1 files changed, 74 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/state_machine/machine.rb b/activemodel/lib/active_model/state_machine/machine.rb
new file mode 100644
index 0000000000..170505c0b2
--- /dev/null
+++ b/activemodel/lib/active_model/state_machine/machine.rb
@@ -0,0 +1,74 @@
+module ActiveModel
+  module StateMachine
+    class Machine
+      attr_accessor :initial_state, :states, :events, :state_index
+      attr_reader :klass, :name
+
+      def initialize(klass, name, options = {}, &block)
+        @klass, @name, @states, @state_index, @events = klass, name, [], {}, {}
+        update(options, &block)
+      end
+
+      def initial_state
+        @initial_state ||= (states.first ? states.first.name : nil)
+      end
+
+      def update(options = {}, &block)
+        if options.key?(:initial) then @initial_state = options[:initial] end
+        if block                  then instance_eval(&block)              end
+        self
+      end
+
+      def fire_event(event, record, persist, *args)
+        state_index[record.current_state(@name)].call_action(:exit, record)
+        if new_state = @events[event].fire(record, *args)
+          state_index[new_state].call_action(:enter, record)
+
+          if record.respond_to?(event_fired_callback)
+            record.send(event_fired_callback, record.current_state, new_state)
+          end
+
+          record.current_state(@name, new_state, persist)
+          record.send(@events[event].success) if @events[event].success
+          true
+        else
+          if record.respond_to?(event_failed_callback)
+            record.send(event_failed_callback, event)
+          end
+
+          false
+        end
+      end
+
+      def states_for_select
+        states.map { |st| [st.display_name, st.name.to_s] }
+      end
+
+      def events_for(state)
+        events = @events.values.select { |event| event.transitions_from_state?(state) }
+        events.map! { |event| event.name }
+      end
+
+      def current_state_variable
+        "@#{@name}_current_state"
+      end
+
+    private
+      def state(name, options = {})
+        @states << (state_index[name] ||= State.new(name, :machine => self)).update(options)
+      end
+
+      def event(name, options = {}, &block)
+        (@events[name] ||= Event.new(self, name)).update(options, &block)
+      end
+
+      def event_fired_callback
+        @event_fired_callback ||= (@name == :default ? '' : "#{@name}_") + 'event_fired'
+      end
+
+      def event_failed_callback
+        @event_failed_callback ||= (@name == :default ? '' : "#{@name}_") + 'event_failed'
+      end
+    end
+  end
+end
+\ No newline at end of file