Package it.unimi.di.big.mg4j.index.cluster

Class DocumentalMergedClusterIndexIterator

java.lang.Object

it.unimi.di.big.mg4j.search.AbstractDocumentIterator

it.unimi.di.big.mg4j.index.cluster.DocumentalMergedClusterDocumentIterator

it.unimi.di.big.mg4j.index.cluster.DocumentalMergedClusterIndexIterator

All Implemented Interfaces:

IndexIterator, DocumentIterator

public class DocumentalMergedClusterIndexIterator
extends DocumentalMergedClusterDocumentIterator
implements IndexIterator

An index iterator merging iterators from local indices.

Author:

Alessandro Arrabito, Sebastiano Vigna

Field Summary

Fields

Modifier and Type	Field	Description
protected long	frequency	The precomputed frequency.
protected int	id	The id associated with this index iterator.
protected DocumentalMergedCluster	index	The reference index.
protected IndexIterator[]	indexIterator	A cached copy of the iterators, to avoid type casts.
protected String	term	The term associated with this index iterator.

Fields inherited from class it.unimi.di.big.mg4j.index.cluster.DocumentalMergedClusterDocumentIterator

currentIterator, documentIterator, globalDocumentPointer, indices, n, queue, strategy, usedIndex

Fields inherited from class it.unimi.di.big.mg4j.search.AbstractDocumentIterator

curr, weight

Fields inherited from interface it.unimi.di.big.mg4j.search.DocumentIterator

END_OF_LIST

Fields inherited from interface it.unimi.di.big.mg4j.index.IndexIterator

END_OF_POSITIONS

Constructor Summary

Constructors

Constructor	Description
DocumentalMergedClusterIndexIterator(DocumentalClusterIndexReader indexReader, IndexIterator[] indexIterator, int[] usedIndex)

Method Summary

Modifier and Type	Method	Description
<T> T	accept(DocumentIteratorVisitor<T> visitor)	Accepts a visitor.
<T> T	acceptOnTruePaths(DocumentIteratorVisitor<T> visitor)	Accepts a visitor after a call to DocumentIterator.nextDocument(), limiting recursion to true paths.
int	count()	Returns the count, that is, the number of occurrences of the term in the current document.
long	frequency()	Returns the frequency, that is, the number of documents that will be returned by this iterator.
int	id()	Returns the id of this index iterator.
DocumentalMergedClusterIndexIterator	id(int id)	Sets the id of this index iterator.
Index	index()	Returns the index over which this iterator is built.
int	nextPosition()	Returns the next position at which the term appears in the current document.
Payload	payload()	Returns the payload, if any, associated with the current document.
String	term()	Returns the term whose inverted list is returned by this index iterator.
DocumentalMergedClusterIndexIterator	term(CharSequence term)	Sets the term whose inverted list is returned by this index iterator.
long	termNumber()	Returns the number of the term whose inverted list is returned by this index iterator.
IndexIterator	weight(double weight)	Sets the weight of this index iterator.

Methods inherited from class it.unimi.di.big.mg4j.index.cluster.DocumentalMergedClusterDocumentIterator

dispose, indices, intervalIterator, intervalIterator, intervalIterators, nextDocument, skipTo

Methods inherited from class it.unimi.di.big.mg4j.search.AbstractDocumentIterator

document, ensureOnADocument, mayHaveNext, weight

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unimi.di.big.mg4j.search.DocumentIterator

dispose, document, indices, intervalIterator, intervalIterator, intervalIterators, mayHaveNext, nextDocument, skipTo, weight

Field Detail

indexIterator

protected final IndexIterator[] indexIterator

A cached copy of the iterators, to avoid type casts.

frequency

protected final long frequency

The precomputed frequency.

index

protected final DocumentalMergedCluster index

The reference index.

term

protected String term

The term associated with this index iterator.

id

protected int id

The id associated with this index iterator.

Constructor Detail

DocumentalMergedClusterIndexIterator

public DocumentalMergedClusterIndexIterator(DocumentalClusterIndexReader indexReader,
                                            IndexIterator[] indexIterator,
                                            int[] usedIndex)
                                     throws IOException

Throws:

IOException

Method Detail

term

public DocumentalMergedClusterIndexIterator term(CharSequence term)

Description copied from interface: IndexIterator

Sets the term whose inverted list is returned by this index iterator.

Usually, the term is automatically set by Index.documents(CharSequence) or by IndexReader.documents(CharSequence), but you can use this method to ensure that IndexIterator.term() doesn't throw an exception.

Specified by:

term in interface IndexIterator

Parameters:

term - a character sequence (that will be defensively copied) that will be assumed to be the term whose inverted list is returned by this index iterator.

Returns:

this index iterator.

term

public String term()

Description copied from interface: IndexIterator

Returns the term whose inverted list is returned by this index iterator.

