patch applied (packages/HaXml): Bugfix in DtdToHaskell: avoid stack overflow.

[Malcolm Wallace]

Wed Jan 13 06:48:31 PST 2010  Malcolm.Wallace at cs.york.ac.uk
  * Bugfix in DtdToHaskell: avoid stack overflow.
  Ignore-this: 19a01a75a21fe89a6ad987cce26608a1
  As reported by Bertram Felgenhauer, the following DTD
      <!ELEMENT dummy EMPTY>
      <!ELEMENT broken (#PCDATA | dummy)* >
  when passed through DtdToHaskell, generated a parser that crashes on
      readXml "<broken>abc</broken>" :: Either String Broken
  instead of giving the correct answer
      Just (Broken [Broken_Str "abc"])
  The fix is to be more careful about generating the parsing expression
      (text `onFail` return "")
  It is wrong to return the empty string inside a 'many' combinator,
  because it simply loops forever.  But it is essential to return the empty
  string if there is no enclosing zero-or-more combinator.

    M ./src/Text/XML/HaXml/DtdToHaskell/Convert.hs -1 +3
    M ./src/Text/XML/HaXml/DtdToHaskell/Instance.hs -22 +24
    M ./src/Text/XML/HaXml/DtdToHaskell/TypeDef.hs -1 +4

View patch online:
http://darcs.haskell.org/packages/HaXml/_darcs/patches/20100113144831-6871e-44d4e134ef827a2f12cf182162157c605edc3351.gz