plugin dev - search.search_tracks_from_string queries

On exaile's wiki I found that I can search through collection using this:
tracks = [x.track for x in search.search_tracks_from_string(exaile.collection, ('artist=="%s"'%artist))]

I was wondering, if it is possible to use a little more complicated query e.g.
' artist=="%(artist)s" and album=="%(album)s" ' % locals()
or something like this
' artist=="%(artist)s" and ( "%(album)s"=="" or album=="%(album)s" )' % locals()
I wanted my plugin to add an album of a certain artist to playlist and sometimes, there is more than one album with the same name, but not the same artist.