[LUCENE-6445] Highlighter TokenSources simplification; just one getAnyTokenStream()

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.2
• Component/s: modules/highlighter
• Lucene Fields: New
• Assignee: David Smiley
• Reporter: David Smiley
• Created: 20/Apr/15 18:38
• Updated: 28/Aug/22 14:31
• Resolved: 28/Apr/15 16:14

Description

The Highlighter "TokenSources" class has quite a few utility methods pertaining to getting a TokenStream from either term vectors or analyzed text. I think it's too much:

• some go to term vectors, some don't. But if you don't want to go to term vectors, then it's quite easy for the caller to invoke the Analyzer for the field value, and to get that field value.
• Some methods return null, some never null; I forget which at a glance.
• Some methods read the Document (to get a field value) from the IndexReader, some don't. Furthermore, it's not an ideal place to get the doc since your app might be using an IndexSearcher with a document cache (e.g. SolrIndexSearcher).
• None of the methods accept a Fields instance from term vectors as a parameter. Based on how Lucene's term vector format works, this is a performance trap if you don't re-use an instance across fields on the document that you're highlighting.

Issue Links

• is related to: LUCENE-6423 New LimitTokenOffsetFilter
• is related to: SOLR-5855 re-use document term-vector Fields instance across fields in the DefaultSolrHighlighter
• relates to: LUCENE-6392 Add offset limit to Highlighter's TokenStreamFromTermVector