/*
 * Copyright (c) 2003, 2021 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package jakarta.xml.bind;

import jakarta.xml.bind.annotation.adapters.XmlAdapter;
import jakarta.xml.bind.attachment.AttachmentUnmarshaller;
import javax.xml.validation.Schema;
import java.io.Reader;

/**
 * The {@code Unmarshaller} class governs the process of deserializing XML
 * data into newly created Java content trees, optionally validating the XML
 * data as it is unmarshalled.  It provides an overloading of unmarshal methods
 * for many different input kinds.
 *
 * <p>
 * Unmarshalling from a File:
 * <blockquote>
 *    <pre>
 *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
 *       Unmarshaller u = jc.createUnmarshaller();
 *       Object o = u.unmarshal( new File( "nosferatu.xml" ) );
 *    </pre>
 * </blockquote>
 *
 *
 * <p>
 * Unmarshalling from an InputStream:
 * <blockquote>
 *    <pre>
 *       InputStream is = new FileInputStream( "nosferatu.xml" );
 *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
 *       Unmarshaller u = jc.createUnmarshaller();
 *       Object o = u.unmarshal( is );
 *    </pre>
 * </blockquote>
 *
 * <p>
 * Unmarshalling from a URL:
 * <blockquote>
 *    <pre>
 *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
 *       Unmarshaller u = jc.createUnmarshaller();
 *       URL url = new URL( "http://beaker.east/nosferatu.xml" );
 *       Object o = u.unmarshal( url );
 *    </pre>
 * </blockquote>
 *
 * <p>
 * Unmarshalling from a StringBuffer using a
 * {@code javax.xml.transform.stream.StreamSource}:
 * <blockquote>
 *    <pre>{@code
 *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
 *       Unmarshaller u = jc.createUnmarshaller();
 *       StringBuffer xmlStr = new StringBuffer( "<?xml version="1.0"?>..." );
 *       Object o = u.unmarshal( new StreamSource( new StringReader( xmlStr.toString() ) ) );
 *    }</pre>
 * </blockquote>
 *
 * <p>
 * Unmarshalling from a {@code org.w3c.dom.Node}:
 * <blockquote>
 *    <pre>
 *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
 *       Unmarshaller u = jc.createUnmarshaller();
 *
 *       DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
 *       dbf.setNamespaceAware(true);
 *       DocumentBuilder db = dbf.newDocumentBuilder();
 *       Document doc = db.parse(new File( "nosferatu.xml"));

