/*******************************************************************************
* Copyright (c) 2004, 2011 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
* Philippe Ombredanne (pombredanne@nexb.com) - bug 125367
*******************************************************************************/
package org.eclipse.ant.internal.core.contentDescriber;
import java.io.IOException;
import java.io.StringReader;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.eclipse.ant.internal.core.IAntCoreConstants;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
/**
* An xml event handler for detecting the project top-level element in an Ant buildfile. Also records whether a default attribute is present for the
* project and if any target or some other typical ant elements are present. There are still cases where we could ignore a valid ant buildfile though.
*
* @since 3.1
*/
public final class AntHandler extends DefaultHandler {
/**
* An exception indicating that the parsing should stop.
*
* @since 3.1
*/
private class StopParsingException extends SAXException {
/**
* All serializable objects should have a stable serialVersionUID
*/
private static final long serialVersionUID = 1L;
/**
* Constructs an instance of <code>StopParsingException</code> with a <code>null</code> detail message.
*/
public StopParsingException() {
super((String) null);
}
}
private static final String PROJECT = "project"; //$NON-NLS-1$
private static final String TARGET = "target"; //$NON-NLS-1$
private static final String MACRODEF = "macrodef"; //$NON-NLS-1$
private static final String TASKDEF = "taskdef"; //$NON-NLS-1$
private static final String TYPEDEF = "typedef"; //$NON-NLS-1$
private static final String PROPERTY = "property"; //$NON-NLS-1$
private static final String CLASSPATH = "classpath"; //$NON-NLS-1$
private static final String PATH = "path"; //$NON-NLS-1$
private static final String IMPORT = "import"; //$NON-NLS-1$
/**
* This is the name of the top-level element found in the XML file. This member variable is <code>null</code> unless the file has been parsed
* successful to the point of finding the top-level element.
*/
private String fTopElementFound = null;
private SAXParserFactory fFactory;
private boolean fDefaultAttributeFound = false;
private boolean fTargetFound = false;
private boolean fAntElementFound = false;
private int fLevel = -1;
/**
* Creates a new SAX parser for use within this instance.
*
* @return The newly created parser.
* @throws ParserConfigurationException
* If a parser of the given configuration cannot be created.
* @throws SAXException
* If something in general goes wrong when creating the parser.
*/
private final SAXParser createParser(SAXParserFactory parserFactory) throws ParserConfigurationException, SAXException, SAXNotRecognizedException, SAXNotSupportedException {
// Initialize the parser.
final SAXParser parser = parserFactory.newSAXParser();
final XMLReader reader = parser.getXMLReader();
// disable DTD validation (bug 63625)
try {
// be sure validation is "off" or the feature to ignore DTD's will not apply
reader.setFeature("http://xml.org/sax/features/validation", false); //$NON-NLS-1$
reader.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false); //$NON-NLS-1$
}
catch (SAXNotRecognizedException e) {
// not a big deal if the parser does not recognize the features
}
catch (SAXNotSupportedException e) {
// not a big deal if the parser does not support the features
}
return parser;
}
private SAXParserFactory getFactory() {
synchronized (this) {
if (fFactory != null) {
return fFactory;
}
fFactory = SAXParserFactory.newInstance();
fFactory.setNamespaceAware(true);
}
return fFactory;
}
protected boolean parseContents(InputSource contents) throws IOException, ParserConfigurationException, SAXException {
// Parse the file into we have what we need (or an error occurs).
try {
fFactory = getFactory();
if (fFactory == null) {
return false;
}
final SAXParser parser = createParser(fFactory);
// to support external entities specified as relative URIs (see bug 63298)
contents.setSystemId("/"); //$NON-NLS-1$
parser.parse(contents, this);
}
catch (StopParsingException e) {
// Abort the parsing normally. Fall through...
}
return true;
}
/*
* Resolve external entity definitions to an empty string. This is to speed up processing of files with external DTDs. Not resolving the contents
* of the DTD is ok, as only the System ID of the DTD declaration is used.
*
* @see org.xml.sax.helpers.DefaultHandler#resolveEntity(java.lang.String, java.lang.String)
*/
@Override
public InputSource resolveEntity(String publicId, String systemId) throws SAXException {
return new InputSource(new StringReader(IAntCoreConstants.EMPTY_STRING));
}
/*
* (non-Javadoc)
*
* @see org.xml.sax.ContentHandler#startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)
*/
@Override
public final void startElement(final String uri, final String elementName, final String qualifiedName, final Attributes attributes) throws SAXException {
fLevel++;
if (fTopElementFound == null) {
fTopElementFound = elementName;
if (!hasRootProjectElement()) {
throw new StopParsingException();
}
if (attributes != null) {
fDefaultAttributeFound = attributes.getValue(IAntCoreConstants.DEFAULT) != null;
if (fDefaultAttributeFound) {
throw new StopParsingException();
}
}
}
if (fLevel == 1 && TARGET.equals(elementName)) {
fTargetFound = true;
throw new StopParsingException();
}
// top level Ant elements
if (fLevel == 1
&& (MACRODEF.equals(elementName) || TASKDEF.equals(elementName) || TYPEDEF.equals(elementName) || PROPERTY.equals(elementName)
|| CLASSPATH.equals(elementName) || PATH.equals(elementName) || IMPORT.equals(elementName))) {
fAntElementFound = true;
throw new StopParsingException();
}
}
/*
* (non-Javadoc)
*
* @see org.xml.sax.ContentHandler#endElement(java.lang.String, java.lang.String, java.lang.String)
*/
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
super.endElement(uri, localName, qName);
fLevel--;
}
protected boolean hasProjectDefaultAttribute() {
return fDefaultAttributeFound;
}
protected boolean hasRootProjectElement() {
return PROJECT.equals(fTopElementFound);
}
protected boolean hasTargetElement() {
return fTargetFound;
}
protected boolean hasAntElement() {
return fAntElementFound;
}
}