gistfile1.rb

# Highlights code contained within the post according to a given language.
def highlight_code string
  post_text = string.gsub(/\r\n/, "\n")
  
  # From Markdown.pl by John Gruber
  regex = /(?:\n\n|\A)((?:(?:[ ]{4} | \t).*\n+)+)((?=^[ ]{0,4}\S)|\Z)/ix
  
  matches = post_text.scan(regex)
  
  for match in matches
    c = match[0].gsub(/^    /, '')    # Removes the 4 leading spaces from Markdown text
    lang = "plain_text"               # Default Language
    
    lines = c.split("\n")             # Splits the lines by newline character
    lang_def = lines[0].split(":")    # Split the first line by colon to get the language param
    
    if lang_def[0].downcase == 'l' || lang_def[0].downcase == 'lang'
      if lang_def[1].strip.length > 0
        lang = lang_def[1].strip.downcase
        lines = lines[1..-1]
      end
    end
    
    code_html = code(lines.join("\n"), :lang => lang, :theme => 'sunburst', :line_numbers => true)
    linetoggle_html = div_to_function "Toggle Line Numbers", :onclick => "linetoggle()", :class => "linetoggle"
    post_text = post_text.gsub(match[0], "\n" + linetoggle_html + "\n" + code_html + "\n\n")
  end
  
  return post_text
end