DEXM : Deux Ex Machina !

DEXM (Deus EX Machina) is a TEFSM (Time Embeded Finite State Machine) implementation.

Installation

just include dist/dexm.js in your page

-- or --

load it via UMD (Require JS) or CommonJS + browserify.

Creating a finite State Machine

Just invoke the factory method with a name for your FSM and eventually options

var m1 = DEXM('my-machine' /*,  options */);

The second parameter 'options' is a ket/value pairs object :

• tickDelay : default 100 milliseconds
• timeTolerance : default 10 milliseconds

Defining states and transitions

The 'def' method is here, to be chained with 'on' calls for your transitions, like this :

m1.def('s1')
  .on('a', 's2')
  .on('b', 's3')
  ...
  .on(eventName, stateName);

m1.def('s2')
  .on('b', 's2')
  .on('a', 's3');

m1.def('s3')
  .on('a', 's1');

Running tour FSM

initialize with "go", then call "accept" :

m1.go('s1');
m1.accept('a');
m1.accept('b');

Transductions

Those are custom actions triggered on entering and on leaving a given state, just use "from" and "to" methods at definition time :

 m1.def('s4')
   .on('a', 's1')
   .from('s1', function() { console.loe('entering...'); })
   .to('s3', function() { console.loe('leaving...'); })

These methods can accept as first argument :

• a statename
• an array of statenames
• a wildcard '*' for all states

Time transitions

Sometime you may want to achieve a transition after a certain time delay, use in this case the "timeout" method in your definitions :

m1.def('s5')
  .on('a', 's1')
  .on('b', 's2')
  .timeout('s3', 3000) // in milliseconds
  .from(['s1', 's2'], function() { ... })
  .to('*'], function() { ... });

This behavior is backed, of course, with setInterval and clearInterval of the window object.

Enjoy !

TODO

• error (bad transition) callback
• halt method for time scheduled transitions
• add internal stack for basic compiling purposes
• hierarchical FSM def('...').sub(another_fsm)
• test, test & retest (the traffic lights demo)