ANN: pyparsing 1.4.11 released

Paul McGuire ptmcg at
Mon Feb 11 01:55:17 CET 2008

I have just uploaded version 1.4.11 of pyparsing to SourceForge.  It
has been a pretty full 2 months since the last release, with
contributions from new users, old users, and also some help from the
Google Highly-Open Participation contest.  I think there are some very
interesting new features in this release.  Please check it out!

(Please note - if you download and install the Windows binary, this
NOT include the HTML doc or examples directory.  TO get these, you
need to download the docs or one of the source distributions.)

The pyparsing wiki is at

Here are the notes for 1.4.11:

Version 1.4.11 - February 10, 2008
- With help from Robert A. Clark, this version of pyparsing
  is compatible with Python 3.0a3.  Thanks for the help,

- Added WordStart and WordEnd positional classes, to support
  expressions that must occur at the start or end of a word.
  Proposed by piranha on the pyparsing wiki, good idea!

- Added matchOnlyAtCol helper parser action, to simplify
  parsing log or data files that have optional fields that are
  column dependent.  Inspired by a discussion thread with
  hubritic on comp.lang.python.

- Added withAttribute.ANY_VALUE as a match-all value when using
  withAttribute.  Used to ensure that an attribute is present,
  without having to match on the actual attribute value.

- Added get() method to ParseResults, similar to dict.get().
  Suggested by new pyparsing user, Alejandro Dubrovksy, thanks!

- Added '==' short-cut to see if a given string matches a
  pyparsing expression.  For instance, you can now write:

    integer = Word(nums)
    if "123" == integer:
       # do something

    print [ x for x in "123 234 asld".split() if x==integer ]
    # prints ['123', '234']

- Simplified the use of nestedExpr when using an expression for
  the opening or closing delimiters.  Now the content expression
  will not have to explicitly negate closing delimiters.  Found
  while working with dfinnie on GHOP Task #277, thanks!

- Fixed bug when defining ignorable expressions that are
  later enclosed in a wrapper expression (such as ZeroOrMore,
  OneOrMore, etc.) - found while working with Prabhu
  Gurumurthy, thanks Prahbu!

- Fixed bug in withAttribute in which keys were automatically
  converted to lowercase, making it impossible to match XML
  attributes with uppercase characters in them.  Using with-
  Attribute requires that you reference attributes in all
  lowercase if parsing HTML, and in correct case when parsing

- Changed '<<' operator on Forward to return None, since this
  is really used as a pseudo-assignment operator, not as a
  left-shift operator.  By returning None, it is easier to
  catch faulty statements such as a << b | c, where precedence
  of operations causes the '|' operation to be performed
  *after* inserting b into a, so no alternation is actually
  implemented.  The correct form is a << (b | c).  With this
  change, an error will be reported instead of silently
  clipping the alternative term.  (Note: this may break some
  existing code, but if it does, the code had a silent bug in
  it anyway.)  Proposed by wcbarksdale on the pyparsing wiki,

- Several unit tests were added to pyparsing's regression
  suite, courtesy of the Google Highly-Open Participation
  Contest.  Thanks to all who administered and took part in
  this event!

Pyparsing is a pure-Python class library for quickly developing
recursive-descent parsers.  Parser grammars are assembled directly in
the calling Python code, using classes such as Literal, Word,
OneOrMore, Optional, etc., combined with operators '+', '|', and '^'
for And, MatchFirst, and Or.  No separate code-generation or external
files are required.  Pyparsing can be used in many cases in place of
regular expressions, with shorter learning curve and greater
readability and maintainability.  Pyparsing comes with a number of
parsing examples, including:
- "Hello, World!" (English, Korean, Greek, and Spanish)
- chemical formulas
- configuration file parser
- web page URL extractor
- 5-function arithmetic expression parser
- subset of CORBA IDL
- chess portable game notation
- simple SQL parser
- search query parser
- EBNF parser/compiler
- Python value string parser (lists, dicts, tuples, with nesting)
  (safe alternative to eval)
- HTML tag stripper
- S-expression parser
- macro substitution preprocessor

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