/**
 * The equivalent of a SQL operation.
 **/
Sql.Filter = new Class
({
	Extends: Sql.Operation
	,Tag: 'sql-filter'
	,Properties:
	{
		alwaysReady:
		{
			type: Boolean
		}
	}

	,isReady: function ()
	{
		if (this.alwaysReady)
			return true;
	
		var e = this.exprs.getArray ();
		for (var i = 0; i < e.length; i++)
		if (e[i].isReady () && e[i].primary)
			return true;
				
		return false;
	}

	,render: function (batch)
	{
		var isReady = false;
		var newOp = new Sql.Operation ({type: this.type});
	
		var e = this.exprs.getArray ();
		for (var i = 0; i < e.length; i++)
		if (e[i].isReady ())
		{
			newOp.exprs.add (e[i]);
			isReady = true;
		}
			
		if (!isReady)
			return 'TRUE';
			
		return newOp.render (batch);
	}
});