content: /*
   * Copyright (C) 2019 The Android Open Source Project
   *
   * 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 android.view.accessibility;
  
  import android.util.SparseArray;
  
  import java.lang.ref.Reference;
  import java.lang.ref.ReferenceQueue;
  import java.lang.ref.WeakReference;
  
  
  final class WeakSparseArray<E> {
  
      private final ReferenceQueue<E> mRefQueue = new ReferenceQueue<>();
      private final SparseArray<WeakReferenceWithId<E>> mSparseArray = new SparseArray<>();
  
      public void append(int key, E value) {
          removeUnreachableValues();
          mSparseArray.append(key, new WeakReferenceWithId(value, mRefQueue, key));
      }
  
      public void remove(int key) {
          removeUnreachableValues();
          mSparseArray.remove(key);
      }
  
      public E get(int key) {
          removeUnreachableValues();
          WeakReferenceWithId<E> ref = mSparseArray.get(key);
          return ref != null ? ref.get() : null;
      }
  
      private void removeUnreachableValues() {
          for (Reference ref = mRefQueue.poll(); ref != null; ref = mRefQueue.poll()) {
              mSparseArray.remove(((WeakReferenceWithId) ref).mId);
          }
      }
  
      private static class WeakReferenceWithId<E> extends WeakReference<E> {
  
          final int mId;
  
          WeakReferenceWithId(E referent, ReferenceQueue<? super E> q, int id) {
              super(referent, q);
              mId = id;
          }
      }
  }
  
  