Runtime rank wrapper for View

[hcedwar]

Provide a thin wrapper over a rank eight View that supports a runtime rank between zero and eight. The member access operator overloads simply fill in the missing arguments to the underlying View operator with the literal value 0. It is assumed that compilers' optimization will eliminate the integer index operations with hard-coded zero values.

[nmhamster]

Should we test out the compiler inling/optimization etc?

[hcedwar]

Would be good, but not necessary as this Kokkos feature will replace an already non-performing application specific feature.

[crtrott]

I just merged the pull request. I think there are a couple more corner cases to be worked on in addition to subviews, but the basic capability seems to be there and the implementation looks fundamentally sound.

[crtrott]

First issue I currently see as outstanding: creating degenerated Views. E.g. a 2D view with second dimension==0 would come out as a 1D view right now. We should fix that by having explicit constructors with different number of arguments.
Second outstanding issue: subviews must be correctly implemented.

[hcedwar]

other option based upon related discussion at ISO/C++ meeting is to change the dimension argument types to ptrdiff_t = -1, then deduce rank by the first non-negative input.

[ndellingwood]

The dynamic rank view with subview functionality is now available in the kokkos develop branch.

The DynRankView code is located in kokkos/containers/src/Kokkos_DynRankView.hpp
Sample usage available in the unit tests kokkos/containers/src/TestDynViewAPI.hpp

A couple comments, including changes from Kokkos::View:

1. Max rank of a DynRankView is 7
2. The rank of the DynRankView is returned by the function rank()
3. subdynrankview is the name for the function to create 'subviews' of dynamic rank views.
4. Every subdynrankview is returned with LayoutStride

[hcedwar]

Fine tune subdynrankview for Trilinos/Intrepid to allow and ignore excess ALL subview arguments.

[ndellingwood]

Modifications to DynRankView and subdynrankview:

1. Enhancement for subdynrankview

Relaxed assumption that number of arguments to a subdynrankview must equal
the rank of the source DynRankView - a subdynrankview can now accept
greater number of arguments than the source dynrankview rank, the
additional are ignored.

1. LayoutStride fix for DynRankView

Added createLayout code for LayoutStride input case for construction of DynRankView

1. Additional unit tests added to check LayoutStride DynRankView input to
   subdynrankview, that subdynrankview ranks contract as expected, and that
   subdynrankview acts properly when given more arguments than source rank.

[crtrott]

Merged into master again. Can this be closed now?