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Created May 24, 2013 09:54
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Finite State Cat
Raw
README.md

Allow me to represent how my cat was acting last night as a finite state machine.

Raw
finiteStateCat.js
var finiteStateCat = StateMachine.create({
initial: 'inside',
events: [
{ name: 'letHerOut', from: 'inside', to: 'outside' },
{ name: 'letHerIn', from: 'outside', to: 'inside' }
],
callbacks: {
oninside:function(){
$("#cat").html("<p>Meows to be let out</p><button type='button' id='letHerOut'>Let Her Out</button>");
$("#letHerOut").on("click",function(){finiteStateCat.letHerOut();})
},
onoutside:function(){
$("#cat").html("<p>realizes it's raining meows to be let in</p><button type='button' id='letHerIn'>Let Her in</button>");
$("#letHerIn").on("click",function(){finiteStateCat.letHerIn();})
}
}
});
Raw
index.html
<!DOCTYPE html>
<meta charset="utf-8">
<body>
<div id="cat"></div>
<script src="//ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<script src="state-machine.js"></script>
<script src="finiteStateCat.js"></script>
Raw
state-machine.js
/*
Javascript State Machine Library - https://github.com/jakesgordon/javascript-state-machine
Copyright (c) 2012, 2013 Jake Gordon and contributors
Released under the MIT license - https://github.com/jakesgordon/javascript-state-machine/blob/master/LICENSE
*/
(function (window) {
var StateMachine = {
//---------------------------------------------------------------------------
VERSION: "2.2.0",
//---------------------------------------------------------------------------
Result: {
SUCCEEDED: 1, // the event transitioned successfully from one state to another
NOTRANSITION: 2, // the event was successfull but no state transition was necessary
CANCELLED: 3, // the event was cancelled by the caller in a beforeEvent callback
PENDING: 4 // the event is asynchronous and the caller is in control of when the transition occurs
},
Error: {
INVALID_TRANSITION: 100, // caller tried to fire an event that was innapropriate in the current state
PENDING_TRANSITION: 200, // caller tried to fire an event while an async transition was still pending
INVALID_CALLBACK: 300 // caller provided callback function threw an exception
},
WILDCARD: '*',
ASYNC: 'async',
//---------------------------------------------------------------------------
create: function(cfg, target) {
var initial = (typeof cfg.initial == 'string') ? { state: cfg.initial } : cfg.initial; // allow for a simple string, or an object with { state: 'foo', event: 'setup', defer: true|false }
var terminal = cfg.terminal || cfg['final'];
var fsm = target || cfg.target || {};
var events = cfg.events || [];
var callbacks = cfg.callbacks || {};
var map = {};
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++)
map[e.name][from[n]] = e.to || from[n]; // allow no-op transition if 'to' is not specified
};
if (initial) {
initial.event = initial.event || 'startup';
add({ name: initial.event, from: 'none', to: initial.state });
}
for(var n = 0 ; n < events.length ; n++)
add(events[n]);
for(var name in map) {
if (map.hasOwnProperty(name))
fsm[name] = StateMachine.buildEvent(name, map[name]);
}
for(var name in callbacks) {
if (callbacks.hasOwnProperty(name))
fsm[name] = callbacks[name]
}
fsm.current = 'none';
fsm.is = function(state) { return (state instanceof Array) ? (state.indexOf(this.current) >= 0) : (this.current === state); };
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, 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.isFinished = function() { return this.is(terminal); };
if (initial && !initial.defer)
fsm[initial.event]();
return fsm;
},
//===========================================================================
doCallback: function(fsm, func, name, from, to, args) {
if (func) {
try {
return func.apply(fsm, [name, from, to].concat(args));
}
catch(e) {
return fsm.error(name, from, to, args, StateMachine.Error.INVALID_CALLBACK, "an exception occurred in a caller-provided callback function", e);
}
}
},
beforeAnyEvent: function(fsm, name, from, to, args) { return StateMachine.doCallback(fsm, fsm['onbeforeevent'], name, from, to, args); },
