Protected Storage

protected-storage.js

/**
 * QuickStorage and ProtectedStorage
 * @brief A caching control mechanism
 * @author Ray Peters <[email protected]>
 */
function QuickStorage(){
    this._cache = {};
}

QuickStorage.prototype.setItem = function( key, val ) {
    this._cache[ key ] = val ? JSON.stringify( val ) : val;
};

QuickStorage.prototype.getItem = function( key ) {
    var item = this._cache[ key ];
    if ( item === undefined ) {
        // Nothing here
        return null;
    }
    return item ? JSON.parse( item ) : item;
};

QuickStorage.prototype.removeItem = function( key ) {
    delete this._cache[ key ];
};

QuickStorage.prototype.empty = function(){
    delete this._cache;
    this._cache = {};
};

QuickStorage.prototype.state = function( data ) {
    if ( data === undefined ) {
        // Getter
        return { "data": JSON.stringify( this._cache ) };
    } else {
        // Setter
        var newCache;
        
        try {
            newCache = data.data ? JSON.parse( data.data ) : {};
        } catch ( e ) {
            console.info( "Trying to set invalid JSON object in QuickStorage." );
        }

        delete this._cache;
        this._cache = newCache || {};
    }
};


var ProtectedStorage = function( authFn ) {
    var cache, _authFn, ownerMap;
    if ( !authFn || typeof authFn !== "function" ) {
        return undefined;
    }

    cache = new QuickStorage();
    _authFn = authFn;
    ownerMap = {};

    return {
        "setItem": function( key, val ) {
            cache.setItem( key, val );
            ownerMap[ key ] = _authFn();
        },
        
        "getItem": function( key ) {
            if ( ownerMap[ key ] !== _authFn() ) {
                // Don't own the item, destroy the entry
                cache.removeItem( key );
                delete ownerMap[ key ];
                return null;
            }
            return cache.getItem( key );
        },
        
        "removeItem": function( key ) {
            cache.removeItem( key );
        },

        "state": function( data ) {
            if ( data === undefined ) {
                // Getter
                return {
                    "authFn": _authFn,
                    "ownerMap": ownerMap,
                    "cache": cache.state()
                };
            } else {
                // Setter
                _authFn = data.authFn;
                ownerMap = data.ownerMap;
                cache.state( data.cache );
            }
        },

        "empty": function(){
            cache.empty();
        }
    };
};

var paneStorage = ProtectedStorage( ( function(){
    var hashRegex = /(#![^&]*)/;
    return function(){
        var hash = window.location.hash,
            ret = hash.match( hashRegex );
        return ret ? ret[0] : hash;
    };
})() );