/*
 * jQuery JSON Plugin
 * version: 2.1 (2009-08-14)
 *
 * This document is licensed as free software under the terms of the
 * MIT License: http://www.opensource.org/licenses/mit-license.php
 *
 * Brantley Harris wrote this plugin. It is based somewhat on the JSON.org 
 * website's http://www.json.org/json2.js, which proclaims:
 * "NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.", a sentiment that
 * I uphold.
 *
 * It is also influenced heavily by MochiKit's serializeJSON, which is 
 * copyrighted 2005 by Bob Ippolito.

http://code.google.com/p/jquery-json/

This plugin makes it simple to convert to and from JSON:

var thing = {plugin: 'jquery-json', version: 2.2};

var encoded = $.toJSON(thing);              //'{"plugin":"jquery-json","version":2.2}'
var name = $.evalJSON(encoded).plugin;      //"jquery-json"
var version = $.evalJSON(encoded).version;  // 2.2
Most people asked me why I would want to do such a thing, which boggles my mind. Javascript makes it relatively easy to convert from JSON, thanks to eval(), but converting to JSON is supposedly an edge requirement.

This plugin exposes four new functions onto the $, or jQuery object:

toJSON: Serializes a javascript object, number, string, or arry into JSON.
evalJSON: Converts from JSON to Javascript, quickly, and is trivial.
secureEvalJSON: Converts from JSON to Javascript, but does so while checking to see if the source is actually JSON, and not with other Javascript statements thrown in.
quoteString: Places quotes around a string, and inteligently escapes any quote, backslash, or control characters.

*/
 
(function($) {
    /** jQuery.toJSON( json-serializble )
        Converts the given argument into a JSON respresentation.

        If an object has a "toJSON" function, that will be used to get the representation.
        Non-integer/string keys are skipped in the object, as are keys that point to a function.

        json-serializble:
            The *thing* to be converted.
     **/
    $.toJSON = function(o)
    {
        if (typeof(JSON) == 'object' && JSON.stringify)
            return JSON.stringify(o);
        
        var type = typeof(o);
    
        if (o === null)
            return "null";
    
        if (type == "undefined")
            return undefined;
        
        if (type == "number" || type == "boolean")
            return o + "";
    
        if (type == "string")
            return $.quoteString(o);
    
        if (type == 'object')
        {
            if (typeof o.toJSON == "function") 
                return $.toJSON( o.toJSON() );
            
            if (o.constructor === Date)
            {
                var month = o.getUTCMonth() + 1;
                if (month < 10) month = '0' + month;

                var day = o.getUTCDate();
                if (day < 10) day = '0' + day;

                var year = o.getUTCFullYear();
                
                var hours = o.getUTCHours();
                if (hours < 10) hours = '0' + hours;
                
                var minutes = o.getUTCMinutes();
                if (minutes < 10) minutes = '0' + minutes;
                
                var seconds = o.getUTCSeconds();
                if (seconds < 10) seconds = '0' + seconds;
                
                var milli = o.getUTCMilliseconds();
                if (milli < 100) milli = '0' + milli;
                if (milli < 10) milli = '0' + milli;

                return '"' + year + '-' + month + '-' + day + 'T' +
                             hours + ':' + minutes + ':' + seconds + 
                             '.' + milli + 'Z"'; 
            }

            if (o.constructor === Array) 
            {
                var ret = [];
                for (var i = 0; i < o.length; i++)
                    ret.push( $.toJSON(o[i]) || "null" );

                return "[" + ret.join(",") + "]";
            }
        
            var pairs = [];
            for (var k in o) {
                var name;
                var type = typeof k;

                if (type == "number")
                    name = '"' + k + '"';
                else if (type == "string")
                    name = $.quoteString(k);
                else
                    continue;  //skip non-string or number keys
            
                if (typeof o[k] == "function") 
                    continue;  //skip pairs where the value is a function.
            
                var val = $.toJSON(o[k]);
            
                pairs.push(name + ":" + val);
            }

            return "{" + pairs.join(", ") + "}";
        }
    };

    /** jQuery.evalJSON(src)
        Evaluates a given piece of json source.
     **/
    $.evalJSON = function(src)
    {
        if (typeof(JSON) == 'object' && JSON.parse)
            return JSON.parse(src);
        return eval("(" + src + ")");
    };
    
    /** jQuery.secureEvalJSON(src)
        Evals JSON in a way that is *more* secure.
    **/
    $.secureEvalJSON = function(src)
    {
        if (typeof(JSON) == 'object' && JSON.parse)
            return JSON.parse(src);
        
        var filtered = src;
        filtered = filtered.replace(/\\["\\\/bfnrtu]/g, '@');
        filtered = filtered.replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']');
        filtered = filtered.replace(/(?:^|:|,)(?:\s*\[)+/g, '');
        
        if (/^[\],:{}\s]*$/.test(filtered))
            return eval("(" + src + ")");
        else
            throw new SyntaxError("Error parsing JSON, source is not valid.");
    };

    /** jQuery.quoteString(string)
        Returns a string-repr of a string, escaping quotes intelligently.  
        Mostly a support function for toJSON.
    
        Examples:
            >>> jQuery.quoteString("apple")
            "apple"
        
            >>> jQuery.quoteString('"Where are we going?", she asked.')
            "\"Where are we going?\", she asked."
     **/
    $.quoteString = function(string)
    {
        if (string.match(_escapeable))
        {
            return '"' + string.replace(_escapeable, function (a) 
            {
                var c = _meta[a];
                if (typeof c === 'string') return c;
                c = a.charCodeAt();
                return '\\u00' + Math.floor(c / 16).toString(16) + (c % 16).toString(16);
            }) + '"';
        }
        return '"' + string + '"';
    };
    
    var _escapeable = /["\\\x00-\x1f\x7f-\x9f]/g;
    
    var _meta = {
        '\b': '\\b',
        '\t': '\\t',
        '\n': '\\n',
        '\f': '\\f',
        '\r': '\\r',
        '"' : '\\"',
        '\\': '\\\\'
    };
})(jQuery);