/**
 * @class Ext.util.JSON
 * Modified version of Douglas Crockford"s json.js that doesn"t
 * mess with the Object prototype
 * http://www.json.org/js.html
 * @singleton
 */
Ext.util.JSON = new (function(){
    var useHasOwn = !!{}.hasOwnProperty,
        isNative = function() {
            var useNative = null;

            return function() {
                if (useNative === null) {
                    useNative = Ext.USE_NATIVE_JSON && window.JSON && JSON.toString() == '[object JSON]';
                }
        
                return useNative;
            };
        }(),
        pad = function(n) {
            return n < 10 ? "0" + n : n;
        },
        doDecode = function(json){
            return eval("(" + json + ')');    
        },
        doEncode = function(o){
            if(!Ext.isDefined(o) || o === null){
                return "null";
            }else if(Ext.isArray(o)){
                return encodeArray(o);
            }else if(Ext.isDate(o)){
                return Ext.util.JSON.encodeDate(o);
            }else if(Ext.isString(o)){
                return encodeString(o);
            }else if(typeof o == "number"){
                //don't use isNumber here, since finite checks happen inside isNumber
                return isFinite(o) ? String(o) : "null";
            }else if(Ext.isBoolean(o)){
                return String(o);
            }else {
                var a = ["{"], b, i, v;
                for (i in o) {
                    // don't encode DOM objects
                    if(!o.getElementsByTagName){
                        if(!useHasOwn || o.hasOwnProperty(i)) {
                            v = o[i];
                            switch (typeof v) {
                            case "undefined":
                            case "function":
                            case "unknown":
                                break;
                            default:
                                if(b){
                                    a.push(',');
                                }
                                a.push(doEncode(i), ":",
                                        v === null ? "null" : doEncode(v));
                                b = true;
                            }
                        }
                    }
                }
                a.push("}");
                return a.join("");
            }    
        },
        m = {
            "\b": '\\b',
            "\t": '\\t',
            "\n": '\\n',
            "\f": '\\f',
            "\r": '\\r',
            '"' : '\\"',
            "\\": '\\\\'
        },
        encodeString = function(s){
            if (/["\\\x00-\x1f]/.test(s)) {
                return '"' + s.replace(/([\x00-\x1f\\"])/g, function(a, b) {
                    var c = m[b];
                    if(c){
                        return c;
                    }
                    c = b.charCodeAt();
                    return "\\u00" +
                        Math.floor(c / 16).toString(16) +
                        (c % 16).toString(16);
                }) + '"';
            }
            return '"' + s + '"';
        },
        encodeArray = function(o){
            var a = ["["], b, i, l = o.length, v;
                for (i = 0; i < l; i += 1) {
                    v = o[i];
                    switch (typeof v) {
                        case "undefined":
                        case "function":
                        case "unknown":
                            break;
                        default:
                            if (b) {
                                a.push(',');
                            }
                            a.push(v === null ? "null" : Ext.util.JSON.encode(v));
                            b = true;
                    }
                }
                a.push("]");
                return a.join("");
        };

    this.encodeDate = function(o){
        return '"' + o.getFullYear() + "-" +
                pad(o.getMonth() + 1) + "-" +
                pad(o.getDate()) + "T" +
                pad(o.getHours()) + ":" +
                pad(o.getMinutes()) + ":" +
                pad(o.getSeconds()) + '"';
    };

    
/**
     * Encodes an Object, Array or other value
     * @param {Mixed} o The variable to encode
     * @return {String} The JSON string
     */
    this.encode = function() {
        var ec;
        return function(o) {
            if (!ec) {
                // setup encoding function on first access
                ec = isNative() ? JSON.stringify : doEncode;
            }
            return ec(o);
        };
    }();


    
/**
     * Decodes (parses) a JSON string to an object. If the JSON is invalid, this function throws a SyntaxError unless the safe option is set.
     * @param {String} json The JSON string
     * @return {Object} The resulting object
     */
    this.decode = function() {
        var dc;
        return function(json) {
            if (!dc) {
                // setup decoding function on first access
                dc = isNative() ? JSON.parse : doDecode;
            }
            return dc(json);
        };
    }();

})();
/**
 * Shorthand for {@link Ext.util.JSON#encode}
 * @param {Mixed} o The variable to encode
 * @return {String} The JSON string
 * @member Ext
 * @method encode
 */
Ext.encode = Ext.util.JSON.encode;
/**
 * Shorthand for {@link Ext.util.JSON#decode}
 * @param {String} json The JSON string
 * @param {Boolean} safe (optional) Whether to return null or throw an exception if the JSON is invalid.
 * @return {Object} The resulting object
 * @member Ext
 * @method decode
 */
Ext.decode = Ext.util.JSON.decode;