property, then when the settings
        //              provider's UI is closed this function is called. Useful, for example,
        //              if the user has just cleared out all storage for this provider using
        //              the settings UI, and you want to update your UI.
        onHideSettingsUI: null,

        initialize: function(){
                // summary:
                //              Allows this storage provider to initialize itself. This is
                //              called after the page has finished loading, so you can not do
                //              document.writes(). Storage Provider subclasses should initialize
                //              themselves inside of here rather than in their function
                //              constructor.
                console.warn("dojox.storage.initialize not implemented");
        },
        
        isAvailable: function(){ /*Boolean*/
                // summary:
                //              Returns whether this storage provider is available on this
                //              platform.
                console.warn("dojox.storage.isAvailable not implemented");
        },

        put: function(  /*string*/ key,
                                        /*object*/ value,
                                        /*function*/ resultsHandler,
                                        /*string?*/ namespace){
                // summary:
                //              Puts a key and value into this storage system.
                // example:
                // |    var resultsHandler = function(status, key, message, namespace){
                // |      alert("status="+status+", key="+key+", message="+message);
                // |    };
                // |    dojox.storage.put("test", "hello world", resultsHandler);
                // description:
                //              Important note: if you are using Dojo Storage in conjunction with
                //              Dojo Offline, then you don't need to provide
                //              a resultsHandler; this is because for Dojo Offline we
                //              use Google Gears to persist data, which has unlimited data
                //              once the user has given permission. If you are using Dojo
                //              Storage apart from Dojo Offline, then under the covers hidden
                //              Flash might be used, which is both asychronous and which might
                //              get denied; in this case you must provide a resultsHandler.
                // key:
                //              A string key to use when retrieving this value in the future.
                // value:
                //              A value to store; this can be any JavaScript type.
                // resultsHandler:
                //              A callback function that will receive three arguments. The
                //              first argument is one of three values: dojox.storage.SUCCESS,
                //              dojox.storage.FAILED, or dojox.storage.PENDING; these values
                //              determine how the put request went. In some storage systems
                //              users can deny a storage request, resulting in a
                //              dojox.storage.FAILED, while in other storage systems a storage
                //              request must wait for user approval, resulting in a
                //              dojox.storage.PENDING status until the request is either
                //              approved or denied, resulting in another call back with
                //              dojox.storage.SUCCESS.
                //              The second argument in the call back is the key name that was being stored.
                //              The third argument in the call back is an optional message that
                //              details possible error messages that might have occurred during
                //              the storage process.
                // namespace:
                //              Optional string namespace that this value will be placed into;
                //              if left off, the value will be placed into dojox.storage.DEFAULT_NAMESPACE
                
                console.warn("dojox.storage.put not implemented");
        },

        get: function(/*string*/ key, /*string?*/ namespace){ /*Object*/
                // summary:
                //              Gets the value with the given key. Returns null if this key is
                //              not in the storage system.
                // key:
                //              A string key to get the value of.
                // namespace:
                //              Optional string namespace that this value will be retrieved from;
                //              if left off, the value will be retrieved from dojox.storage.DEFAULT_NAMESPACE
                // returns:
                //              Any JavaScript object type; null if the key is not present
                console.warn("dojox.storage.get not implemented");
        },

        hasKey: function(/*string*/ key, /*string?*/ namespace){
                // summary:
                //              Determines whether the storage has the given key.
                return !!this.get(key, namespace); // Boolean
        },

        getKeys: function(/*string?*/ namespace){ /*Array*/
                // summary:
                //              Enumerates all of the available keys in this storage system.
                // returns:
                //              Array of available keys
                console.warn("dojox.storage.getKeys not implemented");
        },
        
        clear: function(/*string?*/ namespace){
                // summary:
                //              Completely clears this storage system of all of it's values and
                //              keys. If 'namespace' is provided just clears the keys in that
                //              namespace.
                console.warn("dojox.storage.clear not implemented");
        },
  
        remove: function(/*string*/ key, /*string?*/ namespace){
                // summary:
                //              Removes the given key from this storage system.
                console.warn("dojox.storage.remove not implemented");
        },
        
        getNamespaces: function(){ /*string[]*/
                console.warn("dojox.storage.getNamespaces not implemented");
        },

        isPermanent: function(){ /*Boolean*/
                // summary:
                //              Returns whether this storage provider's values are persisted
                //              when this platform is shutdown.
                console.warn("dojox.storage.isPermanent not implemented");
        },

        getMaximumSize: function(){ /* mixed */
                // summary:
                //              The maximum storage allowed by this provider
                // returns:
                //              Returns the maximum storage size
                //              supported by this provider, in
                //              thousands of bytes (i.e., if it
                //              returns 60 then this means that 60K
                //              of storage is supported).
                //
                //              If this provider can not determine
                //              it's maximum size, then
                //              dojox.storage.SIZE_NOT_AVAILABLE is
                //              returned; if there is no theoretical
                //              limit on the amount of storage
                //              this provider can return, then
                //              dojox.storage.SIZE_NO_LIMIT is
                //              returned
                console.warn("dojox.storage.getMaximumSize not implemented");
        },
                
