001 /*
002 * Java Genetic Algorithm Library (jenetics-6.3.0).
003 * Copyright (c) 2007-2021 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.Serializable;
034 import java.util.Objects;
035
036 import io.jenetics.Gene;
037 import io.jenetics.Phenotype;
038 import io.jenetics.internal.util.Requires;
039 import io.jenetics.util.ISeq;
040
041 /**
042 * Represents a state of the GA at the start of an evolution step.
043 *
044 * @see EvolutionResult
045 * @see EvolutionInit
046 * @see EvolutionStreamable#stream(EvolutionStart)
047 *
048 * @param <G> the gene type
049 * @param <C> the fitness type
050 *
051 * @implNote
052 * This class is immutable and thread-safe.
053 *
054 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
055 * @since 3.1
056 * @version 6.0
057 */
058 public final class EvolutionStart<
059 G extends Gene<?, G>,
060 C extends Comparable<? super C>
061 >
062 implements Serializable
063 {
064
065 private static final long serialVersionUID = 2L;
066
067 private final ISeq<Phenotype<G, C>> _population;
068 private final long _generation;
069
070 private final boolean _dirty;
071
072 EvolutionStart(
073 final ISeq<Phenotype<G, C>> population,
074 final long generation,
075 final boolean dirty
076 ) {
077 _population = requireNonNull(population);
078 _generation = Requires.positive(generation);
079 _dirty = dirty;
080 }
081
082 /**
083 * Return the population before the evolution step.
084 *
085 * @return the start population
086 */
087 public ISeq<Phenotype<G, C>> population() {
088 return _population;
089 }
090
091 /**
092 * Return the generation of the start population.
093 *
094 * @return the start generation
095 */
096 public long generation() {
097 return _generation;
098 }
099
100 /**
101 * Indicates whether the population is guaranteed to be evaluated. If this
102 * flag is {@code true}, the population possibly contains unevaluated
103 * individuals.
104 *
105 * @return {@code false}, if it is guaranteed that all individuals has
106 * already been evaluated, {@code true} otherwise
107 */
108 boolean isDirty() {
109 return _dirty;
110 }
111
112 @Override
113 public int hashCode() {
114 return hash(_generation, hash(_population, hash(getClass())));
115 }
116
117 @Override
118 public boolean equals(final Object obj) {
119 return obj == this ||
120 obj instanceof EvolutionStart &&
121 _generation == ((EvolutionStart)obj)._generation &&
122 Objects.equals(_population, ((EvolutionStart)obj)._population);
123 }
124
125 @Override
126 public String toString() {
127 return format(
128 "EvolutionStart[population-size=%d, generation=%d]",
129 _population.size(), _generation
130 );
131 }
132
133 /**
134 * Create a new evolution start object with the given population and for the
135 * given generation.
136 *
137 * @param <G> the gene type
138 * @param <C> the fitness type
139 * @param population the start population.
140 * @param generation the start generation of the population
141 * @return a new evolution start object
142 * @throws java.lang.NullPointerException if the given {@code population} is
143 * {@code null}.
144 * @throws IllegalArgumentException if the given {@code generation} is
145 * smaller then one
146 */
147 public static <G extends Gene<?, G>, C extends Comparable<? super C>>
148 EvolutionStart<G, C> of(
149 final ISeq<Phenotype<G, C>> population,
150 final long generation
151 ) {
152 return new EvolutionStart<>(population, generation, true);
153 }
154
155 /**
156 * An empty evolution start object, which can be used as initial evolution
157 * value. The evolution {@link Engine} is then responsible for creating the
158 * proper initial population,
159 *
160 * @since 5.1
161 *
162 * @param <G> the gene type
163 * @param <C> the fitness type
164 * @return an empty evolution start object
165 */
166 public static <G extends Gene<?, G>, C extends Comparable<? super C>>
167 EvolutionStart<G, C> empty() {
168 return new EvolutionStart<>(ISeq.empty(), 1, false);
169 }
170
171
172 /* *************************************************************************
173 * Java object serialization
174 * ************************************************************************/
175
176 private Object writeReplace() {
177 return new Serial(Serial.EVOLUTION_START, this);
178 }
179
180 private void readObject(final ObjectInputStream stream)
181 throws InvalidObjectException
182 {
183 throw new InvalidObjectException("Serialization proxy required.");
184 }
185
186 void write(final ObjectOutput out) throws IOException {
187 out.writeObject(_population);
188 writeLong(_generation, out);
189 }
190
191 @SuppressWarnings({"unchecked", "rawtypes"})
192 static Object read(final ObjectInput in)
193 throws IOException, ClassNotFoundException
194 {
195 return new EvolutionStart(
196 (ISeq)in.readObject(),
197 readLong(in),
198 true
199 );
200 }
201
202 }
|