grammar Bristlecode
  rule root
    (tag / text)* <RootNode>
  end

  rule text
    (!tag .)+ <TextNode>
  end

  rule tag
    bold / italic
  end

  ##############################
  # bold
  ##############################

  rule bold
    bold_open
    ((!bold_close .)+ <TextNode>)
    bold_close
    <BoldNode>
  end

  rule bold_open
    '[b]' <BoldOpenNode> / '[B]' <BoldOpenNode>
  end

  rule bold_close
    '[/b]' <BoldCloseNode> / '[/B]' <BoldCloseNode>
  end

  ##############################
  # italic
  ##############################

  rule italic
    italic_open
    ((!italic_close .)+ <TextNode>)
    italic_close
    <ItalicNode>
  end

  rule italic_open
    '[i]' <ItalicOpenNode> / '[I]' <ItalicOpenNode>
  end

  rule italic_close
    '[/i]' <ItalicCloseNode> / '[/I]' <ItalicCloseNode>
  end
end