/****************************************************************************/
/* File: XMLStreamHelper.java */
/* Author: F. Georges */
/* Company: H2O Consulting */
/* Date: 2010-05-13 */
/* Tags: */
/* Copyright (c) 2010 Florent Georges (see end of file.) */
/* ------------------------------------------------------------------------ */
package org.expath.pkg.repo.parser;
import javax.xml.namespace.QName;
import javax.xml.stream.StreamFilter;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.transform.Source;
import org.expath.pkg.repo.PackageException;
/**
* Helper class for the package {@link javax.xml.stream}.
*
* @author Florent Georges
*/
public class XMLStreamHelper
{
public XMLStreamHelper(String targetNS)
{
myTargetNS = targetNS;
}
public String getTargetNs()
{
return myTargetNS;
}
public XMLStreamReader makeParser(Source desc)
throws PackageException
{
try {
XMLInputFactory factory = XMLInputFactory.newInstance();
XMLStreamReader reader = factory.createXMLStreamReader(desc);
StreamFilter filter = new WhitespaceFilter();
return factory.createFilteredReader(reader, filter);
}
catch ( XMLStreamException ex ) {
throw new PackageException("Error parsing the package descriptor", ex);
}
}
public void ensureDocument(XMLStreamReader parser)
throws PackageException
{
int event = parser.getEventType();
if ( event != XMLStreamConstants.START_DOCUMENT ) {
stateError("The current event is not START_DOCUMENT", event);
}
}
public boolean isNextElement(XMLStreamReader parser, String local_name)
throws PackageException
{
try {
parser.next();
return isElement(parser, local_name);
}
catch ( XMLStreamException ex ) {
throw new PackageException("Error parsing the package descriptor", ex);
}
}
public void ensureNextElement(XMLStreamReader parser, String local_name)
throws PackageException
{
try {
parser.next();
ensureElement(parser, local_name);
}
catch ( XMLStreamException ex ) {
throw new PackageException("Error parsing the package descriptor", ex);
}
}
public boolean isElement(XMLStreamReader parser, String local_name)
throws PackageException
{
int event = parser.getEventType();
if ( event != XMLStreamConstants.START_ELEMENT ) {
return false;
}
if ( ! new QName(myTargetNS, local_name).equals(parser.getName()) ) {
return false;
}
return true;
}
public void ensureElement(XMLStreamReader parser, String local_name)
throws PackageException
{
int event = parser.getEventType();
if ( event != XMLStreamConstants.START_ELEMENT ) {
stateError("The current event is not START_ELEMENT", event);
}
if ( ! new QName(myTargetNS, local_name).equals(parser.getName()) ) {
throw new PackageException("The element is not a pkg:" + local_name);
}
}
public String getEventName(int event)
throws PackageException
{
switch ( event ) {
case XMLStreamConstants.ATTRIBUTE:
return "ATTRIBUTE";
case XMLStreamConstants.CDATA:
return "CDATA";
case XMLStreamConstants.CHARACTERS:
return "CHARACTERS";
case XMLStreamConstants.COMMENT:
return "COMMENT";
case XMLStreamConstants.DTD:
return "DTD";
case XMLStreamConstants.END_DOCUMENT:
return "END_DOCUMENT";
case XMLStreamConstants.END_ELEMENT:
return "END_ELEMENT";
case XMLStreamConstants.ENTITY_DECLARATION:
return "ENTITY_DECLARATION";
case XMLStreamConstants.ENTITY_REFERENCE:
return "ENTITY_REFERENCE";
case XMLStreamConstants.NAMESPACE:
return "NAMESPACE";
case XMLStreamConstants.NOTATION_DECLARATION:
return "NOTATION_DECLARATION";
case XMLStreamConstants.PROCESSING_INSTRUCTION:
return "PROCESSING_INSTRUCTION";
case XMLStreamConstants.SPACE:
return "SPACE";
case XMLStreamConstants.START_DOCUMENT:
return "START_DOCUMENT";
case XMLStreamConstants.START_ELEMENT:
return "START_ELEMENT";
default:
throw new PackageException("Unknown event code: " + event);
}
}
public String getAttributeValue(XMLStreamReader parser, String name)
throws PackageException
{
String value = parser.getAttributeValue(null, name);
if ( value == null ) {
throw new PackageException("The element does not have an attribute " + name);
}
return value;
}
public String getElementValue(XMLStreamReader parser)
throws PackageException
{
return accumulateStringValue(parser);
}
private String accumulateStringValue(XMLStreamReader parser)
throws PackageException
{
StringBuilder buf = new StringBuilder();
try {
int event;
while ( (event = parser.next()) != XMLStreamConstants.END_ELEMENT ) {
if ( event != XMLStreamConstants.CHARACTERS ) {
stateError("Current event is not CHARACTERS", event);
}
buf.append(parser.getTextCharacters(), parser.getTextStart(), parser.getTextLength());
}
}
catch ( XMLStreamException ex ) {
throw new PackageException("Error parsing the package descriptor", ex);
}
return buf.toString();
}
/**
* The parser's current event must be START_ELEMENT.
*
* Ignore all this element end stops on the corresponding END_ELEMENT event.
*/
public void ignoreElement(XMLStreamReader parser)
throws PackageException
{
// ignore this element entirely
int opened = 1;
while ( opened > 0 ) {
try {
parser.next();
if ( parser.getEventType() == XMLStreamConstants.START_ELEMENT ) {
++opened;
}
else if ( parser.getEventType() == XMLStreamConstants.END_ELEMENT ) {
--opened;
}
}
catch ( XMLStreamException ex ) {
throw new PackageException("Error reading the package descriptor", ex);
}
}
}
public boolean stateError(String msg, int event)
throws PackageException
{
String event_name = getEventName(event);
throw new PackageException(msg + " (" + event_name + ")");
}
private String myTargetNS;
/**
* Filter out whitespace text nodes, as well as comments and PIs.
*
* TODO: Mmh... Could maybe use nextTag() instead of next() on the parser
* in order to achieve the same purpose?
*/
private static class WhitespaceFilter
implements StreamFilter
{
@Override
public boolean accept(XMLStreamReader parser)
{
int event = parser.getEventType();
return event != XMLStreamConstants.COMMENT
&& event != XMLStreamConstants.PROCESSING_INSTRUCTION
&& event != XMLStreamConstants.SPACE
&& ( event != XMLStreamConstants.CHARACTERS || ! parser.isWhiteSpace() );
}
}
}
/* ------------------------------------------------------------------------ */
/* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS COMMENT. */
/* */
/* The contents of this file are subject to the Mozilla Public License */
/* Version 1.0 (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.mozilla.org/MPL/. */
/* */
/* Software distributed under the License is distributed on an "AS IS" */
/* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See */
/* the License for the specific language governing rights and limitations */
/* under the License. */
/* */
/* The Original Code is: all this file. */
/* */
/* The Initial Developer of the Original Code is Florent Georges. */
/* */
/* Contributor(s): none. */
/* ------------------------------------------------------------------------ */