MultiMap.java

/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2006, University of Maryland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.util;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

/**
 * @author pugh
 */
public class MultiMap<K, V> {
    final Class<? extends Collection<V>> containerClass;

    @SuppressWarnings("unchecked")
    public MultiMap(@SuppressWarnings("rawtypes") Class<? extends Collection> c) {
        containerClass = (Class<? extends Collection<V>>) c;
    }

    private Collection<V> makeCollection() {
        try {
            return containerClass.newInstance();
        } catch (InstantiationException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    }

    Map<K, Collection<V>> map = new HashMap<K, Collection<V>>();

    public Collection<? extends K> keySet() {
        return map.keySet();
    }

    public boolean containsKey(K k) {
        return map.containsKey(k);
    }
    public void clear() {
        map.clear();
    }

    public void add(K k, V v) {
        Collection<V> s = map.get(k);
        if (s == null) {
            s = makeCollection();
            map.put(k, s);
        }
        s.add(v);
    }

    public void remove(K k, V v) {
        Collection<V> s = map.get(k);
        if (s != null) {
            s.remove(v);
            if (s.isEmpty())
                map.remove(k);
        }
    }

    public void removeAll(K k) {
        map.remove(k);
    }

    public Collection<V> get(K k) {
        Collection<V> s = map.get(k);
        if (s != null)
            return s;
        return Collections.<V> emptySet();
    }

    public Map<K, Collection<V>> asMap() {
        return map;
    }

}