org.terrier.structures.indexing.singlepass

Class FileRunIterator<K extends PostingInRun>

java.lang.Object

org.terrier.structures.indexing.singlepass.RunIterator

org.terrier.structures.indexing.singlepass.FileRunIterator<K>

Type Parameters:

K -

All Implemented Interfaces:

Closeable, AutoCloseable, Iterator<PostingInRun>

public class FileRunIterator<K extends PostingInRun>
extends RunIterator

Reads runs of flushed term posting lists by reading them from files.

Since:

2.2

Author:

Craig Macdonald

Field Summary

Fields

Modifier and Type	Field and Description
protected int	currentPosting Current Posting List number
protected int	maxSize max number of pointers any term in the run
protected BitIn	mbis Input stream for reading the run.
protected int	size Number of postings in this run
protected DataInputStream	stringDIS Input stream for reading the terms.

Fields inherited from class org.terrier.structures.indexing.singlepass.RunIterator

flushNo, numberOfFields, posting, postingClass

Constructor Summary

Constructors

Constructor and Description
FileRunIterator(String filename, String termsFile, int runNo, Class<? extends PostingInRun> _postingInRunClass, int fieldCount) Load a new run from files.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes the run files being processed
boolean	hasNext() Are there more posting to process in this run?
PostingInRun	next() Move to the next posting in this run
String	readString() Reads the String identifying a term from the underlying stream.
int	readTermFrequency() Reads the term frequency for the current posting, and aligns the stream.

Methods inherited from class org.terrier.structures.indexing.singlepass.RunIterator

createPosting, current, getRunNo, remove

Methods inherited from class java.lang.Object

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

Field Detail

mbis

protected BitIn mbis

Input stream for reading the run.

stringDIS

protected DataInputStream stringDIS

Input stream for reading the terms.

size

protected int size

Number of postings in this run

currentPosting

protected int currentPosting

Current Posting List number

maxSize

protected int maxSize

max number of pointers any term in the run

Constructor Detail

FileRunIterator

public FileRunIterator(String filename,
               String termsFile,
               int runNo,
               Class<? extends PostingInRun> _postingInRunClass,
               int fieldCount)
                throws Exception

Load a new run from files.

Parameters:

filename - the filename of the file containing the posting lists

termsFile - the filename of the file containing the term names

runNo - the number of this run

_postingInRunClass - the class that all postings in this class have

Throws:

Exception

Method Detail

close

public void close()
           throws IOException

Closes the run files being processed

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class RunIterator

Throws:

IOException

hasNext

public boolean hasNext()

Are there more posting to process in this run?

Specified by:

hasNext in interface Iterator<PostingInRun>

Specified by:

hasNext in class RunIterator

next

public PostingInRun next()

Move to the next posting in this run

Specified by:

next in interface Iterator<PostingInRun>

Specified by:

next in class RunIterator

readTermFrequency

public int readTermFrequency()
                      throws IOException

Reads the term frequency for the current posting, and aligns the stream.

Returns:

the frequency read.

Throws:

IOException - if an I/O error occurs.

readString

public String readString()
                  throws IOException

Reads the String identifying a term from the underlying stream.

Returns:

the String with the term.

Throws:

IOException - if an I/O error occurs.