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

java.lang.Object
  extended by it.unimi.di.mg4j.search.AbstractDocumentIterator
      extended by it.unimi.di.mg4j.index.cluster.DocumentalMergedClusterDocumentIterator
          extended by it.unimi.di.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
protected  int 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.mg4j.index.cluster.DocumentalMergedClusterDocumentIterator
currentIterator, documentIterator, globalDocumentPointer, indices, n, queue, strategy, usedIndex
 
Fields inherited from class it.unimi.di.mg4j.search.AbstractDocumentIterator
curr, weight
 
Fields inherited from interface it.unimi.di.mg4j.index.IndexIterator
END_OF_POSITIONS
 
Fields inherited from interface it.unimi.di.mg4j.search.DocumentIterator
END_OF_LIST
 
Constructor Summary
DocumentalMergedClusterIndexIterator(DocumentalClusterIndexReader indexReader, IndexIterator[] indexIterator, int[] usedIndex)
           
 
Method Summary
<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.
 int 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.
 int 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.mg4j.index.cluster.DocumentalMergedClusterDocumentIterator
dispose, indices, intervalIterator, intervalIterator, intervalIterators, nextDocument, skipTo
 
Methods inherited from class it.unimi.di.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.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 int 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(int), 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 int 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 int 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(int).

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 IndexIterator
Specified by:
weight in interface DocumentIterator
Overrides:
weight in class AbstractDocumentIterator
Parameters:
weight - the weight of this index iterator.
Returns:
this document iterator.
See Also:
DocumentIterator.weight(double)