Package org.apache.lucene.search

Class Filter

java.lang.Object

org.apache.lucene.search.Filter

Direct Known Subclasses:

CachingWrapperFilter, DocTermOrdsRangeFilter, FieldCacheRangeFilter, FieldCacheTermsFilter, FieldValueFilter, MultiTermQueryWrapperFilter, QueryWrapperFilter

public abstract class Filter
extends Object

Abstract base class for restricting which documents may be returned during searching.

Constructor Summary

Constructors

Constructor	Description
Filter()

Method Summary

Modifier and Type	Method	Description
abstract DocIdSet	getDocIdSet(AtomicReaderContext context, Bits acceptDocs)	Creates a DocIdSet enumerating the documents that should be permitted in search results.

Methods inherited from class java.lang.Object

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

Constructor Detail

Filter

public Filter()

Method Detail

getDocIdSet

public abstract DocIdSet getDocIdSet(AtomicReaderContext context,
                                     Bits acceptDocs)
                              throws IOException

Creates a DocIdSet enumerating the documents that should be permitted in search results. NOTE: null can be returned if no documents are accepted by this Filter.

Note: This method will be called once per segment in the index during searching. The returned DocIdSet must refer to document IDs for that segment, not for the top-level reader.

Parameters:

context - a AtomicReaderContext instance opened on the index currently searched on. Note, it is likely that the provided reader info does not represent the whole underlying index i.e. if the index has more than one segment the given reader only represents a single segment. The provided context is always an atomic context, so you can call AtomicReader.fields() on the context's reader, for example.

acceptDocs - Bits that represent the allowable docs to match (typically deleted docs but possibly filtering other documents)

Returns:

a DocIdSet that provides the documents which should be permitted or prohibited in search results. NOTE: null should be returned if the filter doesn't accept any documents otherwise internal optimization might not apply in the case an empty DocIdSet is returned.

Throws:

IOException