class RDoc::Parser

def self.alias_extension(old_ext, new_ext)
  old_ext = old_ext.sub(/^\.(.*)/, '\1')
  new_ext = new_ext.sub(/^\.(.*)/, '\1')
  parser = can_parse_by_name "xxx.#{old_ext}"
  return false unless parser
  RDoc::Parser.parsers.unshift [/\.#{new_ext}$/, parser]
  true
end