Convert string to object. The string format is like facebook api: https://developers.facebook.com/tools/explorer

new_params.js

/*
Example usage Parse
var string = "user(1),about,accounts.limit(20).fields(hometown,albums.limit(10).fields(comments))"
PARAMS.parse(string);
return {
  'about': null,
	'accounts': {
		'fields': {
			'hometown': null,
			'albums': {
				'fields': {
					'comments': null
				},
				'limit': '10'
			}
		},
		'limit': '20'
	},
	'user': '1'
}

Example usage strigify

PARAMS.strigify(object);
return "user(1),about,accounts.limit(20).fields(hometown,albums.limit(10).fields(comments))"
*/
(function(){
  
  var PARAMS = window.PARAMS = {
  	parse: function(str){
  		var attrs             = [],
  			aux                 = str.split(""),
  			arr                 = {},
  			attr                = '',
  			_sub_attr           = '',
  			r                   = 0,
  			f                   = 0,
  			v                   = 0,
  			d                   = 0,
  			_c_value            = null,
  			_sub                = 0,
  			_p_start            = 0;
  
  		for(var i in aux) {
  			var c          = aux[i];
  			switch(c){
  				case '(':
  					r++;
  					f   = 1;
  					if(_p_start === 0) _p_start = i;
  					break;
  				case ')':
  					r--;
  					break;
  				case '.':
  					d      = 1;
  					_sub   = 1;
  					break;
  				case ',':
  					v      = 1;
  					break;
  			}
  			if(v === 0 && !_sub){
  				attr        += c;
  			}
  			if(_sub){
  				if(d === 0 && f === 0 && v === 0)
  					_sub_attr   += c;
  			}
  			if(r === 0 && f == 1) {
  				_c_value             = str.substr(++_p_start , i - _p_start);
  				if(_sub){
  					_sub_attr = _sub_attr.replace(_c_value, '');
  				}else{
  					attr = attr.replace('(' + _c_value + ')', '');
  				}
  				if(_sub_attr){
  					arr[attr]               = arr[attr] || {};
  					arr[attr][_sub_attr]    = _c_value;
  					if(_sub_attr == "fields")
  						arr[attr][_sub_attr]    = this.parse(_c_value);
  				}else{
  					arr[attr]               = _c_value;
  				}
  				_c_value    = '';
  				_p_start    = 0;
  				f           = 0;
  				_sub_attr   = '';
  			}
  			if((v && r === 0) || i == aux.length - 1){
  				if(!arr[attr]) arr[attr]    = null;
  				attrs.push(attr);
  				attr         = '';
  				_sub         = 0;
  			}
  			v = 0;
  			d = 0;
  		}
  		return arr;
  	},
  	stringify: function(obj){
  		var unparsed        = '';
  		if(typeof(obj) == typeof({})){
  			for(var i in obj){
  				var current     = obj[i];
  				unparsed		+= unparsed ? ',' + i : i;
  				if(typeof(current) == typeof({})){
  					for(var j in current){
  						unparsed += '.' + j;
  						if(current[j]){
  							unparsed += '(' + this.stringify(current[j]) + ')';
  						}
  					}
  				}else{
  					if(current){
  						unparsed += '(' + current + ')';
  					}
  				}
  			}
  		}else{
  			unparsed += obj;
  		}
  		return unparsed;
  	}
  };
}())