Extract generic callbacks middleware from dispatcher

1 files changed, 40 insertions, 0 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/callbacks.rb b/actionpack/lib/action_dispatch/middleware/callbacks.rb
new file mode 100644
index 0000000000..0a2b4cf5f7
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/callbacks.rb
@@ -0,0 +1,40 @@
+module ActionDispatch
+  class Callbacks
+    include ActiveSupport::Callbacks
+    define_callbacks :prepare, :before, :after
+
+    class << self
+      # DEPRECATED
+      alias_method :prepare_dispatch, :prepare
+      alias_method :before_dispatch, :before
+      alias_method :after_dispatch, :after
+    end
+
+    # Add a preparation callback. Preparation callbacks are run before every
+    # request in development mode, and before the first request in production
+    # mode.
+    #
+    # An optional identifier may be supplied for the callback. If provided,
+    # to_prepare may be called again with the same identifier to replace the
+    # existing callback. Passing an identifier is a suggested practice if the
+    # code adding a preparation block may be reloaded.
+    def self.to_prepare(identifier = nil, &block)
+      @prepare_callbacks ||= ActiveSupport::Callbacks::CallbackChain.new
+      callback = ActiveSupport::Callbacks::Callback.new(:prepare, block, :identifier => identifier)
+      @prepare_callbacks.replace_or_append!(callback)
+    end
+
+    def initialize(app, prepare_each_request = false)
+      @app, @prepare_each_request = app, prepare_each_request
+      run_callbacks :prepare
+    end
+
+    def call(env)
+      run_callbacks :before
+      run_callbacks :prepare if @prepare_each_request
+      @app.call(env)
+    ensure
+      run_callbacks :after, :enumerator => :reverse_each
+    end
+  end
+end