How to access a capture group by name?

Question

Say I have a MatchResult m:

>>> var m = Regex("(?<foo>hello) world").find("hello world")!!

How can I access the group named "foo" by name? According to the docs MatchGroupCollection implements the get(String) operator, but if I try it I get an exception:

>>> m.groups["foo"]
error: type mismatch: inferred type is String but Int was expected
m.groups["foo"]
         ^

Answer 1

It is the MatchNamedGroupCollection that allows getting by name, the MatchGroupCollection only allows getting by integer index.

So you need to check the group type before getting the match by name.

Something like: (m.groups as MatchNamedGroupCollection)["foo"]