tail recursive

tail_recursive.js

function tailRecursive(func) {
	var firstcall = true;
	var targs;
	var CONTINUE = {};

	return function() {
		var args = arguments;
		var err, threw;

		if (firstcall) {
			firstcall = false;
			try {
				while (true) {
					var result = func.apply(this, args);
					if (result === CONTINUE) {
						args = targs;
					} else {
						return result;
					}
				}
			} catch(e) {
				threw = true;
				err = e;
			} finally {
				firstcall = true;
				if (threw)
					throw err;
			}
		} else {
			targs = args;
			return CONTINUE;
		}
	};
}

var sum = tailRecursive(function(n, acc) {
	acc = acc || 0;

	if (n === 0)
		return acc;

	return sum(n - 1, acc + n);
});
sum(100000);