it.unimi.dsi.mg4j.search
Class LowPassDocumentIterator

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

All Implemented Interfaces:

DocumentIterator, IntIterator, Iterator

public class LowPassDocumentIterator

extends AbstractIntIterator

implements DocumentIterator

A document iterator that filters another document iterator, returning just intervals (and containing documents) whose length does not exceed a given threshold.

Since:

0.9

Author:

Paolo Boldi, Sebastiano Vigna

Field Summary

protected int

threshold The iterator threshold.

Constructor Summary

LowPassDocumentIterator(DocumentIterator it, int threshold)
Creates a new low-pass document iterator over a given iterator.

Method Summary

int	document() Returns the last document returned by IntIterator.nextInt().
boolean	hasNext()
Set	indices() Returns the set of indices over which this iterator is built.
IntervalIterator	intervalIterator() Returns the interval iterator of this document iterator for single-index queries.
IntervalIterator	intervalIterator(Index index) Returns the interval iterator of this document iterator for the given index.
Map	intervalIterators() Returns an unmodifiable map from indices to interval iterators.
int	nextDocument() A synonym for IntIterator.nextInt().
int	nextInt()
int	skipTo(int n) Skips all documents smaller than n.
String	toString()

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, wait, wait, wait

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

skip

Methods inherited from interface java.util.Iterator

next, remove

Field Detail

threshold

protected final int threshold

The iterator threshold.

Constructor Detail

LowPassDocumentIterator

public LowPassDocumentIterator(DocumentIterator it,
                               int threshold)

Creates a new low-pass document iterator over a given iterator.

Parameters:

it - the iterator to be filtered.

threshold - the filter threshold.

Method Detail

indices

public Set indices()

Description copied from interface: DocumentIterator

Returns the set of indices over which this iterator is built.

Specified by:

indices in interface DocumentIterator

Returns:

the set of indices over which this iterator is built.

skipTo

public int skipTo(int n)

Description copied from interface: DocumentIterator

Skips all documents smaller than n.

Let k be the last document returned by IntIterator.nextInt(). If k is larger than or equal to n, then this method does nothing and returns k. Otherwise, a call to this method is equivalent to

 while( hasNext() && ( k = nextInt() ) < n );
 return hasNext() ? k : -1;
 

Beware that the first document larger than or equal to n (which is returned by this method) will not be returned by the next call to IntIterator.nextInt().

Specified by:

skipTo in interface DocumentIterator

Parameters:

n - a document index.

Returns:

-1, if all documents produced by this iterator are smaller than n; otherwise, an document larger than or equal to n as described above.

nextInt

public int nextInt()

Specified by:

nextInt in interface IntIterator

document

public int document()

Description copied from interface: DocumentIterator

Returns the last document returned by IntIterator.nextInt().

Specified by:

document in interface DocumentIterator

Returns:

the last document returned by IntIterator.nextInt(), or -1 if no document has been returned yet.

nextDocument

public int nextDocument()

Description copied from interface: DocumentIterator

A synonym for IntIterator.nextInt().

Specified by:

nextDocument in interface DocumentIterator

Returns:

the next document.

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator

intervalIterators

public Map intervalIterators()

Description copied from interface: DocumentIterator

Returns an unmodifiable map from indices to interval iterators.

After a call to IntIterator.nextInt(), this map can be used to retrieve the intervals in the current document. An invocation of Map.get(java.lang.Object) on this map with argument index yields the same result as intervalIterator(index).

Specified by:

intervalIterators in interface DocumentIterator

Returns:

a map from indices to interval iterators over the current document.

See Also:

DocumentIterator.intervalIterator(Index)

intervalIterator

public IntervalIterator intervalIterator()

Description copied from interface: DocumentIterator

Returns the interval iterator of this document iterator for single-index queries.

This is a commodity method that can be used only for queries built over a single index.

Specified by:

intervalIterator in interface DocumentIterator

Returns:

an interval iterator.

See Also:

DocumentIterator.intervalIterator(Index)

intervalIterator

public IntervalIterator intervalIterator(Index index)

Description copied from interface: DocumentIterator

Returns the interval iterator of this document iterator for the given index.

After a call to IntIterator.nextInt(), this iterator can be used to retrieve the intervals in the current document (the one returned by IntIterator.nextInt()) for the index index.

Note that it is guaranteed that at least one index will return an interval. However, for disjunctive queries it cannot be guaranteed that all indices will return an interval.

Specified by:

intervalIterator in interface DocumentIterator

Parameters:

index - an index (must be one over which the query was built).

Returns:

an interval iterator over the current document in index.

toString

public String toString()