Skinny Coffee Machine

A simple state machine with observers.

Skinny Coffee Machine is a simple JavaScript state machine written in CoffeeScript. It was originally developed whilst rewriting version 2.0 of jQuery Endless Scroll.

Usage

Define State Machines

@coffeeMachine.power = new SkinnyCoffeeMachine
  default: 'off'
  events:
    turnOn:
      off: 'on'
    turnOff:
      on: 'off'
  on:
    turnOn:  (from, to) -> "#{from.toUpperCase()} to #{to.toUpperCase()}"
    turnOff: (from, to) -> "#{from.toUpperCase()} to #{to.toUpperCase()}"
  before:
    turnOff: (from, to) -> "Before switching to #{to.toUpperCase()}"
  after:
    turnOn:  (from, to) -> "After switching to #{to.toUpperCase()}"
    turnOff: (from, to) -> "After switching to #{to.toUpperCase()}"

@coffeeMachine.mode = new SkinnyCoffeeMachine
  default: 'latte'
  events:
    next:
      latte: 'cappuccino'
      cappuccino: 'espresso'
      espresso: 'lungo'
      lungo: 'latte'
    last:
      latte: 'lungo'
      lungo: 'espresso'
      espresso: 'cappuccino'
      cappuccino: 'latte'

Switch/Change States

You may use either switch or change for switching states:

@coffeeMachine.power.currentState() #=> "off"

@coffeeMachine.power.switch('turnOn')

@coffeeMachine.power.currentState() #=> "on"

To change states multiple times:

@coffeeMachine.mode.currentState() #=> "latte"

@coffeeMachine.mode.change('next', 3)

@coffeeMachine.mode.currentState() #=> "cappuccino"

Observers

In order to provide more flexibility on state transition callbacks, you may use observers to dynamically add and remove events.

To start observing:

@coffeeMachine.power.observeBefore('turnOn').start 'labelA', (from, to) => "Observer A before switching to #{to.toUpperCase()}"
@coffeeMachine.power.observeOn(    'turnOn').start 'labelB', (from, to) => "Observer B on switching to #{to.toUpperCase()}"
@coffeeMachine.power.observeAfter( 'turnOn').start 'labelC', (from, to) => "Observer C after switching to #{to.toUpperCase()}"

To stop observing:

@coffeeMachine.power.observeBefore('turnOn').stop('labelA')

Contribute

Skinny Coffee Machine uses Grunt, PhantomJS and Mocha.

After you have Grunt and PhantomJS set up, you may run tests by:

grunt

To automatically compile CoffeeScript as well as run tests during development, you may use:

grunt watch

License

Copyright (c) 2012 Fred Wu

Licensed under the MIT license.