| using System; |
| using System.Runtime.CompilerServices; |
| |
| namespace Lucene.Net.Support |
| { |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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. |
| */ |
| |
| internal class IdentityWeakReference<T> : WeakReference |
| where T : class |
| { |
| private readonly int hash; |
| private static readonly object NULL = new object(); |
| |
| public IdentityWeakReference(T target) |
| : base(target ?? NULL) |
| { |
| hash = RuntimeHelpers.GetHashCode(target); |
| } |
| |
| public override int GetHashCode() |
| { |
| return hash; |
| } |
| |
| public override bool Equals(object o) |
| { |
| if (ReferenceEquals(this, o)) |
| { |
| return true; |
| } |
| if (o is IdentityWeakReference<T> iwr && ReferenceEquals(this.Target, iwr.Target)) |
| { |
| return true; |
| } |
| return false; |
| } |
| |
| public new T Target |
| { // note: if this.NULL is the target, it will not cast to T, so the "as" will return null as we would expect. |
| get => base.Target as T; |
| set => base.Target = value; |
| } |
| } |
| } |