Segmented Ranges?

[Christophe Travert]

"bearophile" , dans le message (digitalmars.D:169611), a écrit :
> struct BilevelScan(Range) {

This is basically std.algorithm.joiner

> So an idea is to introduce in D the multi-level Ranges:
> SegmentedInputRange
> SegmentedOutputRange
> SegmentedForwardRange
> SegmentedBidirectionalRange
> SegmentedRandomAccessRange
> 
> I think a Segmented Input Range is more complex than an Input 
> Range. Inventing such ranges is like finding the miminal set of 
> axioms that allow to write down a theorem, that is to efficiently 
> implement the normal algorithms. This is not an easy for me, I 
> don't know much about this topic.

I would only use this axiom:
- a SegmentedRange defines a bySegment property, returning a Range of 
Range bearing the same element type as SegmentedRange.

and define BySegment!Range as the type returned by range.bySegment, and 
SegmentType!Range as the type returned by range.bySegment.front.

Then it is up to the implementer of the algorithm to test the type of 
a SegmentedRange (InputRange, OutputRange, etc.), the type of 
BySegment!Range, and the type of SegmentType!Range when needed. There 
are too many combinaisons to make specific range types for all of them.
Moreover SegmentedRandomAccessRange would be ambiguous: is it a 
RandomAccessRange, a Range whose BySegment method returns a 
RandomAccessRange, a Range whose SegmentType is a RandomAccessRange, 
or all of them ?

-- 
Christophe