001 /*
002 * Java Genetic Algorithm Library (jenetics-5.1.0).
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;
021
022 import java.util.Iterator;
023 import java.util.NoSuchElementException;
024 import java.util.stream.IntStream;
025 import java.util.stream.Stream;
026
027 import io.jenetics.util.Factory;
028 import io.jenetics.util.ISeq;
029 import io.jenetics.util.Verifiable;
030
031 /**
032 * A chromosome consists of one or more genes. It also provides a factory
033 * method for creating new, random chromosome instances of the same type and the
034 * same constraint.
035 *
036 * @implSpec
037 * Implementations of the {@code Chromosome} interface must be <em>immutable</em>
038 * and guarantee an efficient random access ({@code O(1)}) to the genes. A
039 * {@code Chromosome} must contains at least one {@code Gene}.
040 *
041 * @see <a href="http://en.wikipedia.org/wiki/Chromosome">Wikipedia: Chromosome</a>
042 * @see Genotype
043 * @see Gene
044 *
045 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
046 * @since 1.0
047 * @version 3.7
048 */
049 public interface Chromosome<G extends Gene<?, G>>
050 extends
051 Verifiable,
052 Iterable<G>,
053 Factory<Chromosome<G>>
054 {
055 /**
056 * A factory method which creates a new {@link Chromosome} of specific type
057 * and the given {@code genes}.
058 *
059 * @param genes the genes of the new chromosome. The given genes array is
060 * not copied.
061 * @return A new {@link Chromosome} of the same type with the given genes.
062 * @throws NullPointerException if the given {@code gene}s are {@code null}.
063 * @throws IllegalArgumentException if the length of the given gene sequence
064 * is smaller than one.
065 */
066 public Chromosome<G> newInstance(final ISeq<G> genes);
067
068 /**
069 * Return the first gene of this chromosome. Each chromosome must contain
070 * at least one gene.
071 *
072 * @return the first gene of this chromosome.
073 */
074 public default G getGene() {
075 return getGene(0);
076 }
077
078 /**
079 * Return the gene on the specified index.
080 *
081 * @param index The gene index.
082 * @return the wanted gene.
083 * @throws IndexOutOfBoundsException if the index is out of range
084 * (index < 1 || index >= length()).
085 */
086 public G getGene(final int index);
087
088 /**
089 * Returns the length of the Chromosome. The minimal length of a
090 * chromosome is one.
091 *
092 * @return Length of the Chromosome
093 */
094 public int length();
095
096 /**
097 * Return an unmodifiable sequence of the genes of this chromosome.
098 *
099 * @return an immutable gene sequence.
100 */
101 public ISeq<G> toSeq();
102
103 @Override
104 public default Iterator<G> iterator() {
105 return new Iterator<G>() {
106 private int cursor = 0;
107
108 @Override
109 public boolean hasNext() {
110 return cursor != length();
111 }
112
113 @Override
114 public G next() {
115 final int i = cursor;
116 if (cursor >= length()) {
117 throw new NoSuchElementException();
118 }
119
120 cursor = i + 1;
121 return getGene(i);
122 }
123 };
124 }
125
126 /**
127 * Casts this {@code Chromosome} to an instance of type {@code C}.
128 * This is a convenient method for an ordinary cast and allows seamless
129 * method-chaining. Instead of
130 * <pre>{@code
131 * final Genotype<BitGene> gt = ...
132 * final int count = ((BitChromosome)gt.getChromosome()).bitCount()
133 * }</pre>
134 * you can write
135 * <pre>{@code
136 * final Genotype<BitGene> gt = ...
137 * final int count = gt.getChromosome()
138 * .as(BitChromosome.class)
139 * .bitCount()
140 * }</pre>
141 * This may lead to a more elegant programming style in some cases.
142 *
143 * @since 3.7
144 *
145 * @param type the target type class
146 * @param <C> the target chromosome type
147 * @return this chromosome casted as {@code C}
148 * @throws NullPointerException if the target type class is {@code null}
149 * @throws ClassCastException if this chromosome can't be casted to a
150 * chromosome of type {@code C}
151 */
152 public default <C extends Chromosome<G>> C as(final Class<C> type) {
153 return type.cast(this);
154 }
155
156 /**
157 * Returns a sequential {@code Stream} of genes with this chromosome as
158 * its source.
159 *
160 * @since 3.3
161 *
162 * @return a sequential {@code Stream} of genes
163 */
164 public default Stream<G> stream() {
165 return IntStream.range(0, length()).mapToObj(this::getGene);
166 }
167
168 }
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