merge with 3.2

This commit is contained in:
Georg Brandl 2012-03-17 17:26:36 +01:00
commit 9758fcfb87
1 changed files with 2 additions and 24 deletions

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@ -1093,28 +1093,6 @@ 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/python3.2/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.
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()
@ -1161,7 +1139,7 @@ creates a phonebook.
First, here is the input. Normally it may come from a file, here we are using
triple-quoted string syntax:
>>> input = """Ross McFluff: 834.345.1254 155 Elm Street
>>> text = """Ross McFluff: 834.345.1254 155 Elm Street
...
... Ronald Heathmore: 892.345.3428 436 Finley Avenue
... Frank Burger: 925.541.7625 662 South Dogwood Way
@ -1175,7 +1153,7 @@ into a list with each nonempty line having its own entry:
.. doctest::
:options: +NORMALIZE_WHITESPACE
>>> entries = re.split("\n+", input)
>>> entries = re.split("\n+", text)
>>> entries
['Ross McFluff: 834.345.1254 155 Elm Street',
'Ronald Heathmore: 892.345.3428 436 Finley Avenue',