Start abstracting the renderer.

3 files changed, 288 insertions, 3 deletions

diff --git a/actionpack/lib/action_view/renderer/abstract_renderer.rb b/actionpack/lib/action_view/renderer/abstract_renderer.rb
index 4a52b3172e..37bc0ae244 100644
--- a/actionpack/lib/action_view/renderer/abstract_renderer.rb
+++ b/actionpack/lib/action_view/renderer/abstract_renderer.rb
@@ -3,9 +3,9 @@ module ActionView
     delegate :find_template, :template_exists?, :with_fallbacks, :update_details,
       :with_layout_format, :formats, :freeze_formats, :to => :@lookup_context
 
-    def initialize(view)
+    def initialize(view, lookup_context)
       @view = view
-      @lookup_context = view.lookup_context
+      @lookup_context = lookup_context
     end
 
     def render
diff --git a/actionpack/lib/action_view/renderer/partial_renderer.rb b/actionpack/lib/action_view/renderer/partial_renderer.rb
index 10cd37d56f..83efc95f39 100644
--- a/actionpack/lib/action_view/renderer/partial_renderer.rb
+++ b/actionpack/lib/action_view/renderer/partial_renderer.rb
@@ -1,8 +1,223 @@
+require 'active_support/core_ext/object/blank'
+
 module ActionView
+  # = Action View Partials
+  #
+  # There's also a convenience method for rendering sub templates within the current controller that depends on a
+  # single object (we call this kind of sub templates for partials). It relies on the fact that partials should
+  # follow the naming convention of being prefixed with an underscore -- as to separate them from regular
+  # templates that could be rendered on their own.
+  #
+  # In a template for Advertiser#account:
+  #
+  #  <%= render :partial => "account" %>
+  #
+  # This would render "advertiser/_account.html.erb" and pass the instance variable @account in as a local variable
+  # +account+ to the template for display.
+  #
+  # In another template for Advertiser#buy, we could have:
+  #
+  #   <%= render :partial => "account", :locals => { :account => @buyer } %>
+  #
+  #   <% @advertisements.each do |ad| %>
+  #     <%= render :partial => "ad", :locals => { :ad => ad } %>
+  #   <% end %>
+  #
+  # This would first render "advertiser/_account.html.erb" with @buyer passed in as the local variable +account+, then
+  # render "advertiser/_ad.html.erb" and pass the local variable +ad+ to the template for display.
+  #
+  # == The :as and :object options
+  #
+  # By default <tt>ActionView::Partials::PartialRenderer</tt> has its object in a local variable with the same
+  # name as the template. So, given
+  #
+  #   <%= render :partial => "contract" %>
+  #
+  # within contract we'll get <tt>@contract</tt> in the local variable +contract+, as if we had written
+  #
+  #   <%= render :partial => "contract", :locals => { :contract  => @contract } %>
+  #
+  # With the <tt>:as</tt> option we can specify a different name for said local variable. For example, if we
+  # wanted it to be +agreement+ instead of +contract+ we'd do:
+  #
+  #   <%= render :partial => "contract", :as => 'agreement' %>
+  #
+  # The <tt>:object</tt> option can be used to directly specify which object is rendered into the partial;
+  # useful when the template's object is elsewhere, in a different ivar or in a local variable for instance.
+  #
+  # Revisiting a previous example we could have written this code:
+  #
+  #   <%= render :partial => "account", :object => @buyer %>
+  #
+  #   <% @advertisements.each do |ad| %>
+  #     <%= render :partial => "ad", :object => ad %>
+  #   <% end %>
+  #
+  # The <tt>:object</tt> and <tt>:as</tt> options can be used together.
+  #
+  # == Rendering a collection of partials
+  #
+  # The example of partial use describes a familiar pattern where a template needs to iterate over an array and
+  # render a sub template for each of the elements. This pattern has been implemented as a single method that
+  # accepts an array and renders a partial by the same name as the elements contained within. So the three-lined
+  # example in "Using partials" can be rewritten with a single line:
+  #
+  #   <%= render :partial => "ad", :collection => @advertisements %>
+  #
+  # This will render "advertiser/_ad.html.erb" and pass the local variable +ad+ to the template for display. An
+  # iteration counter will automatically be made available to the template with a name of the form
+  # +partial_name_counter+. In the case of the example above, the template would be fed +ad_counter+.
+  #
+  # The <tt>:as</tt> option may be used when rendering partials.
+  #
+  # You can specify a partial to be rendered between elements via the <tt>:spacer_template</tt> option.
+  # The following example will render <tt>advertiser/_ad_divider.html.erb</tt> between each ad partial:
+  #
+  #   <%= render :partial => "ad", :collection => @advertisements, :spacer_template => "ad_divider" %>
+  #
+  # If the given <tt>:collection</tt> is nil or empty, <tt>render</tt> will return nil. This will allow you
+  # to specify a text which will displayed instead by using this form:
+  #
+  #   <%= render(:partial => "ad", :collection => @advertisements) || "There's no ad to be displayed" %>
+  #
