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/*
* Copyright 2017 ~ 2025 the original author or authors. James Wong
*
* 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.wl4g.infra.common.collection;
import static java.util.Collections.synchronizedList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.concurrent.atomic.AtomicBoolean;
import com.wl4g.infra.common.lang.Assert2;
/**
* The {@link List} is applicable to the registration of framework instances.
* Its feature is that after the registration is successful, it cannot be
* modified.
*
* Note: it uses synchronous lock to control thread safety. It is not applicable
* to high concurrency scenarios, but more applicable to registration
* configuration when starting server.
*
* @author Wangl.sir
* @version v1.0 2019年8月1日
* @since
*/
public class OnceUnmodifiableList implements List {
/**
* Read only list.
*/
final private List readOnlyList;
/**
* One-time modifiable map status marker.
*/
final private AtomicBoolean modified = new AtomicBoolean(false);
public OnceUnmodifiableList(List readOnlyList) {
Assert2.state(null != readOnlyList, "Once modifiable read only list must not be null.");
this.readOnlyList = synchronizedList(readOnlyList);
}
@Override
public int size() {
return readOnlyList.size();
}
@Override
public boolean isEmpty() {
return readOnlyList.isEmpty();
}
@Override
public boolean contains(Object o) {
return readOnlyList.contains(o);
}
@Override
public Iterator iterator() {
return readOnlyList.iterator();
}
@Override
public Object[] toArray() {
return readOnlyList.toArray();
}
@Override
public T[] toArray(T[] a) {
return readOnlyList.toArray(a);
}
@Override
public boolean add(E e) {
Assert2.notNull(e, "Once modifiable final list value must not be null.");
if (modified.compareAndSet(false, true)) {
return readOnlyList.add(e);
}
throw new UnsupportedOperationException("A modifiable list does not support multiple modifications.");
}
@Override
public boolean remove(Object o) {
Assert2.notNull(o, "Once modifiable final list value must not be null.");
if (modified.compareAndSet(false, true)) {
return readOnlyList.remove(o);
}
throw new UnsupportedOperationException("A modifiable list does not support multiple modifications.");
}
@Override
public boolean containsAll(Collection c) {
return readOnlyList.containsAll(c);
}
@Override
public boolean addAll(Collection c) {
Assert2.notNull(c, "Once modifiable final list value must not be null.");
if (modified.compareAndSet(false, true)) {
return readOnlyList.addAll(c);
}
throw new UnsupportedOperationException("A modifiable list does not support multiple modifications.");
}
@Override
public boolean addAll(int index, Collection c) {
Assert2.notNull(c, "Once modifiable final list value must not be null.");
if (modified.compareAndSet(false, true)) {
return readOnlyList.addAll(index, c);
}
throw new UnsupportedOperationException("A modifiable list does not support multiple modifications.");
}
@Override
public boolean removeAll(Collection c) {
Assert2.notNull(c, "Once modifiable final list value must not be null.");
if (modified.compareAndSet(false, true)) {
return readOnlyList.remove(c);
}
throw new UnsupportedOperationException("A modifiable list does not support multiple modifications.");
}
@Override
public boolean retainAll(Collection c) {
Assert2.notNull(c, "Once modifiable final list value must not be null.");
if (modified.compareAndSet(false, true)) {
return readOnlyList.retainAll(c);
}
throw new UnsupportedOperationException("A modifiable list does not support multiple modifications.");
}
@Override
public void clear() {
readOnlyList.clear();
}
@Override
public E get(int index) {
return readOnlyList.get(index);
}
@Override
public E set(int index, E element) {
Assert2.notNull(index, "Once modifiable final list index must not be null.");
Assert2.notNull(element, "Once modifiable final list element must not be null.");
if (modified.compareAndSet(false, true)) {
return readOnlyList.set(index, element);
}
throw new UnsupportedOperationException("A modifiable list does not support multiple modifications.");
}
@Override
public void add(int index, E element) {
Assert2.notNull(index, "Once modifiable final list index must not be null.");
Assert2.notNull(element, "Once modifiable final list element must not be null.");
if (modified.compareAndSet(false, true)) {
readOnlyList.add(index, element);
}
throw new UnsupportedOperationException("A modifiable list does not support multiple modifications.");
}
@Override
public E remove(int index) {
if (modified.compareAndSet(false, true)) {
return readOnlyList.remove(index);
}
throw new UnsupportedOperationException("A modifiable list does not support multiple modifications.");
}
@Override
public int indexOf(Object o) {
return readOnlyList.indexOf(o);
}
@Override
public int lastIndexOf(Object o) {
return readOnlyList.lastIndexOf(o);
}
@Override
public ListIterator listIterator() {
return readOnlyList.listIterator();
}
@Override
public ListIterator listIterator(int index) {
return readOnlyList.listIterator(index);
}
@Override
public List subList(int fromIndex, int toIndex) {
return readOnlyList.subList(fromIndex, toIndex);
}
}
