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

Class AbstractDocumentCollection

java.lang.Object

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

it.unimi.di.big.mg4j.document.AbstractDocumentCollection

All Implemented Interfaces:

DocumentCollection, DocumentSequence, SafelyCloseable, FlyweightPrototype<DocumentCollection>, Closeable, AutoCloseable

Direct Known Subclasses:

ConcatenatedDocumentCollection, FileSetDocumentCollection, JavamailDocumentCollection, JdbcDocumentCollection, SimpleCompressedDocumentCollection, SubDocumentCollection, TRECDocumentCollection, WikipediaDocumentCollection, ZipDocumentCollection

public abstract class AbstractDocumentCollection
extends AbstractDocumentSequence
implements DocumentCollection, SafelyCloseable

An abstract, safely closeable implementation of a document collection.

This class provides ready-made implementation of the iterator() method. Concrete subclasses are encouraged to provide optimised, reuse-oriented versions of the iterator() method. Note that since this implementation uses document() to implement the iterator, creating two iterators concurrently will usually lead to unpredictable results.

As a commodity, the ensureDocumentIndex(long) method can be called whenever it is necessary to check that a document index is not out of range.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	AbstractDocumentCollection.PropertyKeys	Symbolic names for common properties of a DocumentCollection.

Field Summary

Fields inherited from interface it.unimi.di.big.mg4j.document.DocumentCollection

DEFAULT_EXTENSION

Constructor Summary

Constructors

Constructor	Description
AbstractDocumentCollection()

Method Summary

Modifier and Type	Method	Description
protected void	ensureDocumentIndex(long index)	Checks that the index is correct (between 0, inclusive, and DocumentCollection.size(), exclusive), and throws an IndexOutOfBoundsException if the index is not correct.
DocumentIterator	iterator()	Returns an iterator over the sequence of documents.
static void	main(String[] arg)
static void	printAllDocuments(DocumentSequence seq)	Prints all documents in a given sequence.
String	toString()

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

close, filename, finalize, load

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unimi.di.big.mg4j.document.DocumentCollection

copy, document, metadata, size, stream

Methods inherited from interface it.unimi.di.big.mg4j.document.DocumentSequence

close, factory, filename

Constructor Detail

AbstractDocumentCollection

public AbstractDocumentCollection()

Method Detail

ensureDocumentIndex

protected void ensureDocumentIndex(long index)

Checks that the index is correct (between 0, inclusive, and DocumentCollection.size(), exclusive), and throws an IndexOutOfBoundsException if the index is not correct.

Parameters:

index - the index to be checked.

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.

Specified by:

iterator in interface DocumentSequence

Returns:

an iterator over the sequence of documents.

Throws:

IOException

See Also:

DocumentCollection

toString

public String toString()

Overrides:

toString in class Object

printAllDocuments

public static void printAllDocuments(DocumentSequence seq)
                              throws IOException

Prints all documents in a given sequence.

Parameters:

seq - the sequence.

Throws:

IOException

main

public static void main(String[] arg)
                 throws Exception

Throws:

Exception