Re: [RFC] Adding a real HashTable implementation to gnulib

[Ben Pfaff]

Much as I like the PSPP hmaps, it probably makes sense for any hash
table implementation in gnulib to match the existing code.

On Tue, Nov 27, 2018 at 02:02:17AM +0100, Darshit Shah wrote:
> Here are the links to the sources in the GNU Wget tree:
> 
> http://git.savannah.gnu.org/cgit/wget.git/tree/src/hash.h
> http://git.savannah.gnu.org/cgit/wget.git/tree/src/hash.c
> 
> At first sight, the implementation in PSPP looks a lot more concise.
> Also, it's usage of fewer preprocessor statements makes me already like it.
> 
> However, it does seem that this implementation is not as general or, complete
> as the existing hash table implementation in gnulib. The version available in
> GNU Wget does implement all the same interfaces with very similar usage
> characteristics.
> 
> One of the things I noticed missing in the implementation in GNU PSPP is the
> ability to grow the size of the table based on a certain threshold of
> "fullness".
> 
> * Ben Pfaff <address@hidden> [181127 00:41]:
> > On Tue, Nov 27, 2018 at 12:16:16AM +0100, Darshit Shah wrote:
> > > I recently tried to use the hash table implementation in gnulib which 
> > > resides
> > > in the "hash" module. However, I quickly realised that the hash table in 
> > > gnulib
> > > seems to be what is otherwise popularly known as a hash set, i.e., it 
> > > supports
> > > storing and retrieving just values from the structure. 
> > > 
> > > On the other hand, a hash table is usually expected to have a key->value
> > > mapping that is stored.
> > > 
> > > Within GNU Wget, we have a fairly portable version of a hash table 
> > > implemented
> > > which I think would be a good addition for gnulib. What do you think?
> > > 
> > > If I get a positive response here, I could extract that code and turn it 
> > > into a
> > > hash table module for gnulib. We should be able to reuse some part of the
> > > existing code in "hash.c" for this purpose as well
> > 
> > Can you point to the Wget hash table?
> > 
> > I'm pretty fond of the hash table implementation we have in PSPP:
> > http://git.savannah.gnu.org/cgit/pspp.git/tree/src/libpspp/hmap.h
> > http://git.savannah.gnu.org/cgit/pspp.git/tree/src/libpspp/hmap.c
> > 
> > 
> 
> -- 
> Thanking You,
> Darshit Shah
> PGP Fingerprint: 7845 120B 07CB D8D6 ECE5 FF2B 2A17 43ED A91A 35B6