More content for RcppAnnoy.h

[eddelbuettel]

Per discussion in #64 we may as well add both these, no?

Comments, @LTLA @jlmelville ? Useful? Useless? Other additions?

#ifdef ANNOYLIB_MULTITHREADED_BUILD
  typedef AnnoyIndexMultiThreadedBuildPolicy AnnoyIndexThreadedBuildPolicy;
#else
  typedef AnnoyIndexSingleThreadedBuildPolicy AnnoyIndexThreadedBuildPolicy;
#endif

typedef Annoy<int32_t, float,    Angular,   Kiss64Random, AnnoyIndexThreadedBuildPolicy> AnnoyAngular;
typedef Annoy<int32_t, float,    Euclidean, Kiss64Random, AnnoyIndexThreadedBuildPolicy> AnnoyEuclidean;
typedef Annoy<int32_t, float,    Manhattan, Kiss64Random, AnnoyIndexThreadedBuildPolicy> AnnoyManhattan;
typedef Annoy<int32_t, uint64_t, Hamming,   Kiss64Random, AnnoyIndexThreadedBuildPolicy> AnnoyHamming;

[eddelbuettel]

See #64 for more content regarding prefixing.

[eddelbuettel]

One possible variant (currently in my file)

// -- convenience typedefs
//    prefixed with Rcpp to ensure we are most unlikely to clash with upstream defines
//    usage of these is entire optional

#ifdef ANNOYLIB_MULTITHREADED_BUILD
  typedef AnnoyIndexMultiThreadedBuildPolicy RcppAnnoyIndexThreadPolicy;
#else
  typedef AnnoyIndexSingleThreadedBuildPolicy RcppAnnoyIndexThreadPolicy;
#endif

typedef Annoy<int32_t, float,    Angular,   Kiss64Random, RcppAnnoyIndexThreadPolicy> RcppAnnoyAngular;
typedef Annoy<int32_t, float,    Euclidean, Kiss64Random, RcppAnnoyIndexThreadPolicy> RcppAnnoyEuclidean;
typedef Annoy<int32_t, float,    Manhattan, Kiss64Random, RcppAnnoyIndexThreadPolicy> RcppAnnoyManhattan;
typedef Annoy<int32_t, uint64_t, Hamming,   Kiss64Random, RcppAnnoyIndexThreadPolicy> RcppAnnoyHamming;

Comments, @LTLA @jlmelville ? Useful? Useless? Other additions?

[LTLA]

Yes, that would help. I'm looking at https://github.com/LTLA/BiocNeighbors/blob/master/src/annoy.h and I can see that I could basically delete lines 5 to 26 and also lines 41-45. Not entirely sure why I needed to define NO_MANUAL_VECTORIZATION; I think it was some attempt at debugging a test failure from differences in compilation settings.

[eddelbuettel]

Turns out I was too ambitious (and had not tried to compile the above). The typedef Annoy<...> does not fly as Annoy is not yet known at that point. So I am reducing it to to just the single/multi threaded policy typedef.