bundles/org.eclipse.wst.xml.core/src/org/eclipse/wst/xml/core/internal/provisional/contentmodel/NullContentModel.java

/*******************************************************************************
 * Copyright (c) 2001, 2004 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
 *     Jens Lukowski/Innoopract - initial renaming/restructuring
 *     
 *******************************************************************************/
package org.eclipse.wst.xml.core.internal.provisional.contentmodel;

import java.util.Iterator;
import java.util.NoSuchElementException;

import org.eclipse.wst.xml.core.internal.contentmodel.CMDocument;
import org.eclipse.wst.xml.core.internal.contentmodel.CMNamedNodeMap;
import org.eclipse.wst.xml.core.internal.contentmodel.CMNamespace;
import org.eclipse.wst.xml.core.internal.contentmodel.CMNode;


/**
 * This class can be used to intialize specific variables that need a content
 * model, until the true content model is available. This prevents having to
 * do lots of null checks.
 */
public class NullContentModel implements CMDocument {

	private static class NullCMNamedNodeMap implements CMNamedNodeMap {
		public int getLength() {
			return 0;
		}

		public CMNode getNamedItem(String name) {
			return null;
		}

		public CMNode item(int index) {
			return null;
		}

		public Iterator iterator() {
			return new NullIterator();
		}

	}

	private static class NullIterator implements Iterator {
		public NullIterator() {
		}

		public boolean hasNext() {
			return false;
		}

		public Object next() {
			throw new NoSuchElementException();
		}

		public void remove() {
			throw new UnsupportedOperationException("can not remove regions via iterator"); //$NON-NLS-1$

		}

	}

	public NullContentModel() {
		super();
	}

	public CMNamedNodeMap getElements() {
		return new NullCMNamedNodeMap();
	}

	public CMNamedNodeMap getEntities() {
		return new NullCMNamedNodeMap();
	}

	public CMNamespace getNamespace() {
		return null;
	}

	public String getNodeName() {
		return null;
	}

	public int getNodeType() {
		return 0;
	}

	public Object getProperty(String propertyName) {
		return null;
	}

	public boolean supports(String propertyName) {
		return false;
	}

}