rpn

function RPNCalculator(){										                  //stack
	this.stack = [];
}

RPNCalculator.prototype.push = function(value){					      //input
	this.stack.push(value);
};

RPNCalculator.prototype.popcompute = function(operatorfunc){	//generic function operator
	if(this.stack.length < 2 ){
		throw 'rpnCalculatorInstance is empty';
	}else{
		var num1 = this.stack.pop();
		var num2 = this.stack.pop();
		this.push(operatorfunc(num1,num2));
	}
};




RPNCalculator.prototype.plus = function(){ 						         //plus operator
	var add = function (a,b){
		return b + a;
	};
	this.popcompute(add);
};

RPNCalculator.prototype.minus = function(){						        //subtract operator
	var subtract = function(a,b){
		return b - a;
	};
	this.popcompute(subtract);
}

RPNCalculator.prototype.times = function(){						        //multiplication operator
	var multiplies = function(a,b){
		return b * a;
	};
	this.popcompute(multiplies);
}

RPNCalculator.prototype.divide = function(){					        //division operator
	var divide = function(a,b){
		return b / a;
	}
	this.popcompute(divide);
}

RPNCalculator.prototype.value = function(){						        //returns the top value
	return this.stack[this.stack.length-1];
}