org.terrier.structures
Class BitPostingIndexInputStream

java.lang.Object
  org.terrier.structures.BitPostingIndexInputStream

All Implemented Interfaces:

Closeable, Iterator<IterablePosting>, PostingIndexInputStream, Skipable

Direct Known Subclasses:

DirectIndexInputStream, InvertedIndexInputStream

public class BitPostingIndexInputStream
extends Object
implements PostingIndexInputStream, Skipable

Input stream for a bit posting index.

Field Summary

protected int	currentEntryCount
protected byte	currentFile
protected BitIndexPointer	currentPointer
protected DocumentIndex	doi
protected int	entriesSkipped
protected int	fieldCount
protected BitIn	file The gamma compressed file containing the terms.
protected byte	fileCount
protected Index	index
protected static org.apache.log4j.Logger	logger
protected Iterator<? extends BitIndexPointer>	pointerList the lexicon input stream providing the offsets
protected Constructor<? extends IterablePosting>	postingConstructor
protected Class<? extends IterablePosting>	postingIteratorClass
protected String	structureName

Constructor Summary

BitPostingIndexInputStream(Index _index, String _structureName, Iterator<? extends BitIndexPointer> _pointerList, Class<? extends IterablePosting> _postingIteratorClass)
Constructs an instance of BitPostingIndexInputStream.

Method Summary

protected BitIndexPointer	_next()
void	close()
Pointer	getCurrentPointer() Returns the pointer associated with the current postings being accessed
protected DocumentIndex	getDocumentIndex(BitIndexPointer pointer)
int	getEntriesSkipped() Returns the number of entries that were skipped during a call to the next().
static String	getFilename(Index _index, String structureName, byte fileCount, byte fileId) Returns filename
static String	getFilename(String path, String prefix, String structureName, byte fileCount, byte fileId) Return filename
IterablePosting	getNextPostings() Return the next IterablePosting object, or null if none defined.
int	getNumberOfCurrentPostings() Returns the number of postings in the current IterablePosting object
BitFilePosition	getPos() Get the file position
boolean	hasNext()
protected IterablePosting	loadPostingIterator(BitIndexPointer pointer)
IterablePosting	next()
void	print() Print a list of the postings to standard out
void	remove() Not supported
void	skip(int numEntries) Skip forward the specified number of entries.

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected static final org.apache.log4j.Logger logger

pointerList

protected final Iterator<? extends BitIndexPointer> pointerList

the lexicon input stream providing the offsets

file

protected BitIn file

The gamma compressed file containing the terms.

postingIteratorClass

protected Class<? extends IterablePosting> postingIteratorClass

postingConstructor

protected Constructor<? extends IterablePosting> postingConstructor

currentEntryCount

protected int currentEntryCount

currentPointer

protected BitIndexPointer currentPointer

fieldCount

protected int fieldCount

entriesSkipped

protected int entriesSkipped

fileCount

protected byte fileCount

currentFile

protected byte currentFile

index

protected Index index

doi

protected DocumentIndex doi

structureName

protected String structureName

Constructor Detail

BitPostingIndexInputStream

public BitPostingIndexInputStream(Index _index,
                                  String _structureName,
                                  Iterator<? extends BitIndexPointer> _pointerList,
                                  Class<? extends IterablePosting> _postingIteratorClass)
                           throws IOException

Constructs an instance of BitPostingIndexInputStream.

Parameters:

_index -

_structureName -

_pointerList -

_postingIteratorClass -

Throws:

IOException

Method Detail

getFilename

public static String getFilename(String path,
                                 String prefix,
                                 String structureName,
                                 byte fileCount,
                                 byte fileId)

Return filename

Parameters:

path -

prefix -

structureName -

fileCount -

fileId -

Returns:

filename

getFilename

public static String getFilename(Index _index,
                                 String structureName,
                                 byte fileCount,
                                 byte fileId)

Returns filename

Parameters:

_index -

structureName -

fileCount -

fileId -

Returns:

filename

getPos

public BitFilePosition getPos()

Get the file position

skip

public void skip(int numEntries)
          throws IOException

Skip forward the specified number of entries. Should be followed by a next() call.

Specified by:

skip in interface Skipable

Parameters:

numEntries - number of entries to skip

Throws:

IOException - if an IO problem occurs.

getNumberOfCurrentPostings

public int getNumberOfCurrentPostings()

Returns the number of postings in the current IterablePosting object

Specified by:

getNumberOfCurrentPostings in interface PostingIndexInputStream

getNextPostings

public IterablePosting getNextPostings()
                                throws IOException

Return the next IterablePosting object, or null if none defined. Use this method instead of hasNext() and next().

Specified by:

getNextPostings in interface PostingIndexInputStream

Returns:

IterablePosting postings for next object

Throws:

IOException - if an I/O problem occurs.

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<IterablePosting>

_next

protected BitIndexPointer _next()

next

public IterablePosting next()

Specified by:

next in interface Iterator<IterablePosting>

getEntriesSkipped

public int getEntriesSkipped()

Returns the number of entries that were skipped during a call to the next().

Specified by:

getEntriesSkipped in interface PostingIndexInputStream

Returns:

int the number of entries skipped.

loadPostingIterator

protected IterablePosting loadPostingIterator(BitIndexPointer pointer)
                                       throws IOException

Throws:

IOException

getDocumentIndex

protected DocumentIndex getDocumentIndex(BitIndexPointer pointer)

print

public void print()

Print a list of the postings to standard out

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Throws:

IOException

remove

public void remove()

Not supported

Specified by:

remove in interface Iterator<IterablePosting>

getCurrentPointer

public Pointer getCurrentPointer()

Returns the pointer associated with the current postings being accessed

Specified by:

getCurrentPointer in interface PostingIndexInputStream