+  # NOTE: Due to backwards compatibility concerns, the collection can't be one of hashes. Normally you'd also
+  # just keep domain objects, like Active Records, in there.
+  #
+  # == Rendering shared partials
+  #
+  # Two controllers can share a set of partials and render them like this:
+  #
+  #   <%= render :partial => "advertisement/ad", :locals => { :ad => @advertisement } %>
+  #
+  # This will render the partial "advertisement/_ad.html.erb" regardless of which controller this is being called from.
+  #
+  # == Rendering objects with the RecordIdentifier
+  #
+  # Instead of explicitly naming the location of a partial, you can also let the RecordIdentifier do the work if
+  # you're following its conventions for RecordIdentifier#partial_path. Examples:
+  #
+  #  # @account is an Account instance, so it uses the RecordIdentifier to replace
+  #  # <%= render :partial => "accounts/account", :locals => { :account => @account} %>
+  #  <%= render :partial => @account %>
+  #
+  #  # @posts is an array of Post instances, so it uses the RecordIdentifier to replace
+  #  # <%= render :partial => "posts/post", :collection => @posts %>
+  #  <%= render :partial => @posts %>
+  #
+  # == Rendering the default case
+  #
+  # If you're not going to be using any of the options like collections or layouts, you can also use the short-hand
+  # defaults of render to render partials. Examples:
+  #
+  #  # Instead of <%= render :partial => "account" %>
+  #  <%= render "account" %>
+  #
+  #  # Instead of <%= render :partial => "account", :locals => { :account => @buyer } %>
+  #  <%= render "account", :account => @buyer %>
+  #
+  #  # @account is an Account instance, so it uses the RecordIdentifier to replace
+  #  # <%= render :partial => "accounts/account", :locals => { :account => @account } %>
+  #  <%= render(@account) %>
+  #
+  #  # @posts is an array of Post instances, so it uses the RecordIdentifier to replace
+  #  # <%= render :partial => "posts/post", :collection => @posts %>
+  #  <%= render(@posts) %>
+  #
+  # == Rendering partials with layouts
+  #
+  # Partials can have their own layouts applied to them. These layouts are different than the ones that are
+  # specified globally for the entire action, but they work in a similar fashion. Imagine a list with two types
+  # of users:
+  #
+  #   <%# app/views/users/index.html.erb &>
+  #   Here's the administrator:
+  #   <%= render :partial => "user", :layout => "administrator", :locals => { :user => administrator } %>
+  #
+  #   Here's the editor:
+  #   <%= render :partial => "user", :layout => "editor", :locals => { :user => editor } %>
+  #
+  #   <%# app/views/users/_user.html.erb &>
+  #   Name: <%= user.name %>
+  #
+  #   <%# app/views/users/_administrator.html.erb &>
+  #   <div id="administrator">
+  #     Budget: $<%= user.budget %>
+  #     <%= yield %>
+  #   </div>
+  #
+  #   <%# app/views/users/_editor.html.erb &>
+  #   <div id="editor">
+  #     Deadline: <%= user.deadline %>
+  #     <%= yield %>
+  #   </div>
+  #
+  # ...this will return:
+  #
+  #   Here's the administrator:
+  #   <div id="administrator">
+  #     Budget: $<%= user.budget %>
+  #     Name: <%= user.name %>
+  #   </div>
+  #
+  #   Here's the editor:
+  #   <div id="editor">
+  #     Deadline: <%= user.deadline %>
+  #     Name: <%= user.name %>
+  #   </div>
+  #
+  # You can also apply a layout to a block within any template:
+  #
+  #   <%# app/views/users/_chief.html.erb &>
+  #   <%= render(:layout => "administrator", :locals => { :user => chief }) do %>
+  #     Title: <%= chief.title %>
+  #   <% end %>
+  #
+  # ...this will return:
+  #
+  #   <div id="administrator">
+  #     Budget: $<%= user.budget %>
+  #     Title: <%= chief.name %>
+  #   </div>
+  #
+  # As you can see, the <tt>:locals</tt> hash is shared between both the partial and its layout.
+  #
+  # If you pass arguments to "yield" then this will be passed to the block. One way to use this is to pass
+  # an array to layout and treat it as an enumerable.
+  #
+  #   <%# app/views/users/_user.html.erb &>
+  #   <div class="user">
+  #     Budget: $<%= user.budget %>
+  #     <%= yield user %>
+  #   </div>
+  #
+  #   <%# app/views/users/index.html.erb &>
+  #   <%= render :layout => @users do |user| %>
+  #     Title: <%= user.title %>
+  #   <% end %>
+  #
+  # This will render the layout for each user and yield to the block, passing the user, each time.
+  #
+  # You can also yield multiple times in one layout and use block arguments to differentiate the sections.
+  #
+  #   <%# app/views/users/_user.html.erb &>
+  #   <div class="user">
+  #     <%= yield user, :header %>
+  #     Budget: $<%= user.budget %>
+  #     <%= yield user, :footer %>
+  #   </div>
+  #
+  #   <%# app/views/users/index.html.erb &>
+  #   <%= render :layout => @users do |user, section| %>
+  #     <%- case section when :header -%>
+  #       Title: <%= user.title %>
+  #     <%- when :footer -%>
+  #       Deadline: <%= user.deadline %>
+  #     <%- end -%>
+  #   <% end %>
   class PartialRenderer < AbstractRenderer #:nodoc:
     PARTIAL_NAMES = Hash.new {|h,k| h[k] = {} }
 
