var Operation = require('./operation');

/**
 * The equivalent of a SQL operation.
 */
module.exports = new Class({
	Extends: 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 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);
	}
});