org.apache.lucene.index

Class MultiPostingsEnum

java.lang.Object

org.apache.lucene.search.DocIdSetIterator

org.apache.lucene.index.PostingsEnum

org.apache.lucene.index.MultiPostingsEnum

public final class MultiPostingsEnum
extends PostingsEnum

Exposes PostingsEnum, merged from PostingsEnum API of sub-segments.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MultiPostingsEnum.EnumWithSlice Holds a PostingsEnum along with the corresponding ReaderSlice.

Field Summary

Fields inherited from class org.apache.lucene.index.PostingsEnum

ALL, FREQS, NONE, OFFSETS, PAYLOADS, POSITIONS

Fields inherited from class org.apache.lucene.search.DocIdSetIterator

NO_MORE_DOCS

Constructor Summary

Constructors

Constructor and Description
MultiPostingsEnum(MultiTermsEnum parent, int subReaderCount) Sole constructor.

Method Summary

Modifier and Type	Method and Description
int	advance(int target) Advances to the first beyond the current whose document number is greater than or equal to target, and returns the document number itself.
boolean	canReuse(MultiTermsEnum parent) Returns true if this instance can be reused by the provided MultiTermsEnum.
long	cost() Returns the estimated cost of this DocIdSetIterator.
int	docID() Returns the following: -1 if DocIdSetIterator.nextDoc() or DocIdSetIterator.advance(int) were not called yet.
int	endOffset() Returns end offset for the current position, or -1 if offsets were not indexed.
int	freq() Returns term frequency in the current document, or 1 if the field was indexed with IndexOptions.DOCS.
int	getNumSubs() How many sub-readers we are merging.
BytesRef	getPayload() Returns the payload at this position, or null if no payload was indexed.
MultiPostingsEnum.EnumWithSlice[]	getSubs() Returns sub-readers we are merging.
int	nextDoc() Advances to the next document in the set and returns the doc it is currently on, or DocIdSetIterator.NO_MORE_DOCS if there are no more docs in the set. NOTE: after the iterator has exhausted you should not call this method, as it may result in unpredicted behavior.
int	nextPosition() Returns the next position, or -1 if positions were not indexed.
MultiPostingsEnum	reset(MultiPostingsEnum.EnumWithSlice[] subs, int numSubs) Re-use and reset this instance on the provided slices.
int	startOffset() Returns start offset for the current position, or -1 if offsets were not indexed.
String	toString()

Methods inherited from class org.apache.lucene.index.PostingsEnum

featureRequested

Methods inherited from class org.apache.lucene.search.DocIdSetIterator

all, empty, range, slowAdvance

Methods inherited from class java.lang.Object

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

Constructor Detail

MultiPostingsEnum

public MultiPostingsEnum(MultiTermsEnum parent,
                         int subReaderCount)

Sole constructor.

Parameters:

parent - The MultiTermsEnum that created us.

subReaderCount - How many sub-readers are being merged.

Method Detail

canReuse

public boolean canReuse(MultiTermsEnum parent)

Returns true if this instance can be reused by the provided MultiTermsEnum.

reset

public MultiPostingsEnum reset(MultiPostingsEnum.EnumWithSlice[] subs,
                               int numSubs)

Re-use and reset this instance on the provided slices.

getNumSubs

public int getNumSubs()

How many sub-readers we are merging.

See Also:

getSubs()

getSubs

public MultiPostingsEnum.EnumWithSlice[] getSubs()

Returns sub-readers we are merging.

freq

public int freq()
         throws IOException

Description copied from class: PostingsEnum

Returns term frequency in the current document, or 1 if the field was indexed with IndexOptions.DOCS. Do not call this before DocIdSetIterator.nextDoc() is first called, nor after DocIdSetIterator.nextDoc() returns DocIdSetIterator.NO_MORE_DOCS.

NOTE: if the PostingsEnum was obtain with PostingsEnum.NONE, the result of this method is undefined.

Specified by:

freq in class PostingsEnum

Throws:

IOException

docID

public int docID()

Description copied from class: DocIdSetIterator

Returns the following:

• -1 if DocIdSetIterator.nextDoc() or DocIdSetIterator.advance(int) were not called yet.
• DocIdSetIterator.NO_MORE_DOCS if the iterator has exhausted.
• Otherwise it should return the doc ID it is currently on.

Specified by:

docID in class DocIdSetIterator

advance

public int advance(int target)
            throws IOException

Description copied from class: DocIdSetIterator

Advances to the first beyond the current whose document number is greater than or equal to target, and returns the document number itself. Exhausts the iterator and returns DocIdSetIterator.NO_MORE_DOCS if target is greater than the highest document number in the set.

The behavior of this method is undefined when called with target ≤ current, or after the iterator has exhausted. Both cases may result in unpredicted behavior.

When target > current it behaves as if written:

 int advance(int target) {
   int doc;
   while ((doc = nextDoc()) < target) {
   }
   return doc;
 }
 

Some implementations are considerably more efficient than that.

NOTE: this method may be called with DocIdSetIterator.NO_MORE_DOCS for efficiency by some Scorers. If your implementation cannot efficiently determine that it should exhaust, it is recommended that you check for that value in each call to this method.

Specified by:

advance in class DocIdSetIterator

Throws:

IOException

nextDoc

public int nextDoc()
            throws IOException

Description copied from class: DocIdSetIterator

Advances to the next document in the set and returns the doc it is currently on, or DocIdSetIterator.NO_MORE_DOCS if there are no more docs in the set.
NOTE: after the iterator has exhausted you should not call this method, as it may result in unpredicted behavior.

Specified by:

nextDoc in class DocIdSetIterator

Throws:

IOException

nextPosition

public int nextPosition()
                 throws IOException

Description copied from class: PostingsEnum

Returns the next position, or -1 if positions were not indexed. Calling this more than PostingsEnum.freq() times is undefined.

Specified by:

nextPosition in class PostingsEnum

Throws:

IOException

startOffset

public int startOffset()
                throws IOException

Description copied from class: PostingsEnum

Returns start offset for the current position, or -1 if offsets were not indexed.

Specified by:

startOffset in class PostingsEnum

Throws:

IOException

endOffset

public int endOffset()
              throws IOException

Description copied from class: PostingsEnum

Returns end offset for the current position, or -1 if offsets were not indexed.

Specified by:

endOffset in class PostingsEnum

Throws:

IOException

getPayload

public BytesRef getPayload()
                    throws IOException

Description copied from class: PostingsEnum

Returns the payload at this position, or null if no payload was indexed. You should not modify anything (neither members of the returned BytesRef nor bytes in the byte[]).

Specified by:

getPayload in class PostingsEnum

Throws:

IOException

cost

public long cost()

Description copied from class: DocIdSetIterator

Returns the estimated cost of this DocIdSetIterator.

This is generally an upper bound of the number of documents this iterator might match, but may be a rough heuristic, hardcoded value, or otherwise completely inaccurate.

Specified by:

cost in class DocIdSetIterator

toString

public String toString()

Overrides:

toString in class Object