[m-rev.] for review: add string.contains_match/2

[Peter Wang]

On Mon, 25 Jul 2022 16:14:55 +1000 Julien Fischer <jfischer at opturion.com> wrote:
> 
> On Mon, 25 Jul 2022, Peter Wang wrote:
> 
> > On Mon, 25 Jul 2022 15:38:10 +1000 Julien Fischer <jfischer at opturion.com> wrote:
> 
> >>   %---------------------%
> >>
> >> +contains_match(P, String) :-
> >> +    contains_match_loop(P, String, 0).
> >> +
> >> +:- pred contains_match_loop(pred(char)::in(pred(in) is semidet), string::in,
> >> +    int::in) is semidet.
> >> +
> >> +contains_match_loop(P, String, Cur) :-
> >> +    unsafe_index_next_repl(String, Cur, Next, Char, not_replaced),
> >> +    ( if P(Char) then
> >> +        true
> >> +    else
> >> +        contains_match_loop(P, String, Next)
> >> +    ).
> >
> > If unsafe_index_next_repl returns replaced_code_unit(_) then P should
> > not succeed, but I think the loop should continue to test the rest of
> > the string.
> 
> I don't have any objections to doing that, however it would not be
> consistent with how all_match/2 and contains_char/2 treat
> replaced_code_unit().

Hmm, I don't know what I was thinking when I updated those predicates,
if I was thinking at all.

It seems clear that:
  - all_match should fail if the string contains any ill-formed sequences
  - contains_char should succeed as long as the string contains the char
    being tested for, even if it contains an ill-formed sequence or
    anything else

I will try to look over the rest of the string predicates tomorrow.

Peter