alexandervasyuk

function Stack() {
	this.stack = new Array();
}

Stack.prototype = {
	isEmpty: function() {
		return this.stack.length == 0;
	},

	pop: function() {

alexandervasyuk

var evaluate = function(node) {
	var token = node.data;
	if (token instanceof Operator) {
		return token.applyFunction(evaluate(node.left), evaluate(node.right));
	} else {
		return node.data;
	}
}

alexandervasyuk

if the token is a left parenthesis, then push it onto the stack.
If the token is a right parenthesis:
	Until the token at the top of the stack is a left parenthesis, pop operators off the stack onto the output stack.
	Pop the left parenthesis from the stack, but not onto the output queue.

alexandervasyuk

function Stack() {
	this.stack = new Array();
}

Stack.prototype = {
	isEmpty: function() {
		return this.stack.length == 0;
	},

	pop: function() {

alexandervasyuk

for (var s = 0; s < input.length; ) {
	var token;
	if (isNaN(input[s])) {
		token = input[s];
		s+=1;
	} else {
		var i = s + 1;
		while(i < input.length && !isNaN(input[i])) {
			i+=1;
		}

alexandervasyuk

		...
		
		if (token.length == 1 && isNaN(token)) { 
			var operator = createOperator(token);
			if (!operatorStack.isEmpty() && operator.lessOrEqualInPrecedenceTo(operatorStack.peek())) {
				var subtree = createSubtree(operatorStack.pop(), null);
				outputStack.push(subtree);
			}
			operatorStack.push(operator);
		} else {

alexandervasyuk

var createSubtree = function createSubtree(operator, tree) {
	if (tree == null) {
		var right = outputStack.pop(),
			left = outputStack.pop();
		tree = new BinaryTreeNode(operator);
		tree.right = right instanceof BinaryTreeNode ? right : new BinaryTreeNode(right);
		tree.left = left instanceof BinaryTreeNode ? left : new BinaryTreeNode(left);
	} else {
		var subtree = tree,
			left = outputStack.pop();

alexandervasyuk

var updateTree = function() {
	var operator = operatorStack.pop(),
		output = outputStack.pop();
	if (head == null) {
		head = new BinaryTreeNode(operator);
		left = outputStack.pop();
		head.left = left instanceof BinaryTreeNode ? left : new BinaryTreeNode(left);
		head.right = output instanceof BinaryTreeNode ? output : new BinaryTreeNode(output);
	} else {
		var subtree = head;

alexandervasyuk

if (token == '(') {
	operatorStack.push(token);
} else if (token == ')') {
	while(operatorStack.peek() != '(') {
		var subtree = createSubtree(operatorStack.pop(), null);
		outputStack.push(subtree);
	}
	operatorStack.pop();
}

alexandervasyuk

function Stack() {
	this.stack = new Array();
}

Stack.prototype = {
	isEmpty: function() {
		return this.stack.length == 0;
	},

	pop: function() {