org.apache.lucene.search
Class FieldCacheDocIdSet

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

public abstract class FieldCacheDocIdSet
extends DocIdSet

Base class for DocIdSet to be used with FieldCache. The implementation of its iterator is very stupid and slow if the implementation of the matchDoc(int) method is not optimized, as iterators simply increment the document id until matchDoc(int) returns true. Because of this matchDoc(int) must be as fast as possible and in no case do any I/O.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Field Summary

protected Bits	acceptDocs
protected int	maxDoc

Constructor Summary

FieldCacheDocIdSet(int maxDoc, Bits acceptDocs)

Method Summary

Bits	bits() Optionally provides a Bits interface for random access to matching documents.
boolean	isCacheable() this DocIdSet is always cacheable (does not go back to the reader for iteration)
DocIdSetIterator	iterator() Provides a DocIdSetIterator to access the set.
protected abstract boolean	matchDoc(int doc) this method checks, if a doc is a hit

Methods inherited from class java.lang.Object

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

Field Detail

maxDoc

protected final int maxDoc

acceptDocs

protected final Bits acceptDocs

Constructor Detail

FieldCacheDocIdSet

public FieldCacheDocIdSet(int maxDoc,
                          Bits acceptDocs)

Method Detail

matchDoc

protected abstract boolean matchDoc(int doc)

this method checks, if a doc is a hit

isCacheable

public final boolean isCacheable()

this DocIdSet is always cacheable (does not go back to the reader for iteration)

Overrides:

isCacheable in class DocIdSet

bits

public final Bits bits()

Description copied from class: DocIdSet

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

Overrides:

bits in class DocIdSet

Returns:

null, if this DocIdSet does not support random access. In contrast to DocIdSet.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.

iterator

public final DocIdSetIterator iterator()
                                throws IOException

Description copied from class: DocIdSet

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

Specified by:

iterator in class DocIdSet

Throws:

IOException