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Manipulation of regular expressions (regex)

Project description

Hachoir regex

hachoir-regex is a Python library for regular expression (regex or regexp) manupulation. You can use a|b (or) and a+b (and) operators. Expressions are optimized during the construction: merge ranges, simplify repetitions, etc. It also contains a class for pattern matching allowing to search multiple strings and regex at the same time.

Website: http://bitbucket.org/haypo/hachoir/wiki/hachoir-regex

Changelog

Version 1.0.5 (2010-01-28)

  • Create a MANIFEST.in to include extra files: regex.rst, test_doc.py, etc.
  • Create an INSTALL file

Version 1.0.4 (2010-01-13)

  • Support b (match a word)
  • Fix parser: support backslash in a range, eg. parse(r”[a]x]”)

Version 1.0.3 (2008-04-01)

  • Raise SyntaxError on unsupported escape character
  • Two dot atoms are always equals

Version 1.0.2 (2007-07-12)

  • Refix PatternMatching without any pattern

Version 1.0.1 (2007-06-28)

  • Fix PatternMatching without any pattern

Version 1.0 (2007-06-28)

  • First public version

Regex examples

Regex are optimized during their creation:

>>> from hachoir_regex import parse, createRange, createString
>>> createString("bike") + createString("motor")
<RegexString 'bikemotor'>
>>> parse('(foo|fooo|foot|football)')
<RegexAnd 'foo(|[ot]|tball)'>

Create character range:

>>> regex = createString("1") | createString("3")
>>> regex
<RegexRange '[13]'>
>>> regex |= createRange("2", "4")
>>> regex
<RegexRange '[1-4]'>

As you can see, you can use classic “a|b” (or) and “a+b” (and) Python operators. Example of regular expressions using repetition:

>>> parse("(a{2,}){3,4}")
<RegexRepeat 'a{6,}'>
>>> parse("(a*|b)*")
<RegexRepeat '[ab]*'>
>>> parse("(a*|b|){4,5}")
<RegexRepeat '(a+|b){0,5}'>

Compute minimum/maximum matched pattern:

>>> r=parse('(cat|horse)')
>>> r.minLength(), r.maxLength()
(3, 5)
>>> r=parse('(a{2,}|b+)')
>>> r.minLength(), r.maxLength()
(1, None)

Pattern maching

Use PatternMaching if you would like to find many strings or regex in a string. Use addString() and addRegex() to add your patterns.

>>> from hachoir_regex import PatternMatching
>>> p = PatternMatching()
>>> p.addString("a")
>>> p.addString("b")
>>> p.addRegex("[cd]")

And then use search() to find all patterns:

>>> for start, end, item in p.search("a b c d"):
...    print "%s..%s: %s" % (start, end, item)
...
0..1: a
2..3: b
4..5: [cd]
6..7: [cd]

You can also attach an objet to a pattern with ‘user’ (user data) argument:

>>> p = PatternMatching()
>>> p.addString("un", 1)
>>> p.addString("deux", 2)
>>> for start, end, item in p.search("un deux"):
...    print "%r at %s: user=%r" % (item, start, item.user)
...
<StringPattern 'un'> at 0: user=1
<StringPattern 'deux'> at 3: user=2

Installation

With distutils:

sudo ./setup.py install

Or using setuptools:

sudo ./setup.py –setuptools install

Project details


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