rank of range

[Ali Çehreli via Digitalmars-d-learn]

On 07/01/2017 10:05 AM, drug wrote:
> Hello!
> Is there a convenient way to get rank of range a.k.a. count of
> dimensions in compile time? Like:
>
> static assert( rankOf!(uint[]) == 1);
> static assert( rankOf!(uint[][][]) == 3);

I'm not aware of one but this seems to work:

template rankOf(R) {
     import std.range : isInputRange, ElementType;

     static if (isInputRange!R) {
         enum rankOf = rankOf!(ElementType!R) + 1;
     } else {
         enum rankOf = 0;
     }
}

unittest {
     static assert (rankOf!long == 0);
     static assert (rankOf!(int[]) == 1);
     static assert (rankOf!(int[][][]) == 3);
}

void main() {
}

Ali