nixpkgs / clucene_core_2 - CLucene is a high-performance, scalable, cross platform, full-featured, open-source indexing and searching API. Specifically, CLucene is the guts of a search engine, the hard stuff. You write the easy stuff: the UI and the process of selecting and parsing your data files to pump them into the search engine yourself, and any specialized queries to pull it back for display or further processing. CLucene is a port of the very popular Java Lucene text search engine API.
Homepage - http://clucene.sourceforge.net