 *       Object o = u.unmarshal( doc );
 *    </pre>
 * </blockquote>
 *
 * <p>
 * Unmarshalling from a {@code javax.xml.transform.sax.SAXSource} using a
 * client specified validating SAX2.0 parser:
 * <blockquote>
 *    <pre>
 *       // configure a validating SAX2.0 parser (Xerces2)
 *       static final String JAXP_SCHEMA_LANGUAGE =
 *           "http://java.sun.com/xml/jaxp/properties/schemaLanguage";
 *       static final String JAXP_SCHEMA_LOCATION =
 *           "http://java.sun.com/xml/jaxp/properties/schemaSource";
 *       static final String W3C_XML_SCHEMA =
 *           "http://www.w3.org/2001/XMLSchema";
 *
 *       System.setProperty( "javax.xml.parsers.SAXParserFactory",
 *                           "org.apache.xerces.jaxp.SAXParserFactoryImpl" );
 *
 *       SAXParserFactory spf = SAXParserFactory.newInstance();
 *       spf.setNamespaceAware(true);
 *       spf.setValidating(true);
 *       SAXParser saxParser = spf.newSAXParser();
 *
 *       try {
 *           saxParser.setProperty(JAXP_SCHEMA_LANGUAGE, W3C_XML_SCHEMA);
 *           saxParser.setProperty(JAXP_SCHEMA_LOCATION, "http://....");
 *       } catch (SAXNotRecognizedException x) {
 *           // exception handling omitted
 *       }
 *
 *       XMLReader xmlReader = saxParser.getXMLReader();
 *       SAXSource source =
 *           new SAXSource( xmlReader, new InputSource( "http://..." ) );
 *
 *       // Setup Jakarta XML Binding to unmarshal
 *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
 *       Unmarshaller u = jc.createUnmarshaller();
 *       ValidationEventCollector vec = new ValidationEventCollector();
 *       u.setEventHandler( vec );
 *
 *       // turn off the Jakarta XML Binding provider's default validation mechanism to
 *       // avoid duplicate validation
 *       u.setValidating( false )
 *
 *       // unmarshal
 *       Object o = u.unmarshal( source );
 *
 *       // check for events
 *       if( vec.hasEvents() ) {
 *          // iterate over events
 *       }
 *    </pre>
 * </blockquote>
 *
 * <p>
 * Unmarshalling from a StAX XMLStreamReader:
 * <blockquote>
 *    <pre>
 *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
 *       Unmarshaller u = jc.createUnmarshaller();
 *
 *       javax.xml.stream.XMLStreamReader xmlStreamReader =
 *           javax.xml.stream.XMLInputFactory().newInstance().createXMLStreamReader( ... );
 *
 *       Object o = u.unmarshal( xmlStreamReader );
 *    </pre>
 * </blockquote>
 *
 * <p>
 * Unmarshalling from a StAX XMLEventReader:
 * <blockquote>
 *    <pre>
 *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
 *       Unmarshaller u = jc.createUnmarshaller();
 *
 *       javax.xml.stream.XMLEventReader xmlEventReader =
 *           javax.xml.stream.XMLInputFactory().newInstance().createXMLEventReader( ... );
 *
 *       Object o = u.unmarshal( xmlEventReader );
 *    </pre>
 * </blockquote>
 *
 * <p>
 * <a id="unmarshalEx"></a>
 * <b>Unmarshalling XML Data</b><br>
 * <blockquote>
 * Unmarshalling can deserialize XML data that represents either an entire XML document
 * or a subtree of an XML document. Typically, it is sufficient to use the
 * unmarshalling methods described by
 * <a href="#unmarshalGlobal">Unmarshal root element that is declared globally</a>.
 * These unmarshal methods utilize {@link JAXBContext}'s mapping of global XML element
 * declarations and type definitions to Jakarta XML Binding mapped classes to initiate the
 * unmarshalling of the root element of  XML data.  When the {@link JAXBContext}'s
 * mappings are not sufficient to unmarshal the root element of XML data,
 * the application can assist the unmarshalling process by using the
 * <a href="#unmarshalByDeclaredType">unmarshal by declaredType methods</a>.
 * These methods are useful for unmarshalling XML data where
 * the root element corresponds to a local element declaration in the schema.
 * </blockquote>
 *
 * <blockquote>
 * An unmarshal method never returns null. If the unmarshal process is unable to unmarshal
 * the root of XML content to a Jakarta XML Binding mapped object, a fatal error is reported that
 * terminates processing by throwing JAXBException.
 * </blockquote>
 *
 * <p>
 * <a id="unmarshalGlobal"></a>
 * <b>Unmarshal a root element that is globally declared</b><br>
 * <blockquote>
 * The unmarshal methods that do not have an {@code declaredType} parameter use
 * {@link JAXBContext} to unmarshal the root element of an XML data. The {@link JAXBContext}
 * instance is the one that was used to create this {@code Unmarshaller}. The {@link JAXBContext}
 * instance maintains a mapping of globally declared XML element and type definition names to
 * Jakarta XML Binding mapped classes. The unmarshal method checks if {@link JAXBContext} has a mapping
 * from the root element's XML name and/or {@code @xsi:type} to a Jakarta XML Binding mapped class.  If it does, it umarshalls the
 * XML data using the appropriate Jakarta XML Binding mapped class. Note that when the root element name is unknown and the root
 * element has an {@code @xsi:type}, the XML data is unmarshalled
 * using that Jakarta XML Binding mapped class as the value of a {@link JAXBElement}.
 * When the {@link JAXBContext} object does not have a mapping for the root element's name
 * nor its {@code @xsi:type}, if it exists,
 * then the unmarshal operation will abort immediately by throwing a {@link UnmarshalException
 * UnmarshalException}. This exception scenario can be worked around by using the unmarshal by
 * declaredType methods described in the next subsection.
 * </blockquote>
 *
 * <p>
 * <a id="unmarshalByDeclaredType"></a>
 * <b>Unmarshal by Declared Type</b><br>
 * <blockquote>
 * The unmarshal methods with a {@code declaredType} parameter enable an
 * application to deserialize a root element of XML data, even when
 * there is no mapping in {@link JAXBContext} of the root element's XML name.
 * The unmarshaller unmarshals the root element using the application provided
 * mapping specified as the {@code declaredType} parameter.
 * Note that even when the root element's element name is mapped by {@link JAXBContext},
 * the {@code declaredType} parameter overrides that mapping for
 * deserializing the root element when using these unmarshal methods.
 * Additionally, when the root element of XML data has an {@code xsi:type} attribute and
 * that attribute's value references a type definition that is mapped
 * to a Jakarta XML Binding mapped class by {@link JAXBContext}, that the root
 * element's {@code xsi:type} attribute takes
 * precedence over the unmarshal methods {@code declaredType} parameter.
 * These methods always return a {@code JAXBElement<declaredType>}
 * instance. The table below shows how the properties of the returned JAXBElement
 * instance are set.
 *
 * <a id="unmarshalDeclaredTypeReturn"></a>
 *   <table class="striped">
 *   <caption>Unmarshal By Declared Type returned JAXBElement</caption>
 *   <thead>
 *     <tr>
