[New-bugs-announce] [issue12729] Python lib re cannot handle Unicode properly due to narrow/wide bug
Tom Christiansen
report at bugs.python.org
Thu Aug 11 21:03:55 CEST 2011
New submission from Tom Christiansen <tchrist at perl.com>:
Python is in flagrant violation of the very most basic premises of Unicode Technical Report #18 on Regular Expressions, which requires that a regex engine support Unicode characters as "basic logical units independent of serialization like UTF‑*". Because sometimes you must specify ".." to match a single Unicode character -- whenever those code points are above the BMP and you are on a narrow build -- Python regexes cannot be reliably used for Unicode text.
% python3.2
Python 3.2 (r32:88445, Jul 21 2011, 14:44:19)
[GCC 4.2.1 (Apple Inc. build 5664)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import re
>>> g = "\N{GREEK SMALL LETTER ALPHA WITH VARIA AND YPOGEGRAMMENI}"
>>> print(g)
ᾲ
>>> print(re.search(r'\w', g))
<_sre.SRE_Match object at 0x10051f988>
>>> p = "\N{MATHEMATICAL SCRIPT CAPITAL P}"
>>> print(p)
𝒫
>>> print(re.search(r'\w', p))
None
>>> print(re.search(r'..', p)) # ← 𝙏𝙃𝙄𝙎 𝙄𝙎 𝙏𝙃𝙀 𝙑𝙄𝙊𝙇𝘼𝙏𝙄𝙊𝙉 𝙍𝙄𝙂𝙃𝙏 𝙃𝙀𝙍𝙀
<_sre.SRE_Match object at 0x10051f988>
>>> print(len(chr(0x1D4AB)))
2
That is illegal in Unicode regular expressions.
----------
components: Regular Expressions
messages: 141917
nosy: tchrist
priority: normal
severity: normal
status: open
title: Python lib re cannot handle Unicode properly due to narrow/wide bug
type: behavior
versions: Python 2.7
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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue12729>
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