A simple promise-based task queue

queue.js

var when = require('../when');

/**
 * A simple promise-based task queue that runs tasks in sequence without
 * overlap.  Adding a task returns a promise that resolves when that task
 * completes.
 */
function Queue() {}

Queue.prototype = {
	/**
	 * Add a new task to this Queue
	 * @param task {Function}
	 * @param ... arguments with which to invoke the task
	 * @return {Promise} a promise that will resolve with the completion value of
	 *  the task.
	 */
	add: function(task) {
		var args = Array.prototype.slice.call(arguments, 1);

		function applyTask() {
			return task.apply(null, args);
		}

		this.current = when(this.current, applyTask, applyTask);

		return this.current;
	}
};