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.engine;
021
022import static java.lang.String.format;
023import static java.util.Objects.requireNonNull;
024import static io.jenetics.internal.util.Hashes.hash;
025import static io.jenetics.internal.util.SerialIO.readLong;
026import static io.jenetics.internal.util.SerialIO.writeLong;
027
028import java.io.IOException;
029import java.io.InvalidObjectException;
030import java.io.ObjectInput;
031import java.io.ObjectInputStream;
032import java.io.ObjectOutput;
033import java.io.Serial;
034import java.io.Serializable;
035import java.util.Objects;
036
037import io.jenetics.Gene;
038import io.jenetics.Genotype;
039import io.jenetics.internal.util.Requires;
040import io.jenetics.util.ISeq;
041
042/**
043 * Represents the initialization value of an evolution stream/iterator.
044 *
045 * @see EvolutionStart
046 * @see EvolutionStreamable#stream(EvolutionInit)
047 *
048 * @param <G> the gene type
049 *
050 * @implNote
051 * This class is immutable and thread-safe.
052 *
053 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
054 * @version 6.0
055 * @since 4.1
056 */
057public final class EvolutionInit<G extends Gene<?, G>>
058        implements Serializable
059{
060
061        @Serial
062        private static final long serialVersionUID = 1L;
063
064        private final ISeq<Genotype<G>> _population;
065        private final long _generation;
066
067        private EvolutionInit(
068                final ISeq<Genotype<G>> population,
069                final long generation
070        ) {
071                _population = requireNonNull(population);
072                _generation = Requires.positive(generation);
073        }
074
075        /**
076         * Return the initial population.
077         *
078         * @return the initial population
079         */
080        public ISeq<Genotype<G>> population() {
081                return _population;
082        }
083
084        /**
085         * Return the generation of the start population.
086         *
087         * @return the start generation
088         */
089        public long generation() {
090                return _generation;
091        }
092
093        @Override
094        public int hashCode() {
095                return hash(_generation, hash(_population));
096        }
097
098        @Override
099        public boolean equals(final Object obj) {
100                return obj == this ||
101                        obj instanceof EvolutionInit<?> other &&
102                        _generation == other._generation &&
103                        Objects.equals(_population, other._population);
104        }
105
106        @Override
107        public String toString() {
108                return format(
109                        "EvolutionStart[population-size=%d, generation=%d]",
110                        _population.size(), _generation
111                );
112        }
113
114        /**
115         * Create a new evolution start object with the given population and for the
116         * given generation.
117         *
118         * @param <G> the gene type
119         * @param population the start population.
120         * @param generation the start generation of the population
121         * @return a new evolution start object
122         * @throws java.lang.NullPointerException if the given {@code population} is
123         *         {@code null}.
124         * @throws IllegalArgumentException if the given {@code generation} is
125         *         smaller then one
126         */
127        public static <G extends Gene<?, G>>
128        EvolutionInit<G> of(
129                final ISeq<Genotype<G>> population,
130                final long generation
131        ) {
132                return new EvolutionInit<>(population, generation);
133        }
134
135
136        /* *************************************************************************
137         *  Java object serialization
138         * ************************************************************************/
139
140        @Serial
141        private Object writeReplace() {
142                return new SerialProxy(SerialProxy.EVOLUTION_INIT, this);
143        }
144
145        @Serial
146        private void readObject(final ObjectInputStream stream)
147                throws InvalidObjectException
148        {
149                throw new InvalidObjectException("Serialization proxy required.");
150        }
151
152        void write(final ObjectOutput out) throws IOException {
153                out.writeObject(_population);
154                writeLong(_generation, out);
155        }
156
157        @SuppressWarnings({"unchecked", "rawtypes"})
158        static Object read(final ObjectInput in)
159                throws IOException, ClassNotFoundException
160        {
161                return new EvolutionInit(
162                        (ISeq)in.readObject(),
163                        readLong(in)
164                );
165        }
166
167}