added catch async and throw async

lib/async_rack.rb

@@ -13,13 +13,19 @@ def autoload(class_name, path)
   module ExtensionMixin
     ::AsyncRack.extend self
     def autoload(class_name, path)
-      super
-      if Rack.autoload? class_name then Rack.autoload(class_name, path)
-      elsif Rack.const_defined? class_name then require path
+      if Rack.const_defined? class_name
+        require path
+      else
+        Rack.autoload class_name, path
+        super
       end
     end
   end
 
+  # New middleware
+  autoload :CatchAsync,     "async_rack/catch_async"
+  autoload :ThrowAsync,     "async_rack/throw_async"
+
   # Wrapped rack middleware
   autoload :Chunked,        "async_rack/chunked"
   autoload :CommonLogger,   "async_rack/commonlogger"

lib/async_rack/catch_async.rb

@@ -0,0 +1,16 @@
+require 'rack'
+module AsyncRack
+  class CatchAsync
+    Rack::CatchAsync = self unless defined? Rack::CatchAsync
+
+    def initialize(app, async_response = [-1, {}, []])
+      @app, @async_response = app, async_response
+    end
+
+    def call(env)
+      response = @async_response
+      catch(:async) { response = @app.call env }
+      response
+    end
+  end
+end

lib/async_rack/throw_async.rb

@@ -0,0 +1,17 @@
+require 'rack'
+
+module AsyncRack
+  class ThrowAsync
+    Rack::ThrowAsync = self unless defined? Rack::ThrowAsync
+
+    def initialize(app, throw_on = [-1, 0])
+      @app, @throw_on = app, throw_on
+    end
+
+    def call(env)
+      response = @app.call env
+      throw :async if @throw_on.include? response.first
+      response
+    end
+  end
+end