Create task.js

lib/task.js

@@ -0,0 +1,108 @@
+//////////////////////////////////////////////////////////////////////////////////
+// Task API (Async implementation in WSH)
+/////////////////////////////////////////////////////////////////////////////////
+
+var Task = function(id, f, params) {
+	this.id = id;
+	this.f = f;
+	this.params = params;
+	this.nextTask = null;
+	this.setNextTask = function(task) {
+		this.nextTask = task;
+	}
+};
+
+var TaskQueue = function() {
+	this._task = null;
+	this.queue = [];
+	this.put = function(task) {
+		try {
+			this._task = task;
+			this.queue.push(this._task);
+			this.lastId++;
+		} catch(e) {
+			console.error("TaskQueue.put exception: " + e.message);
+		}
+
+		return this;
+	};
+	this.get = function() {
+		var task = null;
+		
+		try {
+			if (this.queue.length > 0) {
+				task = this.queue[0];
+				this.queue = this.queue.slice(1);
+			}
+		} catch(e) {
+			console.error("TaskQueue.get: " + e.message);
+		}
+		
+		return task;
+	};
+	this.next = function() {
+		var result = null;
+		
+		try {
+			var task = this.get();
+
+			if (task != null) {
+				try {
+					result = task.f.apply(null, task.params);
+				} catch (e) {
+					console.error("Task exception: " + e.message);
+				}
+				
+				if (task.nextTask != null) {
+					this.put(task.nextTask);
+				}
+			}
+		} catch(e) {
+			console.error("TaskQueue.next: " + e.message);
+		}
+
+		return result;
+	};
+	this.then = function(task) {
+		try {
+			this._task.setNextTask(task);
+			this._task = task;
+			return this;
+		} catch(e) {
+			console.error("TaskQueue.then: " + e.message);
+		}
+	};
+	this.lastId = 0;
+};
+
+exports.createQueue = function() {
+	return new TaskQueue();
+};
+
+exports.makeTask = function(q, f, params) {
+	try {
+		if (q instanceof TaskQueue) {
+			return new Task(q.lastId, f, params);
+		}
+	} catch(e) {
+		console.error("makeTask exception: " + e.message);
+	}
+};
+
+exports.putTask = function(q, f, params) {
+	try {
+		if (q instanceof TaskQueue) {
+			return q.put(new Task(q.lastId, f, params));
+		}
+	} catch(e) {
+		console.error("putTask exception: " + e.message);
+	}
+};
+
+exports.nextTask = function(q) {
+	try {
+		return q.next();
+	} catch(e) {
+		console.error("nextTask exception: " + e.message);
+	}
+};