promise-as3のPromise#when実装

promise_snipet

public function when( ...args ):Promise {
	if( args.length == 1 && args[0] is Array ) {
		args = args[0];
	}

	// 引数が0個ならreject
	if( args.length == 0 ) {
		return this.then(
						function( value:* ):void {
							Deferred.reject('arguments must not be empty.');
						},
						function( reason:* ):void {
							Deferred.reject( reason );
						}
						);
	}

	var d:Deferred = new Deferred();

	this.then(
					function( value:* ):void {
						var results:Array = [];
						var resolvedCount:uint = 0;

						for( var i:int = 0, l:int = args.length; i < l; i++ ) {
							var callback:Function = (function( index:uint ):Function {
								return function( value:* ):void {
									results[index] = value;

									// すべてのコールバックの実行が完了したらresolve
									if ( ++resolvedCount == args.length ) {
										d.resolve(results);
										d = null;
									}
								}
							})(i);

							var errback:Function = function( error:* ):void {
								d.reject(error);
							};

							if ( Promise.isThenable(args[i]) ) {
								args[i].then(callback, errback);
							} else if ( args[i] is Function ) {
								Promise.when(value).then(args[i]).then(callback, errback);
							}
						}
					},
					function( reason:* ):void {
						d.reject( reason );
					}
					);
	return d.promise;
}