-    def initialize(view)
+    def initialize(view, *)
       super
       @partial_names = PARTIAL_NAMES[@view.controller.class.name]
     end
diff --git a/actionpack/lib/action_view/renderer/renderer.rb b/actionpack/lib/action_view/renderer/renderer.rb
new file mode 100644
index 0000000000..f0ee103d80
--- /dev/null
+++ b/actionpack/lib/action_view/renderer/renderer.rb
@@ -0,0 +1,70 @@
+module ActionView
+  # This is the main entry point for rendering. It basically delegates
+  # to other objects like TemplateRenderer and PartialRenderer which
+  # actually renders the template.
+  class Renderer
+    attr_accessor :lookup_context
+
+    # TODO: render_context should not be an initialization parameter
+    def initialize(lookup_context, render_context)
+      @render_context = render_context
+      @lookup_context = lookup_context
+      @view_flow = OutputFlow.new
+    end
+
+    # Returns the result of a render that's dictated by the options hash. The primary options are:
+    #
+    # * <tt>:partial</tt> - See ActionView::Partials.
+    # * <tt>:file</tt> - Renders an explicit template file (this used to be the old default), add :locals to pass in those.
+    # * <tt>:inline</tt> - Renders an inline template similar to how it's done in the controller.
+    # * <tt>:text</tt> - Renders the text passed in out.
+    #
+    # If no options hash is passed or :update specified, the default is to render a partial and use the second parameter
+    # as the locals hash.
+    def render(options = {}, locals = {}, &block)
+      case options
+      when Hash
+        if block_given?
+          _render_partial(options.merge(:partial => options[:layout]), &block)
+        elsif options.key?(:partial)
+          _render_partial(options)
+        else
+          _render_template(options)
+        end
+      else
+        _render_partial(:partial => options, :locals => locals)
+      end
+    end
+
+    # Render but returns a valid Rack body. If fibers are defined, we return
+    # a streaming body that renders the template piece by piece.
+    #
+    # Note that partials are not supported to be rendered with streaming,
+    # so in such cases, we just wrap them in an array.
+    def render_body(options)
+      if options.key?(:partial)
+        [_render_partial(options)]
+      else
+        StreamingTemplateRenderer.new(@render_context, @lookup_context).render(options)
+      end
+    end
+
+    private
+
+    def _render_template(options) #:nodoc:
+      _template_renderer.render(options)
+    end
+
+    def _template_renderer #:nodoc:
+      @_template_renderer ||= TemplateRenderer.new(@render_context, @lookup_context)
+    end
+
+    def _render_partial(options, &block) #:nodoc:
+      _partial_renderer.setup(options, block).render
+    end
+
+    def _partial_renderer #:nodoc:
+      @_partial_renderer ||= PartialRenderer.new(@render_context, @lookup_context)
+    end
+  end
+end
\ No newline at end of file