html_with_pygments.rb

# create a custom renderer that allows highlighting of code blocks
class HTMLwithPygments < Redcarpet::Render::HTML
  def block_code(code, language)
    if language.to_s.end_with?("CHL")
      language = language[0...-3]
      code = Pygments.highlight(code, lexer: language, options: { linespans: Digest::SHA1.base64digest(code) })
      code = code.gsub(/<span class="(?:[a-z]+)">==<\/span>(.*?)<span class="(?:[a-z]+)">==<\/span>/, %{<span class="highlight">\\1</span>}.html_safe)
    else
      Pygments.highlight(code, lexer: language, options: { linespans: Digest::SHA1.base64digest(code) })
    end
  end
end