/*\
title: $:/core/modules/filters/untagged.js
type: application/javascript
module-type: filteroperator

Filter operator returning all the selected tiddlers that are untagged

\*/
(function(){

/*jslint node: true, browser: true */
/*global $tw: false */
"use strict";

/*
Export our filter function
*/
exports.untagged = function(source,operator,options) {
	var results = [],
		isTagged = (operator.operand || operator.suffix || "").toLowerCase() === "no" ? 
			function(tiddler) {
				return false;
			} : function(tiddler) {
				return tiddler && $tw.utils.isArray(tiddler.fields.tags) && tiddler.fields.tags.length > 0;
			};
	if(operator.prefix === "!") {
		source(function(tiddler,title) {
			if(isTagged(tiddler)) {
				$tw.utils.pushTop(results,title);
			}
		});
	} else {
		source(function(tiddler,title) {
			if(!isTagged(tiddler)) {
				$tw.utils.pushTop(results,title);
			}
		});
	}
	return results;
};

})();