Issue jakesgordon#22 - A Function to cancel a transition after StateMachine.ASYNC

jakesgordon · jakesgordon · commit 1180b8ab3f0c · 2012-05-09T06:55:48.000-07:00
diff --git a/README.md b/README.md
@@ -1,4 +1,4 @@
-Javascript Finite State Machine (v2.1.0)
+Javascript Finite State Machine (v2.2.0)
 ========================================
 
 This standalone javascript micro-framework provides a finite state machine for your pleasure.
@@ -193,6 +193,7 @@ For example, using jQuery effects:
       }
     });
 
+>> _NOTE: If you decide to cancel the ASYNC event, you can call `fsm.transition.cancel();`
 
 State Machine Classes
 =====================
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
@@ -1,3 +1,8 @@
+Version 2.2.0 (unreleased)
+--------------------------
+
+ * Allow async event transition to be cancelled (issue #22)
+
 Version 2.1.0 (January 7th 2012)
 --------------------------------
 
diff --git a/demo/demo.js b/demo/demo.js
@@ -46,7 +46,7 @@ Demo = function() {
 
       onleavegreen:  function(event, from, to) { log("LEAVE   STATE: green");  },
       onleaveyellow: function(event, from, to) { log("LEAVE   STATE: yellow"); },
-      onleavered:    function(event, from, to) { log("LEAVE   STATE: red");    async(to); return false; },
+      onleavered:    function(event, from, to) { log("LEAVE   STATE: red");    async(to); return StateMachine.ASYNC; },
 
       ongreen:       function(event, from, to) { log("ENTER   STATE: green");  },
       onyellow:      function(event, from, to) { log("ENTER   STATE: yellow"); },
diff --git a/state-machine.js b/state-machine.js
@@ -4,7 +4,7 @@
 
     //---------------------------------------------------------------------------
 
-    VERSION: "2.1.0",
+    VERSION: "2.2.0",
 
     //---------------------------------------------------------------------------
 
@@ -122,6 +122,10 @@
           StateMachine.changeState(fsm, name, from, to, args);
           StateMachine.afterEvent( fsm, name, from, to, args);
         };
+        this.transition.cancel = function() { // provide a way for caller to cancel async transition if desired (issue #22)
+          fsm.transition = null;
+          StateMachine.afterEvent(fsm, name, from, to, args);
+        }
 
         var leave = StateMachine.leaveState(this, name, from, to, args);
         if (false === leave) {
diff --git a/state-machine.min.js b/state-machine.min.js
diff --git a/test/test_async.js b/test/test_async.js
@@ -246,6 +246,45 @@ test("state transition fired without completing previous transition", function()
 
 //-----------------------------------------------------------------------------
 
+test("state transition can be cancelled (github issue #22)", function() {
+
+  var fsm = StateMachine.create({
+    initial: 'green',
+    events: [
+      { name: 'warn',  from: 'green',  to: 'yellow' },
+      { name: 'panic', from: 'yellow', to: 'red'    },
+      { name: 'calm',  from: 'red',    to: 'yellow' },
+      { name: 'clear', from: 'yellow', to: 'green'  }
+    ],
+    callbacks: {
+      onleavegreen:  function() { return StateMachine.ASYNC; },
+      onleaveyellow: function() { return StateMachine.ASYNC; },
+      onleavered:    function() { return StateMachine.ASYNC; }
+    }
+  });
+
+                    equals(fsm.current, 'green',  "initial state should be green");
+  fsm.warn();       equals(fsm.current, 'green',  "should still be green because we haven't transitioned yet");
+  fsm.transition(); equals(fsm.current, 'yellow', "warn event should transition from green to yellow");
+  fsm.panic();      equals(fsm.current, 'yellow', "should still be yellow because we haven't transitioned yet");
+                    equals(fsm.can('panic'), false, "but cannot panic a 2nd time because a transition is still pending")
+
+  raises(fsm.panic.bind(fsm), /event panic inappropriate because previous transition did not complete/);
+
+  fsm.transition.cancel();
+
+  equals(fsm.current,     'yellow', "should still be yellow because we cancelled the async transition");
+  equals(fsm.can('panic'), true,    "can now panic again because we cancelled previous async transition");
+
+  fsm.panic();
+  fsm.transition();
+
+  equals(fsm.current, 'red', "should finally be red now that we completed the async transition");
+
+});
+
+//-----------------------------------------------------------------------------
+
 test("callbacks are ordered correctly", function() {
 
   var called = [];
