[LUCENE-7627] Improve TermsEnum automaton filtering APIs

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 6.4
• Lucene Fields: New
• Assignee: Alan Woodward
• Reporter: Alan Woodward
• Created: 11/Jan/17 11:34
• Updated: 28/Aug/22 15:08
• Resolved: 14/Jan/17 10:54

Description

To filter a TermsEnum by a CompiledAutomaton, we currently have a number of different possibilities:

• Terms.intersect(CompiledAutomaton, BytesRef) - efficient, but only works on NORMAL type automata
• CompiledAutomaton.getTerms(Terms) - efficient, works on all automaton types, but requires a Terms instead of a TermsEnum, so no use for eg SortedDocValues.termsEnum()
• AutomatonTermsEnum - takes a TermsEnum, so it's more general than the Terms methods above, but agian only works on NORMAL automata

It's easy to do the wrong thing here, and at the moment we only guard against incorrect usage via runtime checks (see eg LUCENE-7576, https://github.com/flaxsearch/marple/issues/24). We should try and clean this up.