org.apache.lucene.search.spans

Class Spans

java.lang.Object

org.apache.lucene.search.DocIdSetIterator

org.apache.lucene.search.spans.Spans

Direct Known Subclasses:

FilterSpans, NearSpansOrdered, NearSpansUnordered, TermSpans

public abstract class Spans
extends DocIdSetIterator

Iterates through combinations of start/end positions per-doc. Each start/end position represents a range of term positions within the current document. These are enumerated in order, by increasing document number, within that by increasing start position and finally by increasing end position.

Field Summary

Fields

Modifier and Type	Field and Description
static int	NO_MORE_POSITIONS

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

NO_MORE_DOCS

Constructor Summary

Constructors

Constructor and Description
Spans()

Method Summary

Methods

Modifier and Type	Method and Description
TwoPhaseIterator	asTwoPhaseIterator() Optional method: Return a TwoPhaseIterator view of this Spans.
abstract int	endPosition() Returns the end position for the current start position, or -1 when nextStartPosition() was not yet called on the current doc.
abstract Collection<byte[]>	getPayload() Returns the payload data for the current start/end position.
abstract boolean	isPayloadAvailable() Checks if a payload can be loaded at the current start/end position.
abstract int	nextStartPosition() Returns the next start position for the current doc.
abstract int	startPosition() Returns the start position in the current doc, or -1 when nextStartPosition() was not yet called on the current doc.
String	toString()

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

advance, all, cost, docID, empty, nextDoc, slowAdvance

Methods inherited from class java.lang.Object

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

Field Detail

NO_MORE_POSITIONS

public static final int NO_MORE_POSITIONS

See Also:

Constant Field Values

Constructor Detail

Spans

public Spans()

Method Detail

nextStartPosition

public abstract int nextStartPosition()
                               throws IOException

Returns the next start position for the current doc. There is always at least one start/end position per doc. After the last start/end position at the current doc this returns NO_MORE_POSITIONS.

Throws:

IOException

startPosition

public abstract int startPosition()

Returns the start position in the current doc, or -1 when nextStartPosition() was not yet called on the current doc. After the last start/end position at the current doc this returns NO_MORE_POSITIONS.

endPosition

public abstract int endPosition()

Returns the end position for the current start position, or -1 when nextStartPosition() was not yet called on the current doc. After the last start/end position at the current doc this returns NO_MORE_POSITIONS.

getPayload

public abstract Collection<byte[]> getPayload()
                                       throws IOException

Returns the payload data for the current start/end position. This is only valid after nextStartPosition() returned an available start position. This method must not be called more than once after each call of nextStartPosition(). However, most payloads are loaded lazily, so if the payload data for the current position is not needed, this method may not be called at all for performance reasons.
Note that the return type is a collection, thus the ordering should not be relied upon.

Returns:

a List of byte arrays containing the data of this payload, otherwise null if isPayloadAvailable is false

Throws:

IOException - if there is a low-level I/O error

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

isPayloadAvailable

public abstract boolean isPayloadAvailable()
                                    throws IOException

Checks if a payload can be loaded at the current start/end position.

Payloads can only be loaded once per call to nextStartPosition().

Returns:

true if there is a payload available at this start/end position that can be loaded

Throws:

IOException

asTwoPhaseIterator

public TwoPhaseIterator asTwoPhaseIterator()

Optional method: Return a TwoPhaseIterator view of this Spans. A return value of null indicates that two-phase iteration is not supported. Note that the returned TwoPhaseIterator's approximation must advance documents synchronously with this iterator: advancing the approximation must advance this iterator and vice-versa. Implementing this method is typically useful on a Spans that has a high per-document overhead for confirming matches. The default implementation returns null.

toString

public String toString()

Overrides:

toString in class Object