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

[Emma Strubell]

Wow, that's extremely helpful!! I happen to particularly enjoy tries, so the
suffix trie sounds like a great idea. The trie class example is really
helpful too, because this will be my first time programming in Python, and
it's a bit easier to figure out what's going on syntax-wise in that simple
trie class than in the middle of the portage source code!

Seriously, thanks again :]

On Sun, Nov 23, 2008 at 11:56 AM, Lucian Poston <lucianposton@×××××.com>wrote:

> > 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<http://search.cpan.org/%7Edavecross/Tie-Hash-Regex-1.02/lib/Tie/Hash/Regex.pm>
>
>