 *       <th scope="col">JAXBElement Property</th>
 *       <th scope="col">Value</th>
 *       </tr>
 *     <tr>
 *       <th scope="col">name</th>
 *       <th scope="col">{@code xml element name}</th>
 *     </tr>
 *   </thead>
 *   <tbody>
 *     <tr>
 *       <th scope="row">value</th>
 *       <td>{@code instanceof declaredType}</td>
 *     </tr>
 *     <tr>
 *       <th scope="row">declaredType</th>
 *       <td>unmarshal method {@code declaredType} parameter</td>
 *     </tr>
 *     <tr>
 *       <th scope="row">scope</th>
 *       <td>{@code null} <i>(actual scope is unknown)</i></td>
 *     </tr>
 *   </tbody>
 *  </table>
 * </blockquote>
 *
 * <p>
 * The following is an example of
 * <a href="#unmarshalByDeclaredType">unmarshal by declaredType method</a>.
 * <p>
 * Unmarshal by declaredType from a {@code org.w3c.dom.Node}:
 * <blockquote>
 *    <pre>{@code
 *       Schema fragment for example
 *       <xs:schema>
 *          <xs:complexType name="FooType">...<\xs:complexType>
 *          <!-- global element declaration "PurchaseOrder" -->
 *          <xs:element name="PurchaseOrder">
 *              <xs:complexType>
 *                 <xs:sequence>
 *                    <!-- local element declaration "foo" -->
 *                    <xs:element name="foo" type="FooType"/>
 *                    ...
 *                 </xs:sequence>
 *              </xs:complexType>
 *          </xs:element>
 *       </xs:schema>
 *
 *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
 *       Unmarshaller u = jc.createUnmarshaller();
 *
 *       DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
 *       dbf.setNamespaceAware(true);
 *       DocumentBuilder db = dbf.newDocumentBuilder();
 *       Document doc = db.parse(new File( "nosferatu.xml"));
 *       Element  fooSubtree = ...; // traverse DOM till reach xml element foo, constrained by a
 *                                  // local element declaration in schema.
 *
 *       // FooType is the Jakarta XML Binding mapping of the type of local element declaration foo.
 *       JAXBElement<FooType> foo = u.unmarshal( fooSubtree, FooType.class);
 *    }</pre>
 * </blockquote>
 *
 * <p>
 * <b>Support for SAX2.0 Compliant Parsers</b><br>
 * <blockquote>
 * A client application has the ability to select the SAX2.0 compliant parser
 * of their choice.  If a SAX parser is not selected, then the Jakarta XML Binding Provider's
 * default parser will be used.  Even though the Jakarta XML Binding Provider's default parser
 * is not required to be SAX2.0 compliant, all providers are required to allow
 * a client application to specify their own SAX2.0 parser.  Some providers may
 * require the client application to specify the SAX2.0 parser at schema compile
 * time. See {@link #unmarshal(javax.xml.transform.Source) unmarshal(Source)}
 * for more detail.
 * </blockquote>
 *
 * <p>
 * <b>Validation and Well-Formedness</b><br>
 * <blockquote>
 * <p>
 * A client application can enable or disable JAXP validation
 * mechanism via the {@code setSchema(javax.xml.validation.Schema)} API.
 * Sophisticated clients can specify their own validating SAX 2.0 compliant
 * parser and bypass the JAXP validation mechanism using the
 * {@link #unmarshal(javax.xml.transform.Source) unmarshal(Source)}  API.
 *
 * <p>
 * Since unmarshalling invalid XML content is defined in Jakarta XML Binding,
 * the Unmarshaller default validation event handler was made more lenient
 * than in JAXB 1.0.  When schema-derived code generated
 * by JAXB 1.0 binding compiler is registered with {@link JAXBContext},
 * the default unmarshal validation handler is
 * {@link jakarta.xml.bind.helpers.DefaultValidationEventHandler} and it
 * terminates the marshal  operation after encountering either a fatal error or an error.
 * For a Jakarta XML Binding client application, there is no explicitly defined default
 * validation handler and the default event handling only
 * terminates the unmarshal operation after encountering a fatal error.
 *
 * </blockquote>
 *
 * <p>
 * <a id="supportedProps"></a>
 * <b>Supported Properties</b><br>
 * <blockquote>
 * <p>
 * There currently are not any properties required to be supported by all
 * Jakarta XML Binding Providers on Unmarshaller.  However, some providers may support
 * their own set of provider specific properties.
 * </blockquote>
 *
 * <p>
 * <a id="unmarshalEventCallback"></a>
 * <b>Unmarshal Event Callbacks</b><br>
 * <blockquote>
 * The {@link Unmarshaller} provides two styles of callback mechanisms
 * that allow application specific processing during key points in the
 * unmarshalling process.  In 'class defined' event callbacks, application
 * specific code placed in Jakarta XML Binding mapped classes is triggered during
 * unmarshalling.  'External listeners' allow for centralized processing
 * of unmarshal events in one callback method rather than by type event callbacks.
 * <p>
 * 'Class defined' event callback methods allow any Jakarta XML Binding mapped class to specify
 * its own specific callback methods by defining methods with the following method signature:
 * <blockquote>
 * <pre>
 *   // This method is called immediately after the object is created and before the unmarshalling of this
 *   // object begins. The callback provides an opportunity to initialize JavaBean properties prior to unmarshalling.
 *   void beforeUnmarshal(Unmarshaller, Object parent);
 *
 *   //This method is called after all the properties (except IDREF) are unmarshalled for this object,
 *   //but before this object is set to the parent object.
 *   void afterUnmarshal(Unmarshaller, Object parent);
 * </pre>
 * </blockquote>
 * The class defined callback methods should be used when the callback method requires
 * access to non-public methods and/or fields of the class.
 * <p>
 * The external listener callback mechanism enables the registration of a {@link Listener}
 * instance with an {@link Unmarshaller#setListener(Listener)}. The external listener receives all callback events,
 * allowing for more centralized processing than per class defined callback methods.  The external listener
 * receives events when unmarshalling process is marshalling to a Jakarta XML Binding element or to Jakarta XML Binding mapped class.
 * <p>
 * The 'class defined' and external listener event callback methods are independent of each other,
 * both can be called for one event.  The invocation ordering when both listener callback methods exist is
 * defined in {@link Listener#beforeUnmarshal(Object, Object)} and {@link Listener#afterUnmarshal(Object, Object)}.
* <p>
 * An event callback method throwing an exception terminates the current unmarshal process.
 *
 * </blockquote>
 *
 * @author <ul><li>Ryan Shoemaker, Sun Microsystems, Inc.</li><li>Kohsuke Kawaguchi, Sun Microsystems, Inc.</li><li>Joe Fialli, Sun Microsystems, Inc.</li></ul>
 * @see JAXBContext
 * @see Marshaller
 * @since 1.6, JAXB 1.0
 */
public interface Unmarshaller {

