Start rewriting 4.0 release note into Markdown

Gemfile

@@ -36,6 +36,7 @@ group :doc do
   # this is our own fork with the fix.
   gem 'sdoc',  github: 'fxn/sdoc'
   gem 'RedCloth', '~> 4.2'
+  gem 'redcarpet', '~> 2.1.1'
   gem 'w3c_validators'
 end
 

guides/Rakefile

@@ -45,7 +45,7 @@ Some arguments may be passed via environment variables:
 
   ONLY=name
     Useful if you want to generate only one or a set of guides.
-    
+
     Generate only association_basics.html:
       ONLY=assoc
 

guides/assets/stylesheets/main.css

@@ -393,7 +393,14 @@ div.code_container {
 	margin: 0.25em 0 1.5em 0;
 }
 
-.note tt, .info tt {border:none; background: none; padding: 0;}
+#mainCol div.todo {
+	background: #fff9d8 url(../images/tab_yellow.gif) no-repeat left top;
+	border: none;
+	padding: 1em 1em 0.25em 48px;
+	margin: 0.25em 0 1.5em 0;
+}
+
+.note tt, .info tt, .todo tt {border:none; background: none; padding: 0;}
 
 #mainCol ul li {
 	list-style:none;

guides/rails_guides.rb

@@ -36,10 +36,11 @@ to the Gemfile, run
 
 and try again.
 ERROR
-
   exit 1
 end
 
+require 'rails_guides/markdown'
+
 require "rails_guides/textile_extensions"
 RedCloth.send(:include, RailsGuides::TextileExtensions)
 

guides/rails_guides/generator.rb

@@ -65,7 +65,7 @@ module RailsGuides
   class Generator
     attr_reader :guides_dir, :source_dir, :output_dir, :edge, :warnings, :all
 
-    GUIDES_RE = /\.(?:textile|erb)$/
+    GUIDES_RE = /\.(?:textile|erb|md|markdown)$/
 
     def initialize(output=nil)
       set_flags_from_environment
@@ -171,8 +171,8 @@ module RailsGuides
     end
 
     def output_file_for(guide)
-      if guide =~/\.textile$/
-        guide.sub(/\.textile$/, '.html')
+      if guide =~ /\.(textile|markdown|md)$/
+        guide.sub(/\.(textile|markdown|md)$/, '.html')
       else
         guide.sub(/\.erb$/, '')
       end
@@ -201,6 +201,11 @@ module RailsGuides
           # Generate the special pages like the home.
           # Passing a template handler in the template name is deprecated. So pass the file name without the extension.
           result = view.render(:layout => layout, :formats => [$1], :file => $`)
+        elsif guide =~ /\.(md|markdown)$/
+          body = File.read(File.join(source_dir, guide))
+          result = RailsGuides::Markdown.new(view, layout).render(body)
+
+          warn_about_broken_links(result) if @warnings
         else
           body = File.read(File.join(source_dir, guide))
           body = set_header_section(body, view)

guides/rails_guides/markdown.rb

@@ -0,0 +1,42 @@
+require 'redcarpet'
+require 'nokogiri'
+require 'rails_guides/markdown/renderer'
+
+module RailsGuides
+  class Markdown
+    def initialize(view, layout)
+      @view = view
+      @layout = layout
+    end
+
+    def render(body)
+      @header, _, @body = body.partition(/^\-{40,}$/)
+      render_header
+      render_body
+    end
+
+    private
+      def engine
+        @engine ||= Redcarpet::Markdown.new(Renderer, {
+          no_intra_emphasis: true,
+          fenced_code_blocks: true,
+          autolink: true,
+          strikethrough: true,
+          superscript: true
+        })
+      end
+
+      def render_header
+        header_content = engine.render(@header)
+        @view.content_for(:header_section) { header_content.html_safe }
+
+        @view.content_for(:page_title) do
+          "Ruby on Rails Guides: #{Nokogiri::HTML(header_content).at(:h2).text}".html_safe
+        end
+      end
+
+      def render_body
+        @view.render(:layout => @layout, :text => engine.render(@body))
+      end
+  end
+end

guides/rails_guides/markdown/renderer.rb

@@ -0,0 +1,48 @@
+module RailsGuides
+  class Markdown
+    class Renderer < Redcarpet::Render::HTML
+      def initialize(options={})
+        super
+      end
+
+      def header(text, header_level)
+        # Always increase the heading level by, so we can use h1, h2 heading in the document
+        header_level += 1
+
+        %(<h#{header_level} id="#{dom_id(text)}">#{text}</h#{header_level}>)
+      end
+
+      def preprocess(full_document)
+        convert_notes(full_document)
+      end
+
+      private
+
+        def convert_notes(body)
+          # The following regexp detects special labels followed by a
+          # paragraph, perhaps at the end of the document.
+          #
+          # It is important that we do not eat more than one newline
+          # because formatting may be wrong otherwise. For example,
+          # if a bulleted list follows the first item is not rendered
+          # as a list item, but as a paragraph starting with a plain
+          # asterisk.
+          body.gsub(/^(TIP|IMPORTANT|CAUTION|WARNING|NOTE|INFO|TODO)[.:](.*?)(\n(?=\n)|\Z)/m) do |m|
+            css_class = case $1
+                        when 'CAUTION', 'IMPORTANT'
+                          'warning'
+                        when 'TIP'
+                          'info'
+                        else
+                          $1.downcase
+                        end
+            %Q(<div class="#{css_class}"><p>#{$2.strip}</p></div>\n)
+          end
+        end
+
+        def dom_id(text)
+          text.downcase.gsub(/[^a-z0-9]+/, '-').strip
+        end
+    end
+  end
+end