001/*
002 * Java Genetic Algorithm Library (jenetics-7.2.0).
003 * Copyright (c) 2007-2023 Franz Wilhelmstötter
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * 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 *
017 * Author:
018 *    Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
019 */
020package io.jenetics.internal.collection;
021
022import static java.util.Objects.requireNonNull;
023
024import java.util.Collections;
025import java.util.Comparator;
026import java.util.Iterator;
027import java.util.List;
028import java.util.ListIterator;
029import java.util.Spliterator;
030import java.util.Spliterators;
031import java.util.function.Function;
032import java.util.stream.Stream;
033
034import io.jenetics.util.ISeq;
035import io.jenetics.util.MSeq;
036
037/**
038 * Contains static {@code Seq} definitions.
039 *
040 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
041 * @version 4.1
042 * @since 3.4
043 */
044public final class Empty {
045        private Empty() {}
046
047        public enum EmptyMSeq implements MSeq<Object> {
048
049                INSTANCE;
050
051                @Override
052                public void set(final int index, final Object value) {
053                        throw new ArrayIndexOutOfBoundsException("MSeq is empty.");
054                }
055
056                @Override
057                public MSeq<Object> sort(
058                        final int start,
059                        final int end,
060                        final Comparator<? super Object> comparator
061                ) {
062                        Array.checkIndex(start, end, length());
063                        return this;
064                }
065
066                @Override
067                public ListIterator<Object> listIterator() {
068                        return Collections.emptyListIterator();
069                }
070
071                @Override
072                public MSeq<Object> subSeq(final int start, final int end) {
073                        Array.checkIndex(start, end, length());
074                        return this;
075                }
076
077                @Override
078                public MSeq<Object> subSeq(final int start) {
079                        Array.checkIndex(start, 0, length());
080                        return this;
081                }
082
083                @Override
084                public <B> MSeq<B> map(final Function<? super Object, ? extends B> mapper) {
085                        requireNonNull(mapper);
086                        return mseq();
087                }
088
089                @Override
090                public MSeq<Object> append(final Object... values) {
091                        return MSeq.of(values);
092                }
093
094                @Override
095                public MSeq<Object> append(final Iterable<?> values) {
096                        return MSeq.of(values);
097                }
098
099                @Override
100                public MSeq<Object> prepend(final Object... values) {
101                        return MSeq.of(values);
102                }
103
104                @Override
105                public MSeq<Object> prepend(final Iterable<?> values) {
106                        return MSeq.of(values);
107                }
108
109                @Override
110                public Stream<Object> stream() {
111                        return Stream.empty();
112                }
113
114                @Override
115                public Stream<Object> parallelStream() {
116                        return Stream.empty();
117                }
118
119                @Override
120                public Spliterator<Object> spliterator() {
121                        return Spliterators.emptySpliterator();
122                }
123
124                @Override
125                public ISeq<Object> toISeq() {
126                        return EmptyISeq.INSTANCE;
127                }
128
129                @Override
130                public MSeq<Object> copy() {
131                        return this;
132                }
133
134                @Override
135                public Object get(final int index) {
136                        throw new ArrayIndexOutOfBoundsException("MSeq is empty: " + index);
137                }
138
139                @Override
140                public int length() {
141                        return 0;
142                }
143
144                @Override
145                public List<Object> asList() {
146                        return Collections.emptyList();
147                }
148
149                @Override
150                public Iterator<Object> iterator() {
151                        return Collections.emptyIterator();
152                }
153
154                @Override
155                public String toString() {
156                        return "[]";
157                }
158
159        }
160
161        public enum EmptyISeq implements ISeq<Object> {
162
163                INSTANCE;
164
165                @Override
166                public Iterator<Object> iterator() {
167                        return Collections.emptyIterator();
168                }
169
170                @Override
171                public ISeq<Object> subSeq(final int start, final int end) {
172                        Array.checkIndex(start, end, length());
173                        return this;
174                }
175
176                @Override
177                public ISeq<Object> subSeq(final int start) {
178                        Array.checkIndex(start, 0, length());
179                        return this;
180                }
181
182                @Override
183                public Object get(final int index) {
184                        throw new ArrayIndexOutOfBoundsException("ISeq is empty: " + index);
185                }
186
187                @Override
188                public int length() {
189                        return 0;
190                }
191
192                @Override
193                public List<Object> asList() {
194                        return Collections.emptyList();
195                }
196
197                @Override
198                public <B> ISeq<B> map(final Function<? super Object, ? extends B> mapper) {
199                        requireNonNull(mapper);
200                        return iseq();
201                }
202
203                @Override
204                public ISeq<Object> append(final Object... values) {
205                        return ISeq.of(values);
206                }
207
208                @Override
209                public ISeq<Object> append(final Iterable<?> values) {
210                        return ISeq.of(values);
211                }
212
213                @Override
214                public ISeq<Object> prepend(final Object... values) {
215                        return ISeq.of(values);
216                }
217
218                @Override
219                public ISeq<Object> prepend(final Iterable<?> values) {
220                        return ISeq.of(values);
221                }
222
223                @Override
224                public Stream<Object> stream() {
225                        return Stream.empty();
226                }
227
228                @Override
229                public Stream<Object> parallelStream() {
230                        return Stream.empty();
231                }
232
233                @Override
234                public Spliterator<Object> spliterator() {
235                        return Spliterators.emptySpliterator();
236                }
237
238                @Override
239                public MSeq<Object> copy() {
240                        return EmptyMSeq.INSTANCE;
241                }
242
243                @Override
244                public String toString() {
245                        return "[]";
246                }
247
248        }
249
250        @SuppressWarnings("unchecked")
251        public static <T> MSeq<T> mseq() {
252                return (MSeq<T>)EmptyMSeq.INSTANCE;
253        }
254
255        @SuppressWarnings("unchecked")
256        public static <T> ISeq<T> iseq() {
257                return (ISeq<T>)EmptyISeq.INSTANCE;
258        }
259
260}