make spiner piecewise grids backwards compatible

[Yurlungur]

PR Summary

In the piecewise grids MR in singularity-eos, @chadmeyer raised a concern that piecewise grids are not backwards compatible with old tables. This MR fixes that issue.

PR Checklist

• Code is formatted. (You can use the format_spiner make target.)
• Adds a test for any bugs fixed. Adds tests for new features.
• If preparing for a new release, update the version in cmake.

[dholladay00]

I have to admit I am not really familiar with the hdf5 bits of this code or the hdf5 interface. That said, I think this should go through the testing on lanl git before being merged.

[Yurlungur]

I have to admit I am not really familiar with the hdf5 bits of this code or the hdf5 interface. That said, I think this should go through the testing on lanl git before being merged.

I don't think it's possible that this will have an impact. But pipeline triggered.

[Yurlungur]

The HDF5 machinery only works on host. And all this is doing is it's checking to see if a file contains only a RegularGrid1D or if it contains a PiecewiseGrid1D if the latter, it loads the whole piecewise grid. If the former, it loads a piecewise grid containing only one segment, the regular grid in the file.

[dholladay00]

I see, it wasn't clear to me that the GitHub testing ran the test you added. Either way, probably still a good idea to run the lanl git testing.

[dholladay00]

@Yurlungur refresh my memory. The template parameter describes the max number of grids but the actual number can be <= to that and is settable at runtime, is that right? Is that what is being done here?

[jhp-lanl]

I admit I'm not familiar with this code, but it seems like an appropriate fix in isolation.

[Yurlungur]

@Yurlungur refresh my memory. The template parameter describes the max number of grids but the actual number can be <= to that and is settable at runtime, is that right? Is that what is being done here?

Yes exactly. :)

[Yurlungur]

Tests passing on re-git. @dholladay00 do you approve?