thetwelvelabs/techne

Finite State Machine implementation

dev-master 2013-01-29 21:31 UTC

Requires

• php: >=5.3.3

MIT

• Chris Woodford

• fsm
• finite-state machine

README

================================

A simple PHP implementation of a Finite-State Machine

Installation

Use Composer to install this library in your project

Create your composer.json file

  {
      "require": {
          "thetwelvelabs/techne": "0.2.*@dev"
      }
  }

Download composer into your application root

  $ curl -s http://getcomposer.org/installer | php

Install your dependencies

  $ php composer.phar install

Usage

Let's use a light switch as a simple example.
A light switch as two states: on and off. The state of a light switch is transitioned from one to the other by flipping the switch. We'll assume that the initial state of the light switch is 'off'

Define your FSM

  $machine = new StateMachine\FiniteStateMachine();
  $machine->setInitialState('off');

Define the transitions

  $turnOff = new StateMachine\Transition('on', 'off');
  $turnOn = new StateMachine\Transition('off', 'on');

Add a guard to the turnOn transition

  // flipping the switch on requires electricity
  $hasElectricity = true;
  $turnOn->before(function() use ($hasElectricity) {
      return $hasElectricity ? true : false;
  });

Define the events

  $machine->addEvent('flip', array($turnOn, $turnOff));

Transition from off to on

  $machine->flip();  
  echo $machine->getCurrentState();
  // prints 'on'  

Transition back to off

  $machine->flip();  
  echo $machine->getCurrentState();
  // prints 'off'