org.apache.axiom.util.stax.XMLFragmentStreamReader Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.axiom.util.stax;
import java.util.NoSuchElementException;
import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import javax.xml.stream.Location;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
/**
* Wrapping XML stream reader that reads a single element from the underlying stream.
* It will generate START_DOCUMENT and END_DOCUMENT events as required to make
* the sequence of events appear as a complete document.
*
* Assume for example that the parent reader is parsing the following document:
*
<a><b>text</b></a>
* If the current event is <b> when the wrapper is created, it will produce
* the following sequence of events:
*
*
* - A synthetic START_DOCUMENT event.
* - START_ELEMENT, CHARACTERS and END_ELEMENT events for
<b>text</b>.
* For these events, the wrapper directly delegates to the parent reader.
* - A synthetic END_DOCUMENT event.
*
* By default, after all events have been consumed from the wrapper, the current event on the
* parent reader will be the event following the last END_ELEMENT of the fragment. In the example
* above this will be </a>. The
* {@link #XMLFragmentStreamReader(XMLStreamReader, boolean)} constructor allows to override this
* behavior.
*
* The wrapper will release the reference to the parent reader when {@link #close()} is called.
* For obvious reasons, the wrapper will never call {@link XMLStreamReader#close()} on the parent
* reader.
*/
public class XMLFragmentStreamReader implements XMLStreamReader {
// The current event is a synthetic START_DOCUMENT event
private static final int STATE_START_DOCUMENT = 0;
// The current event is from the fragment and there will be more events from the fragment
private static final int STATE_IN_FRAGMENT = 1;
// The current event is the final END_ELEMENT event from the fragment
private static final int STATE_FRAGMENT_END = 2;
// The current event is a synthetic END_DOCUMENT event
private static final int STATE_END_DOCUMENT = 3;
private XMLStreamReader parent;
private final boolean proceedToNext;
private int state;
private int depth;
/**
* Constructor.
*
* @param parent the parent reader to read the fragment from
* @throws IllegalStateException if the current event on the parent is not a START_ELEMENT
*/
public XMLFragmentStreamReader(XMLStreamReader parent) {
this(parent, true);
}
/**
* Constructor.
*
* @param parent
* the parent reader to read the fragment from
* @param proceedToNext
* determines whether the parent reader should be positioned on the
* {@link XMLStreamConstants#END_ELEMENT} event of the fragment ({@code false}) or on
* event following the {@link XMLStreamConstants#END_ELEMENT} event ({@code true})
* after all events have been consumed from the wrapper
* @throws IllegalStateException
* if the current event on the parent is not a START_ELEMENT
*/
public XMLFragmentStreamReader(XMLStreamReader parent, boolean proceedToNext) {
this.parent = parent;
this.proceedToNext = proceedToNext;
if (parent.getEventType() != START_ELEMENT) {
throw new IllegalStateException("Expected START_ELEMENT as current event");
}
}
@Override
public int getEventType() {
switch (state) {
case STATE_START_DOCUMENT:
return START_DOCUMENT;
case STATE_IN_FRAGMENT:
return parent.getEventType();
case STATE_FRAGMENT_END:
return END_ELEMENT;
case STATE_END_DOCUMENT:
return END_DOCUMENT;
default:
// We will never get here; just make the compiler happy.
