com.blazebit.persistence.EmptyPagedList Maven / Gradle / Ivy

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/*
 * Copyright 2014 - 2019 Blazebit.
 *
 * 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.blazebit.persistence;

import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

/**
 * An implementation that serves as an immutable empty {@link PagedList}.
 *
 * @param  the type of elements in this list
 * @author Christian Beikov
 * @since 1.2.0
 */
class EmptyPagedList implements PagedList {

    @Override
    public int getSize() {
        return 0;
    }

    @Override
    public long getTotalSize() {
        return 0;
    }

    @Override
    public int getPage() {
        return 0;
    }

    @Override
    public int getTotalPages() {
        return 0;
    }

    @Override
    public int getFirstResult() {
        return 0;
    }

    @Override
    public int getMaxResults() {
        return 0;
    }

    @Override
    public KeysetPage getKeysetPage() {
        return null;
    }

    @Override
    public int size() {
        return 0;
    }

    @Override
    public boolean isEmpty() {
        return true;
    }

    @Override
    public boolean contains(Object o) {
        return false;
    }

    @Override
    public Iterator iterator() {
        return Collections.emptyIterator();
    }

    @Override
    public Object[] toArray() {
        return new Object[0];
    }

    @Override
    public  T1[] toArray(T1[] a) {
        if (a.length > 0) {
            a[0] = null;
        }
        return a;
    }

    @Override
    public boolean add(T t) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean remove(Object o) {
        return false;
    }

    @Override
    public boolean containsAll(Collection c) {
        return c.isEmpty();
    }

    @Override
    public boolean addAll(Collection c) {
        if (!c.isEmpty()) {
            throw new UnsupportedOperationException();
        }
        return false;
    }

    @Override
    public boolean addAll(int index, Collection c) {
        checkIndex(index);
        if (!c.isEmpty()) {
            throw new UnsupportedOperationException();
        }
        return false;
    }

    @Override
    public boolean removeAll(Collection c) {
        return false;
    }

    @Override
    public boolean retainAll(Collection c) {
        return false;
    }

    @Override
    public void clear() {
    }

    @Override
    public T get(int index) {
        throw new IndexOutOfBoundsException("Index: " + index);
    }

    @Override
    public T set(int index, T element) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void add(int index, T element) {
        throw new UnsupportedOperationException();
    }

    @Override
    public T remove(int index) {
        throw new UnsupportedOperationException();
    }

    @Override
    public int indexOf(Object o) {
        return -1;
    }

    @Override
    public int lastIndexOf(Object o) {
        return -1;
    }

    @Override
    public ListIterator listIterator() {
        return Collections.emptyListIterator();
    }

    @Override
    public ListIterator listIterator(int index) {
        checkIndex(index);
        return Collections.emptyListIterator();
    }

    private void checkIndex(int index) {
        if (index != 0) {
            throw new IndexOutOfBoundsException("Index: " + index + ", Size: 0");
        }
    }

    @Override
    public List subList(int fromIndex, int toIndex) {
        checkIndex(fromIndex);
        checkIndex(toIndex);
        return null;
    }

    @Override
    public boolean equals(Object o) {
        return (o instanceof PagedList) && ((List) o).isEmpty();
    }

    @Override
    public int hashCode() {
        return 1;
    }
}