de.dhke.projects.cutil.collections.cow.CopyOnWriteMultiMapEntrySet.java Source code

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Here is the source code for de.dhke.projects.cutil.collections.cow.CopyOnWriteMultiMapEntrySet.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.cow;

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

/**
 *
 * @author Peter Wullinger <java@dhke.de>
 */
class CopyOnWriteMultiMapEntrySet<K, V> implements Set<Map.Entry<K, Collection<V>>> {

    private CopyOnWriteMultiMap<K, V> _cowMap;
    /// </editor-fold>
    private MultiMap<K, V> _lastBaseMap = null;
    private Set<Entry<K, Collection<V>>> _cachedEntrySet = null;

    protected CopyOnWriteMultiMapEntrySet(final CopyOnWriteMultiMap<K, V> cowMap) {
        _cowMap = cowMap;
    }

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

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

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

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

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

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

    @Override
    public boolean add(final Entry<K, Collection<V>> e) {
        _cowMap.copy();
        return _cowMap.putAll(e.getKey(), e.getValue());
    }

    @Override
    public boolean remove(final Object o) {
        _cowMap.copy();
        return getOriginalEntrySet().remove(o);
    }

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

    @Override
    public boolean addAll(final Collection<? extends Entry<K, Collection<V>>> c) {
        _cowMap.copy();
        return getOriginalEntrySet().addAll(c);
    }

    @Override
    public boolean retainAll(final Collection<?> c) {
        _cowMap.copy();
        return getOriginalEntrySet().retainAll(c);
    }

    @Override
    public boolean removeAll(final Collection<?> c) {
        _cowMap.copy();
        return getOriginalEntrySet().removeAll(c);
    }

    @Override
    public void clear() {
        _cowMap.copy();
        getOriginalEntrySet().clear();
    }

    private Set<Entry<K, Collection<V>>> getOriginalEntrySet() {
        /* cache entrty set to avoid re-fetch */
        if (_lastBaseMap != _cowMap.getDecoratee()) {
            _lastBaseMap = _cowMap.getDecoratee();
            _cachedEntrySet = _lastBaseMap.entrySet();
        }
        assert _cachedEntrySet != null;
        return _cachedEntrySet;
    }

    /// <editor-fold defaultstate="collapsed" desc="class Itr">
    private class Itr implements Iterator<Map.Entry<K, Collection<V>>> {

        private final Iterator<K> _keyIterator;
        private final boolean _collectionAlreadyCopied;

        Itr() {
            _collectionAlreadyCopied = _cowMap.isWasCopied();
            _keyIterator = _cowMap.getDecoratee().keySet().iterator();
        }

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

        @Override
        public Entry<K, Collection<V>> next() {
            K nextKey = _keyIterator.next();
            return new DefaultMapEntry<>(nextKey, _cowMap.get(nextKey));
        }

        @Override
        public void remove() {
            if (_collectionAlreadyCopied)
                _keyIterator.remove();
            else
                throw new UnsupportedOperationException(
                        "Cannot remove from untouched CopyOnWriteMultiMap via iterator.");
        }
    }
}