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Regular expression reverser for Python

Project description

unmatcher tries to solve the following problem:

Given a regular expression, find any string that matches the expression.

Why? Mostly just because. But one possible application is to generate test data for string processing functions.


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Most typical elements of regexes are supported:

  • multipliers: *, +
  • capture groups: |, ( ) (including backreferences)
  • character classes (\d|\w|\s etc.) and character sets ([])


unmatcher module exposes a single reverse function. It takes a regular expression - either in text or compiled form - and returns a random string that matches it:

>>> import unmatcher
>>> print unmatcher.reverse(r'\d')

Additional arguments can be provided, specifying predefined values for capture groups inside the expression. Use positional arguments for numbered groups ('\1', etc.):

>>> import unmatcher
>>> print unmatcher.reverse(r'<(\w+)>.*</\1>', 'h1')

and keyword arguments for named groups:

>>> import unmatcher
>>> print unmatcher.reverse('(?P<foo>\w+)__(?P=foo)', foo='bar')

Note that a predefined value is not validated against actual subexpression for the capture group.

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Filename, size & hash SHA256 hash help File type Python version Upload date
unmatcher-0.1.4.tar.gz (7.4 kB) Copy SHA256 hash SHA256 Source None Sep 16, 2017

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