        putMultiple: function(  /*array*/ keys,
                                                        /*array*/ values,
                                                        /*function*/ resultsHandler,
                                                        /*string?*/ namespace){
                // summary:
                //              Puts multiple keys and values into this storage system.
                // example:
                // |    var resultsHandler = function(status, key, message){
                // |      alert("status="+status+", key="+key+", message="+message);
                // |    };
                // |    dojox.storage.put(["test"], ["hello world"], resultsHandler);
                // description:
                //              Important note: if you are using Dojo Storage in conjunction with
                //              Dojo Offline, then you don't need to provide
                //              a resultsHandler; this is because for Dojo Offline we
                //              use Google Gears to persist data, which has unlimited data
                //              once the user has given permission. If you are using Dojo
                //              Storage apart from Dojo Offline, then under the covers hidden
                //              Flash might be used, which is both asychronous and which might
                //              get denied; in this case you must provide a resultsHandler.
                // keys:
                //              An array of string keys to use when retrieving this value in the future,
                //              one per value to be stored
                // values:
                //              An array of values to store; this can be any JavaScript type, though the
                //              performance of plain strings is considerably better
                // resultsHandler:
                //              A callback function that will receive three arguments. The
                //              first argument is one of three values: dojox.storage.SUCCESS,
                //              dojox.storage.FAILED, or dojox.storage.PENDING; these values
                //              determine how the put request went. In some storage systems
                //              users can deny a storage request, resulting in a
                //              dojox.storage.FAILED, while in other storage systems a storage
                //              request must wait for user approval, resulting in a
                //              dojox.storage.PENDING status until the request is either
                //              approved or denied, resulting in another call back with
                //              dojox.storage.SUCCESS.
                //              The second argument in the call back is the key name that was being stored.
                //              The third argument in the call back is an optional message that
                //              details possible error messages that might have occurred during
                //              the storage process.
                // namespace:
                //              Optional string namespace that this value will be placed into;
                //              if left off, the value will be placed into dojox.storage.DEFAULT_NAMESPACE
                
                for(var i = 0; i < keys.length; i++){
                        dojox.storage.put(keys[i], values[i], resultsHandler, namespace);
                }
        },

        getMultiple: function(/*array*/ keys, /*string?*/ namespace){ /*Object*/
                // summary:
                //              Gets the values corresponding to each of the given keys.
                //              Returns a null array element for each given key that is
                //              not in the storage system.
                // keys:
                //              An array of string keys to get the value of.
                // namespace:
                //              Optional string namespace that this value will be retrieved from;
                //              if left off, the value will be retrieved from dojox.storage.DEFAULT_NAMESPACE
                // returns:
                //              Any JavaScript object type; null if the key is not present
                
                var results = [];
                for(var i = 0; i < keys.length; i++){
                        results.push(dojox.storage.get(keys[i], namespace));
                }
                
                return results;
        },

        removeMultiple: function(/*array*/ keys, /*string?*/ namespace) {
                // summary:
                //              Removes the given keys from this storage system.
                
                for(var i = 0; i < keys.length; i++){
                        dojox.storage.remove(keys[i], namespace);
                }
        },
        
        isValidKeyArray: function( keys) {
                if(keys === null || keys === undefined || !dojo.isArray(keys)){
                        return false;
                }

                //      JAC: This could be optimized by running the key validity test
                //      directly over a joined string
                return !dojo.some(keys, function(key){
                        return !this.isValidKey(key);
                }, this); // Boolean
        },

        hasSettingsUI: function(){ /*Boolean*/
                // summary:
                //              Determines whether this provider has a settings UI.
                return false;
        },

        showSettingsUI: function(){
                // summary:
                //              If this provider has a settings UI, determined
                //              by calling hasSettingsUI(), it is shown.
                console.warn("dojox.storage.showSettingsUI not implemented");
        },

        hideSettingsUI: function(){
                // summary:
                //              If this provider has a settings UI, hides it.
                console.warn("dojox.storage.hideSettingsUI not implemented");
        },
        
        isValidKey: function(/*string*/ keyName){ /*Boolean*/
                // summary:
                //              Subclasses can call this to ensure that the key given is valid
                //              in a consistent way across different storage providers. We use
                //              the lowest common denominator for key values allowed: only
                //              letters, numbers, and underscores are allowed. No spaces.
                if(keyName === null || keyName === undefined){
                        return false;
                }
                        
                return /^[0-9A-Za-z_]*$/.test(keyName);
        },
        
        getResourceList: function(){ /* Array[] */
                // summary:
                //              Returns a list of URLs that this
                //              storage provider might depend on.
                // description:
                //              This method returns a list of URLs that this
                //              storage provider depends on to do its work.
                //              This list is used by the Dojo Offline Toolkit
                //              to cache these resources to ensure the machinery
                //              used by this storage provider is available offline.
                //              What is returned is an array of URLs.
                //              Note that Dojo Offline uses Gears as its native
                //              storage provider, and does not support using other
                //              kinds of storage providers while offline anymore.
                
                return [];
        }
});