Added ActionView::Base.register_template_handler for easy integration of an alternative template language to ERb and Builder. See test/controller/custom_handler_test.rb for a usage example #656 [Jamis Buck]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@694 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Added ActionView::Base.register_template_handler for easy integration of an alternative template language to ERb and Builder. See test/controller/custom_handler_test.rb for a usage example #656 [Jamis Buck]
+
 * Added AssetTagHelper that provides methods for linking a HTML page together with other assets, such as javascripts, stylesheets, and feeds.
 
 * Added FormTagHelper that provides a number of methods for creating form tags that doesn't rely on conventions with an object assigned to the template like FormHelper does. With the FormTagHelper, you provide the names and values yourself.

actionpack/lib/action_view/base.rb

@@ -130,6 +130,7 @@ module ActionView #:nodoc:
 
     @@compiled_erb_templates = {}
     @@loaded_templates = {}
+    @@template_handlers = {}
 
     def self.load_helpers(helper_dir)#:nodoc:
       Dir.foreach(helper_dir) do |helper_file| 
@@ -151,6 +152,10 @@ module ActionView #:nodoc:
       end
     end
 
+    def self.register_template_handler(extension, klass)
+      @@template_handlers[extension] = klass
+    end
+
     def initialize(base_path = nil, assigns_for_first_render = {}, controller = nil)#:nodoc:
       @base_path, @assigns = base_path, assigns_for_first_render
       @controller = controller
@@ -193,26 +198,32 @@ module ActionView #:nodoc:
     # Renders the +template+ which is given as a string as either rhtml or rxml depending on <tt>template_extension</tt>.
     # The hash in <tt>local_assigns</tt> is made available as local variables.
     def render_template(template_extension, template, local_assigns = {})
-      b = binding
-      local_assigns.each { |key, value| eval "#{key} = local_assigns[\"#{key}\"]", b }
-      @assigns.each { |key, value| instance_variable_set "@#{key}", value }
-      xml = Builder::XmlMarkup.new(:indent => 2)
-      
-      send(pick_rendering_method(template_extension), template, binding)
+      send(pick_rendering_method(template_extension), template_extension,
+        template, local_assigns)
     end
 
     def pick_template_extension(template_path)#:nodoc:
-      if erb_template_exists?(template_path)
+      if match = delegate_template_exists?(template_path)
+        match.first
+      elsif erb_template_exists?(template_path)
         "rhtml"
       elsif builder_template_exists?(template_path)
         "rxml"
       else
-        raise ActionViewError, "No rhtml or rxml template found for #{template_path}"
+        raise ActionViewError, "No rhtml, rxml, or delegate template found for #{template_path}"
       end
     end
     
     def pick_rendering_method(template_extension)#:nodoc:
-      (template_extension == "rxml" ? "rxml" : "rhtml") + "_render"
+      if @@template_handlers[template_extension]
+        "delegate_render"
+      else
+        (template_extension == "rxml" ? "rxml" : "rhtml") + "_render"
+      end
+    end
+
+    def delegate_template_exists?(template_path)#:nodoc:
+      @@template_handlers.find { |k,| template_exists?(template_path, k) }
     end
 
     def erb_template_exists?(template_path)#:nodoc:
@@ -224,7 +235,7 @@ module ActionView #:nodoc:
     end
 
     def file_exists?(template_path)#:nodoc:
-      erb_template_exists?(template_path) || builder_template_exists?(template_path)
+      erb_template_exists?(template_path) || builder_template_exists?(template_path) || delegate_template_exists?(template_path)
     end
 
     # Returns true is the file may be rendered implicitly.
@@ -250,16 +261,32 @@ module ActionView #:nodoc:
         @@loaded_templates[template_path]
       end
 
-      def rhtml_render(template, binding)
-        @@compiled_erb_templates[template] ||= ERB.new(template, nil, '-')
-        @@compiled_erb_templates[template].result(binding)
+      def evaluate_locals(local_assigns = {})
+        b = binding
+
+        local_assigns.each { |key, value| eval "#{key} = local_assigns[\"#{key}\"]", b }
+        @assigns.each { |key, value| instance_variable_set "@#{key}", value }
+        xml = Builder::XmlMarkup.new(:indent => 2)
+
+        b
       end
 
-      def rxml_render(template, binding)
+      def rhtml_render(extension, template, local_assigns)
+        b = evaluate_locals(local_assigns)
+        @@compiled_erb_templates[template] ||= ERB.new(template, nil, '-')
+        @@compiled_erb_templates[template].result(b)
+      end
+
+      def rxml_render(extension, template, local_assigns)
         @controller.headers["Content-Type"] ||= 'text/xml'
-        eval(template, binding)
+        eval(template, evaluate_locals(local_assigns))
+      end
+
+      def delegate_render(extension, template, local_assigns)
+        delegator = @@template_handlers[extension].new(self)
+        delegator.render(template, local_assigns)
       end
   end
 end
 
-require 'action_view/template_error'
+require 'action_view/template_error'

actionpack/test/controller/custom_handler_test.rb

@@ -0,0 +1,33 @@
+require File.dirname(__FILE__) + '/../abstract_unit'
+
+class CustomHandler
+  def initialize( view )
+    @view = view
+  end
+
+  def render( template, local_assigns )
+    [ template,
+      local_assigns,
+      @view ]
+  end
+end
+
+class CustomHandlerTest < Test::Unit::TestCase
+  def setup
+    ActionView::Base.register_template_handler "foo", CustomHandler
+    @view = ActionView::Base.new
+  end
+
+  def test_custom_render
+    result = @view.render_template( "foo", "hello <%= one %>", "one" => "two" )
+    assert_equal(
+      [ "hello <%= one %>", { "one" => "two" }, @view ],
+      result )
+  end
+
+  def test_unhandled_extension
+    # uses the ERb handler by default if the extension isn't recognized
+    result = @view.render_template( "bar", "hello <%= one %>", "one" => "two" )
+    assert_equal "hello two", result
+  end
+end