// Copyright (c) 2011 Firebase.co and Contributors - http://www.firebase.co
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.


var Expression = require("../Expressions").Expression

function IsEmpty() {

}
IsEmpty.prototype = new Expression()
IsEmpty.prototype.isEmptyCore = function(val) {
	var isEmpty = (val == undefined || val == null || val == '')
	this.end(isEmpty)
}
IsEmpty.prototype.execute = function() {
	var self = this
	
	if(this.hasHint()) {
		this.isEmptyCore(this.getHintVariableValue())
	} else {
		this.runInput(function(res) {
				self.isEmptyCore(res)
			})
	}
}

module.exports = {
	name:"isEmpty",
	flags: ["hint"],
	implementation:IsEmpty
}