Deferred.as

## Deferred.as
package async
{
	public class Deferred implements Promise
	{

		private const pending:Array = [];

		private var processed:Boolean;

		private var completed:Boolean;

		private var completionAction:String;

		private var completionValue:*;

		private var onResolved:Function;

		private var onRejected:Function;

		public function Deferred(onResolved:Function = null, onRejected:Function = null)
		{
			this.onResolved = onResolved;
			this.onRejected = onRejected || throwError;
		}

		public function resolve(result:*):void
		{
			processed || process(onResolved, result);
		}

		public function reject(error:*):void
		{
			processed || process(onRejected, error);
		}

		public function then(onResolved:Function = null, onRejected:Function = null):Promise
		{
			if (onResolved || onRejected)
			{
				const deferred:Deferred = new Deferred(onResolved, onRejected);
				NextTick.call(schedule, [deferred]);
				return deferred;
			}
			return this;
		}

		private function throwError(error:*):void
		{
			throw error;
		}

		private function schedule(deferred:Deferred):void
		{
			pending.push(deferred);
			completed && propagate();
		}

		private function propagate():void
		{
			for each (var deferred:Deferred in pending)
				deferred[completionAction](completionValue);
			pending.length = 0;
		}

		private function complete(action:String, value:*):void
		{
			onResolved = null;
			onRejected = null;
			completionAction = action;
			completionValue = value;
			completed = true;
			propagate();
		}

		private function completeResolved(result:*):void
		{
			complete('resolve', result);
		}

		private function completeRejected(error:*):void
		{
			complete('reject', error);
		}

		private function process(closure:Function, value:*):void
		{
			processed = true;
			try
			{
				closure && (value = closure(value));
				value is Promise
					? Promise(value).then(completeResolved, completeRejected)
					: completeResolved(value);
			}
			catch (error:*)
			{
				completeRejected(error);
			}
		}
	}
}

## NextTick.as
package async
{
	import flash.display.Sprite;
	import flash.events.Event;

	public class NextTick
	{
		private static const SPR:Sprite = new Sprite();

		private static const Q:Array = [];

		public static function call(closure:Function, args:Array = null):void
		{
			Q.push(new Scope(closure, args));
			Q.length == 1 && SPR.addEventListener(Event.ENTER_FRAME, run);
		}

		private static function run(e:Event):void
		{
			SPR.removeEventListener(Event.ENTER_FRAME, run);
			for each (var scope:Scope in Q.splice(0))
				scope.execute();
		}
	}
}

class Scope
{
	private var _closure:Function;

	private var _args:Array;

	public function Scope(closure:Function, args:Array)
	{
		_closure = closure;
		_args = args;
	}

	public function execute():void
	{
		_args ? _closure.apply(null, _args) : _closure();
	}
}

## Promise.as
package async
{

	public interface Promise
	{
		function then(onResolved:Function = null, onRejected:Function = null):Promise;
	}
}