const version for foreach/opApply

[Era Scarecrow]

On Saturday, 9 June 2012 at 10:09:25 UTC, Matthias Walter wrote:
> First, thank you for your answer. I've already made some tiny 
> modifications in order to make BitArray work for my purposes:
>
> https://github.com/xammy/phobos/commit/eb46d99217f2bf1e6d173964e2954248b08146d6
>
> If you plan to create pull requests for your changes - please 
> consider my changes as well. When do you expect to finish, 
> I.e., create a pull request for phobos?

  Curious... Almost all of the changes you proposed I've already 
added in my version, the toHash is the only one missing and I 
don't know if I can work that very well. The new version is going 
to include 'slice-like' features, which is mostly a couple extra 
numbers specifying the offset in bits from the beginning to the 
end; The problem with that is hashing would have a huge speed 
drop.

  I'm adding an 'realign' function that handles those cases, but 
the downside is shared slices where you would want to make 
changes may or may not work. Caching the result would also be 
useful... Hmmm...

  I don't suppose you have a toHash where I can enter the odd bits 
and then also bulk ones and have the hash return the same could 
you? I can see xor easily having this type of effect...

  Anyways, here's some things I can do so far; Got a few 
improvements left to do, but not many. (const & immutable 
friendly of course :) )

--

const BitArray ba = BitArray([1,1,0,0,1]);
const BitArray slice = ba[1 .. ba.length];
BitArray m = slice.dup;
immutable BitArray im = slice.idup;

assert(slice == ba[1 .. ba.length]);
assert(slice == [1,0,0,1]);
assert(slice == m);
assert(slice == im);

assert(slice.isCompact);
writeln("GC not used");