Initial work on fibered layout.

actionpack/lib/action_view.rb

@@ -44,6 +44,7 @@ module ActionView
       autoload :AbstractRenderer
       autoload :PartialRenderer
       autoload :TemplateRenderer
+      autoload :FiberedTemplateRenderer
     end
 
     autoload_at "action_view/template/resolver" do

actionpack/lib/action_view/base.rb

@@ -153,7 +153,7 @@ module ActionView #:nodoc:
       end
     end
 
-    attr_accessor :_template
+    attr_accessor :_template, :_view_flow, :magic_medicine
     attr_internal :request, :controller, :config, :assigns, :lookup_context
 
     delegate :formats, :formats=, :locale, :locale=, :view_paths, :view_paths=, :to => :lookup_context
@@ -181,8 +181,8 @@ module ActionView #:nodoc:
       self.helpers = Module.new unless self.class.helpers
 
       @_config = {}
-      @_content_for  = Hash.new { |h,k| h[k] = ActiveSupport::SafeBuffer.new }
       @_virtual_path = nil
+      @_view_flow = Flow.new
       @output_buffer = nil
 
       if @_controller = controller
@@ -195,10 +195,6 @@ module ActionView #:nodoc:
       @_lookup_context.formats = formats if formats
     end
 
-    def store_content_for(key, value)
-      @_content_for[key] = value
-    end
-
     def controller_path
       @controller_path ||= controller && controller.controller_path
     end
@@ -209,4 +205,49 @@ module ActionView #:nodoc:
 
     ActiveSupport.run_load_hooks(:action_view, self)
   end
+
+  class Flow
+    attr_reader :content
+
+    def initialize
+      @content = Hash.new { |h,k| h[k] = ActiveSupport::SafeBuffer.new }
+    end
+
+    def get(key)
+      @content[key]
+    end
+
+    def set(key, value)
+      @content[key] = value
+    end
+
+    def append(key, value)
+      @content[key] << value
+    end
+  end
+
+  class FiberedFlow < Flow
+    def initialize(flow, fiber)
+      @content = flow.content
+      @fiber   = fiber
+    end
+
+    def get(key)
+      return super if @content.key?(key)
+
+      begin
+        @waiting_for = key
+        Fiber.yield
+      ensure
+        @waiting_for = nil
+      end
+
+      super
+    end
+
+    def set(key, value)
+      super
+      @fiber.resume if @waiting_for == key
+    end
+  end
 end

actionpack/lib/action_view/helpers/capture_helper.rb

@@ -135,8 +135,8 @@ module ActionView
       # for elements that will be fragment cached.
       def content_for(name, content = nil, &block)
         content = capture(&block) if block_given?
-        @_content_for[name] << content if content
+        result = @_view_flow.append(name, content) if content
-        @_content_for[name] unless content
+        result unless content
       end
 
       # content_for? simply checks whether any content has been captured yet using content_for
@@ -158,7 +158,7 @@ module ActionView
       #   </body>
       #   </html>
       def content_for?(name)
-        @_content_for[name].present?
+        @_view_flow.get(name).present?
       end
 
       # Use an alternate output buffer for the duration of the block.

actionpack/lib/action_view/renderer/fibered_template_renderer.rb

@@ -0,0 +1,35 @@
+require 'action_view/renderer/template_renderer'
+require 'fiber'
+
+module ActionView
+  class FiberedTemplateRenderer < TemplateRenderer #:nodoc:
+    # Renders the given template. An string representing the layout can be
+    # supplied as well.
+    def render_template(template, layout_name = nil, locals = {}) #:nodoc:
+      view, locals = @view, locals || {}
+
+      final = nil
+      layout  = layout_name && find_layout(layout_name, locals.keys)
+      yielder = lambda { |*name| view._layout_for(*name) }
+
+      instrument(:template, :identifier => template.identifier, :layout => layout.try(:virtual_path)) do
+        @fiber = Fiber.new do
+          final = if layout
+            layout.render(view, locals, &yielder)
+          else
+            view._layout_for
+          end
+        end
+
+        @view._view_flow = FiberedFlow.new(view._view_flow, @fiber)
+        @fiber.resume
+
+        content = template.render(view, locals, &yielder)
+        view._view_flow.set(:layout, content)
+        @fiber.resume while @fiber.alive?
+      end
+
+      final
+    end
+  end
+end

