Generating HTML markup from github flavored markdown including syntax highlighting

application_helper.rb

 @md_renderer = Redcarpet::Markdown.new(Redcarpet::Render::HTML,
                                       :autolink => true,
                                       :space_after_headers => true, 
                                       :fenced_code_blocks => true)

def markdown(text)
  syntax_highlighter(@md_renderer.render(text)).html_safe
end

def syntax_highlighter(html)
  doc = Nokogiri::HTML(html)
  doc.search("//code[@class]").each do |code|
    code.replace Albino.colorize(code.text.rstrip, code[:class])
    # or use coderay
    #code.replace CodeRay.scan(code.text.rstrip, code[:class]).html(:line_numbers => :table)
  end
  doc.to_s
end