Why std.algorithm.sort can't be applied to char[]?

[Jonathan M Davis via Digitalmars-d-learn]

On Wed, 14 May 2014 08:27:45 +0000
monarch_dodra via Digitalmars-d-learn
<digitalmars-d-learn at puremagic.com> wrote:

> On Monday, 12 May 2014 at 18:44:22 UTC, Jonathan M Davis via
> Digitalmars-d-learn wrote:
> > Sure, you can cast char[] to ubyte[] and sort that if you know
> > that the array
> > only holds pure ASCII. In fact, you can use
> > std.string.representation to do it
> > - e.g.
> >
> > auto ascii = str.representation;
> >
> > and if str were mutable, then you could sort it. But that will
> > only work if
> > the string only contains ASCII characters. Regardless, he
> > wanted to know why
> > he couldn't sort char[], and I explained why - all strings are
> > treated as
> > ranges of dchar, making it so that if their element type is
> > char or wchar, so
> > they're not random access and thus can't be sorted.
>
> Arguably, a smart enough implementation should know how to sort a
> "char[]", while still preserving codepoint integrity.

I don't think that that can be done at the same algorithmic complexity though.
So, I don't know if that would be acceptable or not from the standpoint of
std.algorithm.sort. But even if it's a good idea, someone would have to
special case sort for char[], and no one has done that.

> As a matter of fact, the built in "sort" property does it.
>
> void main()
> {
>      char[] s = "éöeèûà".dup;
>      s.sort;
>      writeln(s);
> }
> //prints:
> eàèéöû

I'm surprised. I thought that one of Bearophile's favorite complaints was that
it didn't sort unicode properly (and hence one of the reasons that it should
be removed). Regardless, I do think that it should be removed.

- Jonathan M Davis