define([ "dojo/_base/declare", "dojo/json" ], function(declare, json) {

	var module = declare("obno.core.safejson", null, {
	});
	
	/**
	 * safely serialize an object to a json string by detecting and skipping circular refs 
	 * circular refs are replaced by a "$ref" attribute point to the __jsonRefID property of the referenced object
	 * if no __jsonRefID property found then the referenced is skipped. 
	 */
	module.stringify = function(value){
		var seen = [];
		return json.stringify(value, function(k, v){
			if (typeof v === 'object' && v !== null && !(Object.prototype.toString.call(v) === '[object Array]') &&
				!(v instanceof Boolean) && !(v instanceof Date) && 
				!(v instanceof Number) && !(v instanceof RegExp) && !(v instanceof String)){
				//have we seen it?
				var seenIdx = seen.indexOf(v); 
				if (seenIdx === -1){
					//add it
					seen.push(v);
					return v;
				}
				//a circular ref
				var obj = seen[seenIdx];
				return {"$ref": obj.__jsonRefID || "?"};
			}
			return v;
			
		});
		seen = [];
	};
	
	return module;

});