[C++] Option for match_substring* to return false on NULL input

[asfimport]

We implemented this in the R bindings as a wrapper in ARROW-16007 (and there's even a start of an implementation at f445450 provided by @ateucher )

This is should be done for match_substring and match_substring_regex (any others?)

Reporter: Jonathan Keane / @jonkeane

_{Note: This issue was originally created as ARROW-16047. Please see the migration documentation for further details.}

[asfimport]

Jonathan Keane / @jonkeane:
I created this ticket as a (possible) follow on and for discussion about how widespread this behavior is + see if it's feasible to do this in C++.

If you're still interested in digging more into the C++ code here, feel free to assign this ticket + send a PR @ateucher (but no pressure!).

[asfimport]

Andy Teucher / @ateucher:
Thanks @jonkeane - this looks great and I'd love to work on it some more. Might be a bit of time before I can allocate the time, but will assign myself when I'm able to start.

Just for clarification on the issue title (and to ensure I understand it correctly)... the current behaviour of match_substring and match_substring_regex is to return NULL for NULL inputs, and the option would be to allow changing that behaviour so that they can return false?

[asfimport]

Jonathan Keane / @jonkeane:
Ah yes, of course. I've updated the title there

[github-actions]

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