it.unimi.dsi.mg4j.search
Class OrDocumentIterator.OrIndexIntervalIterator

java.lang.Object
  extended by it.unimi.dsi.fastutil.objects.AbstractObjectIterator<Interval>
      extended by it.unimi.dsi.mg4j.search.AbstractDocumentIterator.AbstractIntervalIterator
          extended by it.unimi.dsi.mg4j.search.AbstractCompositeDocumentIterator.AbstractCompositeIndexIntervalIterator
              extended by it.unimi.dsi.mg4j.search.OrDocumentIterator.OrIndexIntervalIterator
All Implemented Interfaces:
ObjectIterator<Interval>, IntervalIterator, Iterator<Interval>
Enclosing class:
OrDocumentIterator

protected class OrDocumentIterator.OrIndexIntervalIterator
extends AbstractCompositeDocumentIterator.AbstractCompositeIndexIntervalIterator
implements IntervalIterator

An optimised interval iterator with the same semantics as that implemented by OrDocumentIterator, but using just IndexIterator.positionArray().


Field Summary
 
Fields inherited from class it.unimi.dsi.mg4j.search.AbstractCompositeDocumentIterator.AbstractCompositeIndexIntervalIterator
count, curr, currPos, position
 
Fields inherited from class it.unimi.dsi.mg4j.search.AbstractDocumentIterator.AbstractIntervalIterator
next
 
Constructor Summary
OrDocumentIterator.OrIndexIntervalIterator(Index index)
           
 
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.
 void reset()
          Resets the internal state of this iterator for a new document.
 
Methods inherited from class it.unimi.dsi.mg4j.search.AbstractCompositeDocumentIterator.AbstractCompositeIndexIntervalIterator
toString
 
Methods inherited from class it.unimi.dsi.mg4j.search.AbstractDocumentIterator.AbstractIntervalIterator
hasNext, next
 
Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObjectIterator
remove, skip
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface it.unimi.dsi.mg4j.search.IntervalIterator
next
 
Methods inherited from interface java.util.Iterator
hasNext, remove
 

Constructor Detail

OrDocumentIterator.OrIndexIntervalIterator

public OrDocumentIterator.OrIndexIntervalIterator(Index index)
Method Detail

reset

public void 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).

Specified by:
reset in interface IntervalIterator
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()
Description copied from interface: IntervalIterator
Returns the next interval provided by this interval iterator, or null if no more intervals are available.

This method has been reintroduced in MG4J 1.2 with a different semantics. The special return value null is used to mark the end of iteration. The reason for this change is providing fully lazy iteration over intervals. Fully lazy iteration does not provide an hasNext() method—you have to actually ask for the next element and check the return value. Fully lazy iteration is much lighter on method calls (half) and in most (if not all) MG4J classes leads to a much simpler logic. Moreover, IntervalIterator.nextInterval() can be specified as throwing an IOException, which avoids the pernicious proliferation of try/catch blocks in very short, low-level methods (it was having a detectable impact on performance).

Specified by:
nextInterval in interface IntervalIterator
Returns:
the next interval, or null if no more intervals are available.

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.