modules/jaxws/src/org/apache/axis2/jaxws/message/util/StackableReader.java

/*
 * Copyright 2004,2005 The Apache Software Foundation.
 * Copyright 2006 International Business Machines Corp.
 *
 * Licensed 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.axis2.jaxws.message.util;

import java.util.Stack;

import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import javax.xml.stream.Location;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

/**
 * StackableReader
 * A StackableStreamReader provides an additional method
 * push(XMLStreamReader)
 * 
 * You can call push(...) to add a new XMLStreamReader.  The
 * next event will use the pushed stream reader.
 * After the XMLStreamReader is consumed, it is automatically popped off 
 * of the stack.
 * 
 * Note the information returned by the StackableReader is only
 * applicable for the topmost XMLStreamReader.  For example the NamespaceContext
 * that is returned is not a combination of all the namespace contexts on the stack.
 */
public class StackableReader implements XMLStreamReader {

	Stack<XMLStreamReader> stack = new Stack<XMLStreamReader>();
	XMLStreamReader current = null;
	
	/**
	 * Create a stackable reader with the initial reader
	 * @param first
	 */
	public StackableReader(XMLStreamReader first) {
		current = first;
	}
	
	/**
	 * Push a new StreamReader
	 * @param streamReader
	 */
	public void push(XMLStreamReader streamReader) throws XMLStreamException {
		// Push the current reader if it is not consumed
		if (current != null &&
		    current.hasNext()) {
			stack.push(current);
		}
		current = streamReader;
	}

	public void close() throws XMLStreamException {
		current.close();
	}

	public int getAttributeCount() {
		return current.getAttributeCount();
	}

	public String getAttributeLocalName(int arg0) {
		return current.getAttributeLocalName(arg0);
	}

	public QName getAttributeName(int arg0) {
		return current.getAttributeName(arg0);
	}

	public String getAttributeNamespace(int arg0) {
		return current.getAttributeNamespace(arg0);
	}

	public String getAttributePrefix(int arg0) {
		return current.getAttributePrefix(arg0);
	}

	public String getAttributeType(int arg0) {
		return current.getAttributeType(arg0);
	}

	public String getAttributeValue(int arg0) {
		return current.getAttributeValue(arg0);
	}

	public String getAttributeValue(String arg0, String arg1) {
		return current.getAttributeValue(arg0, arg1);
	}

	public String getCharacterEncodingScheme() {
		return current.getCharacterEncodingScheme();
	}

	public String getElementText() throws XMLStreamException {
		return current.getElementText();
	}

	public String getEncoding() {
		return current.getEncoding();
	}

	public int getEventType() {
		return current.getEventType();
	}

	public String getLocalName() {
		return current.getLocalName();
	}

	public Location getLocation() {
		return current.getLocation();
	}

	public QName getName() {
		return current.getName();
	}

	public NamespaceContext getNamespaceContext() {
		return current.getNamespaceContext();
	}

	public int getNamespaceCount() {
		return current.getNamespaceCount();
	}

	public String getNamespacePrefix(int arg0) {
		return current.getNamespacePrefix(arg0);
	}

	public String getNamespaceURI() {
		return current.getNamespaceURI();
	}

	public String getNamespaceURI(int arg0) {
		return current.getNamespaceURI(arg0);
	}

	public String getNamespaceURI(String arg0) {
		return current.getNamespaceURI(arg0);
	}

	public String getPIData() {
		return current.getPIData();
	}

	public String getPITarget() {
		return current.getPITarget();
	}

	public String getPrefix() {
		return current.getPrefix();
	}

	public Object getProperty(String arg0) throws IllegalArgumentException {
		return current.getProperty(arg0);
	}

	public String getText() {
		return current.getText();
	}

	public char[] getTextCharacters() {
		return current.getTextCharacters();
	}

	public int getTextCharacters(int arg0, char[] arg1, int arg2, int arg3) throws XMLStreamException {
		return current.getTextCharacters(arg0, arg1, arg2, arg3);
	}

	public int getTextLength() {
		return current.getTextLength();
	}

	public int getTextStart() {
		return current.getTextStart();
	}

	public String getVersion() {
		return current.getVersion();
	}

	public boolean hasName() {
		return current.hasName();
	}

	public boolean hasNext() throws XMLStreamException {
		// This code assumes that the stack only contains readers that are not consumed
		if (!current.hasNext() &&
			!stack.isEmpty()) {
			return stack.peek().hasNext();
		}
		return current.hasNext();
	}

	public boolean hasText() {
		return current.hasText();
	}

	public boolean isAttributeSpecified(int arg0) {
		return current.isAttributeSpecified(arg0);
	}

	public boolean isCharacters() {
		return current.isCharacters();
	}

	public boolean isEndElement() {
		return current.isEndElement();
	}

	public boolean isStandalone() {
		return current.isStandalone();
	}

	public boolean isStartElement() {
		return current.isStartElement();
	}

	public boolean isWhiteSpace() {
		return current.isWhiteSpace();
	}

	public int next() throws XMLStreamException {
		// Only next is allowed to pop the stack
		if (!current.hasNext() &&
		    !stack.isEmpty()) {
			current = stack.pop();
		}
		// The assumption is that the event on the stream reader was processed
		// prior to pushing a new xmlstreamreader.  thus we proceed to the next
		// event in all cases
		int tag = current.next();
		
		// Skip start document and end document events for 
		// stacked stream readers
		if ((tag == this.START_DOCUMENT || 
		    tag == this.END_DOCUMENT) &&
		    !stack.isEmpty()) {
			tag = next();
		}
		
		return tag;
	}

	public int nextTag() throws XMLStreamException {
		if (!current.hasNext() &&
			!stack.isEmpty()) {
			return stack.peek().nextTag();
		}
		return current.nextTag();
	}

	public void require(int arg0, String arg1, String arg2) throws XMLStreamException {
		current.require(arg0, arg1, arg2);
	}

	public boolean standaloneSet() {
		return current.standaloneSet();
	}
	
	
}