/*
GNU LESSER GENERAL PUBLIC LICENSE
Copyright (C) 2006 The Lobo Project
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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Contact info: lobochief@users.sourceforge.net
*/
/*
* Created on Oct 8, 2005
*/
package org.lobobrowser.util;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.eclipse.jdt.annotation.Nullable;
public class WeakValueHashMap<K, @Nullable V> implements Map<K, V> {
private final Map<K, LocalWeakReference> map = new HashMap<>();
private final ReferenceQueue<V> queue = new ReferenceQueue<>();
public WeakValueHashMap() {
super();
}
public int size() {
return this.map.size();
}
public boolean isEmpty() {
return this.map.isEmpty();
}
public boolean containsKey(final Object key) {
return map.containsKey(key);
}
public boolean containsValue(final Object value) {
throw new UnsupportedOperationException();
}
public V get(final Object key) {
this.checkQueue();
final LocalWeakReference wf = this.map.get(key);
return wf == null ? null : wf.get();
}
public V put(final K key, final V value) {
this.checkQueue();
return this.putImpl(key, value);
}
private final V putImpl(final K key, final V value) {
if (value == null) {
throw new IllegalArgumentException("null values not accepted");
}
final LocalWeakReference ref = new LocalWeakReference(key, value);
final LocalWeakReference oldWf = this.map.put(key, ref);
return oldWf == null ? null : oldWf.get();
}
public V remove(final Object key) {
this.checkQueue();
final LocalWeakReference wf = this.map.remove(key);
return wf == null ? null : wf.get();
}
public void putAll(final Map<? extends K, ? extends V> t) {
this.checkQueue();
t.forEach((k, v) -> this.putImpl(k, v));
}
public void clear() {
this.checkQueue();
this.map.clear();
}
public Set<K> keySet() {
return this.map.keySet();
}
@SuppressWarnings("unchecked")
private final void checkQueue() {
final ReferenceQueue<V> queue = this.queue;
LocalWeakReference ref;
while ((ref = (LocalWeakReference) queue.poll()) != null) {
this.map.remove(ref.getKey());
}
}
public Collection<V> values() {
checkQueue();
final Stream<V> m =
this.map.values().stream()
.map(t -> t == null ? null : t.get())
.filter(t -> t != null);
return m.collect(Collectors.toList());
}
public Set<Entry<K, V>> entrySet() {
throw new UnsupportedOperationException();
}
private class LocalWeakReference extends WeakReference<V> {
private final K key;
public LocalWeakReference(final K key, final V target) {
super(target, queue);
this.key = key;
}
public K getKey() {
return key;
}
/*
public boolean equals(final Object other) {
final K target1 = this.get();
final Object target2 = other instanceof LocalWeakReference ? ((LocalWeakReference) other).get() : null;
return Objects.equals(target1, target2);
}
public int hashCode() {
final Object target = this.get();
return target == null ? 0 : target.hashCode();
}*/
}
}