Usually, the term is automatically set by IndexReader.documents(CharSequence) or IndexReader.documents(long), but you can supply your own term with IndexIterator.term(CharSequence).

Specified by:

term in interface IndexIterator

Returns:

the term over which this iterator is built, as a compact mutable string.

See Also:

IndexIterator.termNumber()

id

public DocumentalMergedClusterIndexIterator id(int id)

Description copied from interface: IndexIterator

Sets the id of this index iterator.

The id is an integer associated with each index iterator. It has no specific semantics, and can be used differently in different contexts. A typical usage pattern, for instance, is using it to assign a unique number to the index iterators contained in a composite document iterator (say, numbering consecutively the leaves of the composite).

Specified by:

id in interface IndexIterator

Parameters:

id - the new id for this index iterator.

Returns:

this index iterator.

id

public int id()

Description copied from interface: IndexIterator

Returns the id of this index iterator.

Specified by:

id in interface IndexIterator

Returns:

the id of this index iterator.

See Also:

IndexIterator.id(int)

index

public Index index()

Description copied from interface: IndexIterator

Returns the index over which this iterator is built.

Specified by:

index in interface IndexIterator

Returns:

the index over which this iterator is built.

frequency

public long frequency()

Description copied from interface: IndexIterator

Returns the frequency, that is, the number of documents that will be returned by this iterator.

Specified by:

frequency in interface IndexIterator

Returns:

the number of documents that will be returned by this iterator.

payload

public Payload payload()
                throws IOException

Description copied from interface: IndexIterator

Returns the payload, if any, associated with the current document.

Specified by:

payload in interface IndexIterator

Returns:

the payload associated with the current document.

Throws:

IOException

count

public int count()
          throws IOException

Description copied from interface: IndexIterator

Returns the count, that is, the number of occurrences of the term in the current document.

Specified by:

count in interface IndexIterator

Returns:

the count (number of occurrences) of the term in the current document.

Throws:

IOException

nextPosition

public int nextPosition()
                 throws IOException

Description copied from interface: IndexIterator

Returns the next position at which the term appears in the current document.

Specified by:

nextPosition in interface IndexIterator

Returns:

the next position of the current document in which the current term appears, or IndexIterator.END_OF_POSITIONS if there are no more positions.

Throws:

IOException

accept

public <T> T accept(DocumentIteratorVisitor<T> visitor)
             throws IOException

Description copied from interface: DocumentIterator

Accepts a visitor.

A document iterator is usually structured as composite, with operators as internal nodes and IndexIterators as leaves. This method implements the visitor pattern.

Specified by:

accept in interface DocumentIterator

Overrides:

accept in class DocumentalMergedClusterDocumentIterator

Parameters:

visitor - the visitor.

Returns:

an object resulting from the visit, or null if the visit was interrupted.

Throws:

IOException

acceptOnTruePaths

public <T> T acceptOnTruePaths(DocumentIteratorVisitor<T> visitor)
                        throws IOException

Description copied from interface: DocumentIterator

Accepts a visitor after a call to DocumentIterator.nextDocument(), limiting recursion to true paths.

After a call to DocumentIterator.nextDocument(), a document iterator is positioned over a document. This call is equivalent to DocumentIterator.accept(DocumentIteratorVisitor), but visits only along true paths.

We define a true path as a path from the root of the composite that passes only through nodes whose associated subtree is positioned on the same document of the root. Note that OrDocumentIterators detach exhausted iterators from the composite tree, so true paths define the subtree that is causing the current document to satisfy the query represented by this document iterator.

For more elaboration, and the main application of this method, see CounterCollectionVisitor.

Specified by:

acceptOnTruePaths in interface DocumentIterator

Overrides:

acceptOnTruePaths in class DocumentalMergedClusterDocumentIterator

Parameters:

visitor - the visitor.

Returns:

an object resulting from the visit, or null if the visit was interrupted.

Throws:

IOException

See Also:

DocumentIterator.accept(DocumentIteratorVisitor), CounterCollectionVisitor

termNumber

public long termNumber()

Description copied from interface: IndexIterator

Returns the number of the term whose inverted list is returned by this index iterator.

Usually, the term number is automatically set by IndexReader.documents(CharSequence) or IndexReader.documents(long).

Specified by:

termNumber in interface IndexIterator

Returns:

the number of the term over which this iterator is built.

See Also:

IndexIterator.term()

weight

public IndexIterator weight(double weight)

Description copied from interface: DocumentIterator

Sets the weight of this index iterator.

Specified by:

weight in interface DocumentIterator

Specified by:

weight in interface IndexIterator

Overrides:

weight in class AbstractDocumentIterator

Parameters:

weight - the weight of this index iterator.

Returns:

this document iterator.

See Also:

DocumentIterator.weight(double)