Expose the C hash functions

[wush978]

wush978/FeatureHashing#26

• register the C functions in init.c
• A prototype of helper header of PMurHash32

[eddelbuettel]

Looks like a very good start!

I am not sure I would declare everything in init.c when I only really export one header. Shall we limit it to just pmurmurhash,h for now (so that you get going) and then figure out the best way of doing things for a new digest 0.7.0, say?

And if I may: as you took inspiration from xts's header, would you mind adding me to the copyright header?

[wush978]

Oh, I originally want to deal with all C hash functions. Limiting to murmurhash sounds good since I am not going to test the others recently. And yes, I would add you to the copyright headers to src/init.c and the inst/include/pmurhash.h. Sorry that I am still new to copyright issues.

I'll submit the changes after Xmas Day.

Happy Xmas Day

[eddelbuettel]

I think we are on the same page. I also want to make all the C level functions available (at the source level) to other R packages. But the currently chosen method is probably the most laborious (yet trusted) so I'd say let do this one now for just pmurmurhash. I can also quickly edit this at my end.

[wush978]

This might be what we need so far. I test the exposed pmurhash.h with FeatureHashing and it passes my unit tests on OS X, Windows and Ubuntu.

[eddelbuettel]

That looks pretty good -- thanks for the update! I will give this one more look-over, try to address one open issue with pmurmurhash (see #9) and then ship this to CRAN so that you can depend on it.

A bit more medium term, we will work out the best way to expose functions (which may just be what you had in init.c, or one of the other previously discussed methods) and maybe create an example package using it.

[eddelbuettel]

Made a minor edit in init.c, added something in ChangeLog for your changes and bumped Date: and Version: