org.eclipse.viatra2.gtasm.patternmatcher.impl/src/org/eclipse/viatra2/gtasm/patternmatcher/impl/patternmatcher/internal/rgg/HistoryList.java

/*******************************************************************************
 * Copyright (c) 2004-2008 Akos Horvath, Gergely Varro and Daniel Varro
 * 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:
 *    Akos Horvath, Gergely Varro - initial API and implementation
 *******************************************************************************/

 package org.eclipse.viatra2.gtasm.patternmatcher.impl.patternmatcher.internal.rgg;

import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;

import org.eclipse.viatra2.gtasm.patternmatcher.impl.patternmatcher.internal.IKeyGenerator;


public class HistoryList<KeyType, ValueType> extends LinkedList<ValueType> {
	private static final long serialVersionUID = 4033836249907829630L;
	private IKeyGenerator<KeyType, ValueType> keyGenerator;
	private Map<KeyType, List<ValueType>> map;
	
	public HistoryList(IKeyGenerator<KeyType, ValueType> keyGenerator) {
		this.keyGenerator = keyGenerator;
		this.map = new HashMap<KeyType, List<ValueType>>();
	}
	
	public List<ValueType> get(KeyType key) {
		return map.get(key);
	}

	public void init() {
		clear();
		map.clear();
	}
	
	public Iterator<ValueType> iterator() {
		return new Itr(super.iterator());
	}
	
	private class Itr implements Iterator<ValueType> {
		private Iterator<ValueType> backingIterator;
		private ValueType lastReturned;

		private Itr(Iterator<ValueType> i) {
			backingIterator = i;
			lastReturned = null;
		}
		
		public boolean hasNext() {
			return backingIterator.hasNext();
		}

		public ValueType next() {
			try {
				lastReturned = backingIterator.next();
				return lastReturned;
			} catch (NoSuchElementException e) {
				lastReturned = null;
				throw e;
			}
		}

		public void remove() {
			if (lastReturned != null) {
				KeyType key = keyGenerator.calculateKey(lastReturned);
				List<ValueType> list = map.get(key);
				if (list == null) {
					list = new LinkedList<ValueType>();
				}
				list.add(lastReturned);
				map.put(key, list);
				backingIterator.remove();
				lastReturned = null;
			} else {
				throw new IllegalStateException();
			}
		}
	}
}