code: /*
   * 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 com.lody.virtual.server.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 java.util.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();
  		}
  	}
  }
  