Added method which returned allowable transitions from current state.

Author: Mathew Goldsborough

state-machine.js

@@ -44,11 +44,19 @@
       var callbacks = cfg.callbacks || {};
       var map       = {};
 
+      // Key/Value pair to track allowable 
+      // transitions (events) from current state
+      var transitions  = {};
+
       var add = function(e) {
         var from = (e.from instanceof Array) ? e.from : (e.from ? [e.from] : [StateMachine.WILDCARD]); // allow 'wildcard' transition if 'from' is not specified
         map[e.name] = map[e.name] || {};
-        for (var n = 0 ; n < from.length ; n++)
+        for (var n = 0 ; n < from.length ; n++) {
+          if(!transitions[e.from]) transitions[e.from] = [];
+          transitions[e.from].push(e.name);
+
           map[e.name][from[n]] = e.to || from[n]; // allow no-op transition if 'to' is not specified
+        }
       };
 
       if (initial) {
@@ -75,6 +83,8 @@
       fsm.cannot  = function(event) { return !this.can(event); };
       fsm.error   = cfg.error || function(name, from, to, args, error, msg, e) { throw e || msg; }; // default behavior when something unexpected happens is to throw an exception, but caller can override this behavior if desired (see github issue #3 and #17)
 
+      fsm.transitions = function() { return transitions[this.current]; };
+
       fsm.isFinished = function() { return this.is(terminal); };
 
       if (initial && !initial.defer)

state-machine.min.js

@@ -111,6 +111,39 @@ test("is", function() {
 
 //-----------------------------------------------------------------------------
 
+test("transitions", 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'  }
+  ]});
+
+  equal(fsm.current, 'green', 'current state should be yellow');
+  deepEqual(fsm.transitions(), ['warn'], 'current transition(s) should be yellow');
+
+  fsm.warn();
+  equal(fsm.current, 'yellow', 'current state should be yellow');
+  deepEqual(fsm.transitions(), ['panic', 'clear'], 'current transition(s) should be panic and clear');
+
+  fsm.panic();
+  equal(fsm.current, 'red', 'current state should be red');
+  deepEqual(fsm.transitions(), ['calm'], 'current transition(s) should be calm');
+
+  fsm.calm();
+  equal(fsm.current, 'yellow', 'current state should be yellow');
+  deepEqual(fsm.transitions(), ['panic', 'clear'], 'current transion(s) should be panic and clear');
+
+  fsm.clear();
+  equal(fsm.current, 'green', 'current state should be green');
+  deepEqual(fsm.transitions(), ['warn'], 'current transion(s) should be warn');
+});
+
+//-----------------------------------------------------------------------------
+
 test("isFinished", function() {
 
   var fsm = StateMachine.create({