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 void	collect(SpanCollector collector) Collect postings data from the leaves of the current 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 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()
abstract int	width() Return the width of the match, which is typically used to compute the slop factor.

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.

width

public abstract int width()

Return the width of the match, which is typically used to compute the slop factor. It is only legal to call this method when the iterator is on a valid doc ID and positioned. The return value must be positive, and lower values means that the match is better.

collect

public abstract void collect(SpanCollector collector)
                      throws IOException

Collect postings data from the leaves of the current Spans. This method should only be called after nextStartPosition(), and before NO_MORE_POSITIONS has been reached.

Parameters:

collector - a SpanCollector

Throws:

IOException

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

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