[m-rev.] for review: Make generic versions of string.to_upper/lower preserve ill-formed sequences.

[Mark Brown]

This looks fine.

On Mon, Nov 4, 2019 at 4:52 PM Peter Wang <novalazy at gmail.com> wrote:
>
> library/string.m:
>     Make generic implementations of string.to_upper and string.to_lower
>     preserve ill-formed sequences. (The foreign language implementations
>     already did so.)
> ---
>  library/string.m | 38 ++++++++++++++++----------------------
>  1 file changed, 16 insertions(+), 22 deletions(-)
>
> diff --git a/library/string.m b/library/string.m
> index 275a49728..c65e857f8 100644
> --- a/library/string.m
> +++ b/library/string.m
> @@ -4468,11 +4468,15 @@ to_upper(S1) = S2 :-
>  :- pragma promise_equivalent_clauses(to_upper/2).
>
>  to_upper(StrIn::in, StrOut::uo) :-
> -    % XXX ILSEQ to_char_list and from_char_list cannot handle ill-formed
> +    % Use to_code_unit_list instead of to_char_list to preserve ill-formed
>      % sequences.
> -    to_char_list(StrIn, List),
> -    char_list_to_upper(List, ListUpp),
> -    from_char_list(ListUpp, StrOut).
> +    to_code_unit_list(StrIn, CodeList0),
> +    list.map(to_upper_code_unit, CodeList0, CodeList),
> +    ( if from_code_unit_list_allow_ill_formed(CodeList, StrPrime) then
> +        StrOut = StrPrime
> +    else
> +        unexpected($pred, "string.from_code_unit_list_allow_ill_formed failed")
> +    ).
>
>  to_upper(X::in, Y::in) :-
>      length(X, LenX),
> @@ -4525,13 +4529,6 @@ to_upper(X::in, Y::in) :-
>      StrOut = new String(cs);
>  ").
>
> -:- pred char_list_to_upper(list(char)::in, list(char)::out) is det.
> -
> -char_list_to_upper([], []).
> -char_list_to_upper([X | Xs], [Y | Ys]) :-
> -    char.to_upper(X, Y),
> -    char_list_to_upper(Xs, Ys).
> -
>  :- pred check_upper_loop(string::in, string::in, int::in, int::in) is semidet.
>
>  check_upper_loop(X, Y, Index, End) :-
> @@ -4564,11 +4561,15 @@ to_lower(S1) = S2 :-
>  :- pragma promise_equivalent_clauses(to_lower/2).
>
>  to_lower(StrIn::in, StrOut::uo) :-
> -    % XXX ILSEQ to_char_list and from_char_list cannot handle ill-formed
> +    % Use to_code_unit_list instead of to_char_list to preserve ill-formed
>      % sequences.
> -    to_char_list(StrIn, List),
> -    char_list_to_lower(List, ListLow),
> -    from_char_list(ListLow, StrOut).
> +    to_code_unit_list(StrIn, CodeList0),
> +    list.map(to_lower_code_unit, CodeList0, CodeList),
> +    ( if from_code_unit_list_allow_ill_formed(CodeList, StrPrime) then
> +        StrOut = StrPrime
> +    else
> +        unexpected($pred, "string.from_code_unit_list_allow_ill_formed failed")
> +    ).
>
>  to_lower(X::in, Y::in) :-
>      length(X, LenX),
> @@ -4621,13 +4622,6 @@ to_lower(X::in, Y::in) :-
>      StrOut = new String(cs);
>  ").
>
> -:- pred char_list_to_lower(list(char)::in, list(char)::out) is det.
> -
> -char_list_to_lower([], []).
> -char_list_to_lower([X | Xs], [Y | Ys]) :-
> -    char.to_lower(X, Y),
> -    char_list_to_lower(Xs, Ys).
> -
>  :- pred check_lower_loop(string::in, string::in, int::in, int::in) is semidet.
>
>  check_lower_loop(X, Y, Index, End) :-
> --
> 2.23.0
>
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