actionpack/lib/action_view/renderer/partial_renderer.rb

@@ -79,7 +79,7 @@ module ActionView
       locals[as] = object
 
       content = @template.render(view, locals) do |*name|
-        view._layout_for(*name, &block)
+        view._block_layout_for(*name, &block)
       end
 
       content = layout.render(view, locals){ content } if layout

actionpack/lib/action_view/renderer/template_renderer.rb

@@ -7,6 +7,7 @@ module ActionView
     def render(options)
       wrap_formats(options[:template] || options[:file]) do
         template = determine_template(options)
+        freeze_formats(template.formats, true)
         render_template(template, options[:layout], options[:locals])
       end
     end
@@ -31,7 +32,6 @@ module ActionView
     # Renders the given template. An string representing the layout can be
     # supplied as well.
     def render_template(template, layout_name = nil, locals = {}) #:nodoc:
-      freeze_formats(template.formats, true)
       view, locals = @view, locals || {}
 
       render_with_layout(layout_name, locals) do |layout|
@@ -47,7 +47,7 @@ module ActionView
 
       if layout
         view = @view
-        view.store_content_for(:layout, content)
+        view._view_flow.set(:layout, content)
         layout.render(view, locals){ |*name| view._layout_for(*name) }
       else
         content

actionpack/lib/action_view/rendering.rb

@@ -73,24 +73,38 @@ module ActionView
     #     Hello David
     #   </html>
     #
-    def _layout_for(*args, &block)
+    def _layout_for(*args)
+      name = args.first
+      name = :layout unless name.is_a?(Symbol)
+      @_view_flow.get(name).html_safe
+    end
+
+    # Returns the content from the Flow unless we have a block.
+    def _block_layout_for(*args, &block)
       name = args.first
 
-      if name.is_a?(Symbol)
+      if !name.is_a?(Symbol) && block
-        @_content_for[name].html_safe
-      elsif block
         capture(*args, &block)
       else
-        @_content_for[:layout].html_safe
+        _layout_for(*args)
       end
     end
 
     def _render_template(options) #:nodoc:
-      _template_renderer.render(options)
+      if @magic_medicine
+        _fibered_template_renderer.render(options)
+      else
+        _template_renderer.render(options)
+      end
     end
 
     def _template_renderer #:nodoc:
       @_template_renderer ||= TemplateRenderer.new(self)
     end
+
+    def _fibered_template_renderer #:nodoc:
+      @_fibered_template_renderer ||= FiberedTemplateRenderer.new(self)
+    end
+
   end
 end

actionpack/test/template/capture_helper_test.rb

@@ -4,7 +4,7 @@ class CaptureHelperTest < ActionView::TestCase
   def setup
     super
     @av = ActionView::Base.new
-    @_content_for = Hash.new {|h,k| h[k] = "" }
+    @_view_flow = ActionView::Flow.new
   end
 
   def test_capture_captures_the_temporary_output_buffer_in_its_block

actionpack/test/template/fibered_render_test.rb

@@ -0,0 +1,27 @@
+# encoding: utf-8
+require 'abstract_unit'
+require 'controller/fake_models'
+
+class TestController < ActionController::Base
+end
+
+
+class FiberedTest < ActiveSupport::TestCase
+
+  def setup
+    view_paths = ActionController::Base.view_paths
+    @assigns = { :secret => 'in the sauce' }
+    @view = ActionView::Base.new(view_paths, @assigns)
+    @view.magic_medicine = true
+    @controller_view = TestController.new.view_context
+  end
+
+  def test_render_template
+    assert_equal "Hello world!", @view.render(:template => "test/hello_world")
+  end
+
+  def test_render_with_layout
+    assert_equal %(<title></title>\nHello world!\n),
+      @view.render(:template => "test/hello_world.erb", :layout => "layouts/yield")
+  end
+end if defined?(Fiber)