webCache LRU

appCache_LRU

var _store = { 
    removeItem : function(k) { 
        delete this[k]; 
    } 
}; 
try { 
    if ("localStorage" in window && window["localStorage"]) 
        _store = window["localStorage"]; 
} catch (e) { } 

function WebCache(name, size, timeout) { 
    var datas = {}; 
    var frees = []; 
    var count = 0; 

    timeout = timeout || 0; 

    function load() { 
        function _new() { 
            datas = {}; 
            frees = []; 
            count = size; 
            for (var i = 0; i < size; i++) 
                frees.push(i); 
        } 

        try { 
            count = new Number(_store[name + '_count']); 
            if (count != size) { 
                for (var i = 0; i < count; i++) { 
                    _store.removeItem(name + '_' + i); 
                    _store.removeItem(name + '_' + i + '_time'); 
                } 
                _store.removeItem(name + '_datas'); 
                _store.removeItem(name + '_frees'); 
                _store.removeItem(name + '_count'); 

                _new(); 
            } else { 
                datas = JSON.parse(_store[name + '_datas']); 
                frees = JSON.parse(_store[name + '_frees']); 
            } 
        } catch (e) { 
            _new(); 
        } 
    } 

    function save() { 
        _store[name + '_datas'] = JSON.stringify(datas); 
        _store[name + '_frees'] = JSON.stringify(frees); 
        _store[name + '_count'] = count.toString(); 
    } 

    function _del(k) { 
        frees.push(datas[k]); 
        delete datas[k]; 
        return false; 
    } 

    function _has(k) { 
        if (datas.hasOwnProperty(k)) { 
            if (timeout <= 0) 
                return true; 

            if (new Date().getTime() 
                    - new Number(_store[name + '_' + datas[k] 
                            + '_time']) >= timeout) 
                return _del(k); 
            return true; 
        } else 
            return false; 
    } 

    function _clean() { 
        if (timeout > 0) { 
            for ( var k in datas) 
                _has(k); 
        } 
    } 

    function _put_data(n, v) { 
        _store[name + '_' + n] = JSON.stringify(v); 
        _store[name + '_' + n + '_time'] = new Date().getTime(); 
        return v; 
    } 

    function _put(k, v) { 
        var n = frees.pop(); 
        datas[k] = n; 

        return _put_data(n, v); 
    } 

    function _update(k, v) { 
        var n = datas[k]; 

        delete datas[k]; 
        datas[k] = n; 

        return _put_data(n, v); 
    } 

    // exists 
    this.has = function(k) { 
        load(); 

        return _has(k); 
    } 

    // fetch data 
    this.get = function(k) { 
        load(); 

        if (_has(k)) { 
            var n = datas[k]; 
            delete datas[k]; 
            datas[k] = n; 

            save(); 

            return JSON.parse(_store[name + '_' + n]); 
        } 
    } 

    // update or insert 
    this.put = function(k, v) { 
        load(); 

        if (_has(k)) 
            _update(k, v); 
        else { 
            if (frees.length == 0) { 
                for ( var k1 in datas) { 
                    if (_has(k1)) { 
                        if (frees.length == 0) 
                            _del(k1); 
                        break; 
                    } 
                } 
            } 

            _put(k, v); 
        } 

        save(); 
    } 

    // update if exists 
    this.set = function(k, v) { 
        load(); 
        if (_has(k)) { 
            _update(k, v); 
            save(); 
        } 
    } 

    this.datas = function() { 
        var ds = {}; 

        load(); 
        _clean(); 

        for ( var k in datas) { 
            ds[k] = JSON.parse(_store[name + '_' + datas[k]]); 
        } 
        return ds; 
    } 

}