/*
* Copyright 2000-2015 JetBrains s.r.o.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.intellij.util.containers;
import gnu.trove.TObjectHashingStrategy;
import org.jetbrains.annotations.NonNls;
import org.jetbrains.annotations.NotNull;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.util.Map;
/**
* Weak keys hash map.
* Null keys are NOT allowed
* Null values are allowed
*/
public final class WeakHashMap<K, V> extends RefHashMap<K, V> {
public WeakHashMap(int initialCapacity, float loadFactor) {
super(initialCapacity, loadFactor);
}
public WeakHashMap(int initialCapacity) {
super(initialCapacity);
}
public WeakHashMap() {
}
public WeakHashMap(@NotNull Map<K, V> t) {
super(t);
}
public WeakHashMap(int initialCapacity, float loadFactor, @NotNull TObjectHashingStrategy<K> strategy) {
super(initialCapacity, loadFactor, strategy);
}
public WeakHashMap(@NotNull TObjectHashingStrategy<K> hashingStrategy) {
super(hashingStrategy);
}
@NotNull
@Override
protected <T> Key<T> createKey(@NotNull T k, @NotNull TObjectHashingStrategy<T> strategy, @NotNull ReferenceQueue<? super T> q) {
return new WeakKey<T>(k, strategy, q);
}
private static class WeakKey<T> extends WeakReference<T> implements Key<T> {
private final int myHash; // Hashcode of key, stored here since the key may be tossed by the GC
@NotNull private final TObjectHashingStrategy<T> myStrategy;
private WeakKey(@NotNull T k, @NotNull TObjectHashingStrategy<T> strategy, @NotNull ReferenceQueue<? super T> q) {
super(k, q);
myStrategy = strategy;
myHash = strategy.computeHashCode(k);
}
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof Key)) return false;
T t = get();
T u = ((Key<T>)o).get();
return keyEqual(t,u,myStrategy);
}
public int hashCode() {
return myHash;
}
@NonNls
@Override
public String toString() {
Object t = get();
return "WeakKey(" + t + ", " + myHash + ")";
}
}
}