    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 *      https://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    /**
    073     * Always throws {@link UnsupportedOperationException}.
    074     *
    075     * @param object Ignored.
    076     * @throws UnsupportedOperationException Always thrown.
    077     */
    078    @Override
    079    public boolean add(final E object) {
    080        throw new UnsupportedOperationException();
    081    }
    082
    083    /**
    084     * Always throws {@link UnsupportedOperationException}.
    085     *
    086     * @param coll Ignored.
    087     * @throws UnsupportedOperationException Always thrown.
    088     */
    089    @Override
    090    public boolean addAll(final Collection<? extends E> coll) {
    091        throw new UnsupportedOperationException();
    092    }
    093
    094    /**
    095     * Always throws {@link UnsupportedOperationException}.
    096     *
    097     * @throws UnsupportedOperationException Always thrown.
    098     */
    099    @Override
    100    public void clear() {
    101        throw new UnsupportedOperationException();
    102    }
    103
    104    @Override
    105    public Iterator<E> descendingIterator() {
    106        return UnmodifiableIterator.unmodifiableIterator(decorated().descendingIterator());
    107    }
    108
    109    // NavigableSet
    110    @Override
    111    public NavigableSet<E> descendingSet() {
    112        return unmodifiableNavigableSet(decorated().descendingSet());
    113    }
    114
    115    @Override
    116    public SortedSet<E> headSet(final E toElement) {
    117        return UnmodifiableSortedSet.unmodifiableSortedSet(decorated().headSet(toElement));
    118    }
    119
    120    @Override
    121    public NavigableSet<E> headSet(final E toElement, final boolean inclusive) {
    122        return unmodifiableNavigableSet(decorated().headSet(toElement, inclusive));
    123    }
    124
    125    @Override
    126    public Iterator<E> iterator() {
    127        return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
    128    }
    129
    130    /**
    131     * Always throws {@link UnsupportedOperationException}.
    132     *
    133     * @throws UnsupportedOperationException Always thrown.
    134     * @since 4.5.0-M1
    135     */
    136    @Override
    137    public E pollFirst() {
    138        throw new UnsupportedOperationException();
    139    }
    140
    141    /**
    142     * Always throws {@link UnsupportedOperationException}.
    143     *
    144     * @throws UnsupportedOperationException Always thrown.
    145     * @since 4.5.0-M1
    146     */
    147    @Override
    148    public E pollLast() {
    149        throw new UnsupportedOperationException();
    150    }
    151
    152    /**
    153     * Deserializes the collection in using a custom routine.
    154     *
    155     * @param in  The input stream
    156     * @throws IOException Thrown if an error occurs while reading from the stream
    157     * @throws ClassNotFoundException if an object read from the stream cannot be loaded
    158     */
    159    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
    160    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    161        in.defaultReadObject();
    162        setCollection((Collection<E>) in.readObject()); // (1)
    163    }
    164
    165    /**
    166     * Always throws {@link UnsupportedOperationException}.
    167     *
    168     * @param object Ignored.
    169     * @throws UnsupportedOperationException Always thrown.
    170     */
    171    @Override
    172    public boolean remove(final Object object) {
    173        throw new UnsupportedOperationException();
    174    }
    175
    176    /**
    177     * Always throws {@link UnsupportedOperationException}.
    178     *
    179     * @param coll Ignored.
    180     * @throws UnsupportedOperationException Always thrown.
    181     */
    182    @Override
    183    public boolean removeAll(final Collection<?> coll) {
    184        throw new UnsupportedOperationException();
    185    }
    186
    187    /**
    188     * Always throws {@link UnsupportedOperationException}.
    189     *
    190     * @param filter Ignored.
    191     * @throws UnsupportedOperationException Always thrown.
    192     * @since 4.4
    193     */
    194    @Override
    195    public boolean removeIf(final Predicate<? super E> filter) {
    196        throw new UnsupportedOperationException();
    197    }
    198
    199    /**
    200     * Always throws {@link UnsupportedOperationException}.
    201     *
    202     * @param coll Ignored.
    203     * @throws UnsupportedOperationException Always thrown.
    204     */
    205    @Override
    206    public boolean retainAll(final Collection<?> coll) {
    207        throw new UnsupportedOperationException();
    208    }
    209
    210    @Override
    211    public NavigableSet<E> subSet(final E fromElement, final boolean fromInclusive, final E toElement,
    212            final boolean toInclusive) {
    213        return unmodifiableNavigableSet(decorated().subSet(fromElement, fromInclusive, toElement, toInclusive));
    214    }
    215
    216    // SortedSet
    217    @Override
    218    public SortedSet<E> subSet(final E fromElement, final E toElement) {
    219        return UnmodifiableSortedSet.unmodifiableSortedSet(decorated().subSet(fromElement, toElement));
    220    }
    221
    222    @Override
    223    public SortedSet<E> tailSet(final E fromElement) {
    224        return UnmodifiableSortedSet.unmodifiableSortedSet(decorated().tailSet(fromElement));
    225    }
    226
    227    @Override
    228    public NavigableSet<E> tailSet(final E fromElement, final boolean inclusive) {
    229        return unmodifiableNavigableSet(decorated().tailSet(fromElement, inclusive));
    230    }
    231
    232    /**
    233     * Serializes this object to an ObjectOutputStream.
    234     *
    235     * @param out The target ObjectOutputStream.
    236     * @throws IOException thrown when an I/O errors occur writing to the target stream.
    237     */
    238    private void writeObject(final ObjectOutputStream out) throws IOException {
    239        out.defaultWriteObject();
    240        out.writeObject(decorated());
    241    }
    242
    243}