001 /*
002 * Java Genetic Algorithm Library (jenetics-8.0.0).
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 */
020 package io.jenetics.engine;
021
022 import static java.lang.String.format;
023 import static java.util.Objects.requireNonNull;
024 import static io.jenetics.internal.util.Hashes.hash;
025 import static io.jenetics.internal.util.SerialIO.readLong;
026 import static io.jenetics.internal.util.SerialIO.writeLong;
027
028 import java.io.IOException;
029 import java.io.InvalidObjectException;
030 import java.io.ObjectInput;
031 import java.io.ObjectInputStream;
032 import java.io.ObjectOutput;
033 import java.io.Serial;
034 import java.io.Serializable;
035 import java.util.Objects;
036
037 import io.jenetics.Gene;
038 import io.jenetics.Phenotype;
039 import io.jenetics.internal.util.Requires;
040 import io.jenetics.util.ISeq;
041
042 /**
043 * Represents a state of the GA at the start of an evolution step.
044 *
045 * @see EvolutionResult
046 * @see EvolutionInit
047 * @see EvolutionStreamable#stream(EvolutionStart)
048 *
049 * @param <G> the gene type
050 * @param <C> the fitness type
051 *
052 * @implNote
053 * This class is immutable and thread-safe.
054 *
055 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
056 * @since 3.1
057 * @version 6.0
058 */
059 public final class EvolutionStart<
060 G extends Gene<?, G>,
061 C extends Comparable<? super C>
062 >
063 implements Serializable
064 {
065
066 @Serial
067 private static final long serialVersionUID = 2L;
068
069 private final ISeq<Phenotype<G, C>> _population;
070 private final long _generation;
071
072 private final boolean _dirty;
073
074 EvolutionStart(
075 final ISeq<Phenotype<G, C>> population,
076 final long generation,
077 final boolean dirty
078 ) {
079 _population = requireNonNull(population);
080 _generation = Requires.positive(generation);
081 _dirty = dirty;
082 }
083
084 /**
085 * Return the population before the evolution step.
086 *
087 * @return the start population
088 */
089 public ISeq<Phenotype<G, C>> population() {
090 return _population;
091 }
092
093 /**
094 * Return the generation of the start population.
095 *
096 * @return the start generation
097 */
098 public long generation() {
099 return _generation;
100 }
101
102 /**
103 * Indicates whether the population is guaranteed to be evaluated. If this
104 * flag is {@code true}, the population possibly contains unevaluated
105 * individuals.
106 *
107 * @return {@code false}, if it is guaranteed that all individuals has
108 * already been evaluated, {@code true} otherwise
109 */
110 boolean isDirty() {
111 return _dirty;
112 }
113
114 @Override
115 public int hashCode() {
116 return hash(_generation, hash(_population, hash(getClass())));
117 }
118
119 @Override
120 public boolean equals(final Object obj) {
121 return obj == this ||
122 obj instanceof EvolutionStart<?, ?> other &&
123 _generation == other._generation &&
124 Objects.equals(_population, other._population);
125 }
126
127 @Override
128 public String toString() {
129 return format(
130 "EvolutionStart[population-size=%d, generation=%d]",
131 _population.size(), _generation
132 );
133 }
134
135 /**
136 * Create a new evolution start object with the given population and for the
137 * given generation.
138 *
139 * @param <G> the gene type
140 * @param <C> the fitness type
141 * @param population the start population.
142 * @param generation the start generation of the population
143 * @return a new evolution start object
144 * @throws java.lang.NullPointerException if the given {@code population} is
145 * {@code null}.
146 * @throws IllegalArgumentException if the given {@code generation} is
147 * smaller then one
148 */
149 public static <G extends Gene<?, G>, C extends Comparable<? super C>>
150 EvolutionStart<G, C> of(
151 final ISeq<Phenotype<G, C>> population,
152 final long generation
153 ) {
154 return new EvolutionStart<>(population, generation, true);
155 }
156
157 /**
158 * An empty evolution start object, which can be used as initial evolution
159 * value. The evolution {@link Engine} is then responsible for creating the
160 * proper initial population,
161 *
162 * @since 5.1
163 *
164 * @param <G> the gene type
165 * @param <C> the fitness type
166 * @return an empty evolution start object
167 */
168 public static <G extends Gene<?, G>, C extends Comparable<? super C>>
169 EvolutionStart<G, C> empty() {
170 return new EvolutionStart<>(ISeq.empty(), 1, false);
171 }
172
173
174 /* *************************************************************************
175 * Java object serialization
176 * ************************************************************************/
177
178 @Serial
179 private Object writeReplace() {
180 return new SerialProxy(SerialProxy.EVOLUTION_START, this);
181 }
182
183 @Serial
184 private void readObject(final ObjectInputStream stream)
185 throws InvalidObjectException
186 {
187 throw new InvalidObjectException("Serialization proxy required.");
188 }
189
190 void write(final ObjectOutput out) throws IOException {
191 out.writeObject(_population);
192 writeLong(_generation, out);
193 }
194
195 @SuppressWarnings({"unchecked", "rawtypes"})
196 static Object read(final ObjectInput in)
197 throws IOException, ClassNotFoundException
198 {
199 return new EvolutionStart(
200 (ISeq)in.readObject(),
201 readLong(in),
202 true
203 );
204 }
205
206 }
|