Allow events that can be fired from any state using a wildcard '*' (or missing) 'from' attribute (github issue jakesgordon#11)

 jakesgordon#11

Author: jakesgordon

state-machine.js

@@ -2,7 +2,7 @@ StateMachine = {
 
   //---------------------------------------------------------------------------
 
-  VERSION: "2.0.1",
+  VERSION: "2.1.0",
 
   //---------------------------------------------------------------------------
 
@@ -12,6 +12,8 @@ StateMachine = {
     INVALID_CALLBACK:   300, // caller provided callback function threw an exception
   },
 
+  WILDCARD: '*',
+
   //---------------------------------------------------------------------------
 
   create: function(cfg, target) {
@@ -23,7 +25,7 @@ StateMachine = {
     var map       = {};
 
     var add = function(e) {
-      var from = (e.from instanceof Array) ? e.from : [e.from];
+      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++)
         map[e.name][from[n]] = e.to || from[n]; // allow no-op transition if 'to' is not specified
@@ -49,7 +51,7 @@ StateMachine = {
 
     fsm.current = 'none';
     fsm.is      = function(state) { return this.current == state; };
-    fsm.can     = function(event) { return !!map[event][this.current] && !this.transition; };
+    fsm.can     = function(event) { return !this.transition && (map[event].hasOwnProperty(this.current) || map[event].hasOwnProperty(StateMachine.WILDCARD)); }
     fsm.cannot  = function(event) { return !this.can(event); };
     fsm.error   = cfg.error || function(name, from, to, args, error, msg) { throw msg; }; // default behavior when something unexpected happens is to throw an exception, but caller can override this behavior if desired (see github issue #3)
 
@@ -90,7 +92,7 @@ StateMachine = {
         return this.error(name, from, to, args, StateMachine.Error.INVALID_TRANSITION, "event " + name + " inappropriate in current state " + this.current);
 
       var from  = this.current;
-      var to    = map[from];
+      var to    = map[from] || map[StateMachine.WILDCARD] || from;
       var args  = Array.prototype.slice.call(arguments); // turn arguments into pure array
 
       if (false === StateMachine.beforeEvent(this, name, from, to, args))

state-machine.min.js

@@ -368,7 +368,7 @@ test("no-op transitions (github issue #5)", function() {
   var fsm = StateMachine.create({
     initial: 'green',
     events: [
-      { name: 'noop',  from: 'green',               }, // NOTE: no 'to' option specified
+      { name: 'noop',  from: 'green',  /* no-op */  },
       { name: 'warn',  from: 'green',  to: 'yellow' },
       { name: 'panic', from: 'yellow', to: 'red'    },
       { name: 'calm',  from: 'red',    to: 'yellow' },
@@ -388,4 +388,64 @@ test("no-op transitions (github issue #5)", function() {
 
 });
 
+//-----------------------------------------------------------------------------
+
+test("wildcard 'from' allows event from any state (github issue #11)", function() {
+
+  var fsm = StateMachine.create({
+    initial: 'stopped',
+    events: [
+      { name: 'prepare', from: 'stopped',      to: 'ready'   },
+      { name: 'start',   from: 'ready',        to: 'running' },
+      { name: 'resume',  from: 'paused',       to: 'running' },
+      { name: 'pause',   from: 'running',      to: 'paused'  },
+      { name: 'stop',    from: '*',            to: 'stopped' }
+  ]});
+
+  equals(fsm.current, 'stopped', "initial state should be stopped");
+
+  fsm.prepare(); equals(fsm.current, 'ready',   "prepare event should transition from stopped to ready");
+  fsm.stop();    equals(fsm.current, 'stopped', "stop event should transition from ready to stopped");
+
+  fsm.prepare(); equals(fsm.current, 'ready',   "prepare event should transition from stopped to ready");
+  fsm.start();   equals(fsm.current, 'running', "start event should transition from ready to running");
+  fsm.stop();    equals(fsm.current, 'stopped', "stop event should transition from running to stopped");
+
+  fsm.prepare(); equals(fsm.current, 'ready',   "prepare event should transition from stopped to ready");
+  fsm.start();   equals(fsm.current, 'running', "start event should transition from ready to running");
+  fsm.pause();   equals(fsm.current, 'paused',  "pause event should transition from running to paused");
+  fsm.stop();    equals(fsm.current, 'stopped', "stop event should transition from paused to stopped");
+
+});
+
+//-----------------------------------------------------------------------------
+
+test("missing 'from' allows event from any state (github issue #11) ", function() {
+
+  var fsm = StateMachine.create({
+    initial: 'stopped',
+    events: [
+      { name: 'prepare', from: 'stopped',      to: 'ready'   },
+      { name: 'start',   from: 'ready',        to: 'running' },
+      { name: 'resume',  from: 'paused',       to: 'running' },
+      { name: 'pause',   from: 'running',      to: 'paused'  },
+      { name: 'stop',    /* any from state */  to: 'stopped' }
+  ]});
+
+  equals(fsm.current, 'stopped', "initial state should be stopped");
+
+  fsm.prepare(); equals(fsm.current, 'ready',   "prepare event should transition from stopped to ready");
+  fsm.stop();    equals(fsm.current, 'stopped', "stop event should transition from ready to stopped");
+
+  fsm.prepare(); equals(fsm.current, 'ready',   "prepare event should transition from stopped to ready");
+  fsm.start();   equals(fsm.current, 'running', "start event should transition from ready to running");
+  fsm.stop();    equals(fsm.current, 'stopped', "stop event should transition from running to stopped");
+
+  fsm.prepare(); equals(fsm.current, 'ready',   "prepare event should transition from stopped to ready");
+  fsm.start();   equals(fsm.current, 'running', "start event should transition from ready to running");
+  fsm.pause();   equals(fsm.current, 'paused',  "pause event should transition from running to paused");
+  fsm.stop();    equals(fsm.current, 'stopped', "stop event should transition from paused to stopped");
+
+});
+