Allow Convertibles to be converted by >= 1 converters.

lib/jekyll/convertible.rb

@@ -62,27 +62,36 @@ module Jekyll
     #
     # Returns nothing.
     def transform
-      self.content = converter.convert(content)
+      converters.reduce(content) do |output, converter|
+        begin
+          converter.convert output
         rescue => e
-      Jekyll.logger.error "Conversion error:", "There was an error converting" +
-        " '#{path}'."
+          Jekyll.logger.error "Conversion error:", "#{converter.class} encountered an error converting '#{path}'."
           raise e
         end
+      end
+    end
 
     # Determine the extension depending on content_type.
     #
     # Returns the String extension for the output file.
     #   e.g. ".html" for an HTML output file.
     def output_ext
-      converter.output_ext(ext)
+      if converters.all? { |c| c.is_a?(Jekyll::Converters::Identity) }
+        ext
+      else
+        converters.map {|c|
+          c.output_ext(ext) unless c.is_a?(Jekyll::Converters::Identity)
+        }.compact.uniq.join("")
+      end
     end
 
     # Determine which converter to use based on this convertible's
     # extension.
     #
     # Returns the Converter instance.
-    def converter
-      @converter ||= site.converters.find { |c| c.matches(ext) }
+    def converters
+      @converters ||= site.converters.select { |c| c.matches(ext) }.sort
     end
 
     # Render Liquid in the content
@@ -159,7 +168,7 @@ module Jekyll
     #
     # Returns true if the layout is invalid, false if otherwise
     def invalid_layout?(layout)
-      !data["layout"].nil? && data["layout"] != "none" && layout.nil? && !(self.is_a? Jekyll::Excerpt)
+      !data["layout"].nil? && layout.nil? && !(self.is_a? Jekyll::Excerpt)
     end
 
     # Recursively render layouts
@@ -205,11 +214,11 @@ module Jekyll
       info = { :filters => [Jekyll::Filters], :registers => { :site => site, :page => payload['page'] } }
 
       # render and transform content (this becomes the final content of the object)
-      payload["highlighter_prefix"] = converter.highlighter_prefix
-      payload["highlighter_suffix"] = converter.highlighter_suffix
+      payload["highlighter_prefix"] = converters.first.highlighter_prefix
+      payload["highlighter_suffix"] = converters.first.highlighter_suffix
 
       self.content = render_liquid(content, payload, info) if render_with_liquid?
-      transform
+      self.content = transform
 
       # output keeps track of what will finally be written
       self.output = content

lib/jekyll/plugin.rb

@@ -56,6 +56,15 @@ module Jekyll
       PRIORITIES[other.priority] <=> PRIORITIES[self.priority]
     end
 
+    # Spaceship is priority [higher -> lower]
+    #
+    # other - The class to be compared.
+    #
+    # Returns -1, 0, 1.
+    def <=>(other)
+      self.class <=> other.class
+    end
+
     # Initialize a new plugin. This should be overridden by the subclass.
     #
     # config - The Hash of configuration options.

test/test_post.rb

@@ -342,9 +342,7 @@ class TestPost < Test::Unit::TestCase
       should "transform textile" do
         @post.process(@real_file)
         @post.read_yaml(@source, @real_file)
-        @post.transform
-
-        assert_equal "<h1>{{ page.title }}</h1>\n<p>Best <strong>post</strong> ever</p>", @post.content
+        assert_equal "<h1>{{ page.title }}</h1>\n<p>Best <strong>post</strong> ever</p>", @post.transform
       end
 
       context "#excerpt" do
@@ -642,41 +640,41 @@ class TestPost < Test::Unit::TestCase
 
     should "process .md as markdown under default configuration" do
       post = setup_post '2011-04-12-md-extension.md'
-      conv = post.converter
+      conv = post.converters.first
       assert conv.kind_of? Jekyll::Converters::Markdown
     end
 
     should "process .text as identity under default configuration" do
       post = setup_post '2011-04-12-text-extension.text'
-      conv = post.converter
+      conv = post.converters.first
       assert conv.kind_of? Jekyll::Converters::Identity
     end
 
     should "process .text as markdown under alternate configuration" do
       @site.config['markdown_ext'] = 'markdown,mdw,mdwn,md,text'
       post = setup_post '2011-04-12-text-extension.text'
-      conv = post.converter
+      conv = post.converters.first
       assert conv.kind_of? Jekyll::Converters::Markdown
     end
 
     should "process .md as markdown under alternate configuration" do
       @site.config['markdown_ext'] = 'markdown,mkd,mkdn,md,text'
       post = setup_post '2011-04-12-text-extension.text'
-      conv = post.converter
+      conv = post.converters.first
       assert conv.kind_of? Jekyll::Converters::Markdown
     end
 
     should "process .mkdn under text if it is not in the markdown config" do
       @site.config['markdown_ext'] = 'markdown,mkd,md,text'
       post = setup_post '2013-08-01-mkdn-extension.mkdn'
-      conv = post.converter
+      conv = post.converters.first
       assert conv.kind_of? Jekyll::Converters::Identity
     end
 
     should "process .text as textile under alternate configuration" do
       @site.config['textile_ext'] = 'textile,text'
       post = setup_post '2011-04-12-text-extension.text'
-      conv = post.converter
+      conv = post.converters.first
       assert conv.kind_of? Jekyll::Converters::Textile
     end