it.unimi.di.mg4j.search
Interface IntervalIterator

All Known Implementing Classes:

AbstractCompositeDocumentIterator.AbstractCompositeIndexIntervalIterator, AbstractCompositeDocumentIterator.AbstractCompositeIntervalIterator, AlignDocumentIterator.AlignIndexIntervalIterator, AlignDocumentIterator.AlignIntervalIterator, AndDocumentIterator.AndIndexIntervalIterator, AndDocumentIterator.AndIntervalIterator, ConsecutiveDocumentIterator.ConsecutiveIndexIntervalIterator, ConsecutiveDocumentIterator.ConsecutiveIntervalIterator, DifferenceDocumentIterator.DifferenceIntervalIterator, IndexIntervalIterator, IntervalIterators.FakeIterator, LowPassDocumentIterator.LowPassIntervalIterator, OrderedAndDocumentIterator.OrderedAndIndexIntervalIterator, OrderedAndDocumentIterator.OrderedAndIntervalIterator, OrDocumentIterator.OrIndexIntervalIterator, OrDocumentIterator.OrIntervalIterator

public interface IntervalIterator

An iterator over intervals.

An interval iterator is lazy—it has just a nextInterval() method and no hasNext() method.

This interface specifies a method extent() returning a positive integer that is supposed to approximate the minimum possible length of an interval returned by this iterator. This method returns -1 if this value cannot be computed.

Method Summary

int	extent() Returns an approximation of a lower bound for the length of an interval returned by this iterator.
void	intervalTerms(IntSet terms) Provides the set of terms that span the current interval.
Interval	nextInterval() Returns the next interval provided by this interval iterator, or null if no more intervals are available.
IntervalIterator	reset() Resets the internal state of this iterator for a new document.

Method Detail

reset

IntervalIterator reset()
                       throws IOException

Resets the internal state of this iterator for a new document.

To reduce object creation, interval iterators are usually created in a lazy fashion by document iterator when they are needed. However, this implies that every time the document iterator is moved, some internal state of the interval iterator must be reset (e.g., because on the new document some of the component interval iterators are now IntervalIterators.TRUE). The semantics of this method is largely implementation dependent, with the important exception that the return value must be IntervalIterators.FALSE if the first call to nextInterval() will return null.

Returns:

IntervalIterators.FALSE if this interval iterator will return null at the first call to nextInterval(); this interval iterator, otherwise.

Throws:

IOException

extent

int extent()

Returns an approximation of a lower bound for the length of an interval returned by this iterator.

Returns:

an approximation of a lower bound for the length of an interval.

nextInterval

Interval nextInterval()
                      throws IOException

Returns the next interval provided by this interval iterator, or null if no more intervals are available.

Returns:

the next interval, or null if no more intervals are available.

Throws:

IOException

intervalTerms

void intervalTerms(IntSet terms)

Provides the set of terms that span the current interval.

For each interval returned by MG4J, there is a set of terms that caused the interval to be returned. The terms appear inside the interval, and certainly at its extremes.

Note that the results of this method must be taken with a grain of salt: there might be different sets of terms causing the current interval, and only one will be returned.

Parameters:

terms - a set of integers that will be filled with the terms spanning the current interval.