The rfind challenge

[FG]

On 2013-01-15 06:51, Andrei Alexandrescu wrote:
> If r is a forward range but not better, this is rather simple:
>
> R rfind(R, E)(R range, E element)
> {
>      for (;;)
>      {
>          auto ahead = range.save.find(element);
>          if (ahead.empty) return range;
>          range = ahead;
>      }
> }

That example creates an infinite loop. Needs a popFront:

     R rfind(R, E)(R range, E element)
     {
         if (range.empty) return range;
         for (;;)
         {
             auto ahead = range.save;
             ahead.popFront();
             ahead = ahead.find(element);
             if (ahead.empty) return range;
             range = ahead;
         }
     }

Another thing: if the element is not found, I think an empty range should be 
returned and not the whole range.