Hi all, There's been some off-list discussion between Dan Marsden, Joel de Guzman and myself on how to address infinite sequences in fusion. Joel suggested to bring the discussion back to the list for more feedback: On Wed, Apr 15, 2009 at 6:21 PM, Joel de Guzman <djowel@gmail.com> wrote:
Stjepan Rajko wrote:
Here is a list and description of all of the concepts that might be relevant:
Forward Sequence begin(s) - returns a Forward Iterator empty(s) - returns a bool front(s) - any type
Finite Forward Sequence refines Forward Sequence end(s) - returns a Forward Iterator size(s) - MPL integral constant
Infinite Forward Sequence refines Forward Sequence empty(s) - returns false size(s) - infinity
Bidirectional Sequence refines Forward Sequence begin(s) - returns a Bidirectional Iterator
Finite Bidirectional Sequence refines Bidirectional Sequence, Finite Forward Sequence end(s) - returns a Bidirectional Iterator back(s) - any type
Infinite Bidirectional Sequence refines Bidirectional Sequence, Infinite Forward Sequence
Random Access Sequence refines Bidirectional Sequence begin(s) - returns a Random Access Iterator
Finite Random Access Sequence refines Random Access Sequence, Finite Bidirectional Sequence end(s) - returns a Random Access Iterator
Infinite Random Access Sequence refines Random Access Sequence, Infinite Bidirectional Sequence
How does that look?
I'd suggest posting that to the Boost list to get more feedback. I have a feeling that infinity is a separate concept orthogonal to traversal. But I'm not sure.
The above layout is almost orthogonal, with Infinite Forward Sequence and Finite Forward Sequence serving as "base" concepts related to Finite / Infinite. I suppose you could have less refined Infinite Sequence and Finite Sequence concepts, but I'm not sure how useful they would be (AFAICT, they could only describe `size` and `empty`). Things aren't perfectly orthogonal because Finite + Bidirectional require `back`, but Finite + Forward do not, and neither do Infinite + Bidirectional. Best, Stjepan
Regards, -- Joel de Guzman http://www.boostpro.com http://spirit.sf.net