Package org.apache.lucene.search

Class DocIdSet

java.lang.Object

org.apache.lucene.search.DocIdSet

All Implemented Interfaces:

Accountable

Direct Known Subclasses:

BitDocIdSet, DocsWithFieldSet, NotDocIdSet, RoaringDocIdSet

public abstract class DocIdSet
extends Object
implements Accountable

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

Field Summary

Fields

Modifier and Type	Field	Description
static final DocIdSet	EMPTY	An empty DocIdSet instance

Fields inherited from interface org.apache.lucene.util.Accountable

NULL_ACCOUNTABLE

Constructor Summary

Constructors

Constructor	Description
DocIdSet()

Method Summary

Modifier and Type	Method	Description
Bits	bits()	Optionally provides a Bits interface for random access to matching documents.
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

Methods inherited from interface org.apache.lucene.util.Accountable

getChildResources, ramBytesUsed

Field Details

EMPTY

public static final DocIdSet EMPTY

An empty DocIdSet instance

Constructor Details

DocIdSet

public DocIdSet()

Method Details

iterator

public abstract DocIdSetIterator iterator()
                                   throws IOException

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

Throws:

IOException

bits

public Bits bits()
          throws IOException

Optionally provides a Bits interface for random access to matching documents.

Returns:

null, if this DocIdSet does not support random access. In contrast to iterator(), a return value of null does not imply that no documents match the filter! The default implementation does not provide random access, so you only need to implement this method if your DocIdSet can guarantee random access to every docid in O(1) time without external disk access (as Bits interface cannot throw IOException). This is generally true for bit sets like FixedBitSet, which return itself if they are used as DocIdSet.

Throws:

IOException