    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.collections4.set;
    018
    019import java.io.IOException;
    020import java.io.ObjectInputStream;
    021import java.io.ObjectOutputStream;
    022import java.util.Collection;
    023import java.util.Iterator;
    024import java.util.NavigableSet;
    025import java.util.SortedSet;
    026import java.util.function.Predicate;
    027
    028import org.apache.commons.collections4.Unmodifiable;
    029import org.apache.commons.collections4.iterators.UnmodifiableIterator;
    030
    031/**
    032 * Decorates another {@code NavigableSet} to ensure it can't be altered.
    033 * <p>
    034 * Attempts to modify it will result in an UnsupportedOperationException.
    035 * </p>
    036 *
    037 * @param <E> the type of the elements in this set
    038 * @since 4.1
    039 */
    040public final class UnmodifiableNavigableSet<E>
    041        extends AbstractNavigableSetDecorator<E>
    042        implements Unmodifiable {
    043
    044    /** Serialization version */
    045    private static final long serialVersionUID = 20150528L;
    046
    047    /**
    048     * Factory method to create an unmodifiable set.
    049     *
    050     * @param <E> the element type
    051     * @param set  the set to decorate, must not be null
    052     * @return a new unmodifiable {@link NavigableSet}
    053     * @throws NullPointerException if set is null
    054     */
    055    public static <E> NavigableSet<E> unmodifiableNavigableSet(final NavigableSet<E> set) {
    056        if (set instanceof Unmodifiable) {
    057            return set;
    058        }
    059        return new UnmodifiableNavigableSet<>(set);
    060    }
    061
    062    /**
    063     * Constructor that wraps (not copies).
    064     *
    065     * @param set  the set to decorate, must not be null
    066     * @throws NullPointerException if set is null
    067     */
    068    private UnmodifiableNavigableSet(final NavigableSet<E> set) {
    069        super(set);
    070    }
    071
    072    @Override
    073    public boolean add(final E object) {
    074        throw new UnsupportedOperationException();
    075    }
    076
    077    @Override
    078    public boolean addAll(final Collection<? extends E> coll) {
    079        throw new UnsupportedOperationException();
    080    }
    081
    082    @Override
    083    public void clear() {
    084        throw new UnsupportedOperationException();
    085    }
    086
    087    @Override
    088    public Iterator<E> descendingIterator() {
    089        return UnmodifiableIterator.unmodifiableIterator(decorated().descendingIterator());
    090    }
    091
    092    // NavigableSet
    093    @Override
    094    public NavigableSet<E> descendingSet() {
    095        return unmodifiableNavigableSet(decorated().descendingSet());
    096    }
    097
    098    @Override
    099    public SortedSet<E> headSet(final E toElement) {
    100        final SortedSet<E> head = decorated().headSet(toElement);
    101        return UnmodifiableSortedSet.unmodifiableSortedSet(head);
    102    }
    103
    104    @Override
    105    public NavigableSet<E> headSet(final E toElement, final boolean inclusive) {
    106        final NavigableSet<E> head = decorated().headSet(toElement, inclusive);
    107        return unmodifiableNavigableSet(head);
    108    }
    109
    110    @Override
    111    public Iterator<E> iterator() {
    112        return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
    113    }
    114
    115    /**
    116     * @since 4.5
    117     */
    118    @Override
    119    public E pollFirst() {
    120        throw new UnsupportedOperationException();
    121    }
    122
    123    /**
    124     * @since 4.5
    125     */
    126    @Override
    127    public E pollLast() {
    128        throw new UnsupportedOperationException();
    129    }
    130
    131    /**
    132     * Read the collection in using a custom routine.
    133     *
    134     * @param in  the input stream
    135     * @throws IOException if an error occurs while reading from the stream
    136     * @throws ClassNotFoundException if an object read from the stream can not be loaded
    137     */
    138    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
    139    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    140        in.defaultReadObject();
    141        setCollection((Collection<E>) in.readObject()); // (1)
    142    }
    143
    144    @Override
    145    public boolean remove(final Object object) {
    146        throw new UnsupportedOperationException();
    147    }
    148
    149    @Override
    150    public boolean removeAll(final Collection<?> coll) {
    151        throw new UnsupportedOperationException();
    152    }
    153
    154    /**
    155     * @since 4.4
    156     */
    157    @Override
    158    public boolean removeIf(final Predicate<? super E> filter) {
    159        throw new UnsupportedOperationException();
    160    }
    161
    162    @Override
    163    public boolean retainAll(final Collection<?> coll) {
    164        throw new UnsupportedOperationException();
    165    }
    166
    167    @Override
    168    public NavigableSet<E> subSet(final E fromElement, final boolean fromInclusive, final E toElement,
    169            final boolean toInclusive) {
    170        final NavigableSet<E> sub = decorated().subSet(fromElement, fromInclusive, toElement, toInclusive);
    171        return unmodifiableNavigableSet(sub);
    172    }
    173
    174    // SortedSet
    175    @Override
    176    public SortedSet<E> subSet(final E fromElement, final E toElement) {
    177        final SortedSet<E> sub = decorated().subSet(fromElement, toElement);
    178        return UnmodifiableSortedSet.unmodifiableSortedSet(sub);
    179    }
    180
    181    @Override
    182    public SortedSet<E> tailSet(final E fromElement) {
    183        final SortedSet<E> tail = decorated().tailSet(fromElement);
    184        return UnmodifiableSortedSet.unmodifiableSortedSet(tail);
    185    }
    186
    187    @Override
    188    public NavigableSet<E> tailSet(final E fromElement, final boolean inclusive) {
    189        final NavigableSet<E> tail = decorated().tailSet(fromElement, inclusive);
    190        return unmodifiableNavigableSet(tail);
    191    }
    192
    193    /**
    194     * Write the collection out using a custom routine.
    195     *
    196     * @param out  the output stream
    197     * @throws IOException if an error occurs while writing to the stream
    198     */
    199    private void writeObject(final ObjectOutputStream out) throws IOException {
    200        out.defaultWriteObject();
    201        out.writeObject(decorated());
    202    }
    203
    204}