RFC on range design for D2

[Sergey Gromov]

Andrei Alexandrescu <SeeWebsiteForEmail at erdani.org> wrote:
> Sergey Gromov wrote:
> > - the union operations look... weird.  Unobvious.  I'm too sleepy now to 
> > propose anything better but I'll definitely give it a try.  The rest of 
> > the interface seems very natural.
> 
> I agree I hadn't known what primitives would be needed when I sat down. 
> Clearly there was a need for some since individual iterators are not 
> available anymore. New ideas would be great; I suggest you validate them 
> by implementing some nontrivial algorithms in std.algorithm with your, 
> um, computational basis of choice :o).

r.before(s)
r.after(s)
r.begin
r.end

Here r.before(s) is everything from the r's first element (inclusive) to 
the first s's element (exclusive); r.after(s) is from last s's element 
(exclusive) to the last element of r (inclusive); r.begin is an empty 
range at the beginning of a parent range; and r.end is an empty range at 
the end of a parent range.  Therefore, according to your diagram: 

r.toBegin(s) => r.before(s)
s.toEnd(r) => s.before(r.end)
s.fromEnd(r) => s.after(r)