    /**
     * Unmarshal XML data from the specified file and return the resulting
     * content tree.
     *
     * <p>
     * Implements <a href="#unmarshalGlobal">Unmarshal Global Root Element</a>.
     *
     * @param f the file to unmarshal XML data from
     * @return the newly created root object of the java content tree
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If the file parameter is null
     */
    public Object unmarshal( java.io.File f ) throws JAXBException;

    /**
     * Unmarshal XML data from the specified InputStream and return the
     * resulting content tree.  Validation event location information may
     * be incomplete when using this form of the unmarshal API.
     *
     * <p>
     * Implements <a href="#unmarshalGlobal">Unmarshal Global Root Element</a>.
     *
     * @param is the InputStream to unmarshal XML data from
     * @return the newly created root object of the java content tree
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If the InputStream parameter is null
     */
    public Object unmarshal( java.io.InputStream is ) throws JAXBException;

    /**
     * Unmarshal XML data from the specified Reader and return the
     * resulting content tree.  Validation event location information may
     * be incomplete when using this form of the unmarshal API,
     * because a Reader does not provide the system ID.
     *
     * <p>
     * Implements <a href="#unmarshalGlobal">Unmarshal Global Root Element</a>.
     *
     * @param reader the Reader to unmarshal XML data from
     * @return the newly created root object of the java content tree
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If the InputStream parameter is null
     * @since 1.6, JAXB 2.0
     */
    public Object unmarshal( Reader reader ) throws JAXBException;

    /**
     * Unmarshal XML data from the specified URL and return the resulting
     * content tree.
     *
     * <p>
     * Implements <a href="#unmarshalGlobal">Unmarshal Global Root Element</a>.
     *
     * @param url the url to unmarshal XML data from
     * @return the newly created root object of the java content tree
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If the URL parameter is null
     */
    public Object unmarshal( java.net.URL url ) throws JAXBException;

    /**
     * Unmarshal XML data from the specified SAX InputSource and return the
     * resulting content tree.
     *
     * <p>
     * Implements <a href="#unmarshalGlobal">Unmarshal Global Root Element</a>.
     *
     * @param source the input source to unmarshal XML data from
     * @return the newly created root object of the java content tree
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If the InputSource parameter is null
     */
    public Object unmarshal( org.xml.sax.InputSource source ) throws JAXBException;

    /**
     * Unmarshal global XML data from the specified DOM tree and return the resulting
     * content tree.
     *
     * <p>
     * Implements <a href="#unmarshalGlobal">Unmarshal Global Root Element</a>.
     *
     * @param node
     *      the document/element to unmarshal XML data from.
     *      The caller must support at least Document and Element.
     * @return the newly created root object of the java content tree
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If the Node parameter is null
     * @see #unmarshal(org.w3c.dom.Node, Class)
     */
    public Object unmarshal( org.w3c.dom.Node node ) throws JAXBException;

