Python regex look-behind requires fixed-width pattern
- by invictus
Hi
When trying to extract the title of a html-page I have always used the following regex:
(?<=<title.*>)([\s\S]*)(?=</title>)
Which will extract everything between the tags in a document and ignore the tags themselves. However, when trying to use this regex in Python it raises the following Exception:
Traceback (most recent call last):
File "test.py", line 21, in
pattern = re.compile('(?<=)([\s\S]*)(?=)')
File "C:\Python31\lib\re.py", line
205, in compile
return _compile(pattern, flags) File "C:\Python31\lib\re.py", line
273, in _compile
p = sre_compile.compile(pattern, flags) File
"C:\Python31\lib\sre_compile.py", line
495, in compile
code = _code(p, flags) File "C:\Python31\lib\sre_compile.py", line
480, in _code
_compile(code, p.data, flags) File "C:\Python31\lib\sre_compile.py",
line 115, in _compile
raise error("look-behind requires fixed-width pattern")
sre_constants.error: look-behind
requires fixed-width pattern
The code I am using is:
pattern = re.compile('(?<=<title.*>)([\s\S]*)(?=</title>)')
m = pattern.search(f)
if I do some minimal adjustments it works:
pattern = re.compile('(?<=<title>)([\s\S]*)(?=</title>)')
m = pattern.search(f)
This will, however, not take into account potential html titles that for some reason have attributes or similar.
Anyone know a good workaround for this issue? Any tips are appreciated.
