Closes #14342: remove out-of-date section about avoiding recursion errors.

This commit is contained in:
Georg Brandl 2012-03-17 17:25:47 +01:00
parent f354f8e369
commit ce54617260
1 changed files with 0 additions and 22 deletions

View File

@ -1077,28 +1077,6 @@ The equivalent regular expression would be ::
(\S+) - (\d+) errors, (\d+) warnings
Avoiding recursion
^^^^^^^^^^^^^^^^^^
If you create regular expressions that require the engine to perform a lot of
recursion, you may encounter a :exc:`RuntimeError` exception with the message
``maximum recursion limit`` exceeded. For example, ::
>>> s = 'Begin ' + 1000*'a very long string ' + 'end'
>>> re.match('Begin (\w| )*? end', s).end()
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/local/lib/python2.5/re.py", line 132, in match
return _compile(pattern, flags).match(string)
RuntimeError: maximum recursion limit exceeded
You can often restructure your regular expression to avoid recursion.
Starting with Python 2.3, simple uses of the ``*?`` pattern are special-cased to
avoid recursion. Thus, the above regular expression can avoid recursion by
being recast as ``Begin [a-zA-Z0-9_ ]*?end``. As a further benefit, such
regular expressions will run faster than their recursive equivalents.
.. _search-vs-match:
search() vs. match()