https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85472
--- Comment #5 from Tim Shen <timshen at gcc dot gnu.org> ---
(In reply to Hans Åberg from comment #4)
> (In reply to Tim Shen from comment #1)
> > I know exactly how libc++ produces this result. It creates an empty
> > match_result during each repetition ("*" operator). It's less confusing but
> > much slower.
>
> I wrote an NFA/DFA that computes all matches, it seems, in an efficient
> manner: Action numbers are marked on the states of the sub-NFAs one is
> interested in. While lexing a string, the partial reverse NFA is recorded,
> which is searched when a final state is encountered. The string position
> action numbers, as marked on the corresponding states, are recorded, and for
> each action number, the contiguous string sequences are the possible
> submatches.
I'm not following the meaning of "action number" and "the partial reverse NFA
is recorded".
How many actions numbers are recorded? for regex_match(s, regex(re)), is it on
the order of O(s.size()), or O(re.size())? The goal is to allocate O(re.size())
of memory exactly once.
