001/*
002 * Java Genetic Algorithm Library (jenetics-8.1.0).
003 * Copyright (c) 2007-2024 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.util;
021
022import static java.lang.String.format;
023import static io.jenetics.internal.util.Hashes.hash;
024import static io.jenetics.internal.util.SerialIO.readInt;
025import static io.jenetics.internal.util.SerialIO.writeInt;
026
027import java.io.DataInput;
028import java.io.DataOutput;
029import java.io.IOException;
030import java.io.InvalidObjectException;
031import java.io.ObjectInputStream;
032import java.io.Serial;
033import java.io.Serializable;
034import java.util.Optional;
035import java.util.stream.IntStream;
036
037/**
038 * Integer range class.
039 *
040 * @implNote
041 * This class is immutable and thread-safe.
042 *
043 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
044 * @version 6.0
045 * @since 3.2
046 */
047public final /*record*/ class IntRange implements Serializable {
048
049        @Serial
050        private static final long serialVersionUID = 2L;
051
052        private final int _min;
053        private final int _max;
054
055        private IntRange(final int min, final int max) {
056                if (min > max) {
057                        throw new IllegalArgumentException(format(
058                                "Min greater than max: %s > %s", min, max
059                        ));
060                }
061
062                _min = min;
063                _max = max;
064        }
065
066        /**
067         * Return the minimum value of the integer range.
068         *
069         * @return the minimum value of the integer range
070         */
071        public int min() {
072                return _min;
073        }
074
075        /**
076         * Return the maximum value of the integer range.
077         *
078         * @return the maximum value of the integer range
079         */
080        public int max() {
081                return _max;
082        }
083
084        /**
085         * Checks whether the given {@code value} is within the range
086         * {@code [min, max)}.
087         *
088         * @since 8.0
089         *
090         * @param value the value to check
091         * @return {@code true} if the {@code value} is with the range
092         *         {@code [min, max)}, {@code false} otherwise
093         */
094        public boolean contains(final int value) {
095                return value >= _min && value < _max;
096        }
097
098        /**
099         * Return the intersection of {@code this} range with the {@code other}.
100         *
101         * @since 8.0
102         *
103         * @param other the intersection range or {@link Optional#empty()} if there
104         *        is none
105         * @return the range intersection
106         */
107        public Optional<IntRange> intersect(final IntRange other) {
108                if (_max <= other._min || _min >= other._max) {
109                        return Optional.empty();
110                } else {
111                        return Optional.of(
112                                IntRange.of(
113                                        Math.max(_min, other._min),
114                                        Math.min(_max, other._max)
115                                )
116                        );
117                }
118        }
119
120        /**
121         * Return the size of the {@code IntRange}: {@code max - min}.
122         *
123         * @since 3.9
124         *
125         * @return the size of the int range
126         */
127        public int size() {
128                return _max - _min;
129        }
130
131        /**
132         * Returns a sequential ordered {@code IntStream} from {@link #min()}
133         * (inclusive) to {@link #max()} (exclusive) by an incremental step of
134         * {@code 1}.
135         * <p>
136         * An equivalent sequence of increasing values can be produced sequentially
137         * using a {@code for} loop as follows:
138         * {@snippet lang="java":
139         * for (int i = range.min(); i < range.max(); ++i) {
140         *     // ...
141         * }
142         * }
143         *
144         * @since 3.4
145         *
146         * @return a sequential {@link IntStream} for the range of {@code int}
147         *         elements
148         */
149        public IntStream stream() {
150                return IntStream.range(_min, _max);
151        }
152
153        /**
154         * Create a new {@code IntRange} object with the given {@code min} and
155         * {@code max} values.
156         *
157         * @param min the lower bound of the integer range
158         * @param max the upper bound of the integer range
159         * @return a new {@code IntRange} object
160         * @throws IllegalArgumentException if {@code min > max}
161         */
162        public static IntRange of(final int min, final int max) {
163                return new IntRange(min, max);
164        }
165
166        /**
167         * Return a new (half-open) range, which contains only the given value:
168         * {@code [value, value + 1)}.
169         *
170         * @since 4.0
171         *
172         * @param value the value of the created (half-open) integer range
173         * @return a new (half-open) range, which contains only the given value
174         */
175        public static IntRange of(final int value) {
176                return of(value, value + 1);
177        }
178
179        @Override
180        public int hashCode() {
181                return hash(_min, hash(_max));
182        }
183
184        @Override
185        public boolean equals(final Object obj) {
186                return obj == this ||
187                        obj instanceof IntRange other &&
188                        _min == other._min &&
189                        _max == other._max;
190        }
191
192        @Override
193        public String toString() {
194                return "[" + _min + ", " + _max + "]";
195        }
196
197
198        /* *************************************************************************
199         *  Java object serialization
200         * ************************************************************************/
201
202        @Serial
203        private Object writeReplace() {
204                return new SerialProxy(SerialProxy.INT_RANGE, this);
205        }
206
207        @Serial
208        private void readObject(final ObjectInputStream stream)
209                throws InvalidObjectException
210        {
211                throw new InvalidObjectException("Serialization proxy required.");
212        }
213
214        void write(final DataOutput out) throws IOException {
215                writeInt(_min, out);
216                writeInt(_max, out);
217        }
218
219        static IntRange read(final DataInput in) throws IOException {
220                return of(readInt(in), readInt(in));
221        }
222
223}