1 files changed, 67 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/state_machine/event.rb b/activemodel/lib/active_model/state_machine/event.rb
new file mode 100644
index 0000000000..cc7d563214
--- /dev/null
+++ b/activemodel/lib/active_model/state_machine/event.rb
@@ -0,0 +1,67 @@
+module ActiveModel
+  module StateMachine
+    class Event
+      attr_reader :name, :success
+      
+      def initialize(name, options = {}, &block)
+        @name, @transitions = name, []
+        machine = options.delete(:machine)
+        if machine
+          machine.klass.send(:define_method, "#{name.to_s}!") do |*args|
+            machine.fire_event(name, self, true, *args)
+          end
+
+          machine.klass.send(:define_method, "#{name.to_s}") do |*args|
+            machine.fire_event(name, self, false, *args)
+          end
+        end
+        update(options, &block)
+      end
+
+      def fire(obj, to_state = nil, *args)
+        transitions = @transitions.select { |t| t.from == obj.current_state }
+        raise InvalidTransition if transitions.size == 0
+
+        next_state = nil
+        transitions.each do |transition|
+          next if to_state && !Array(transition.to).include?(to_state)
+          if transition.perform(obj)
+            next_state = to_state || Array(transition.to).first
+            transition.execute(obj, *args)
+            break
+          end
+        end
+        next_state
+      end
+
+      def transitions_from_state?(state)
+        @transitions.any? { |t| t.from? state }
+      end
+
+      def success?
+        !!@success
+      end
+
+      def ==(event)
+        if event.is_a? Symbol
+          name == event
+        else
+          name == event.name
+        end
+      end
+
+      def update(options = {}, &block)
+        if options.key?(:success) then @success = options[:success] end
+        if block                  then instance_eval(&block)        end
+        self
+      end
+
+    private
+      def transitions(trans_opts)
+        Array(trans_opts[:from]).each do |s|
+          @transitions << StateTransition.new(trans_opts.merge({:from => s.to_sym}))
+        end
+      end
+    end
+  end
+end