BitArray Slicing

[Ezneh via Digitalmars-d-learn]

On Wednesday, 21 December 2016 at 11:49:06 UTC, Ilya Yaroshenko 
wrote:
> On Wednesday, 21 December 2016 at 09:08:51 UTC, Ezneh wrote:
>> Hi, in one of my projects I have to get a slice from a 
>> BitArray.
>>
>> I am trying to achieve that like this :
>>
>> void foo(BitArray ba)
>> {
>>    auto slice = ba[0..3]; // Assuming it has more than 4 
>> elements
>> }
>>
>> The problem is that I get an error :
>>
>> "no operator [] overload for type BitArray".
>>
>> Is there any other way to get a slice from a BitArray ?
>>
>> Thanks,
>> Ezneh.
>
> Mir allows you to define simple alternative to BitArray:
>
> https://github.com/libmir/mir
>
> ------
> struct BitMap
> {
>     size_t* ptr;
>
>     import core.bitop;
>
>     bool opIndex(size_t index) const
>     {
>         return bt(ptr, index) != 0;
>     }
>
>     void opIndexAssign(bool val, size_t index)
>     {
>         if(val)
>             bts(ptr, index);
>         else
>             btr(ptr, index);
>     }
> }
>
> import mir.ndslice;
>
> void main()
> {
>     auto arr = new size_t[3];
>     auto sl = BitMap(arr.ptr).sliced(size_t.sizeof * 8 * 
> arr.length);
>
>     sl[4] = true;
>     sl[100] = true;
>     sl.popFrontN(3);
>     assert(sl[1]);
>     assert(sl[97]);
>
>     auto sl2 = sl[1...3]; // slicing
> }
> ------

Thanks, I'll check that solution to see if it fits my needs.

As an off-topic question, is there any plan in Mir to implement 
the Tiny Mersenne Twister[1] algorithm (or a wrapper for it) ?

[1] 
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/TINYMT/index.html