    /**
     * Unmarshal XML data by Jakarta XML Binding mapped {@code declaredType}
     * and return the resulting content tree.
     *
     * <p>
     * Implements <a href="#unmarshalByDeclaredType">Unmarshal by Declared Type</a>
     *
     * @param node
     *      the document/element to unmarshal XML data from.
     *      The caller must support at least Document and Element.
     * @param declaredType
     *      appropriate Jakarta XML Binding mapped class to hold {@code node}'s XML data.
     *
     * @return <a href="#unmarshalDeclaredTypeReturn">JAXBElement</a> representation of {@code node}
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If any parameter is null
     * @since 1.6, JAXB 2.0
     */
    public <T> JAXBElement<T> unmarshal( org.w3c.dom.Node node, Class<T> declaredType ) throws JAXBException;

    /**
     * Unmarshal XML data from the specified XML Source and return the
     * resulting content tree.
     *
     * <p>
     * Implements <a href="#unmarshalGlobal">Unmarshal Global Root Element</a>.
     *
     * <p>
     * <a id="saxParserPlugable"></a>
     * <b>SAX 2.0 Parser Pluggability</b>
     * <p>
     * A client application can choose not to use the default parser mechanism
     * supplied with their Jakarta XML Binding provider.  Any SAX 2.0 compliant parser can be
     * substituted for the Jakarta XML Binding provider's default mechanism.  To do so, the
     * client application must properly configure a {@code SAXSource} containing
     * an {@code XMLReader} implemented by the SAX 2.0 parser provider.  If the
     * {@code XMLReader} has an {@code org.xml.sax.ErrorHandler} registered
     * on it, it will be replaced by the Jakarta XML Binding Provider so that validation errors
     * can be reported via the {@code ValidationEventHandler} mechanism of
     * Jakarta XML Binding.  If the {@code SAXSource} does not contain an {@code XMLReader},
     * then the Jakarta XML Binding provider's default parser mechanism will be used.
     * <p>
     * This parser replacement mechanism can also be used to replace the Jakarta XML Binding
     * provider's unmarshal-time validation engine.  The client application
     * must properly configure their SAX 2.0 compliant parser to perform
     * validation (as shown in the example above).  Any {@code SAXParserExceptions}
     * encountered by the parser during the unmarshal operation will be
     * processed by the Jakarta XML Binding provider and converted into Jakarta XML Binding
     * {@code ValidationEvent} objects which will be reported back to the
     * client via the {@code ValidationEventHandler} registered with the
     * {@code Unmarshaller}.  <i>Note:</i> specifying a substitute validating
     * SAX 2.0 parser for unmarshalling does not necessarily replace the
     * validation engine used by the Jakarta XML Binding provider for performing on-demand
     * validation.
     * <p>
     * The only way for a client application to specify an alternate parser
     * mechanism to be used during unmarshal is via the
     * {@code unmarshal(SAXSource)} API.  All other forms of the unmarshal
     * method (File, URL, Node, etc) will use the Jakarta XML Binding provider's default
     * parser and validator mechanisms.
     *
     * @param source the XML Source to unmarshal XML data from (providers are
     *        only required to support SAXSource, DOMSource, and StreamSource)
     * @return the newly created root object of the java content tree
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If the Source parameter is null
     * @see #unmarshal(javax.xml.transform.Source, Class)
     */
    public Object unmarshal( javax.xml.transform.Source source )
        throws JAXBException;


    /**
     * Unmarshal XML data from the specified XML Source by {@code declaredType} and return the
     * resulting content tree.
     *
     * <p>
     * Implements <a href="#unmarshalByDeclaredType">Unmarshal by Declared Type</a>
     *
     * <p>
     * See <a href="#saxParserPlugable">SAX 2.0 Parser Pluggability</a>
     *
     * @param source the XML Source to unmarshal XML data from (providers are
     *        only required to support SAXSource, DOMSource, and StreamSource)
     * @param declaredType
     *      appropriate Jakarta XML Binding mapped class to hold {@code source}'s xml root element
     * @return Java content rooted by <a href="#unmarshalDeclaredTypeReturn">JAXBElement</a>
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If any parameter is null
     * @since 1.6, JAXB 2.0
     */
    public <T> JAXBElement<T> unmarshal( javax.xml.transform.Source source, Class<T> declaredType )
        throws JAXBException;

