Bugs item #1113484, was opened at 2005-01-31 22:46
Message generated for change (Comment added) made by calvin
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1113484&group_id=5470
Category: Regular Expressions
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Wummel (calvin)
Assigned to: Gustavo Niemeyer (niemeyer)
Summary: document {m} regex matcher wrt empty matches
Initial Comment:
The {m} matcher seems not to be applicable to (some)
empty matches. For example this will raise a regex
compile error:
>>> re.compile("(a*){4}")
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/lib/python2.3/sre.py", line 179, in compile
return _compile(pattern, flags)
File "/usr/lib/python2.3/sre.py", line 230, in _compile
raise error, v # invalid expression
sre_constants.error: nothing to repeat
However this matcher is compiled without error:
>>> re.compile("(\ba*){4}")
<_sre.SRE_Pattern object at 0xb7f86c58>
I don't know why the first example gives an error, but
it should perhaps be mentioned in the documentation
about the {} regex operator.
----------------------------------------------------------------------
>Comment By: Wummel (calvin)
Date: 2005-02-03 18:06
Message:
Logged In: YES
user_id=9205
Oops, it should have been:
>>> re.compile(r"(\ba*){4}")
And now the error is consistent (now tested in Python 2.4
instead of 2.3):
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/lib/python2.4/sre.py", line 180, in compile
return _compile(pattern, flags)
File "/usr/lib/python2.4/sre.py", line 227, in _compile
raise error, v # invalid expression
sre_constants.error: nothing to repeat
So it seems that {m} operator does not like potentially
empty matches.
----------------------------------------------------------------------
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1113484&group_id=5470
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
