Interface LeafCollector
- All Known Implementing Classes:
FilterLeafCollector
,SimpleCollector
,TopScoreDocCollector.ScorerLeafCollector
,TotalHitCountCollector
setScorer(org.apache.lucene.search.Scorable)
method, to hold onto the passed Scorer
instance, and call Scorable.score()
within
the collect method to compute the current hit's score. If your collector may request the score
for a single hit multiple times, you should use ScoreCachingWrappingScorer
.
NOTE: The doc that is passed to the collect method is relative to the current reader. If your collector needs to resolve this to the docID space of the Multi*Reader, you must re-base it by recording the docBase from the most recent setNextReader call. Here's a simple example showing how to collect docIDs into a BitSet:
IndexSearcher searcher = new IndexSearcher(indexReader); final BitSet bits = new BitSet(indexReader.maxDoc()); searcher.search(query, new Collector() { public LeafCollector getLeafCollector(LeafReaderContext context) throws IOException { final int docBase = context.docBase; return new LeafCollector() { // ignore scorer public void setScorer(Scorer scorer) throws IOException { } public void collect(int doc) throws IOException { bits.set(docBase + doc); } }; } });
Not all collectors will need to rebase the docID. For example, a collector that simply counts the total number of hits would skip it.
- WARNING: This API is experimental and might change in incompatible ways in the next release.
-
Method Summary
Modifier and TypeMethodDescriptionvoid
collect
(int doc) Called once for every document matching a query, with the unbased document number.default DocIdSetIterator
Optionally returns an iterator over competitive documents.void
Called before successive calls tocollect(int)
.
-
Method Details
-
setScorer
Called before successive calls tocollect(int)
. Implementations that need the score of the current document (passed-in tocollect(int)
), should save the passed-in Scorer and call scorer.score() when needed.- Throws:
IOException
-
collect
Called once for every document matching a query, with the unbased document number.Note: The collection of the current segment can be terminated by throwing a
CollectionTerminatedException
. In this case, the last docs of the currentLeafReaderContext
will be skipped andIndexSearcher
will swallow the exception and continue collection with the next leaf.Note: This is called in an inner search loop. For good search performance, implementations of this method should not call
IndexSearcher.doc(int)
orIndexReader.document(int)
on every hit. Doing so can slow searches by an order of magnitude or more.- Throws:
IOException
-
competitiveIterator
Optionally returns an iterator over competitive documents.Collectors should delegate this method to their comparators if their comparators provide the skipping functionality over non-competitive docs.
The default is to return
null
which is interpreted as the collector provide any competitive iterator.- Throws:
IOException
-