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

Class CompositeDocumentFactory

java.lang.Object

it.unimi.di.big.mg4j.document.AbstractDocumentFactory

it.unimi.di.big.mg4j.document.CompositeDocumentFactory

All Implemented Interfaces:

DocumentFactory, FlyweightPrototype<DocumentFactory>, Serializable

public class CompositeDocumentFactory
extends AbstractDocumentFactory

A composite factory that passes the input stream to a sequence of factories in turn.

Factories can be composed. A composite factory will pass in turn the input stream given to getDocument(InputStream, Reference2ObjectMap) to the underlying factories, after calling InputStream.reset(). Document sequences using composite factories must pass to getDocument(InputStream, Reference2ObjectMap) a MultipleInputStream that can be reset enough times.

Note that in general composite factories support only sequential access to field content (albeit skipping items is allowed).

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	CompositeDocumentFactory.CompositeDocument	A document obtained by composition of documents of underyling factories.

Nested classes/interfaces inherited from interface it.unimi.di.big.mg4j.document.DocumentFactory

DocumentFactory.FieldType

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	CompositeDocumentFactory(DocumentFactory[] documentFactory, String[] fieldName)	Creates a new composite document factory using the factories in a given array.

Method Summary

Modifier and Type	Method	Description
CompositeDocumentFactory	copy()
int	fieldIndex(String fieldName)	Returns the index of a field, given its symbolic name.
String	fieldName(int field)	Returns the symbolic name of a field.
DocumentFactory.FieldType	fieldType(int field)	Returns the type of a field.
Document	getDocument(InputStream rawContent, Reference2ObjectMap<Enum<?>,Object> metadata)	Returns the document obtained by parsing the given byte stream.
static DocumentFactory	getFactory(DocumentFactory... documentFactory)	Returns a document factory composing the given document factories.
static DocumentFactory	getFactory(DocumentFactory[] documentFactory, String[] fieldName)	Returns a document factory composing the given document factories.
int	numberOfFields()	Returns the number of fields present in the documents produced by this factory.

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

ensureFieldIndex, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

CompositeDocumentFactory

protected CompositeDocumentFactory(DocumentFactory[] documentFactory,
                                   String[] fieldName)

Creates a new composite document factory using the factories in a given array.

Parameters:

documentFactory - an array of document factories that will composed.

fieldName - an array of names for the resulting field, or null.

Method Detail

copy

public CompositeDocumentFactory copy()

getFactory

public static DocumentFactory getFactory(DocumentFactory[] documentFactory,
                                         String[] fieldName)

Returns a document factory composing the given document factories.

By passing an optional array of field names, it is possible to rename the fields of the composing factories.

Parameters:

documentFactory - an array of document factories that will composed.

fieldName - an array of names for the resulting field, or null.

Returns:

a composed document factory (the first element of the argument, for arguments of length 1).

getFactory

public static DocumentFactory getFactory(DocumentFactory... documentFactory)

Returns a document factory composing the given document factories.

Parameters:

documentFactory - document factories that will composed.

Returns:

a composed document factory (the first element of the argument, for arguments of length 1).

numberOfFields

public int numberOfFields()

Description copied from interface: DocumentFactory

Returns the number of fields present in the documents produced by this factory.

Returns:

the number of fields present in the documents produced by this factory.

fieldName

public String fieldName(int field)

Description copied from interface: DocumentFactory

Returns the symbolic name of a field.

Parameters:

field - the index of a field (between 0 inclusive and DocumentFactory.numberOfFields() exclusive}).

Returns:

the symbolic name of the field-th field.

fieldIndex

public int fieldIndex(String fieldName)

Description copied from interface: DocumentFactory

Returns the index of a field, given its symbolic name.

Parameters:

fieldName - the name of a field of this factory.

Returns:

the corresponding index, or -1 if there is no field with name fieldName.

fieldType

public DocumentFactory.FieldType fieldType(int field)

Description copied from interface: DocumentFactory

Returns the type of a field.

The possible types are defined in DocumentFactory.FieldType.

Parameters:

field - the index of a field (between 0 inclusive and DocumentFactory.numberOfFields() exclusive}).

Returns:

the type of the field-th field.

getDocument

public Document getDocument(InputStream rawContent,
                            Reference2ObjectMap<Enum<?>,Object> metadata)
                     throws IOException

Description copied from interface: DocumentFactory

Returns the document obtained by parsing the given byte stream.

The parameter metadata actually replaces the lack of a simple keyword-based parameter-passing system in Java. This method might take several different type of “suggestions” which have been collected by the collection: typically, the document title, a URI representing the document, its MIME type, its encoding and so on. Some of this information might be set by default (as it happens, for instance, in a PropertyBasedDocumentFactory). Implementations of this method must consult the metadata provided by the collection, possibly complete them with default factory metadata, and proceed to the document construction.

Parameters:

rawContent - the raw content from which the document should be extracted; it must not be closed, as resource management is a responsibility of the DocumentCollection.

metadata - a map from enums (e.g., keys taken in PropertyBasedDocumentFactory) to various kind of objects.

Returns:

the document obtained by parsing the given character sequence.

Throws:

IOException