RunQueue

src.json

@@ -7,6 +7,7 @@
     "date-formatting.js",
     "common/Class.js",
     "common/Promise.js",
+    "common/RunQueue.js",
     "common/EmitterMixin.js",
     "common/ListenerMixin.js",
     "common/MouseIgnorerMixin.js",

src/common/RunQueue.js

@@ -0,0 +1,61 @@
+
+function RunQueue() {
+	var q = []; // array of runFuncs
+
+
+	this.clear = function() {
+		q = []; // TODO: reject all promises?
+	};
+
+	this.push = function(taskFunc) {
+		return new Promise(function(resolve) {
+
+			// should run this function when it's taskFunc's turn to run.
+			// responsible for popping itself off the queue.
+			var runFunc = function() {
+				Promise.resolve(taskFunc()) // result might be async, coerce to promise
+					.then(resolve) // resolve RunQueue::push's promise, for the caller. will receive result of taskFunc.
+					.then(function() {
+						q.shift(); // pop itself off
+
+						// run the next task, if any
+						if (q.length) {
+							q[0]();
+						}
+					});
+			};
+
+			// always put the task at the end of the queue, BEFORE running the task
+			q.push(runFunc);
+
+			// if it's the only task in the queue, run immediately
+			if (q.length === 1) {
+				runFunc();
+			}
+		});
+	};
+}
+
+FC.RunQueue = RunQueue;
+
+/*
+q = new RunQueue();
+
+function work(i) {
+	return q.push(function() {
+		trigger();
+		console.log('work' + i);
+	});
+}
+
+var cnt = 0;
+
+function trigger() {
+	if (cnt < 5) {
+		cnt++;
+		work(cnt);
+	}
+}
+
+work(9);
+*/