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.

Declaration

public abstract DocIdSet GetDocIdSet(AtomicReaderContext context, IBits acceptDocs)

Parameters

Type	Name	Description
AtomicReaderContext	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 Fields on the context's reader, for example.
IBits	acceptDocs	IBits that represent the allowable docs to match (typically deleted docs but possibly filtering other documents)

Returns

Type	Description
DocIdSet	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 emptyDocIdSet is returned.

NewAnonymous(Func<AtomicReaderContext, IBits, DocIdSet>)

Creates a new instance with the ability to specify the body of the GetDocIdSet(AtomicReaderContext, IBits) method through the getDocIdSet parameter. Simple example:

var filter = Filter.NewAnonymous(getDocIdSet: (context, acceptDocs) =>
{
    if (acceptDocs is null) acceptDocs = new Bits.MatchAllBits(5);
    OpenBitSet bitset = new OpenBitSet(5);
    if (acceptDocs.Get(1)) bitset.Set(1);
    if (acceptDocs.Get(3)) bitset.Set(3);
    return new DocIdBitSet(bitset);
});

LUCENENET specific

Declaration

public static Filter NewAnonymous(Func<AtomicReaderContext, IBits, DocIdSet> getDocIdSet)

Parameters

Type	Name	Description
Func<AtomicReaderContext, IBits, DocIdSet>	getDocIdSet	A delegate method that represents (is called by) the GetDocIdSet(AtomicReaderContext, IBits) method. It accepts a AtomicReaderContext context and a IBits acceptDocs and returns the DocIdSet for this filter.

Returns

Type	Description
Filter