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	/*
	* Copyright (c) 2005, 2016, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package javax.xml.transform.stax;

	import javax.xml.stream.XMLEventReader;
	import javax.xml.stream.XMLStreamConstants;
	import javax.xml.stream.XMLStreamException;
	import javax.xml.stream.XMLStreamReader;
	import javax.xml.stream.events.XMLEvent;
	import javax.xml.transform.Source;

	/**
	* <p>Acts as a holder for an XML {@link Source} in the
	* form of a StAX reader,i.e.
	* {@link XMLStreamReader} or {@link XMLEventReader}.
	* <code>StAXSource</code> can be used in all cases that accept
	* a <code>Source</code>, e.g. {@link javax.xml.transform.Transformer},
	* {@link javax.xml.validation.Validator} which accept
	* <code>Source</code> as input.
	*
	* <p><code>StAXSource</code>s are consumed during processing
	* and are not reusable.</p>
	*
	* @author Neeraj Bajaj
	* @author Jeff Suttor
	*
	* @see <a href="http://jcp.org/en/jsr/detail?id=173">
	* JSR 173: Streaming API for XML</a>
	* @see XMLStreamReader
	* @see XMLEventReader
	*
	* @since 1.6
	*/
	public class StAXSource implements Source {

	/** If {@link javax.xml.transform.TransformerFactory#getFeature(String name)}
	* returns true when passed this value as an argument,
	* the Transformer supports Source input of this type.
	*/
	public static final String FEATURE =
	"http://javax.xml.transform.stax.StAXSource/feature";

	/** <p><code>XMLEventReader</code> to be used for source input.</p> */
	private XMLEventReader xmlEventReader = null;

	/** <p><code>XMLStreamReader</code> to be used for source input.</p> */
	private XMLStreamReader xmlStreamReader = null;

	/** <p>System identifier of source input.</p> */
	private String systemId = null;

	/**
	* <p>Creates a new instance of a <code>StAXSource</code>
	* by supplying an {@link XMLEventReader}.</p>
	*
	* <p><code>XMLEventReader</code> must be a
	* non-<code>null</code> reference.</p>
	*
	* <p><code>XMLEventReader</code> must be in
	* {@link XMLStreamConstants#START_DOCUMENT} or
	* {@link XMLStreamConstants#START_ELEMENT} state.</p>
	*
	* @param xmlEventReader <code>XMLEventReader</code> used to create
	* this <code>StAXSource</code>.
	*
	* @throws XMLStreamException If <code>xmlEventReader</code> access
	* throws an <code>Exception</code>.
	* @throws IllegalArgumentException If <code>xmlEventReader</code> ==
	* <code>null</code>.
	* @throws IllegalStateException If <code>xmlEventReader</code>
	* is not in <code>XMLStreamConstants.START_DOCUMENT</code> or
	* <code>XMLStreamConstants.START_ELEMENT</code> state.
	*/
	public StAXSource(final XMLEventReader xmlEventReader)
	throws XMLStreamException {

	if (xmlEventReader == null) {
	throw new IllegalArgumentException(
	"StAXSource(XMLEventReader) with XMLEventReader == null");
	}

	// TODO: This is ugly ...
	// there is no way to know the current position(event) of
	// XMLEventReader. peek() is the only way to know the next event.
	// The next event on the input stream should be
	// XMLStreamConstants.START_DOCUMENT or
	// XMLStreamConstants.START_ELEMENT.
	XMLEvent event = xmlEventReader.peek();
	int eventType = event.getEventType();
	if (eventType != XMLStreamConstants.START_DOCUMENT
	&& eventType != XMLStreamConstants.START_ELEMENT) {
	throw new IllegalStateException(
	"StAXSource(XMLEventReader) with XMLEventReader "
	+ "not in XMLStreamConstants.START_DOCUMENT or "
	+ "XMLStreamConstants.START_ELEMENT state");
	}

	this.xmlEventReader = xmlEventReader;
	systemId = event.getLocation().getSystemId();
	}

