[gentoo-portage-dev] [Patch] Restriction framework, new search code, metascan2

[Marius Mauch]

This is another attempt to prepare the way for including metascan, this
time based on a new restriction framework (which has absolutely nothing
to do with the one in savior/bcportage) included in the attached and
completely undocumented patch (once you get the concept it should be
self-explanatory however).
It basically consists of three class hierarchies:
- dataclasses responsibe for delivering the data to match against
- filterclasses implementing the match algorithms
- boolean connectors to combine multiple restrictions
There is a fourth type called prefilter that can adjust the match
algorithm of filter classes (e.g. a Split() class to break multi-value
metadata fields up for the string matchers).

The filterclasses and connectors implement the same interface for
performing the matches, so the most basic application would be:

for cpv in cpvlist:
	if restriction.filter.PartialMatch(data.Metadata(key, db), value).match(cpv):
		matches.append(cpv)

For a more complex application see the patched emerge or metascan2
(at d.g.o/~genone/scripts).

A word of warning: I've just written all this code in the past few hours, 
it is absolutely unoptimized, incomplete and certainly has bugs (none known 
though).
That also means I'm not interested in comments about the code or algorithm 
yet, as this needs a lot of work and so far I've only done the work to get 
it working, mainly sending this mail so people can play with it a bit.

Marius

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