[m-rev.] for review: add array.swap/4 and array.unsafe_swap/4

[Julien Fischer]

On Mon, 12 Nov 2018, Zoltan Somogyi wrote:

> On Mon, 12 Nov 2018 17:20:04 +1100 (AEDT), Julien Fischer <jfischer at opturion.com> wrote:
>> +    % swap(I, J, !Array):
>> +    % Swap the item in the I'th position with the item in the J'th position.
>> +    % Throws an exception if either of I or J is out-of-bounds.
>> +    %
>> +:- pred swap(int, int, array(T), array(T)).
>> +:- mode swap(in, in, array_di, array_uo) is det.
>> +
>> +    % As above, but omit the bounds check.
>
> I would say checks (plural).

Done.

>> @@ -350,6 +362,7 @@
>>   %:- mode copy(array_ui) = array_uo is det.
>>   :- mode copy(in) = array_uo is det.
>>
>> +
>>       % resize(Size, Init, Array0, Array):
>>       % The array is expanded or shrunk to make it fit the new size `Size'.
>>       % Any new entries are filled with `Init'. Throws an exception if
>
> ?

Deleted, that was inadvertent.

>
>> @@ -2141,9 +2154,9 @@ fill_range(Item, Lo, Hi, !Array) :-
>>       ( if Lo > Hi then
>>           unexpected($pred, "empty range")
>>       else if not in_bounds(!.Array, Lo) then
>> -        out_of_bounds_error(!.Array, Lo, "fill_range")
>> +        arg_out_of_bounds_error(!.Array, "second", Lo, "fill_range")
>>       else if not in_bounds(!.Array, Hi) then
>> -        out_of_bounds_error(!.Array, Hi, "fill_range")
>> +        arg_out_of_bounds_error(!.Array, "third", Hi, "fill_range")
>>       else
>>           do_fill_range(Item, Lo, Hi, !Array)
>
> The arg order of arg_out_of_bounds seems strange: the arg number and
> the pred name logically belong next to each other, but you put the index
> between them.

Changed so they are number and pred name are next to each other.

>> +test_swap(Elems, I, J, !IO) :-
>> +    io.write_string("================\n", !IO),
>> +    array.from_list(Elems, Array0),
>> +    io.write_string("Array0 = ", !IO),
>> +    io.write_line(Array0, !IO),
>> +    io.format("Swap: %d <-> %d\n", [i(I), i(J)], !IO),
>> +    ( try [] (
>> +        array.swap(I, J, Array0, Array)
>> +    ) then
>> +        io.write_string("Array = ", !IO),
>> +        io.write_line(Array, !IO)
>> +    catch index_out_of_bounds(S) ->
>> +        io.write_string("EXCEPTION: ", !IO),
>> +        io.write_line(S, !IO)
>> +    ).
>
> The formatting of the try block is strange. The close paren
> before "then" looks like closing the whole thing, because it
> aligns with the open paren before "try", not the open paren
> after "try".

Fixed.

Thanks for that!

Julien.