afterAnyEvent: function(fsm, name, from, to, args) { return StateMachine.doCallback(fsm, fsm['onafterevent'] || fsm['onevent'], name, from, to, args); },
leaveAnyState: function(fsm, name, from, to, args) { return StateMachine.doCallback(fsm, fsm['onleavestate'], name, from, to, args); },
enterAnyState: function(fsm, name, from, to, args) { return StateMachine.doCallback(fsm, fsm['onenterstate'] || fsm['onstate'], name, from, to, args); },
changeState: function(fsm, name, from, to, args) { return StateMachine.doCallback(fsm, fsm['onchangestate'], name, from, to, args); },
beforeThisEvent: function(fsm, name, from, to, args) { return StateMachine.doCallback(fsm, fsm['onbefore' + name], name, from, to, args); },
afterThisEvent: function(fsm, name, from, to, args) { return StateMachine.doCallback(fsm, fsm['onafter' + name] || fsm['on' + name], name, from, to, args); },
leaveThisState: function(fsm, name, from, to, args) { return StateMachine.doCallback(fsm, fsm['onleave' + from], name, from, to, args); },
enterThisState: function(fsm, name, from, to, args) { return StateMachine.doCallback(fsm, fsm['onenter' + to] || fsm['on' + to], name, from, to, args); },
beforeEvent: function(fsm, name, from, to, args) {
if ((false === StateMachine.beforeThisEvent(fsm, name, from, to, args)) ||
(false === StateMachine.beforeAnyEvent( fsm, name, from, to, args)))
return false;
},
afterEvent: function(fsm, name, from, to, args) {
StateMachine.afterThisEvent(fsm, name, from, to, args);
StateMachine.afterAnyEvent( fsm, name, from, to, args);
},
leaveState: function(fsm, name, from, to, args) {
var specific = StateMachine.leaveThisState(fsm, name, from, to, args),
general = StateMachine.leaveAnyState( fsm, name, from, to, args);
if ((false === specific) || (false === general))
return false;
else if ((StateMachine.ASYNC === specific) || (StateMachine.ASYNC === general))
return StateMachine.ASYNC;
},
enterState: function(fsm, name, from, to, args) {
StateMachine.enterThisState(fsm, name, from, to, args);
StateMachine.enterAnyState( fsm, name, from, to, args);
},
//===========================================================================
buildEvent: function(name, map) {
return function() {
var from = this.current;
var to = map[from] || map[StateMachine.WILDCARD] || from;
var args = Array.prototype.slice.call(arguments); // turn arguments into pure array
if (this.transition)
return this.error(name, from, to, args, StateMachine.Error.PENDING_TRANSITION, "event " + name + " inappropriate because previous transition did not complete");
if (this.cannot(name))
return this.error(name, from, to, args, StateMachine.Error.INVALID_TRANSITION, "event " + name + " inappropriate in current state " + this.current);
if (false === StateMachine.beforeEvent(this, name, from, to, args))
return StateMachine.Result.CANCELLED;
if (from === to) {
StateMachine.afterEvent(this, name, from, to, args);
return StateMachine.Result.NOTRANSITION;
}
// prepare a transition method for use EITHER lower down, or by caller if they want an async transition (indicated by an ASYNC return value from leaveState)
var fsm = this;
this.transition = function() {
fsm.transition = null; // this method should only ever be called once
fsm.current = to;
StateMachine.enterState( fsm, name, from, to, args);
StateMachine.changeState(fsm, name, from, to, args);
StateMachine.afterEvent( fsm, name, from, to, args);
return StateMachine.Result.SUCCEEDED;
};
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) {
this.transition = null;
return StateMachine.Result.CANCELLED;
}
else if (StateMachine.ASYNC === leave) {
return StateMachine.Result.PENDING;
}
else {
if (this.transition) // need to check in case user manually called transition() but forgot to return StateMachine.ASYNC
return this.transition();
}
};
}
}; // StateMachine
//===========================================================================
if ("function" === typeof define) {
define(function(require) { return StateMachine; });
}
else {
window.StateMachine = StateMachine;
}
}(this));
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