NullPointer.java

/*
 * 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.
 */
/*******************************************************************************
 * Copyright (c) 2010 BestSolution.at 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: Tom Schindl <tom.schindl@bestsolution.at> - adjustment to EObject
 ******************************************************************************/
package org.eclipse.e4.emf.internal.xpath;

import java.util.Locale;

import org.apache.commons.jxpath.JXPathContext;
import org.apache.commons.jxpath.ri.QName;
import org.apache.commons.jxpath.ri.model.NodePointer;

/**
 * Pointer whose value is <code>null</code>.
 */
public class NullPointer extends EStructuralFeatureOwnerPointer {
	private QName name;
	private String id;

	private static final long serialVersionUID = 2193425983220679887L;

	/**
	 * Create a new NullPointer.
	 * 
	 * @param name
	 *            node name
	 * @param locale
	 *            Locale
	 */
	public NullPointer(QName name, Locale locale) {
		super(null, locale);
		this.name = name;
	}

	/**
	 * Used for the root node.
	 * 
	 * @param parent
	 *            parent pointer
	 * @param name
	 *            node name
	 */
	public NullPointer(NodePointer parent, QName name) {
		super(parent);
		this.name = name;
	}

	/**
	 * Create a new NullPointer.
	 * 
	 * @param locale
	 *            Locale
	 * @param id
	 *            String
	 */
	public NullPointer(Locale locale, String id) {
		super(null, locale);
		this.id = id;
	}

	@Override
	public QName getName() {
		return name;
	}

	@Override
	public Object getBaseValue() {
		return null;
	}

	@Override
	public boolean isCollection() {
		return false;
	}

	@Override
	public boolean isLeaf() {
		return true;
	}

	@Override
	public boolean isActual() {
		return false;
	}

	@Override
	public EStructuralFeaturePointer getPropertyPointer() {
		return new NullEStructuralFeaturePointer(this);
	}

	@Override
	public NodePointer createPath(JXPathContext context, Object value) {
		if (parent != null) {
			return parent.createPath(context, value).getValuePointer();
		}
		throw new UnsupportedOperationException("Cannot create the root object: " + asPath());
	}

	@Override
	public NodePointer createPath(JXPathContext context) {
		if (parent != null) {
			return parent.createPath(context).getValuePointer();
		}
		throw new UnsupportedOperationException("Cannot create the root object: " + asPath());
	}

	@Override
	public NodePointer createChild(JXPathContext context, QName name, int index) {
		return createPath(context).createChild(context, name, index);
	}

	@Override
	public NodePointer createChild(JXPathContext context, QName name, int index, Object value) {
		return createPath(context).createChild(context, name, index, value);
	}

	@Override
	public int hashCode() {
		return name == null ? 0 : name.hashCode();
	}

	@Override
	public boolean equals(Object object) {
		if (object == this) {
			return true;
		}

		if (!(object instanceof NullPointer)) {
			return false;
		}

		NullPointer other = (NullPointer) object;
		return name == other.name || name != null && name.equals(other.name);
	}

	@Override
	public String asPath() {
		if (id != null) {
			return "id(" + id + ")";
		}
		return parent == null ? "null()" : super.asPath();
	}

	@Override
	public int getLength() {
		return 0;
	}
}