throw new IllegalStateException();
}
}
@Override
public int next() throws XMLStreamException {
switch (state) {
case STATE_START_DOCUMENT:
state = STATE_IN_FRAGMENT;
return START_ELEMENT;
case STATE_IN_FRAGMENT:
int type = parent.next();
switch (type) {
case START_ELEMENT:
depth++;
break;
case END_ELEMENT:
if (depth == 0) {
state = STATE_FRAGMENT_END;
} else {
depth--;
}
}
return type;
case STATE_FRAGMENT_END:
if (proceedToNext) {
parent.next();
}
state = STATE_END_DOCUMENT;
return END_DOCUMENT;
default:
throw new NoSuchElementException("End of document reached");
}
}
@Override
public int nextTag() throws XMLStreamException {
switch (state) {
case STATE_START_DOCUMENT:
state = STATE_IN_FRAGMENT;
return START_ELEMENT;
case STATE_END_DOCUMENT:
case STATE_FRAGMENT_END:
throw new NoSuchElementException();
default:
int result = parent.nextTag();
switch (result) {
case START_ELEMENT:
depth++;
break;
case END_ELEMENT:
if (depth == 0) {
state = STATE_FRAGMENT_END;
} else {
depth--;
}
}
return result;
}
}
@Override
public void close() throws XMLStreamException {
parent = null;
}
@Override
public Object getProperty(String name) throws IllegalArgumentException {
return parent.getProperty(name);
}
@Override
public String getCharacterEncodingScheme() {
if (state == STATE_START_DOCUMENT) {
return null;
} else {
throw new IllegalStateException();
}
}
@Override
public String getEncoding() {
if (state == STATE_START_DOCUMENT) {
return null;
} else {
throw new IllegalStateException();
}
}
@Override
public String getVersion() {
return "1.0";
}
@Override
public boolean isStandalone() {
return true;
}
@Override
public boolean standaloneSet() {
return false;
}
@Override
public Location getLocation() {
return parent.getLocation();
}
@Override
public int getAttributeCount() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getAttributeCount();
}
}
@Override
public String getAttributeLocalName(int index) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getAttributeLocalName(index);
}
}
@Override
public QName getAttributeName(int index) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getAttributeName(index);
}
}
@Override
public String getAttributeNamespace(int index) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getAttributeNamespace(index);
}
}
@Override
public String getAttributePrefix(int index) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getAttributePrefix(index);
}
}
@Override
public String getAttributeType(int index) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getAttributeType(index);
}
}
@Override
public String getAttributeValue(int index) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getAttributeValue(index);
}
}
@Override
public boolean isAttributeSpecified(int index) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.isAttributeSpecified(index);
}
}
@Override
public String getAttributeValue(String namespaceURI, String localName) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getAttributeValue(namespaceURI, localName);
}
}
@Override
public String getElementText() throws XMLStreamException {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getElementText();
}
}
@Override
public String getLocalName() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getLocalName();
}
}
@Override
public QName getName() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getName();
}
}
@Override
public String getPrefix() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getPrefix();
}
}
@Override
public String getNamespaceURI() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getNamespaceURI();
}
}
@Override
public int getNamespaceCount() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getNamespaceCount();
}
}
@Override
public String getNamespacePrefix(int index) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getNamespacePrefix(index);
}
}
@Override
public String getNamespaceURI(int index) {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getNamespaceURI(index);
}
}
@Override
public String getNamespaceURI(String prefix) {
// It is not clear whether this method is allowed in all states.
// The XMLStreamReader Javadoc suggest it is, but Woodstox doesn't
// allow it on states other than START_ELEMENT and END_ELEMENT.
// We emulate behavior of Woodstox.
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getNamespaceURI(prefix);
}
}
@Override
public NamespaceContext getNamespaceContext() {
return parent.getNamespaceContext();
}
@Override
public String getPIData() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getPIData();
}
}
@Override
public String getPITarget() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getPITarget();
}
}
@Override
public String getText() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getText();
}
}
@Override
public char[] getTextCharacters() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getTextCharacters();
}
}
@Override
public int getTextCharacters(int sourceStart, char[] target, int targetStart, int length)
throws XMLStreamException {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return getTextCharacters(sourceStart, target, targetStart, length);
}
}
@Override
public int getTextLength() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getTextLength();
}
}
@Override
public int getTextStart() {
if (state == STATE_START_DOCUMENT || state == STATE_END_DOCUMENT) {
throw new IllegalStateException();
} else {
return parent.getTextStart();
}
}
@Override
public boolean hasName() {
return state != STATE_START_DOCUMENT && state != STATE_END_DOCUMENT && parent.hasName();
}
@Override
public boolean hasNext() throws XMLStreamException {
return state != STATE_END_DOCUMENT;
}
@Override
public boolean hasText() {
return state != STATE_START_DOCUMENT && state != STATE_END_DOCUMENT && parent.hasText();
}
@Override
public boolean isCharacters() {
return state != STATE_START_DOCUMENT && state != STATE_END_DOCUMENT && parent.isCharacters();
}
@Override
public boolean isStartElement() {
return state != STATE_START_DOCUMENT && state != STATE_END_DOCUMENT && parent.isStartElement();
}
@Override
public boolean isEndElement() {
return state != STATE_START_DOCUMENT && state != STATE_END_DOCUMENT && parent.isEndElement();
}
@Override
public boolean isWhiteSpace() {
return state != STATE_START_DOCUMENT && state != STATE_END_DOCUMENT && parent.isWhiteSpace();
}
@Override
public void require(int type, String namespaceURI, String localName) throws XMLStreamException {
switch (state) {
case STATE_START_DOCUMENT:
if (type != START_DOCUMENT) {
throw new XMLStreamException("Expected START_DOCUMENT");
}
break;
case STATE_END_DOCUMENT:
if (type != END_DOCUMENT) {
throw new XMLStreamException("Expected END_DOCUMENT");
}
break;
default:
parent.require(type, namespaceURI, localName);
}
}
}