	/**
	* <p>Creates a new instance of a <code>StAXSource</code>
	* by supplying an {@link XMLStreamReader}.</p>
	*
	* <p><code>XMLStreamReader</code> must be a
	* non-<code>null</code> reference.</p>
	*
	* <p><code>XMLStreamReader</code> must be in
	* {@link XMLStreamConstants#START_DOCUMENT} or
	* {@link XMLStreamConstants#START_ELEMENT} state.</p>
	*
	* @param xmlStreamReader <code>XMLStreamReader</code> used to create
	* this <code>StAXSource</code>.
	*
	* @throws IllegalArgumentException If <code>xmlStreamReader</code> ==
	* <code>null</code>.
	* @throws IllegalStateException If <code>xmlStreamReader</code>
	* is not in <code>XMLStreamConstants.START_DOCUMENT</code> or
	* <code>XMLStreamConstants.START_ELEMENT</code> state.
	*/
	public StAXSource(final XMLStreamReader xmlStreamReader) {

	if (xmlStreamReader == null) {
	throw new IllegalArgumentException(
	"StAXSource(XMLStreamReader) with XMLStreamReader == null");
	}

	int eventType = xmlStreamReader.getEventType();
	if (eventType != XMLStreamConstants.START_DOCUMENT
	&& eventType != XMLStreamConstants.START_ELEMENT) {
	throw new IllegalStateException(
	"StAXSource(XMLStreamReader) with XMLStreamReader"
	+ "not in XMLStreamConstants.START_DOCUMENT or "
	+ "XMLStreamConstants.START_ELEMENT state");
	}

	this.xmlStreamReader = xmlStreamReader;
	systemId = xmlStreamReader.getLocation().getSystemId();
	}

	/**
	* <p>Get the <code>XMLEventReader</code> used by this
	* <code>StAXSource</code>.</p>
	*
	* <p><code>XMLEventReader</code> will be <code>null</code>.
	* if this <code>StAXSource</code> was created with a
	* <code>XMLStreamReader</code>.</p>
	*
	* @return <code>XMLEventReader</code> used by this
	* <code>StAXSource</code>.
	*/
	public XMLEventReader getXMLEventReader() {

	return xmlEventReader;
	}

	/**
	* <p>Get the <code>XMLStreamReader</code> used by this
	* <code>StAXSource</code>.</p>
	*
	* <p><code>XMLStreamReader</code> will be <code>null</code>
	* if this <code>StAXSource</code> was created with a
	* <code>XMLEventReader</code>.</p>
	*
	* @return <code>XMLStreamReader</code> used by this
	* <code>StAXSource</code>.
	*/
	public XMLStreamReader getXMLStreamReader() {

	return xmlStreamReader;
	}

	/**
	* <p>In the context of a <code>StAXSource</code>, it is not appropriate
	* to explicitly set the system identifier.
	* The <code>XMLStreamReader</code> or <code>XMLEventReader</code>
	* used to construct this <code>StAXSource</code> determines the
	* system identifier of the XML source.</p>
	*
	* <p>An {@link UnsupportedOperationException} is <strong>always</strong>
	* thrown by this method.</p>
	*
	* @param systemId Ignored.
	*
	* @throws UnsupportedOperationException Is <strong>always</strong>
	* thrown by this method.
	*/
	@Override
	public void setSystemId(final String systemId) {

	throw new UnsupportedOperationException(
	"StAXSource#setSystemId(systemId) cannot set the "
	+ "system identifier for a StAXSource");
	}

	/**
	* <p>Get the system identifier used by this
	* <code>StAXSource</code>.</p>
	*
	* <p>The <code>XMLStreamReader</code> or <code>XMLEventReader</code>
	* used to construct this <code>StAXSource</code> is queried to determine
	* the system identifier of the XML source.</p>
	*
	* <p>The system identifier may be <code>null</code> or
	* an empty <code>""</code> <code>String</code>.</p>
	*
	* @return System identifier used by this <code>StAXSource</code>.
	*/
	@Override
	public String getSystemId() {

	return systemId;
	}

	/**
	* Indicates whether the {@code StAXSource} object is empty. Since a
	* {@code StAXSource} object can never be empty, this method always returns
	* false.
	*
	* @return unconditionally false
	*/
	@Override
	public boolean isEmpty() {
	return false;
	}
	}

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