[m-rev.] for review: Reduce memory allocation in string.to_upper, string.to_lower.

[Julien Fischer]

Hi Peter,

On Mon, 20 Jun 2016, Peter Wang wrote:

> library/string.m:
> 	Implement to_upper(in, uo) and to_lower(in, uo) with foreign
> 	code, not creating intermediate character lists.
>
> 	Implement to_upper(in, in) and to_lower(in, in) modes without
> 	allocating memory.
>
> 	Be more specific in documentation about which characters are
> 	affected by some functions/predicates.

...

> diff --git a/library/string.m b/library/string.m
> index 55ef8b3..c13f7d4 100644
> --- a/library/string.m
> +++ b/library/string.m
> @@ -768,19 +768,19 @@
> %
>
>     % Convert the first character (if any) of a string to uppercase.
> -    % Note that this only converts unaccented Latin letters.
> +    % Note that this only converts letters (a-z) in the ASCII range.
>     %

It may be worth extending that comment to say that base letters that lie
in the ASCII range in strings containing combining characters will also
be converted, for example:

     io.write_string("a\u0301\n", !IO)       ==> á
     io.write_string(to_upper("a\u0301\n")   ==> Á

Julien.