it.unimi.di.mg4j.document
Class CompositeDocumentFactory

java.lang.Object
  it.unimi.di.mg4j.document.AbstractDocumentFactory
      it.unimi.di.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

protected class

CompositeDocumentFactory.CompositeDocument A document obtained by composition of documents of underyling factories.

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

DocumentFactory.FieldType

Constructor Summary

protected

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

Method Summary

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.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