001 /*
002 * Java Genetic Algorithm Library (jenetics-2.0.2).
003 * Copyright (c) 2007-2014 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@gmx.at)
019 */
020 package org.jenetics;
021
022 import static org.jenetics.internal.util.object.checkProbability;
023 import static org.jenetics.internal.util.object.eq;
024
025 import org.jenetics.internal.util.HashBuilder;
026
027 /**
028 * Abstract implementation of the alterer interface.
029 *
030 * @author <a href="mailto:franz.wilhelmstoetter@gmx.at">Franz Wilhelmstötter</a>
031 * @since 1.0
032 * @version 2.0 — <em>$Date: 2014-03-30 $</em>
033 */
034 public abstract class AbstractAlterer<G extends Gene<?, G>>
035 implements Alterer<G>
036 {
037
038 /**
039 * Return an alterer which does nothing.
040 *
041 * @param <G> the <i>gene</i> typ
042 * @return an alterer which does nothing.
043 */
044 public static <G extends Gene<?, G>> Alterer<G> Null() {
045 return new Alterer<G>() {
046 @Override
047 public <C extends Comparable<? super C>> int alter(
048 final Population<G, C> population,
049 final int generation
050 ) {
051 return 0;
052 }
053
054 @Override
055 public int hashCode() {
056 return HashBuilder.of(getClass()).value();
057 }
058
059 @Override
060 public boolean equals(final Object obj) {
061 return obj == this ||
062 obj != null && obj.getClass() == getClass();
063 }
064
065 @Override
066 public String toString() {
067 return "Alterer.Null";
068 }
069 };
070 }
071
072 public static final double DEFAULT_ALTER_PROBABILITY = 0.2;
073
074 /**
075 * The altering probability.
076 */
077 protected final double _probability;
078
079 /**
080 * Constructs an alterer with a given recombination probability.
081 *
082 * @param probability The recombination probability.
083 * @throws IllegalArgumentException if the {@code probability} is not in the
084 * valid range of {@code [0, 1]}.
085 */
086 protected AbstractAlterer(final double probability) {
087 _probability = checkProbability(probability);
088 }
089
090 /**
091 * Return the recombination/alter probability for this alterer.
092 *
093 * @return The recombination probability.
094 */
095 public double getProbability() {
096 return _probability;
097 }
098
099 @Override
100 public int hashCode() {
101 return HashBuilder.of(getClass()).and(_probability).value();
102 }
103
104 @Override
105 public boolean equals(final Object obj) {
106 if (obj == this) {
107 return true;
108 }
109 if (!(obj instanceof AbstractAlterer<?>)) {
110 return false;
111 }
112
113 final AbstractAlterer<?> alterer = (AbstractAlterer<?>)obj;
114 return eq(_probability, alterer._probability);
115 }
116 }
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