AbstractItemListXMLParser.java

/*******************************************************************************
 * Copyright (c) 2012, 2014 Wind River Systems, Inc. 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:
 * Wind River Systems - initial API and implementation
 *******************************************************************************/

package org.eclipse.tcf.te.launch.core.persistence;

import java.io.IOException;
import java.util.List;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;
import org.eclipse.tcf.te.launch.core.activator.CoreBundleActivator;
import org.eclipse.tcf.te.runtime.persistence.PersistenceManager;
import org.eclipse.tcf.te.runtime.persistence.interfaces.IPersistenceDelegate;
import org.osgi.framework.Bundle;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * AbstractItemListXMLParser
 */
public abstract class AbstractItemListXMLParser<ItemType> extends DefaultHandler {
	private final static int IN_ITEMS_DEFINITION = 1;
	private final static int IN_ITEM_DEFINITION = 2;

	private SAXParser parser;

	private int parseState;
	private String lastData;
	private String lastType;
	private List<ItemType> items;

	private final String containerTag;
	private final String itemTag;

	public static final String ATTR_TYPE = "type"; //$NON-NLS-1$

	/**
	 * Constructor
	 */
	public AbstractItemListXMLParser(String tagName) {
		super();
		Assert.isNotNull(tagName);

		containerTag = tagName + "s"; //$NON-NLS-1$
		itemTag = tagName;

		SAXParserFactory factory = SAXParserFactory.newInstance();
		factory.setNamespaceAware(false);
		factory.setValidating(false);
		try {
			parser = factory.newSAXParser();
		}
		catch (ParserConfigurationException e) {
			IStatus status = new Status(IStatus.ERROR, CoreBundleActivator.getUniqueIdentifier(), e.getClass().getName(), e);
			Platform.getLog(CoreBundleActivator.getContext().getBundle()).log(status);
		}
		catch (SAXException e) {
			IStatus status = new Status(IStatus.ERROR, CoreBundleActivator.getUniqueIdentifier(), e.getClass().getName(), e);
			Platform.getLog(CoreBundleActivator.getContext().getBundle()).log(status);
		}
	}

	/**
	 * Returns the associated XML parser instance.
	 */
	public SAXParser getXMLReader() {
		return parser;
	}

	/**
	 * Reset the XML parser to a defined start point.
	 */
	public void initXMLParser() {
		parseState = 0;
		lastData = null;
		lastType = null;
		items = null;
	}

	/**
	 * Associate the list instance to store the identified contexts.
	 */
	public void setItems(List<ItemType> items) {
		this.items = items;
	}

	/*
	 * (non-Javadoc)
	 * @see org.xml.sax.helpers.DefaultHandler#endElement(java.lang.String, java.lang.String,
	 * java.lang.String)
	 */
	@Override
	public void endElement(String uri, String localName, String name) throws SAXException {
		if (containerTag.equalsIgnoreCase(name) && (parseState & IN_ITEMS_DEFINITION) == IN_ITEMS_DEFINITION) {
			parseState ^= IN_ITEMS_DEFINITION;
		}
		if (itemTag.equalsIgnoreCase(name) && (parseState & IN_ITEM_DEFINITION) == IN_ITEM_DEFINITION) {
			parseState ^= IN_ITEM_DEFINITION;

			// The item encoded string is in last data
			if (lastType != null && lastData != null) {
				Class<?> clazz = null;
				try {
					clazz = CoreBundleActivator.getContext().getBundle().loadClass(lastType);
				}
				catch (ClassNotFoundException e) {
				}

				// If the class could not be loaded by our own bundle class loader, try to find
				// the bundle from the class name and try to load the class through the bundle.
				if (clazz == null) {
					String bundleId = lastType;
					Bundle bundle = null;
					while (bundleId != null && bundle == null) {
						bundle = Platform.getBundle(bundleId);
						if (bundle == null) {
							int i = bundleId.lastIndexOf('.');
							if (i != -1) {
								bundleId = bundleId.substring(0, i);
							} else {
								bundleId = null;
							}
						}
					}

					if (bundle != null) {
						try {
							clazz = bundle.loadClass(lastType);
						}
						catch (ClassNotFoundException e) {
							if (Platform.inDebugMode()) {
								IStatus status = new Status(IStatus.ERROR, CoreBundleActivator.getUniqueIdentifier(),
												"Launch framework internal error: " + e.getLocalizedMessage(), e); //$NON-NLS-1$
								Platform.getLog(CoreBundleActivator.getContext().getBundle()).log(status);
							}
						}
					}
				}

				if (clazz != null) {
					IPersistenceDelegate delegate = PersistenceManager.getInstance().getDelegate(clazz, lastData);
					if (delegate != null) {
						try {
							@SuppressWarnings("unchecked")
                            ItemType item = (ItemType)delegate.read(getReadClass(), lastData);
							if (items != null && !items.contains(item)) {
								items.add(item);
							}
						}
						catch (IOException e) {
							if (Platform.inDebugMode()) {
								IStatus status = new Status(IStatus.ERROR, CoreBundleActivator.getUniqueIdentifier(),
												"Launch framework internal error: " + e.getLocalizedMessage(), e); //$NON-NLS-1$
								Platform.getLog(CoreBundleActivator.getContext().getBundle()).log(status);
							}
						}
					}
				}
			}
		}
	}

	protected abstract Class<?> getReadClass();

	/* (non-Javadoc)
	 * @see org.xml.sax.helpers.DefaultHandler#startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)
	 */
	@Override
	public void startElement(String uri, String localName, String name, Attributes attributes) throws SAXException {
		// Each time we start a new element, throw away the lastData content
		lastData = null;

		if (containerTag.equalsIgnoreCase(name)) {
			parseState |= IN_ITEMS_DEFINITION;
		}
		if (itemTag.equalsIgnoreCase(name) && (parseState & IN_ITEMS_DEFINITION) == IN_ITEMS_DEFINITION) {
			parseState |= IN_ITEM_DEFINITION;
			lastType = attributes.getValue(ATTR_TYPE);
		}
	}

	/* (non-Javadoc)
	 * @see org.xml.sax.helpers.DefaultHandler#characters(char[], int, int)
	 */
	@Override
	public void characters(char ch[], int start, int length) {
		if (lastData == null) {
			lastData = new String(ch, start, length).trim();
		}
		else {
			lastData += new String(ch, start, length).trim();
		}
	}
}