it.unimi.dsi.mg4j.search
Class AbstractDocumentIterator

java.lang.Object
  it.unimi.dsi.fastutil.ints.AbstractIntIterator
      it.unimi.dsi.mg4j.search.AbstractDocumentIterator

All Implemented Interfaces:

IntIterator, DocumentIterator, Iterable<Interval>, Iterator<Integer>

Direct Known Subclasses:

AbstractCompositeDocumentIterator, AlignDocumentIterator, DifferenceDocumentIterator, DocumentalConcatenatedClusterDocumentIterator, DocumentalMergedClusterDocumentIterator, FalseDocumentIterator, LowPassDocumentIterator, NotDocumentIterator, PayloadPredicateDocumentIterator, TrueDocumentIterator

public abstract class AbstractDocumentIterator
extends AbstractIntIterator
implements DocumentIterator

An abstract iterator on documents that implements hasNext() and nextInt() using nextDocument(), and provides support for the DocumentIterator.weight()/DocumentIterator.weight(double) methods.

As explained elsewhere, since MG4J 1.2 the iteration logic has been made fully lazy, and the standard IntIterator methods are available as a commodity, but their use in performance-sensitive environments is strongly discouraged. The fully lazy implementation needs some bridging to be accessible using java.util's semi-lazy iterators, and this class provides the necessary code.

Instances of this class keep track of the next document to be returned, if it has been already peeked at by hasNext(), and of the last document returned by nextInt() or nextDocument(). Concrete subclasses must implement nextDocument() so that after it has been called last is equal to the returned document (possibly -1) and next is -1 (of course, if next has already been set nextDocument() must behave exactly like the implementation of nextInt() found in this class). Methods performing actions depending on the last document returned should throw an IllegalStateException if called when last is -1.

Nested Class Summary

protected static class

AbstractDocumentIterator.AbstractIntervalIterator

Field Summary

protected int	last The last document returned by this iterator, or -1 if the iterator has never be advanced or if its state has been modified since the last call to nextInt() or nextDocument() because of a call to hasNext().
protected int	next The next document to be returned, if it has already been peeked at by hasNext(), or -1.
protected double	weight The weight of this iterator.

Constructor Summary

AbstractDocumentIterator()

Method Summary

int	document() Returns last, if it is not -1; otherwise, throws an IllegalStateException.
boolean	hasNext() Checks whether next has been already set; if not, peeks at the document returned by nextDocument().
IntervalIterator	iterator() Invokes DocumentIterator.intervalIterator()
int	nextInt() Deprecated.
double	weight() Returns the weight associated to this iterator.
DocumentIterator	weight(double weight) Sets the weight of this index iterator.

Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractIntIterator

next, remove, skip

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unimi.dsi.mg4j.search.DocumentIterator

accept, acceptOnTruePaths, dispose, indices, intervalIterator, intervalIterator, intervalIterators, nextDocument, skipTo

Methods inherited from interface it.unimi.dsi.fastutil.ints.IntIterator

skip

Methods inherited from interface java.util.Iterator

next, remove

Field Detail

last

protected int last

The last document returned by this iterator, or -1 if the iterator has never be advanced or if its state has been modified since the last call to nextInt() or nextDocument() because of a call to hasNext().

next

protected int next

The next document to be returned, if it has already been peeked at by hasNext(), or -1.

weight

protected double weight

The weight of this iterator.

Constructor Detail

AbstractDocumentIterator

public AbstractDocumentIterator()

Method Detail

weight

public double weight()

Description copied from interface: DocumentIterator

Returns the weight associated to this iterator.

The number returned by this method has no fixed semantics: different scorers might choose different interpretations, or even ignore it.

Specified by:

weight in interface DocumentIterator

Returns:

the weight associated to this iterator.

weight

public DocumentIterator weight(double weight)

Description copied from interface: DocumentIterator

Sets the weight of this index iterator.

Specified by:

weight in interface DocumentIterator

Parameters:

weight - the weight of this index iterator.

Returns:

this document iterator.

iterator

public IntervalIterator iterator()

Invokes DocumentIterator.intervalIterator()

Specified by:

iterator in interface DocumentIterator

Specified by:

iterator in interface Iterable<Interval>

Returns:

DocumentIterator.intervalIterator().

hasNext

public boolean hasNext()

Checks whether next has been already set; if not, peeks at the document returned by nextDocument().

Specified by:

hasNext in interface Iterator<Integer>

Returns:

true if next is not -1 or if nextDocument() has returned a valid document pointer.

nextInt

@Deprecated
public int nextInt()

Deprecated.

Checks whether there is an element to be returned, sets last to next, next to -1, and returns last.

Specified by:

nextInt in interface IntIterator

Specified by:

nextInt in interface DocumentIterator

Overrides:

nextInt in class AbstractIntIterator

Returns:

the next document pointer, as cached by hasNext().

See Also:

DocumentIterator.nextDocument()

document

public int document()

Returns last, if it is not -1; otherwise, throws an IllegalStateException.

Specified by:

document in interface DocumentIterator

Returns:

last, if it is not -1.

Throws:

IllegalStateException - if last is -1.