python regex: duplicate names in named groups

Question

Is there a way to use same name in regex named group in python? e.g.(?P<n>foo)|(?P<n>bar).

Use case: I am trying to capture type and id with this regex:
/(?=videos)((?P<type>videos)/(?P<id>d+))|(?P<type>w+)/?(?P<v>v)?/?(?P<id>d+)?
from this strings:

• /channel/v/123
• /ch/v/41500082
• /channel
• /videos/41500082

For now I am getting error: redefinition of group name 'id' as group 6; was group 3

Answer 1

The answer is: Python re does not support identically named groups.

Python PyPi regex module supports a branch reset feature:

Branch reset

(?|...|...)

Capture group numbers will be reused across the alternatives, but groups with different names will have different group numbers.

Examples:

>>> regex.match(r"(?|(first)|(second))", "first").groups()
('first',)
>>> regex.match(r"(?|(first)|(second))", "second").groups()
('second',)

Note that there is only one group.

And here is a live Python 2.7 demo:

import regex
s = "foo bar"
rx = regex.compile(r"(?P<n>foo)|(?P<n>bar)")
print([x.group("n") for x in rx.finditer(s)])
// => ['foo', 'bar']