IndexBasedArrayIterator.java
/*
* Copyright 2020 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 androidx.collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
abstract class IndexBasedArrayIterator<T> implements Iterator<T> {
private int mSize;
private int mIndex;
private boolean mCanRemove;
IndexBasedArrayIterator(int startingSize) {
mSize = startingSize;
}
protected abstract T elementAt(int index);
protected abstract void removeAt(int index);
@Override
public final boolean hasNext() {
return mIndex < mSize;
}
@Override
public T next() {
if (!hasNext()) throw new NoSuchElementException();
T res = elementAt(mIndex);
mIndex++;
mCanRemove = true;
return res;
}
@Override
public void remove() {
if (!mCanRemove) {
throw new IllegalStateException();
}
// Attempt removal first so an UnsupportedOperationException retains a valid state.
removeAt(--mIndex);
mSize--;
mCanRemove = false;
}
}