Reshape method

[artv3]

Summary

This PR adds helper methods to views to create Reshape methods with compile time options C and Fortran style indexing

[artv3]

@MrBurmark , @rhornung67 I think the example for the reshape method can be simplified. I just pushed up a new version. I was a bit worried the previous version might have too much going on.

[artv3]

Just pushed up an iteration which ties Reshape to the permuted layout usage in view.

[rchen20]

I like this idea: it makes permutations and layouts much easier to use. However, I think it should be called something like ViewMaker, or something else. When I see Reshape, I think that this will take an existing View I've already defined, and will alter its dimensions. Instead, this PR is creating a wrapper that returns a new View, and can be used to construct Views from scratch. I realize that ReShape is used in a similar way in MFEM as well, so if everyone else is on board with this then that's fine with me too.

[rhornung67]

I like this idea: it makes permutations and layouts much easier to use. However, I think it should be called something like ViewMaker, or something else. When I see Reshape, I think that this will take an existing View I've already defined, and will alter its dimensions. Instead, this PR is creating a wrapper that returns a new View, and can be used to construct Views from scratch. I realize that ReShape is used in a similar way in MFEM as well, so if everyone else is on board with this then that's fine with me too.

That's actually a good point. What about make_permuted_view? We have several make_*_view helpers and this would be consistent with what we already have.

[artv3]

I like this idea: it makes permutations and layouts much easier to use. However, I think it should be called something like ViewMaker, or something else. When I see Reshape, I think that this will take an existing View I've already defined, and will alter its dimensions. Instead, this PR is creating a wrapper that returns a new View, and can be used to construct Views from scratch. I realize that ReShape is used in a similar way in MFEM as well, so if everyone else is on board with this then that's fine with me too.

That's actually a good point. What about make_permuted_view? We have several make_*_view helpers and this would be consistent with what we already have.

Maybe we can debate this at the RAJA Hackathon, this falls in line with documentation and our desire to perform general clean up.

[rhornung67]

Coming up with good, intuitive names is hard.

[MrBurmark]

I second make_permuted_view. That's more in line with our existing API. I assume reshape as a name comes from the function in eigen?

[rchen20]

Another idea would be to add this functionality as partial specializations of the existing make_view function, and get rid of the ReShape object entirely. What's implemented here is a way to create both permuted and non-permuted Views, so the functionality is generic enough to sit under the make_view umbrella.

[artv3]

Thank you all, through teamwork we have improved the API and implementation details. I believe we are ready for another review.

[artv3]

@MrBurmark, if you have a second can you provide a review here? I think we are good to go once you take a look.