001/*
002 * Java Genetic Algorithm Library (jenetics-9.1.0).
003 * Copyright (c) 2007-2026 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.SerialIO.readLong;
025import static io.jenetics.internal.util.SerialIO.writeLong;
026
027import java.io.IOException;
028import java.io.InvalidObjectException;
029import java.io.ObjectInput;
030import java.io.ObjectInputStream;
031import java.io.ObjectOutput;
032import java.io.Serial;
033import java.io.Serializable;
034import java.util.Objects;
035
036import io.jenetics.Gene;
037import io.jenetics.Genotype;
038import io.jenetics.internal.util.Requires;
039import io.jenetics.util.ISeq;
040
041/**
042 * Represents the initialization value of an evolution stream/iterator.
043 *
044 * @see EvolutionStart
045 * @see EvolutionStreamable#stream(EvolutionInit)
046 *
047 * @param <G> the gene type
048 *
049 * @implNote
050 * This class is immutable and thread-safe.
051 *
052 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
053 * @version 6.0
054 * @since 4.1
055 */
056public final class EvolutionInit<G extends Gene<?, G>>
057        implements Serializable
058{
059
060        @Serial
061        private static final long serialVersionUID = 1L;
062
063        private final ISeq<Genotype<G>> _population;
064        private final long _generation;
065
066        private EvolutionInit(
067                final ISeq<Genotype<G>> population,
068                final long generation
069        ) {
070                _population = requireNonNull(population);
071                _generation = Requires.positive(generation);
072        }
073
074        /**
075         * Return the initial population.
076         *
077         * @return the initial population
078         */
079        public ISeq<Genotype<G>> population() {
080                return _population;
081        }
082
083        /**
084         * Return the generation of the start population.
085         *
086         * @return the start generation
087         */
088        public long generation() {
089                return _generation;
090        }
091
092        @Override
093        public int hashCode() {
094                return Objects.hash(_generation, _population);
095        }
096
097        @Override
098        public boolean equals(final Object obj) {
099                return obj instanceof EvolutionInit<?> other &&
100                        _generation == other._generation &&
101                        Objects.equals(_population, other._population);
102        }
103
104        @Override
105        public String toString() {
106                return format(
107                        "EvolutionStart[population-size=%d, generation=%d]",
108                        _population.size(), _generation
109                );
110        }
111
112        /**
113         * Create a new evolution start object with the given population and for the
114         * given generation.
115         *
116         * @param <G> the gene type
117         * @param population the start population.
118         * @param generation the start generation of the population
119         * @return a new evolution start object
120         * @throws java.lang.NullPointerException if the given {@code population} is
121         *         {@code null}.
122         * @throws IllegalArgumentException if the given {@code generation} is
123         *         smaller then one
124         */
125        public static <G extends Gene<?, G>>
126        EvolutionInit<G> of(
127                final ISeq<Genotype<G>> population,
128                final long generation
129        ) {
130                return new EvolutionInit<>(population, generation);
131        }
132
133
134        /* *************************************************************************
135         *  Java object serialization
136         * ************************************************************************/
137
138        @Serial
139        private Object writeReplace() {
140                return new SerialProxy(SerialProxy.EVOLUTION_INIT, this);
141        }
142
143        @Serial
144        private void readObject(final ObjectInputStream stream)
145                throws InvalidObjectException
146        {
147                throw new InvalidObjectException("Serialization proxy required.");
148        }
149
150        void write(final ObjectOutput out) throws IOException {
151                out.writeObject(_population);
152                writeLong(_generation, out);
153        }
154
155        @SuppressWarnings({"unchecked", "rawtypes"})
156        static Object read(final ObjectInput in)
157                throws IOException, ClassNotFoundException
158        {
159                return new EvolutionInit(
160                        (ISeq)in.readObject(),
161                        readLong(in)
162                );
163        }
164
165}