Example Treetop grammar fragment

grammar PivotalStories
  rule stories
    story*
  end

  rule story
    story_label:one_line "\n" feature*
  end

  rule feature
    indent '- ' title
    ( "\n" long_description
    / description "\n"
    )
  end

  rule title
    plain_text
  end

  rule long_description
    (indent indent one_line)*
  end

  # An in-line description
  rule description
    '(' description ')'
    /
    plain_text
  end

  def plain_text
    (!non_plain .)*
  end

  # Any text to end of line:
  rule one_line
    (!"\n" .)*
  end

  rule indent
    '  '
  end

  # Characters not allowed in a one-line text fragment
  rule non_plain
    [()] / "\n"
  end

end

Example txt to pivotal format

LabelForNestedStories AnotherLabel
  - Feature title (single line description in parens)
  - Some other feature (you don't need blank lines seperating your stories but you can use them for extra readability in the file)

  - Another feature
      Multi-line description of this feature.
      Use two tabs to indent for easy visual parsing.
      
  [] Chores look like checkboxes (short description in parens)

  [] Another chore
      Multi-line descriptions for chores work the same way.

      Possible steps:
      1. Collect underpants
      2. ?
      3. Profit!


  - Another feature here with no description


AnotherLabelForSomeFeatures
  - Feature One

  - Feature two