python-rex

Welcome to python-Rex

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Python Rex is regular expressions for humans. (Rex is also abbreviation from re X tended).

Rex is for the re standard module <http://docs.python.org/2/library/index.html>_ as requests <http://docs.python-requests.org/en/latest/>_ is for urllib module <http://docs.python.org/2/library/urllib.html>_.

Rex also is latin for "king" <http://en.wikipedia.org/wiki/Rex>_, and the king of regular expressions is Perl. So Rex API tries to mimic at least some Perl's idioms.

Supported Python versions: 2.6, 2.7, 3.3

Installation

::

pip install python-rex

or

::

pip install -e git+https://github.com/cypreess/python-rex.git#egg=rex-dev

There are no external dependencies.

::

from rex import rex

Quickstart

Do that::

from rex import rex print ("Your ticket number: XyZ-1047. Have fun!" == rex("/[a-z]{3}-(\d{4})/i"))[1]

instead of doing that::

import re regex = re.compile("[a-z]{3}-(\d{4})", flags=re.IGNORECASE) m = regex.search("Your ticket number: XyZ-1047. Have fun!")

if m is not None: print m.group(1) else: print None

or in shorter way

print m.group(1) if m else None

(both should print 1047).

Docs

So far Rex supports:

• simple matching (first match),
• substitution,
• all python re flags.

Matching

The most obvious usage - test condition by matching to string::

if 'This is a dog' == rex('/dog/'):
    print 'Oh yeah'

or::

if 'My lucky 777 number' == rex('/[0-9]+/'):
    print 'Number found'

You can use Perl notation and prepend m character to your search::

if 'My lucky 777 number' == rex('m/[0-9]+/'):
    print 'Number found'

but you can also simply check your match::

if ('My lucky 777 number' == rex('m/[0-9]+/'))[0] == '777':
    print 'Number found'

or even groups::

if ('My lucky 777 number' == rex('m/(?P<number>[0-9]+)/'))['number'] == '777':
    print 'Number found'

Remember a mess with re module when it does not match anything? Rex won't let you down, it will kindly return None for whatever you ask::

>>> print ('My lucky 777 number' == rex('m/(?P<number>[0-9]+)/'))['no_such_group']
None

>>> print ("I don't tell you my lucky number" == rex('m/(?P<number>[0-9]+)/'))['number']
None

Substituting

Substitution can be made by prefixing pattern with s character (like in perl expression)::

>>> print "This is a cat" == rex('s/CAT/dog/i')
This is a dog

Flags

Every Rex pattern as in Perl patterns allows to suffix some flags, e.g. rex('/pattern/iu') for enabling i and u flag. Rex supports all standard python re flags:

• d - re.DEBUG
• i - re.IGNORECASE
• l - re.LOCALE
• m - re.MULTILINE
• s - re.DOTALL
• u - re.UNICODE
• x - re.VERBOSE

Caching

Rex caches all patterns so reusing patterns is super fast. You can always clear Rex cache by calling rex_clear_cache() or disable caching for specific patterns rex('/pattern/', cache=False).

Rex for orthodox

If you are so orthodox pythonist that couldn't leave with overloaded == operator syntax in your codebase, you can use "orthodox mode" of rex. Just put the string to match/substitute against as a second argument::

>>> bool(rex("/dog/", "This is a dog"))
True
>>> rex("s/cat/dog/", "This is a cat")
'This is a dog'

Additionally Rex objects are callable. This is especially useful in situations where you need to process many values against the same regular expression::

>>> my_re = rex("/foo/")
>>> for thing in ["foobar", "bar", "barfoo"]:
...     print bool(my_re(thing))
True
False
True