Class: MicroMachine

Inherits:
Object
  • Object
show all
Defined in:
lib/micromachine.rb

Overview

Finite State Machine

Usage:

machine = MicroMachine.new(:new) # Initial state.

machine.transitions_for[:confirm] = { :new => :confirmed }
machine.transitions_for[:ignore]  = { :new => :ignored }
machine.transitions_for[:reset]   = { :confirmed => :new, :ignored => :new }

machine.trigger(:confirm)  #=> true
machine.trigger(:ignore)   #=> false
machine.trigger(:reset)    #=> true
machine.trigger(:ignore)   #=> true

It also handles callbacks that are executed when entering a different state.

machine.on(:confirmed) do
  puts "Confirmed"
end

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(initial_state) ⇒ MicroMachine 



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# File 'lib/micromachine.rb', line 25

def initialize initial_state
  @state = initial_state
  @transitions_for = Hash.new
  @callbacks = Hash.new { |hash, key| hash[key] = [] }
end

Instance Attribute Details

#state ⇒ Object (readonly)

Returns the value of attribute state.



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# File 'lib/micromachine.rb', line 23

def state
  @state
end

#transitions_for ⇒ Object (readonly)

Returns the value of attribute transitions_for.



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# File 'lib/micromachine.rb', line 22

def transitions_for
  @transitions_for
end

Instance Method Details

#on(key, &block) ⇒ Object 



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# File 'lib/micromachine.rb', line 31

def on key, &block
  @callbacks[key] << block
end

#trigger(event) ⇒ Object 



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# File 'lib/micromachine.rb', line 35

def trigger event
  if transitions_for[event][@state]
    @state = transitions_for[event][@state]
    @callbacks[@state].each { |callback| callback.call }
    true
  end
end