    /**
     * Unmarshal XML data from the specified pull parser and return the
     * resulting content tree.
     *
     * <p>
     * Implements <a href="#unmarshalGlobal">Unmarshal Global Root Element</a>.
     *
     * <p>
     * This method assumes that the parser is on a START_DOCUMENT or
     * START_ELEMENT event.  Unmarshalling will be done from this
     * start event to the corresponding end event.  If this method
     * returns successfully, the {@code reader} will be pointing at
     * the token right after the end event.
     *
     * @param reader
     *      The parser to be read.
     * @return
     *      the newly created root object of the java content tree.
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If the {@code reader} parameter is null
     * @throws IllegalStateException
     *      If {@code reader} is not pointing to a START_DOCUMENT or
     *      START_ELEMENT  event.
     * @since 1.6, JAXB 2.0
     * @see #unmarshal(javax.xml.stream.XMLStreamReader, Class)
     */
    public Object unmarshal( javax.xml.stream.XMLStreamReader reader )
        throws JAXBException;

    /**
     * Unmarshal root element to Jakarta XML Binding mapped {@code declaredType}
     * and return the resulting content tree.
     *
     * <p>
     * This method implements <a href="#unmarshalByDeclaredType">unmarshal by declaredType</a>.
     * <p>
     * This method assumes that the parser is on a START_DOCUMENT or
     * START_ELEMENT event. Unmarshalling will be done from this
     * start event to the corresponding end event.  If this method
     * returns successfully, the {@code reader} will be pointing at
     * the token right after the end event.
     *
     * @param reader
     *      The parser to be read.
     * @param declaredType
     *      appropriate Jakarta XML Binding mapped class to hold {@code reader}'s START_ELEMENT XML data.
     *
     * @return   content tree rooted by <a href="#unmarshalDeclaredTypeReturn">JAXBElement</a> representation
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If any parameter is null
     * @since 1.6, JAXB 2.0
     */
    public <T> JAXBElement<T> unmarshal( javax.xml.stream.XMLStreamReader reader, Class<T> declaredType ) throws JAXBException;

    /**
     * Unmarshal XML data from the specified pull parser and return the
     * resulting content tree.
     *
     * <p>
     * This method is an <a href="#unmarshalGlobal">Unmarshal Global Root method</a>.
     *
     * <p>
     * This method assumes that the parser is on a START_DOCUMENT or
     * START_ELEMENT event.  Unmarshalling will be done from this
     * start event to the corresponding end event.  If this method
     * returns successfully, the {@code reader} will be pointing at
     * the token right after the end event.
     *
     * @param reader
     *      The parser to be read.
     * @return
     *      the newly created root object of the java content tree.
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If the {@code reader} parameter is null
     * @throws IllegalStateException
     *      If {@code reader} is not pointing to a START_DOCUMENT or
     *      START_ELEMENT event.
     * @since 1.6, JAXB 2.0
     * @see #unmarshal(javax.xml.stream.XMLEventReader, Class)
     */
    public Object unmarshal( javax.xml.stream.XMLEventReader reader )
        throws JAXBException;

    /**
     * Unmarshal root element to Jakarta XML Binding mapped {@code declaredType}
     * and return the resulting content tree.
     *
     * <p>
     * This method implements <a href="#unmarshalByDeclaredType">unmarshal by declaredType</a>.
     *
     * <p>
     * This method assumes that the parser is on a START_DOCUMENT or
     * START_ELEMENT event. Unmarshalling will be done from this
     * start event to the corresponding end event.  If this method
     * returns successfully, the {@code reader} will be pointing at
     * the token right after the end event.
     *
     * @param reader
     *      The parser to be read.
     * @param declaredType
     *      appropriate Jakarta XML Binding mapped class to hold {@code reader}'s START_ELEMENT XML data.
     *
     * @return   content tree rooted by <a href="#unmarshalDeclaredTypeReturn">JAXBElement</a> representation
     *
     * @throws JAXBException
     *     If any unexpected errors occur while unmarshalling
     * @throws UnmarshalException
     *     If the {@link ValidationEventHandler ValidationEventHandler}
     *     returns false from its {@code handleEvent} method or the
     *     {@code Unmarshaller} is unable to perform the XML to Java
     *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
     * @throws IllegalArgumentException
     *      If any parameter is null
     * @since 1.6, JAXB 2.0
     */
    public <T> JAXBElement<T> unmarshal( javax.xml.stream.XMLEventReader reader, Class<T> declaredType ) throws JAXBException;

    /**
     * Get an unmarshaller handler object that can be used as a component in
     * an XML pipeline.
     *
     * <p>
     * The Jakarta XML Binding Provider can return the same handler object for multiple
     * invocations of this method. In other words, this method does not
     * necessarily create a new instance of {@code UnmarshallerHandler}. If the
     * application needs to use more than one {@code UnmarshallerHandler}, it
     * should create more than one {@code Unmarshaller}.
     *
     * @return the unmarshaller handler object
     * @see UnmarshallerHandler
     */
    public UnmarshallerHandler getUnmarshallerHandler();

