org.apache.lucene.search
Class DocIdSet

java.lang.Object
  org.apache.lucene.search.DocIdSet

Direct Known Subclasses:

DocIdBitSet, FieldCacheDocIdSet, FilteredDocIdSet, FixedBitSet, OpenBitSet, SortedVIntList

public abstract class DocIdSet
extends Object

A DocIdSet contains a set of doc ids. Implementing classes must only implement iterator() to provide access to the set.

Field Summary

static DocIdSet

EMPTY_DOCIDSET An empty DocIdSet instance for easy use, e.g.

Constructor Summary

DocIdSet()

Method Summary

boolean	isCacheable() This method is a hint for CachingWrapperFilter, if this DocIdSet should be cached without copying it into a BitSet.
abstract DocIdSetIterator	iterator() Provides a DocIdSetIterator to access the set.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EMPTY_DOCIDSET

public static final DocIdSet EMPTY_DOCIDSET

An empty DocIdSet instance for easy use, e.g. in Filters that hit no documents.

Constructor Detail

DocIdSet

public DocIdSet()

Method Detail

iterator

public abstract DocIdSetIterator iterator()
                                   throws IOException

Provides a DocIdSetIterator to access the set. This implementation can return null or EMPTY_DOCIDSET.iterator() if there are no docs that match.

Throws:

IOException

isCacheable

public boolean isCacheable()

This method is a hint for CachingWrapperFilter, if this DocIdSet should be cached without copying it into a BitSet. The default is to return false. If you have an own DocIdSet implementation that does its iteration very effective and fast without doing disk I/O, override this method and return true.