Class: Golem::Model::StateMachine

Inherits:
Object
  • Object
show all
Defined in:
lib/golem/model/state_machine.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name) ⇒ StateMachine

Returns a new instance of StateMachine.



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# File 'lib/golem/model/state_machine.rb', line 25

def initialize(name)
  @name = name
  @states = Golem::Util::ElementCollection.new(Golem::Model::State)
  @events = Golem::Util::ElementCollection.new(Golem::Model::Event)
  @transition_errors = []
  @throw_exceptions = false
  @is_transitioning = false
end

Instance Attribute Details

#events ⇒ Object (readonly)

Returns the value of attribute events.



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# File 'lib/golem/model/state_machine.rb', line 16

def events
  @events
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/golem/model/state_machine.rb', line 11

def name
  @name
end

#on_all_events ⇒ Object

Callback executed on every successful event.



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# File 'lib/golem/model/state_machine.rb', line 23

def on_all_events
  @on_all_events
end

#on_all_transitions ⇒ Object

Callback executed on every successful transition.



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# File 'lib/golem/model/state_machine.rb', line 20

def on_all_transitions
  @on_all_transitions
end

#state_attribute ⇒ Object

Returns the value of attribute state_attribute.



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# File 'lib/golem/model/state_machine.rb', line 12

def state_attribute
  @state_attribute
end

#state_attribute_reader ⇒ Object

Returns the value of attribute state_attribute_reader.



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# File 'lib/golem/model/state_machine.rb', line 13

def state_attribute_reader
  @state_attribute_reader
end

#state_attribute_writer ⇒ Object

Returns the value of attribute state_attribute_writer.



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# File 'lib/golem/model/state_machine.rb', line 14

def state_attribute_writer
  @state_attribute_writer
end

#states ⇒ Object (readonly)

Returns the value of attribute states.



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# File 'lib/golem/model/state_machine.rb', line 15

def states
  @states
end

#transition_errors ⇒ Object

Returns the value of attribute transition_errors.



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# File 'lib/golem/model/state_machine.rb', line 17

def transition_errors
  @transition_errors
end

Instance Method Details

#all_events ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 47

def all_events
  @events
end

#all_states ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 43

def all_states
  @states
end

#determine_transition_on_event(obj, event, *args) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 121

def determine_transition_on_event(obj, event, *args)
  event = @events[event] unless event.is_a?(Golem::Model::Event)

  from_state = states[get_current_state_of(obj)]
  possible_transitions = from_state.transitions_on_event[event.name]

  selected_transition = determine_transition(possible_transitions, obj, *args)

  if selected_transition.nil?
    if @cannot_transition_because.blank?
      msg = "#{event.name.to_s.inspect} is not a valid action for #{obj} because no outgoing transitions are available when #{name.blank? ? "the state" : "#{name} "} is #{from_state}."
      msg << "\n\tPossible transitions are: \n\t\t#{possible_transitions.collect.collect{|t| t.to_s}.join("\n\t\t")}" unless possible_transitions.blank?
    elsif @cannot_transition_because.length == 1
      msg = "#{event.name.to_s.inspect} is not a valid action for #{obj} because #{@cannot_transition_because.first}."
    else
      msg = "#{event.name.to_s.inspect} is not a valid action for #{obj} because #{@cannot_transition_because.uniq.join(" and ")}"
    end

    if @throw_exceptions
      raise Golem::ImpossibleEvent.new(msg, event, obj, @cannot_transition_because)
    else
      obj.transition_errors << msg
    end
  end

  return selected_transition
end

#fire_event(obj, event, *args) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 79

def fire_event(obj, event, *args)
  @transition_errors = []
  transition = determine_transition_on_event(obj, event, *args)
  
  on_all_events.call(obj, event, args) if on_all_events

  if transition
    @is_transitioning = true
    
    before_state = states[get_current_state_of(obj)]
    before_state.callbacks[:on_exit].call(obj, *args) if before_state.callbacks[:on_exit]
  
    set_current_state_of(obj, transition.to.name)
    transition.callbacks[:on_transition].call(obj, *args) if transition.callbacks[:on_transition]
    on_all_transitions.call(obj, event, transition, *args) if on_all_transitions

    after_state = states[get_current_state_of(obj)]
    after_state.callbacks[:on_enter].call(obj, *args) if after_state.callbacks[:on_enter]
    
    @is_transitioning = false
    
    save_result = true
    if obj.respond_to?(:save!)
      if @throw_exceptions
        save_result = obj.save!
      else
        (save_result = obj.save!) rescue return false
      end
    elsif obj.respond_to?(:save)
      if @throw_exceptions
        save_result = obj.save
      else
        (save_result = obj.save) rescue return false
      end
    end
    
    return save_result
  else
    return false
  end
end

#fire_event_with_exceptions(obj, event, *args) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 69

def fire_event_with_exceptions(obj, event, *args)
  @throw_exceptions = true
  fire_event(obj, event, *args)
end

#fire_event_without_exceptions(obj, event, *args) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 74

def fire_event_without_exceptions(obj, event, *args)
  @throw_exceptions = false
  fire_event(obj, event, *args)
end

#get_current_state_of(obj) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 56

def get_current_state_of(obj)
  obj.send(state_attribute)
end

#get_or_define_event(event) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 164

def get_or_define_event(event)
  if events[event]
    return events[event]
  else
    case event
    when Golem::Model::Event
      return events[event] = event
    when String, Symbol
      return events[event] = Golem::Model::Event.new(event)
    else
      raise ArgumentError, "Event must be a Golem::Model::Event, String, or Symbol but is a #{event.class}"
    end
  end
end

#get_or_define_state(state) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 149

def get_or_define_state(state)
  if states[state]
    return states[state]
  else
    case state
    when Golem::Model::State
      return states[state] = state
    when String, Symbol
      return states[state] = Golem::Model::State.new(state)
    else
      raise ArgumentError, "State must be a Golem::Model::State, String, or Symbol but is a #{state.class}"
    end
  end
end

#init(obj) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 64

def init(obj)
  # set the initial state
  set_current_state_of(obj, get_current_state_of(obj) || initial_state)
end

#initial_state ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 34

def initial_state
  @initial_state
end

#initial_state=(state) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 38

def initial_state=(state)
  # for the sake of readability in debugging, we store initial state by name rather than by reference to a State object
  @initial_state = state.name
end

#is_transitioning? ⇒ Boolean

true if this statemachine is currently in the middle of a transition

Returns:

  • (Boolean) 


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# File 'lib/golem/model/state_machine.rb', line 52

def is_transitioning?
  @is_transitioning
end

#set_current_state_of(obj, state) ⇒ Object 



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# File 'lib/golem/model/state_machine.rb', line 60

def set_current_state_of(obj, state)
  obj.send("#{state_attribute}=".to_sym, state)
end