[m-rev.] for post-commit review: optimize a test

[Peter Wang]

On Mon, 10 Jul 2023 01:46:30 +1000 "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:
> Make a test more efficient.
> 
> library/string.builder.m:
>     Add a predicate that tests whether the total length of the string
>     implicit in a string builder is within a limit, or not.
> 
>     Add a function that returns that total length.
> 
> NEWS.md:
>     Announce the new predicate and function.
> 
> compiler/parse_tree_out_term.m:
>     Use the new predicate to optimize a test.

> +%---------------------%
> +
> +    % Return the total length of the string that to_string would return,
> +    % without constructing that string (yet).
> +    %
> +    % Note that once you call this function, you cannot add any new entries
> +    % to the given string builder state, because it loses its uniqueness.
> +    %
> +:- func total_length(string.builder.state) = int.

The documentation should mention what it is counting.
string.length counts code units, so I suggest naming this function
total_code_points or count_code_points or num_code_points, etc.

Similarly for total_length_is_at_most.

Peter