it.unimi.di.mg4j.search
Class AndDocumentIterator.AndIndexIntervalIterator

java.lang.Object
  it.unimi.di.mg4j.search.AbstractCompositeDocumentIterator.AbstractCompositeIndexIntervalIterator
      it.unimi.di.mg4j.search.AndDocumentIterator.AndIndexIntervalIterator

All Implemented Interfaces:

IntervalIterator

Enclosing class:

AndDocumentIterator

protected class AndDocumentIterator.AndIndexIntervalIterator
extends AbstractCompositeDocumentIterator.AbstractCompositeIndexIntervalIterator
implements IntervalIterator

An interval iterator returning the AND (in the Clarke−Cormack−Burkowski lattice) of the component interval iterators.

Field Summary

Fields inherited from class it.unimi.di.mg4j.search.AbstractCompositeDocumentIterator.AbstractCompositeIndexIntervalIterator

curr

Constructor Summary

protected

AndDocumentIterator.AndIndexIntervalIterator(Index index, int n) Creates a new AND interval iterator.

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.

Methods inherited from class it.unimi.di.mg4j.search.AbstractCompositeDocumentIterator.AbstractCompositeIndexIntervalIterator

toString

Methods inherited from class java.lang.Object

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

Constructor Detail

AndDocumentIterator.AndIndexIntervalIterator

protected AndDocumentIterator.AndIndexIntervalIterator(Index index,
                                                       int n)

Creates a new AND interval iterator.

Parameters:

index - the index of the iterator.

n - the number of component iterators.

Method Detail

reset

public IntervalIterator reset()
                       throws IOException

Description copied from interface: IntervalIterator

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 IntervalIterator.nextInterval() will return null.

Specified by:

reset in interface IntervalIterator

Returns:

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

Throws:

IOException

intervalTerms

public void intervalTerms(IntSet terms)

Description copied from interface: IntervalIterator

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.

Specified by:

intervalTerms in interface IntervalIterator

Parameters:

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

nextInterval

public Interval nextInterval()
                      throws IOException

Description copied from interface: IntervalIterator

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

Specified by:

nextInterval in interface IntervalIterator

Returns:

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

Throws:

IOException

extent

public int extent()

Description copied from interface: IntervalIterator

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

Specified by:

extent in interface IntervalIterator

Returns:

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