org.apache.rocketmq.shaded.com.google.common.collect.AbstractIndexedListIterator Maven / Gradle / Ivy
/*
* Copyright (C) 2009 The Guava Authors
*
* 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 org.apache.rocketmq.shaded.com.google.common.collect;
import static org.apache.rocketmq.shaded.com.google.common.base.Preconditions.checkPositionIndex;
import org.apache.rocketmq.shaded.com.google.common.annotations.GwtCompatible;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* This class provides a skeletal implementation of the {@link ListIterator} interface across a
* fixed number of elements that may be retrieved by position. It does not support {@link #remove},
* {@link #set}, or {@link #add}.
*
* @author Jared Levy
*/
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractIndexedListIterator
extends UnmodifiableListIterator {
private final int size;
private int position;
/** Returns the element with the specified index. This method is called by {@link #next()}. */
@ParametricNullness
protected abstract E get(int index);
/**
* Constructs an iterator across a sequence of the given size whose initial position is 0. That
* is, the first call to {@link #next()} will return the first element (or throw {@link
* NoSuchElementException} if {@code size} is zero).
*
* @throws IllegalArgumentException if {@code size} is negative
*/
protected AbstractIndexedListIterator(int size) {
this(size, 0);
}
/**
* Constructs an iterator across a sequence of the given size with the given initial position.
* That is, the first call to {@link #nextIndex()} will return {@code position}, and the first
* call to {@link #next()} will return the element at that index, if available. Calls to {@link
* #previous()} can retrieve the preceding {@code position} elements.
*
* @throws IndexOutOfBoundsException if {@code position} is negative or is greater than {@code
* size}
* @throws IllegalArgumentException if {@code size} is negative
*/
protected AbstractIndexedListIterator(int size, int position) {
checkPositionIndex(position, size);
this.size = size;
this.position = position;
}
@Override
public final boolean hasNext() {
return position < size;
}
@Override
@ParametricNullness
public final E next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return get(position++);
}
@Override
public final int nextIndex() {
return position;
}
@Override
public final boolean hasPrevious() {
return position > 0;
}
@Override
@ParametricNullness
public final E previous() {
if (!hasPrevious()) {
throw new NoSuchElementException();
}
return get(--position);
}
@Override
public final int previousIndex() {
return position - 1;
}
}