/*
* Copyright 2003-2016 JetBrains s.r.o.
*
* 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 jetbrains.mps.nodeEditor.cells.collections;
import org.jetbrains.annotations.NotNull;
/**
* User: shatalin
* Date: 10/02/16
*/
public class EmptyContainer<T> extends AbstractContainer<T> {
private static Container ourInstance;
public static <T> Container<T> getInstance() {
if (ourInstance == null) {
ourInstance = new UnmodifiableContainer<>(new EmptyContainer<>());
}
//noinspection unchecked
return ourInstance;
}
private EmptyContainer() {
}
@Override
protected Entry<T> getEntry(@NotNull T item) {
return null;
}
@Override
protected Entry<T> createEntry(@NotNull T item) {
return null;
}
@Override
protected Entry<T> deleteEntry(@NotNull Entry<T> entry) {
return null;
}
}