    /**
     * Allow an application to register a {@code ValidationEventHandler}.
     * <p>
     * The {@code ValidationEventHandler} will be called by the Jakarta XML Binding Provider
     * if any validation errors are encountered during calls to any of the
     * unmarshal methods.  If the client application does not register a
     * {@code ValidationEventHandler} before invoking the unmarshal methods,
     * then {@code ValidationEvents} will be handled by the default event
     * handler which will terminate the unmarshal operation after the first
     * error or fatal error is encountered.
     * <p>
     * Calling this method with a null parameter will cause the Unmarshaller
     * to revert back to the default event handler.
     *
     * @param handler the validation event handler
     * @throws JAXBException if an error was encountered while setting the
     *         event handler
     */
    public void setEventHandler( ValidationEventHandler handler )
        throws JAXBException;

    /**
     * Return the current event handler or the default event handler if one
     * hasn't been set.
     *
     * @return the current ValidationEventHandler or the default event handler
     *         if it hasn't been set
     * @throws JAXBException if an error was encountered while getting the
     *         current event handler
     */
    public ValidationEventHandler getEventHandler()
        throws JAXBException;

    /**
     * Set the particular property in the underlying implementation of
     * {@code Unmarshaller}.  This method can only be used to set one of
     * the standard Jakarta XML Binding defined properties above or a provider specific
     * property.  Attempting to set an undefined property will result in
     * a PropertyException being thrown.  See <a href="#supportedProps">
     * Supported Properties</a>.
     *
     * @param name the name of the property to be set. This value can either
     *              be specified using one of the constant fields or a user
     *              supplied string.
     * @param value the value of the property to be set
     *
     * @throws PropertyException when there is an error processing the given
     *                            property or value
     * @throws IllegalArgumentException
     *      If the name parameter is null
     */
    public void setProperty( String name, Object value )
        throws PropertyException;

    /**
     * Get the particular property in the underlying implementation of
     * {@code Unmarshaller}.  This method can only be used to get one of
     * the standard Jakarta XML Binding defined properties above or a provider specific
     * property.  Attempting to get an undefined property will result in
     * a PropertyException being thrown.  See <a href="#supportedProps">
     * Supported Properties</a>.
     *
     * @param name the name of the property to retrieve
     * @return the value of the requested property
     *
     * @throws PropertyException
     *      when there is an error retrieving the given property or value
     *      property name
     * @throws IllegalArgumentException
     *      If the name parameter is null
     */
    public Object getProperty( String name ) throws PropertyException;

    /**
     * Specify the JAXP {@link javax.xml.validation.Schema Schema}
     * object that should be used to validate subsequent unmarshal operations
     * against.  Passing null into this method will disable validation.
     *
     * <p>
     * Initially this property is set to {@code null}.
     *
     * @param schema Schema object to validate unmarshal operations against or null to disable validation
     * @throws UnsupportedOperationException could be thrown if this method is
     *         invoked on an Unmarshaller created from a JAXBContext referencing
     *         JAXB 1.0 mapped classes
     * @since 1.6, JAXB 2.0
     */
    public void setSchema( Schema schema );

    /**
     * Get the JAXP {@link javax.xml.validation.Schema Schema} object
     * being used to perform unmarshal-time validation.  If there is no
     * Schema set on the unmarshaller, then this method will return null
     * indicating that unmarshal-time validation will not be performed.
     *
     * @return the Schema object being used to perform unmarshal-time
     *      validation or null if not present
     * @throws UnsupportedOperationException could be thrown if this method is
     *         invoked on an Unmarshaller created from a JAXBContext referencing
     *         JAXB 1.0 mapped classes
     * @since 1.6, JAXB 2.0
     */
    public Schema getSchema();

    /**
     * Associates a configured instance of {@link XmlAdapter} with this unmarshaller.
     *
     * <p>
     * This is a convenience method that invokes {@code setAdapter(adapter.getClass(),adapter);}.
     *
     * @see #setAdapter(Class,XmlAdapter)
     * @throws IllegalArgumentException
     *      if the adapter parameter is null.
     * @throws UnsupportedOperationException
     *      if invoked agains a JAXB 1.0 implementation.
     * @since 1.6, JAXB 2.0
     */
    public <A extends XmlAdapter<?, ?>> void setAdapter( A adapter );

