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/**
* Copyright (c) 2008, SnakeYAML
*
* 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.yaml.snakeyaml.util;
import java.util.AbstractList;
import java.util.Collections;
import java.util.List;
public class ArrayUtils {
private ArrayUtils() {}
/**
* Returns an unmodifiable {@code List} backed by the given array. The method doesn't copy the
* array, so the changes to the array will affect the {@code List} as well.
*
* @param <E> class of the elements in the array
* @param elements - array to convert
* @return {@code List} backed by the given array
*/
public static <E> List<E> toUnmodifiableList(E[] elements) {
return elements.length == 0 ? Collections.<E>emptyList()
: new UnmodifiableArrayList<E>(elements);
}
/**
* Returns an unmodifiable {@code List} containing the second array appended to the first one. The
* method doesn't copy the arrays, so the changes to the arrays will affect the {@code List} as
* well.
*
* @param <E> class of the elements in the array
* @param array1 - the array to extend
* @param array2 - the array to add to the first
* @return {@code List} backed by the given arrays
*/
public static <E> List<E> toUnmodifiableCompositeList(E[] array1, E[] array2) {
List<E> result;
if (array1.length == 0) {
result = toUnmodifiableList(array2);
} else if (array2.length == 0) {
result = toUnmodifiableList(array1);
} else {
result = new CompositeUnmodifiableArrayList<E>(array1, array2);
}
return result;
}
private static class UnmodifiableArrayList<E> extends AbstractList<E> {
private final E[] array;
UnmodifiableArrayList(E[] array) {
this.array = array;
}
@Override
public E get(int index) {
if (index >= array.length) {
throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + size());
}
return array[index];
}
@Override
public int size() {
return array.length;
}
}
private static class CompositeUnmodifiableArrayList<E> extends AbstractList<E> {
private final E[] array1;
private final E[] array2;
CompositeUnmodifiableArrayList(E[] array1, E[] array2) {
this.array1 = array1;
this.array2 = array2;
}
@Override
public E get(int index) {
E element;
if (index < array1.length) {
element = array1[index];
} else if (index - array1.length < array2.length) {
element = array2[index - array1.length];
} else {
throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + size());
}
return element;
}
@Override
public int size() {
return array1.length + array2.length;
}
}
}
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