content: /*
   * Copyright (C) 2011 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 top.niunaijun.blackbox.core.system.pm;
  
  import java.util.AbstractSet;
  import java.util.Iterator;
  
  /**
   * A fast immutable set wrapper for an array that is optimized for non-concurrent iteration.
   * The same iterator instance is reused each time to avoid creating lots of garbage.
   * Iterating over an array in this fashion is 2.5x faster than iterating over a {@link HashSet}
   * so it is worth copying the contents of the set to an array when iterating over it
   * hundreds of times.
   * @hide
   */
  public final class FastImmutableArraySet<T> extends AbstractSet<T> {
      FastIterator<T> mIterator;
      T[] mContents;
  
      public FastImmutableArraySet(T[] contents) {
          mContents = contents;
      }
  
      @Override
      public Iterator<T> iterator() {
          FastIterator<T> it = mIterator;
          if (it == null) {
              it = new FastIterator<T>(mContents);
              mIterator = it;
          } else {
              it.mIndex = 0;
          }
          return it;
      }
  
      @Override
      public int size() {
          return mContents.length;
      }
  
      private static final class FastIterator<T> implements Iterator<T> {
          private final T[] mContents;
          int mIndex;
  
          public FastIterator(T[] contents) {
              mContents = contents;
          }
  
          @Override
          public boolean hasNext() {
              return mIndex != mContents.length;
          }
  
          @Override
          public T next() {
              return mContents[mIndex++];
          }
  
          @Override
          public void remove() {
              throw new UnsupportedOperationException();
          }
      }
  }
  