Package org.terrier.structures.postings

Class ANDIterablePosting

java.lang.Object

org.terrier.structures.postings.IterablePostingImpl

org.terrier.structures.postings.ANDIterablePosting

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, IterablePosting, Posting

Direct Known Subclasses:

PhraseIterablePosting, ProximityIterablePosting

public class ANDIterablePosting
extends IterablePostingImpl

An instance of IterablePostings that works with passed arrays of ids and frequencies. The document must contain all of the terms in the query to be matched (AND)

Author:

Richard McCreadie

Field Summary

Fields

Modifier and Type	Field	Description
protected int	currentId
protected int	frequency
protected IterablePosting[]	ips
protected int	termCount

Fields inherited from interface org.terrier.structures.postings.IterablePosting

END_OF_LIST, EOL

Constructor Summary

Constructors

Constructor	Description
ANDIterablePosting(IterablePosting[] _ips, EntryStatistics[] _p)
ANDIterablePosting(IterablePosting[] _ips, Pointer[] _p)

Method Summary

Modifier and Type	Method	Description
WritablePosting	asWritablePosting()	Copy this posting to one free of an iterator.
protected boolean	calculateFrequency()	returns true if the document matches
void	close()
boolean	endOfPostings()	Status method to see if this posting list iterator has been finished.
int	getDocumentLength()	Return the length of the document of the current posting in tokens.
int	getFrequency()	Return the frequency of the term in the current document, in tokens.
int	getId()	Return the id of the current posting.
int	next()	Move this iterator to the next posting.
int	next(int targetID)	This implementation of next(int) which uses next()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.terrier.structures.postings.Posting

setId

Field Detail

currentId

protected int currentId

ips

protected IterablePosting[] ips

termCount

protected final int termCount

frequency

protected int frequency

Constructor Detail

ANDIterablePosting

public ANDIterablePosting(IterablePosting[] _ips,
                          EntryStatistics[] _p)
                   throws java.io.IOException

Throws:

java.io.IOException

ANDIterablePosting

public ANDIterablePosting(IterablePosting[] _ips,
                          Pointer[] _p)
                   throws java.io.IOException

Throws:

java.io.IOException

Method Detail

getId

public int getId()

Description copied from interface: Posting

Return the id of the current posting. For the inverted index, this is the current docid; for the direct index it corresponds to the current term id.

Returns:

id of the posting.

getFrequency

public int getFrequency()

Description copied from interface: Posting

Return the frequency of the term in the current document, in tokens.

Returns:

frequency of the term in the current document, in tokens.

getDocumentLength

public int getDocumentLength()

Description copied from interface: Posting

Return the length of the document of the current posting in tokens. Usually uses the DocumentIndex, may do otherwise if document length statistics are in posting list.

Returns:

length of the document of the current posting in tokens.

next

public int next(int targetID)
         throws java.io.IOException

Description copied from class: IterablePostingImpl

This implementation of next(int) which uses next()

Specified by:

next in interface IterablePosting

Overrides:

next in class IterablePostingImpl

Parameters:

targetID - id of the posting to find in this posting list.

Returns:

id of the posting found, or EOL if end of posting list is reached.

Throws:

java.io.IOException

next

public int next()
         throws java.io.IOException

Description copied from interface: IterablePosting

Move this iterator to the next posting.

Returns:

id of next posting, or EOL if end of posting list.

Throws:

java.io.IOException

calculateFrequency

protected boolean calculateFrequency()

returns true if the document matches

endOfPostings

public boolean endOfPostings()

Description copied from interface: IterablePosting

Status method to see if this posting list iterator has been finished.

Returns:

true if IterablePosting.next() or IterablePosting.next(int) would return EOL or have returned EOL.

close

public void close()
           throws java.io.IOException

Throws:

java.io.IOException

asWritablePosting

public WritablePosting asWritablePosting()

Description copied from interface: Posting

Copy this posting to one free of an iterator. Kind of like a clone.

Returns:

an identical posting, but which can be manipulated free of this iterator