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.SortedSet;
025import java.util.function.Predicate;
026
027import org.apache.commons.collections4.Unmodifiable;
028import org.apache.commons.collections4.iterators.UnmodifiableIterator;
029
030/**
031 * Decorates another {@code SortedSet} to ensure it can't be altered.
032 * <p>
033 * This class is Serializable from Commons Collections 3.1.
034 * </p>
035 * <p>
036 * Attempts to modify it will result in an UnsupportedOperationException.
037 * </p>
038 *
039 * @param <E> the type of the elements in this set
040 * @since 3.0
041 */
042public final class UnmodifiableSortedSet<E>
043        extends AbstractSortedSetDecorator<E>
044        implements Unmodifiable {
045
046    /** Serialization version */
047    private static final long serialVersionUID = -725356885467962424L;
048
049    /**
050     * Factory method to create an unmodifiable set.
051     *
052     * @param <E> the element type
053     * @param set  the set to decorate, must not be null
054     * @return a new unmodifiable {@link SortedSet}
055     * @throws NullPointerException if set is null
056     * @since 4.0
057     */
058    public static <E> SortedSet<E> unmodifiableSortedSet(final SortedSet<E> set) {
059        if (set instanceof Unmodifiable) {
060            return set;
061        }
062        return new UnmodifiableSortedSet<>(set);
063    }
064
065    /**
066     * Constructor that wraps (not copies).
067     *
068     * @param set  the set to decorate, must not be null
069     * @throws NullPointerException if set is null
070     */
071    private UnmodifiableSortedSet(final SortedSet<E> set) {
072        super(set);
073    }
074
075    @Override
076    public boolean add(final E object) {
077        throw new UnsupportedOperationException();
078    }
079
080    @Override
081    public boolean addAll(final Collection<? extends E> coll) {
082        throw new UnsupportedOperationException();
083    }
084
085    @Override
086    public void clear() {
087        throw new UnsupportedOperationException();
088    }
089
090    @Override
091    public SortedSet<E> headSet(final E toElement) {
092        final SortedSet<E> head = decorated().headSet(toElement);
093        return unmodifiableSortedSet(head);
094    }
095
096    @Override
097    public Iterator<E> iterator() {
098        return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
099    }
100
101    /**
102     * Deserializes the collection in using a custom routine.
103     *
104     * @param in  the input stream
105     * @throws IOException if an error occurs while reading from the stream
106     * @throws ClassNotFoundException if an object read from the stream cannot be loaded
107     */
108    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
109    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
110        in.defaultReadObject();
111        setCollection((Collection<E>) in.readObject()); // (1)
112    }
113
114    @Override
115    public boolean remove(final Object object) {
116        throw new UnsupportedOperationException();
117    }
118
119    @Override
120    public boolean removeAll(final Collection<?> coll) {
121        throw new UnsupportedOperationException();
122    }
123
124    /**
125     * @since 4.4
126     */
127    @Override
128    public boolean removeIf(final Predicate<? super E> filter) {
129        throw new UnsupportedOperationException();
130    }
131
132    @Override
133    public boolean retainAll(final Collection<?> coll) {
134        throw new UnsupportedOperationException();
135    }
136
137    @Override
138    public SortedSet<E> subSet(final E fromElement, final E toElement) {
139        final SortedSet<E> sub = decorated().subSet(fromElement, toElement);
140        return unmodifiableSortedSet(sub);
141    }
142
143    @Override
144    public SortedSet<E> tailSet(final E fromElement) {
145        final SortedSet<E> tail = decorated().tailSet(fromElement);
146        return unmodifiableSortedSet(tail);
147    }
148
149    /**
150     * Serializes this object to an ObjectOutputStream.
151     *
152     * @param out the target ObjectOutputStream.
153     * @throws IOException thrown when an I/O errors occur writing to the target stream.
154     */
155    private void writeObject(final ObjectOutputStream out) throws IOException {
156        out.defaultWriteObject();
157        out.writeObject(decorated());
158    }
159
160}