de.dhke.projects.cutil.collections.aspect.AspectMultiMapKeySet.java Source code

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Here is the source code for de.dhke.projects.cutil.collections.aspect.AspectMultiMapKeySet.java

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/**
 * (c) 2009-2014 Peter Wullinger
 *
 * $Id$
 *
 * Use, modification and restribution of this file are covered by the
 * terms of the Artistic License 2.0.
 *
 * You should have received a copy of the license terms in a file named
 * "LICENSE" together with this software package.
 *
 * Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT
 * HOLDER AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES. THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
 * A PARTICULAR PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED TO THE
 * EXTENT PERMITTED BY YOUR LOCAL LAW. UNLESS REQUIRED BY LAW, NO
 * COPYRIGHT HOLDER OR CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT
 * OF THE USE OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 **/
package de.dhke.projects.cutil.collections.aspect;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import org.apache.commons.collections15.MultiMap;
import org.apache.commons.collections15.keyvalue.DefaultMapEntry;

/**
 *
 * @param <K> 
 * @param <V> 
 * @param <M> 
 * @author Peter Wullinger <java@dhke.de>
 */
public class AspectMultiMapKeySet<K, V, M extends MultiMap<K, V>> implements Set<K> {
    private final AspectMultiMap<K, V, M> _aspectMap;
    private final Set<K> _keySet;

    public AspectMultiMapKeySet(final AspectMultiMap<K, V, M> aspectMap) {
        _aspectMap = aspectMap;
        _keySet = _aspectMap.getDecoratee().keySet();
    }

    @Override
    public int size() {
        return _keySet.size();
    }

    @Override
    public boolean isEmpty() {
        return _keySet.isEmpty();
    }

    @Override
    public boolean contains(final Object o) {
        return _keySet.contains(o);
    }

    @Override
    public Iterator<K> iterator() {
        return new Itr();
    }

    @Override
    public Object[] toArray() {
        return _keySet.toArray();
    }

    @Override
    public <T> T[] toArray(final T[] a) {
        return _keySet.toArray(a);
    }

    @Override
    public boolean add(final K e) {
        throw new UnsupportedOperationException("Cannot add to key set");
    }

    @Override
    public boolean remove(final Object o) {
        if (_aspectMap.containsKey(o)) {
            /* dispatch to map */
            _aspectMap.remove(o);
            return true;
        } else
            return false;
    }

    @Override
    public boolean containsAll(final Collection<?> c) {
        return _keySet.containsAll(c);
    }

    @Override
    public boolean addAll(final Collection<? extends K> c) {
        throw new UnsupportedOperationException("Cannot add to key set");
    }

    @Override
    public boolean retainAll(final Collection<?> c) {
        return batchRemove(c, true);
    }

    @Override
    public boolean removeAll(final Collection<?> c) {
        return batchRemove(c, false);
    }

    @Override
    public void clear() {
        if (!isEmpty()) {
            /* assumption: clearing the keyset also clears the map */
            _aspectMap.notifyBeforeCollectionCleared(_aspectMap);
            _keySet.clear();
            _aspectMap.notifyAfterCollectionCleared(_aspectMap);
        }
    }

    private boolean batchRemove(final Collection<?> c, final boolean retain) {
        for (K key : _keySet) {
            if (c.contains(key) != retain) {
                Collection<V> values = _aspectMap.get(key);
                for (V value : values) {
                    Map.Entry<K, V> entry = new DefaultMapEntry<>(key, value);
                    _aspectMap.notifyBeforeElementRemoved(_aspectMap, entry);
                }
            }
        }

        Iterator<K> iter = _keySet.iterator();
        boolean wasRemoved = false;
        while (iter.hasNext()) {
            K key = iter.next();
            if (c.contains(key) != retain) {
                /* use a copy, as the original collection may be modified */
                Collection<V> values = new ArrayList<>(_aspectMap.get(key));
                iter.remove();
                wasRemoved = true;
                for (V value : values) {
                    Map.Entry<K, V> entry = new DefaultMapEntry<>(key, value);
                    _aspectMap.notifyAfterElementRemoved(_aspectMap, entry);
                }
            }
        }
        return wasRemoved;
    }

    private class Itr implements Iterator<K> {
        private final Iterator<K> _keyIter;
        private K _current;

        Itr() {
            _keyIter = _keySet.iterator();
            _current = null;
        }

        @Override
        public boolean hasNext() {
            return _keyIter.hasNext();
        }

        @Override
        public K next() {
            _current = _keyIter.next();
            return _current;
        }

        @Override
        public void remove() {
            /* we operate on copy in the case the MultiMap returns the real value collection */
            Collection<V> values = new ArrayList<>(_aspectMap.getDecoratee().get(_current));
            for (V value : values) {
                Map.Entry<K, V> entry = new DefaultMapEntry<>(_current, value);
                _aspectMap.notifyBeforeElementRemoved(_aspectMap, entry);
            }
            _keyIter.remove();
            for (V value : values) {
                Map.Entry<K, V> entry = new DefaultMapEntry<>(_current, value);
                _aspectMap.notifyAfterElementRemoved(_aspectMap, entry);
            }
        }
    }
}