    /**
     * Associates a configured instance of {@link XmlAdapter} with this unmarshaller.
     *
     * <p>
     * Every unmarshaller internally maintains a
     * {@link java.util.Map}&lt;{@link Class},{@link XmlAdapter}&gt;,
     * which it uses for unmarshalling classes whose fields/methods are annotated
     * with {@link jakarta.xml.bind.annotation.adapters.XmlJavaTypeAdapter}.
     *
     * <p>
     * This method allows applications to use a configured instance of {@link XmlAdapter}.
     * When an instance of an adapter is not given, an unmarshaller will create
     * one by invoking its default constructor.
     *
     * @param type
     *      The type of the adapter. The specified instance will be used when
     *      {@link jakarta.xml.bind.annotation.adapters.XmlJavaTypeAdapter#value()}
     *      refers to this type.
     * @param adapter
     *      The instance of the adapter to be used. If null, it will un-register
     *      the current adapter set for this type.
     * @throws IllegalArgumentException
     *      if the type parameter is null.
     * @throws UnsupportedOperationException
     *      if invoked agains a JAXB 1.0 implementation.
     * @since 1.6, JAXB 2.0
     */
    public <A extends XmlAdapter<?, ?>> void setAdapter( Class<A> type, A adapter );

    /**
     * Gets the adapter associated with the specified type.
     *
     * This is the reverse operation of the {@link #setAdapter} method.
     *
     * @throws IllegalArgumentException
     *      if the type parameter is null.
     * @throws UnsupportedOperationException
     *      if invoked agains a JAXB 1.0 implementation.
     * @since 1.6, JAXB 2.0
     */
    public <A extends XmlAdapter<?, ?>> A getAdapter( Class<A> type );

    /**
     * <p>Associate a context that resolves cid's, content-id URIs, to
     * binary data passed as attachments.</p>
     * <p>Unmarshal time validation, enabled via {@link #setSchema(Schema)},
     * must be supported even when unmarshaller is performing XOP processing.
     * </p>
     *
     * @throws IllegalStateException if attempt to concurrently call this
     *                               method during a unmarshal operation.
     */
    void setAttachmentUnmarshaller(AttachmentUnmarshaller au);

    AttachmentUnmarshaller getAttachmentUnmarshaller();

    /**
     * <p>
     * Register an instance of an implementation of this class with {@link Unmarshaller} to externally listen
     * for unmarshal events.
     * </p>
     * <p>
     * This class enables pre and post processing of an instance of a Jakarta XML Binding mapped class
     * as XML data is unmarshalled into it. The event callbacks are called when unmarshalling
     * XML content into a JAXBElement instance or a Jakarta XML Binding mapped class that represents a complex type definition.
     * The event callbacks are not called when unmarshalling to an instance of a
     * Java datatype that represents a simple type definition.
     * </p>
     * <p>
     * External listener is one of two different mechanisms for defining unmarshal event callbacks.
     * See <a href="Unmarshaller.html#unmarshalEventCallback">Unmarshal Event Callbacks</a> for an overview.
     * </p>
     * (@link #setListener(Listener)}
     * (@link #getListener()}
     *
     * @since 1.6, JAXB 2.0
     */
    public static abstract class Listener {

        /**
         * Do-nothing constructor for the derived classes.
         */
        protected Listener() {
        }

        /**
         * <p>
         * Callback method invoked before unmarshalling into {@code target}.
         * </p>
         * <p>
         * This method is invoked immediately after {@code target} was created and
         * before the unmarshalling of this object begins. Note that
         * if the class of {@code target} defines its own {@code beforeUnmarshal} method,
         * the class specific callback method is invoked before this method is invoked.
         *
         * @param target non-null instance of Jakarta XML Binding mapped class prior to unmarshalling into it.
         * @param parent instance of Jakarta XML Binding mapped class that will eventually reference {@code target}.
         *               {@code null} when {@code target} is root element.
         */
        public void beforeUnmarshal(Object target, Object parent) {
        }

        /**
         * <p>
         * Callback method invoked after unmarshalling XML data into {@code target}.
         * </p>
         * <p>
         * This method is invoked after all the properties (except IDREF)
         * are unmarshalled into {@code target},
         * but before {@code target} is set into its {@code parent} object.
         * Note that if the class of {@code target} defines its own {@code afterUnmarshal} method,
         * the class specific callback method is invoked before this method is invoked.
         *
         * @param target non-null instance of Jakarta XML Binding mapped class prior to unmarshalling into it.
         * @param parent instance of Jakarta XML Binding mapped class that will reference {@code target}.
         *               {@code null} when {@code target} is root element.
         */
        public void afterUnmarshal(Object target, Object parent) {
        }
    }

    /**
     * <p>
     * Register unmarshal event callback {@link Listener} with this {@link Unmarshaller}.
     *
     * <p>
     * There is only one Listener per Unmarshaller. Setting a Listener replaces the previous set Listener.
     * One can unregister current Listener by setting listener to {@code null}.
     *
     * @param listener  provides unmarshal event callbacks for this {@link Unmarshaller}
     * @since 1.6, JAXB 2.0
     */
    public void     setListener(Listener listener);

    /**
     * <p>Return {@link Listener} registered with this {@link Unmarshaller}.
     *
     * @return registered {@link Listener} or {@code null}
     *         if no Listener is registered with this Unmarshaller.
     * @since 1.6, JAXB 2.0
     */
    public Listener getListener();
}