Package it.unimi.di.big.mg4j.document

Class ConcatenatedDocumentSequence

java.lang.Object

it.unimi.di.big.mg4j.document.AbstractDocumentSequence

it.unimi.di.big.mg4j.document.ConcatenatedDocumentSequence

All Implemented Interfaces:

DocumentSequence, SafelyCloseable, Closeable, AutoCloseable

public class ConcatenatedDocumentSequence
extends AbstractDocumentSequence

A document sequence exhibiting a list of underlying document sequences, called segments, as a single sequence. The underlying sequences are (virtually) concatenated—that is, the first document of the second sequence is renumbered to the size of the first sequence, and so on. All underlying sequences must use the same factory class.

Author:

Paolo Boldi, Sebastiano Vigna

Constructor Summary

Constructors

Modifier	Constructor	Description
	ConcatenatedDocumentSequence(DocumentSequence... sequence)	Creates a new concatenated document sequence using giving component sequences.
	ConcatenatedDocumentSequence(String... sequenceName)	Creates a new concatenated document sequence using giving serialised component sequences.
protected	ConcatenatedDocumentSequence(String[] sequenceName, DocumentSequence[] sequence)	Creates a new concatenated document sequence using giving component sequences.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes this document sequence, releasing all resources.
DocumentFactory	factory()	Returns the factory used by this sequence.
void	filename(CharSequence filename)	Does nothing.
DocumentIterator	iterator()	Returns an iterator over the sequence of documents.

Methods inherited from class it.unimi.di.big.mg4j.document.AbstractDocumentSequence

finalize, load

Methods inherited from class java.lang.Object

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

Constructor Detail

ConcatenatedDocumentSequence

public ConcatenatedDocumentSequence(DocumentSequence... sequence)
                             throws IOException

Creates a new concatenated document sequence using giving component sequences.

Parameters:

sequence - a list of component sequences.

Throws:

IOException

ConcatenatedDocumentSequence

public ConcatenatedDocumentSequence(String... sequenceName)
                             throws IOException

Creates a new concatenated document sequence using giving serialised component sequences.

Parameters:

sequenceName - a list of serialised component sequences.

Throws:

IOException

ConcatenatedDocumentSequence

protected ConcatenatedDocumentSequence(String[] sequenceName,
                                       DocumentSequence[] sequence)
                                throws IOException

Creates a new concatenated document sequence using giving component sequences.

Parameters:

sequenceName -

sequence - a list of component sequences.

Throws:

IOException

Method Detail

filename

public void filename(CharSequence filename)

Description copied from class: AbstractDocumentSequence

Does nothing.

Specified by:

filename in interface DocumentSequence

Overrides:

filename in class AbstractDocumentSequence

Parameters:

filename - the filename of this document sequence.

factory

public DocumentFactory factory()

Description copied from interface: DocumentSequence

Returns the factory used by this sequence.

Every document sequence is based on a document factory that transforms raw bytes into a sequence of characters. The factory contains useful information such as the number of fields.

Returns:

the factory used by this sequence.

close

public void close()
           throws IOException

Description copied from interface: DocumentSequence

Closes this document sequence, releasing all resources.

You should always call this method after having finished with this document sequence. Implementations are invited to call this method in a finaliser as a safety net (even better, implement SafelyCloseable), but since there is no guarantee as to when finalisers are invoked, you should not depend on this behaviour.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in interface DocumentSequence

Overrides:

close in class AbstractDocumentSequence

Throws:

IOException

iterator

public DocumentIterator iterator()
                          throws IOException

Description copied from interface: DocumentSequence

Returns an iterator over the sequence of documents.

Warning: this method can be safely called just one time. For instance, implementations based on standard input will usually throw an exception if this method is called twice.

Implementations may decide to override this restriction (in particular, if they implement DocumentCollection). Usually, however, it is not possible to obtain two iterators at the same time on a collection.

Returns:

an iterator over the sequence of documents.

Throws:

IOException

See Also:

DocumentCollection