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/*
* Java Genetic Algorithm Library (jenetics-8.1.0).
* Copyright (c) 2007-2024 Franz Wilhelmstötter
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Author:
* Franz Wilhelmstötter ([email protected])
*/
package io.jenetics.ext;
import java.util.random.RandomGenerator;
import io.jenetics.Chromosome;
import io.jenetics.Mutator;
import io.jenetics.MutatorResult;
import io.jenetics.internal.math.Probabilities;
import io.jenetics.ext.util.FlatTreeNode;
import io.jenetics.ext.util.TreeNode;
/**
* Abstract class for mutating tree chromosomes.
*
* @author Franz Wilhelmstötter
* @version 4.1
* @since 4.1
*/
public abstract class TreeMutator<
A,
G extends TreeGene,
C extends Comparable
>
extends Mutator
{
public TreeMutator() {
this(DEFAULT_ALTER_PROBABILITY);
}
public TreeMutator(final double probability) {
super(probability);
}
/**
* Mutates the given chromosome.
*
* @param chromosome the chromosome to mutate
* @param p the mutation probability for the underlying genetic objects
* @param random the random engine used for the genotype mutation
* @return the mutation result
*/
@Override
protected MutatorResult> mutate(
final Chromosome chromosome,
final double p,
final RandomGenerator random
) {
final int P = Probabilities.toInt(p);
return random.nextInt() < P
? mutate(chromosome)
: new MutatorResult<>(chromosome, 0);
}
private MutatorResult> mutate(final Chromosome chromosome) {
final TreeNode tree = TreeNode.ofTree(chromosome.gene());
mutate(tree);
final var flat = FlatTreeNode.ofTree(tree);
final var genes = flat.map(t -> chromosome.gene().newInstance(t));
return new MutatorResult<>(chromosome.newInstance(genes), 1);
}
/**
* This method does the actual mutating, in place.
*
* @param tree the mutable tree to mutate
*/
protected abstract void mutate(final TreeNode tree);
}