Javascript Workflow Processor

workflow-demo.js

(function () {
	var sayHi = function (token) {
			if (!token.progress) token.progress = {};
			token.progress.saidHi = (token.progress.saidHi||0) + 1;
			//true == simply proceed; false == reject workflow
			return true;
		},
		shakeIt = function (token, next) {
			token.progress.shook = (token.progress.shook||0) + 1;
			next('right');
		},
		fakeIt = function (token, next) {
			token.progress.faked = (token.progress.faked||0) + 1;
			next(true);
		},
		breakIt = function (token) {
			token.progress.broken = (token.progress.broken||0) + 1;
			return true;
		},
		bakeIt = function (token) {
			token.progress.baked = (token.progress.baked||0) + 1;
			return true;
		};
	
	
	
	var wf = new WorkFlow( //Workflow
		sayHi,
		[ //Parallel
			[ //Sequence
				shakeIt,
				{ //Branch
					left: fakeIt,
					right: [ //Parallel
						breakIt, 
						shakeIt 
					]
				}
			],
			bakeIt
		],
		sayHi,
		[ sayHi, fakeIt, breakIt ], //Parallel
		sayHi
	);
	var then = +new Date();
	wf({ token: 'A' })
		.done(function (token) {
			var now = +new Date();
			console.log("Running time: ", now-then, 'ms');
		})
		.progress(function (token) {
			var prg = token.progress;
			console.log([
				"Said Hi "+(prg.saidHi||0),
				"Shook "+(prg.shook||0),
				"Faked "+(prg.faked||0),
				"Broken "+(prg.broken||0),
				"Baked "+(prg.baked||0)
			].join('; '));
		});
}());

workflow.js

/**
 * WorkFlow processor
 *
 * @author Bryan Elliott <ook@codemonkeybryan.com>
 * @info
 *		Create a managed, asynchronous workflow, with a corresponding 
 *	jQuery.Promise.  Each step may be synchronous, or asynchronous, meaning 
 *	user-invoked and AJAX calls can be integrated into a sequential workflow.
 *
 * 
 * @class 	WorkFlow(...)
 * @info 	Constructor for creating #WorkFlow objects
 * @type	#Action	A Function, #Parallel, #Branch, or #WorkFlow
 * @type	#Sequence	A Function or an array of #Actions; the first #Action in a #Sequence MUST NOT be a #Branch
 * @type	#Parallel	An array of #Sequences
 * @type	#Branch	An object containing a set of name to #Sequence relationships
 * @rest	#Action	taken together, the sequence of actions to perform
 * @return	Function	An executable #WorkFlow
 *
 * @function	#WorkFlow(token)
 * @info	An instance of WorkFlow
 * @param	Object token	a state object to be passed through the steps of the #WorkFlow
 * @return	jQuery.Promise	Resolved when the #WorkFlow is either resolved or rejected.
 * 
 * @depends	jQuery.Deferred
 **/
 
var WorkFlow = (function () {
	var getFnName = !!(function getFnName() {}).name ? function (f) {
		if (f.original instanceof Function) 
			return arguments.callee(f.original());
		return f.name;
	} : function (f) {
		if (f.original instanceof Function) 
			return arguments.callee(f.original());
		return f.toString().replace(/function\s*([^\( ]*)[\s\S]*$/, '$1');
	}; 

	var WorkFlow = function () {
		var inst = this,
			sequence = Array.prototype.slice.call(arguments);
		return function Flow(token) {
			if (!(this instanceof arguments.callee)) {
				return new arguments.callee(token);
			}
			var flow = this;
			flow.sequence = Array.prototype.slice.call(sequence);
			
			flow.processSequence = function () {
				WorkFlow.prototype.processSequence.apply(flow, arguments);
			};
			WorkFlow.prototype.execute.apply(this, arguments);
			return this.deferred.promise();
		};
	};
	
	WorkFlow.prototype.resolve = function (token) {
		this.deferred.resolveWith(this, token);
	};
	WorkFlow.prototype.reject = function (token) {
		this.deferred.rejectWith(this, token);
	};
	WorkFlow.prototype.processSequence = function (sequence, sequenceComplete) {
		if (sequence instanceof Function)
			sequence = [ sequence ];
		var i, 
			inst = this,
			promise = this.deferred.promise(),
			methods = [];
		if (sequence[0] instanceof Object && !(sequence[0] instanceof Array) && !(sequence[0] instanceof Function)) 
			throw new Error("Branches MUST NOT be the first item in a sequence");
			
		for (i=0; i<sequence.length; i++) (function (item, index) {
			var next = function (result) {
				inst.deferred.notifyWith(promise, [inst.token]);
				inst.lastResult = result;
				if (result===false) {
					inst.deferred.rejectWith(promise, [inst.token]);
					return;
				}
				index++;
				if (index < methods.length) {
					methods[index].call();
					return;
				}
				if (index === methods.length) {
					inst.deferred.notifyWith(promise, [inst.token]);
					sequenceComplete(inst);
					return;
				}
				throw new Error("Workflow reached an illegal state");
			};
			if (item instanceof Array) {
				var parallel = item,
					count = parallel.length;
				item = function (token, proceed) {
					for (var i=0; i<parallel.length; i++) (function (seq, index) {
						setTimeout(function () {
							inst.processSequence(seq, function () {
								if (--count > 0) {
									return;
								}
								proceed();
							});
						},1);
						
					}(parallel[i], i));
				};
			}
			if (item instanceof Object && !(item instanceof Function)) {
				var branch = item,
					item = function (token, proceed) {
						var seq = branch[inst.lastResult];
						if (!seq) 
							throw new Error("Could not switch to branch \""+inst.lastResult+"\"");
						inst.processSequence(seq, function () {
							proceed();
						});
					}
			}
			
			methods[index] = function () {
				var ret = item.call(inst.deferred, inst.token, next);
				if (typeof ret !== 'undefined')
					next(ret);
			};
		}(sequence[i], i));
		methods[0]();
	};
	WorkFlow.prototype.execute = function (token, next) {
		if (!!this.token)
			throw new Error("Cannot execute workflow already in progress");
		this.token = token || {};
		this.deferred = new jQuery.Deferred();
		WorkFlow.prototype.processSequence.call(this, this.sequence, function (inst) {
			inst.deferred.resolveWith(inst.deferred.promise(), [inst.token]);
			if (next instanceof Function)
				next(true);
		});
		return this.deferred.promise();
	};
	
	return WorkFlow;
}());