001 /*
002 * Java Genetic Algorithm Library (jenetics-1.6.0).
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 1.0 — <em>$Date: 2014-03-01 $</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 * @return an alterer which does nothing.
042 */
043 public static <G extends Gene<?, G>> Alterer<G> Null() {
044 return new Alterer<G>() {
045 @Override
046 public <C extends Comparable<? super C>> int alter(
047 final Population<G, C> population,
048 final int generation
049 ) {
050 return 0;
051 }
052
053 @Override
054 public int hashCode() {
055 return HashBuilder.of(getClass()).value();
056 }
057
058 @Override
059 public boolean equals(final Object obj) {
060 return obj == this ||
061 obj != null && obj.getClass() == getClass();
062 }
063
064 @Override
065 public String toString() {
066 return "Alterer.Null";
067 }
068 };
069 }
070
071 public static final double DEFAULT_ALTER_PROBABILITY = 0.2;
072
073 /**
074 * The altering probability.
075 */
076 protected final double _probability;
077
078 /**
079 * Constructs an alterer with a given recombination probability.
080 *
081 * @param probability The recombination probability.
082 * @throws IllegalArgumentException if the {@code probability} is not in the
083 * valid range of {@code [0, 1]}.
084 */
085 protected AbstractAlterer(final double probability) {
086 _probability = checkProbability(probability);
087 }
088
089 /**
090 * Return the recombination/alter probability for this alterer.
091 *
092 * @return The recombination probability.
093 */
094 public double getProbability() {
095 return _probability;
096 }
097
098 @Override
099 public int hashCode() {
100 return HashBuilder.of(getClass()).and(_probability).value();
101 }
102
103 @Override
104 public boolean equals(final Object obj) {
105 if (obj == this) {
106 return true;
107 }
108 if (!(obj instanceof AbstractAlterer<?>)) {
109 return false;
110 }
111
112 final AbstractAlterer<?> alterer = (AbstractAlterer<?>)obj;
113 return eq(_probability, alterer._probability);
114 }
115 }
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