Package org.apache.lucene.queries.intervals

Class IntervalIterator

java.lang.Object

org.apache.lucene.search.DocIdSetIterator

org.apache.lucene.queries.intervals.IntervalIterator

Direct Known Subclasses:

IntervalFilter

public abstract class IntervalIterator
extends DocIdSetIterator

A DocIdSetIterator that also allows iteration over matching intervals in a document.

Once the iterator is positioned on a document by calling DocIdSetIterator.advance(int) or DocIdSetIterator.nextDoc(), intervals may be retrieved by calling nextInterval() until NO_MORE_INTERVALS is returned.

The limits of the current interval are returned by start() and end(). When the iterator has been moved to a new document, but before nextInterval() has been called, both these methods return -1.

Note that it is possible for a document to return NO_MORE_INTERVALS on the first call to nextInterval()

Field Summary

Fields

Modifier and Type	Field	Description
static int	NO_MORE_INTERVALS	When returned from nextInterval(), indicates that there are no more matching intervals on the current document

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

NO_MORE_DOCS

Constructor Summary

Constructors

Constructor	Description
IntervalIterator()

Method Summary

Modifier and Type	Method	Description
abstract int	end()	The end of the current interval
abstract int	gaps()	The number of gaps within the current interval
abstract float	matchCost()	An indication of the average cost of iterating over all intervals in a document
abstract int	nextInterval()	Advance the iterator to the next interval
abstract int	start()	The start of the current interval
String	toString()
int	width()	The width of the current interval

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

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

Methods inherited from class java.lang.Object

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

Field Detail

NO_MORE_INTERVALS

public static final int NO_MORE_INTERVALS

When returned from nextInterval(), indicates that there are no more matching intervals on the current document

See Also:

Constant Field Values

Constructor Detail

IntervalIterator

public IntervalIterator()

Method Detail

start

public abstract int start()

The start of the current interval

Returns -1 if nextInterval() has not yet been called and NO_MORE_INTERVALS once the iterator is exhausted.

end

public abstract int end()

The end of the current interval

Returns -1 if nextInterval() has not yet been called and NO_MORE_INTERVALS once the iterator is exhausted.

gaps

public abstract int gaps()

The number of gaps within the current interval

Note that this returns the number of gaps between the immediate sub-intervals of this interval, and does not include the gaps inside those sub-intervals.

Should not be called before nextInterval(), or after it has returned NO_MORE_INTERVALS

width

public int width()

The width of the current interval

nextInterval

public abstract int nextInterval()
                          throws IOException

Advance the iterator to the next interval

Should not be called after DocIdSetIterator.NO_MORE_DOCS is returned by DocIdSetIterator.nextDoc() or DocIdSetIterator.advance(int). If that's the case in some existing code, please consider opening an issue. However, after NO_MORE_INTERVALS is returned by this method, it might be called again.

Returns:

the start of the next interval, or NO_MORE_INTERVALS if there are no more intervals on the current document

Throws:

IOException

matchCost

public abstract float matchCost()

An indication of the average cost of iterating over all intervals in a document

See Also:

TwoPhaseIterator.matchCost()

toString

public String toString()

Overrides:

toString in class Object