| /* |
| * 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 android.util; |
| |
| 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(); |
| } |
| } |
| } |