[issue40980] group names of bytes regexes are strings
Quentin Wenger
report at bugs.python.org
Tue Jun 16 07:51:43 EDT 2020
Quentin Wenger <wenger.quentin at bluewin.ch> added the comment:
> So b'\xe9' is mapped to \u00e9, it is `é`.
Yes but \xe9 is not strictly valid utf-8, or say not the canonical representation of "é". So there is no way to get \xe9 starting from é without leaving utf-8. So starting with é as group name, I cannot programmatically encode it into a bytes pattern.
> Of course, characters with Unicode code point greater than 0xff are impossible to appear in `bytes`.
But \xce and \x94 are both lower than \xff, yet using \xce\x94 ("Δ".encode()) in a group name fails.
According to the doc, the sole constraint on group names is that they have to be valid and unique Python identifiers. So this should work:
```
# Δ is a valid identifier
>>> "Δ".isidentifier()
True
>>> Δ = 1
>>> Δ
1
>>> import re
>>> name = "Δ"
>>> re.match(b"(?P<" + name.encode() + b">)", b"")
Traceback (most recent call last):
File "<pyshell#4>", line 1, in <module>
re.match(b"(?P<" + name.encode() + b">)", b"")
File "/usr/lib/python3.8/re.py", line 191, in match
return _compile(pattern, flags).match(string)
File "/usr/lib/python3.8/re.py", line 304, in _compile
p = sre_compile.compile(pattern, flags)
File "/usr/lib/python3.8/sre_compile.py", line 764, in compile
p = sre_parse.parse(p, flags)
File "/usr/lib/python3.8/sre_parse.py", line 948, in parse
p = _parse_sub(source, state, flags & SRE_FLAG_VERBOSE, 0)
File "/usr/lib/python3.8/sre_parse.py", line 443, in _parse_sub
itemsappend(_parse(source, state, verbose, nested + 1,
File "/usr/lib/python3.8/sre_parse.py", line 703, in _parse
raise source.error(msg, len(name) + 1)
re.error: bad character in group name 'Î\x94' at position 4
re.match(b'(?P<\xce\x94>)', b'').groupdict()
```
----------
_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40980>
_______________________________________
More information about the Python-bugs-list
mailing list