001 /*
002 * Java Genetic Algorithm Library (jenetics-4.4.0).
003 * Copyright (c) 2007-2019 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
026 import java.util.Objects;
027
028 import io.jenetics.Gene;
029 import io.jenetics.Genotype;
030 import io.jenetics.internal.util.require;
031 import io.jenetics.util.ISeq;
032
033 /**
034 * Represents the initialization value of an evolution stream/iterator.
035 *
036 * @see EvolutionStart
037 * @see EvolutionStreamable#stream(EvolutionInit)
038 * @see Engine#iterator(EvolutionInit)
039 *
040 * @param <G> the gene type
041 *
042 * @implNote
043 * This class is immutable and thread-safe.
044 *
045 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
046 * @version 4.1
047 * @since 4.1
048 */
049 public final class EvolutionInit<G extends Gene<?, G>> {
050
051 private final ISeq<Genotype<G>> _population;
052 private final long _generation;
053
054 private EvolutionInit(
055 final ISeq<Genotype<G>> population,
056 final long generation
057 ) {
058 _population = requireNonNull(population);
059 _generation = require.positive(generation);
060 }
061
062 /**
063 * Return the initial population.
064 *
065 * @return the initial population
066 */
067 public ISeq<Genotype<G>> getPopulation() {
068 return _population;
069 }
070
071 /**
072 * Return the generation of the start population.
073 *
074 * @return the start generation
075 */
076 public long getGeneration() {
077 return _generation;
078 }
079
080 @Override
081 public int hashCode() {
082 return hash(_generation, hash(_population));
083 }
084
085 @Override
086 public boolean equals(final Object obj) {
087 return obj == this ||
088 obj instanceof EvolutionInit &&
089 _generation == ((EvolutionInit)obj)._generation &&
090 Objects.equals(_population, ((EvolutionInit)obj)._population);
091 }
092
093 @Override
094 public String toString() {
095 return format(
096 "EvolutionStart[population-size=%d, generation=%d]",
097 _population.size(), _generation
098 );
099 }
100
101 /**
102 * Create a new evolution start object with the given population and for the
103 * given generation.
104 *
105 * @param <G> the gene type
106 * @param population the start population.
107 * @param generation the start generation of the population
108 * @return a new evolution start object
109 * @throws java.lang.NullPointerException if the given {@code population} is
110 * {@code null}.
111 * @throws IllegalArgumentException if the given {@code generation} is
112 * smaller then one
113 */
114 public static <G extends Gene<?, G>>
115 EvolutionInit<G> of(
116 final ISeq<Genotype<G>> population,
117 final long generation
118 ) {
119 return new EvolutionInit<>(population, generation);
120 }
121
122 }
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