Re: [gentoo-portage-dev] search functionality in emerge

[Lucian Poston]

> Thanks for the replies! I know there are a couple programs out there that
> basically already do what I'm looking to do... Unfortunately I wasn't aware
> of these pre-existing utilities until after I submitted my project proposal
> to my professor. So, I'm looking to implement a better search myself.
> Preferably by editing the existing portage code, not writing a separate
> program. So if anyone can offer any help regarding the actual implementation
> of search in portage, I would greatly appreciate it!

Most of the search implementation is in
/usr/lib/portage/pym/_emerge/__init__.py in class search.  The class's
execute() method simply iterates over all packages (and descriptions
and package sets) and matches against the searchkey.  You might need
to look into pym/portage/dbapi/porttree.py for portdbapi as well.

If you intend to index and support fast regex lookup, then you need to
do some fancy indexing, which I'm not terribly familiar with.  You
could follow in the steps of eix[1] or other indexed search utilities
and design some sort of index layout, which is easier than the
following thought.  You might consider implementing a suffix trie or
similar that has sublinear regexp lookup and marshalling the structure
for the index.  I couldn't find a python implementation for something
like this, but here is a general trie class[2] that you might start
with if you go that route.  There is a perl module[3],
Tie::Hash::Regex, that does that, but properly implementing that in
python would be a chore. :)

That project sounds interesting and fun. Good luck!

Lucian Poston

[1] https://projects.gentooexperimental.org/eix/wiki/IndexFileLayout
[2] http://www.koders.com/python/fid7B6BC1651A9E8BBA547552FE3F039479A4DECC45.aspx
[3] http://search.cpan.org/~davecross/Tie-Hash-Regex-1.02/lib/Tie/Hash/Regex.pm