Package it.unimi.di.big.mg4j.search.visitor

Class CounterSetupVisitor

java.lang.Object

it.unimi.di.big.mg4j.search.visitor.AbstractDocumentIteratorVisitor

it.unimi.di.big.mg4j.search.visitor.CounterSetupVisitor

All Implemented Interfaces:

DocumentIteratorVisitor<Boolean>

public class CounterSetupVisitor
extends AbstractDocumentIteratorVisitor

A visitor using the information collected by a TermCollectionVisitor to set up term frequencies and counters.

Term frequencies and counts are stored in publicly accessible parallel arrays of integers indexed by offsets, as defined by a TermCollectionVisitor provided at construction time. Additionally, the index number (a position into the array returned by TermCollectionVisitor.indices()) and the term for each offset are available.

When instances of this class perform a visit, they prepare the arrays and fill those contaning frequencies and index numbers. It is up to an instance of CounterCollectionVisitor (which requires an instance of this class in its constructor) to fill the counts with data related to the current document.

For a more complete picture, see CounterCollectionVisitor.

Field Summary

Fields

Modifier and Type	Field	Description
int[]	count	For each offset, its count.
long[]	frequency	For each offset, its frequency.
int[]	indexNumber	For each offset, the corresponding index as a position in TermCollectionVisitor.indices().
String[]	offset2Term	For each offset, the corresponding term.
int[]	offset2TermId	For each offset, its term id.
String[]	termId2Term	For each term id, the corresponding term.

Constructor Summary

Constructors

Constructor	Description
CounterSetupVisitor(TermCollectionVisitor termCollectionVisitor)	Creates a new counter-setup visitor based on a given term-collection visitor.

Method Summary

Modifier and Type	Method	Description
void	clear()	Zeroes all counters, but not frequencies.
CounterSetupVisitor	prepare()	Prepares the internal state of this visitor using data from the associated TermCollectionVisitor.
String	toString()
void	update(IndexIterator indexIterator)	Updates the count using the provided index iterator.
Boolean	visit(IndexIterator indexIterator)	Visits an IndexIterator leaf.

Methods inherited from class it.unimi.di.big.mg4j.search.visitor.AbstractDocumentIteratorVisitor

newArray, visit, visit, visit, visitPost, visitPre

Methods inherited from class java.lang.Object

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

Field Detail

indexNumber

public int[] indexNumber

For each offset, the corresponding index as a position in TermCollectionVisitor.indices().

offset2Term

public String[] offset2Term

For each offset, the corresponding term.

count

public int[] count

For each offset, its count.

frequency

public long[] frequency

For each offset, its frequency.

offset2TermId

public int[] offset2TermId

For each offset, its term id.

termId2Term

public String[] termId2Term

For each term id, the corresponding term.

Constructor Detail

CounterSetupVisitor

public CounterSetupVisitor(TermCollectionVisitor termCollectionVisitor)

Creates a new counter-setup visitor based on a given term-collection visitor.

Parameters:

termCollectionVisitor - a term-collection visitor.

Method Detail

prepare

public CounterSetupVisitor prepare()

Prepares the internal state of this visitor using data from the associated TermCollectionVisitor.

Note that because of this dependency, it is essential that you first prepare and visit with the associated TermCollectionVisitor, and then prepare and visit with this visitor.

Specified by:

prepare in interface DocumentIteratorVisitor<Boolean>

Overrides:

prepare in class AbstractDocumentIteratorVisitor

Returns:

this visitor.

visit

public Boolean visit(IndexIterator indexIterator)
              throws IOException

Description copied from interface: DocumentIteratorVisitor

Visits an IndexIterator leaf.

Parameters:

indexIterator - the leaf to be visited.

Returns:

an appropriate return value if the visit should continue, or null.

Throws:

IOException

update

public void update(IndexIterator indexIterator)
            throws IOException

Updates the count using the provided index iterator.

This method is usually called back by a CounterCollectionVisitor built upon this counter-setup visitor. It simply retrieves the index iterator id and use it as an index into count to store IndexIterator.count().

Parameters:

indexIterator - an index iterator.

Throws:

IOException

clear

public void clear()

Zeroes all counters, but not frequencies.

toString

public String toString()

Overrides:

toString in class Object