001/*
002 * Java Genetic Algorithm Library (jenetics-7.2.0).
003 * Copyright (c) 2007-2023 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 */
020package io.jenetics.internal.engine;
021
022import static java.util.Objects.requireNonNull;
023
024import java.util.Spliterator;
025import java.util.function.Consumer;
026import java.util.function.Function;
027import java.util.function.Supplier;
028
029import io.jenetics.Gene;
030import io.jenetics.engine.Evolution;
031import io.jenetics.engine.EvolutionResult;
032import io.jenetics.engine.EvolutionStart;
033
034/**
035 * The {@code Spliterator} implementation of the {@code EvolutionStream}.
036 *
037 * @param <G> the gene type
038 * @param <C> the evolution result type
039 *
040 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
041 * @since 3.0
042 * @version 5.1
043 */
044public final class EvolutionSpliterator<
045        G extends Gene<?, G>,
046        C extends Comparable<? super C>
047>
048        implements Spliterator<EvolutionResult<G, C>>
049{
050
051        private final Supplier<EvolutionStart<G, C>> _start;
052        private final Evolution<G, C> _evolution;
053
054        private long _estimate;
055        private EvolutionStart<G, C> _next = null;
056
057        private EvolutionSpliterator(
058                final Supplier<EvolutionStart<G, C>> start,
059                final Evolution<G, C> evolution,
060                final long estimate
061        ) {
062                _evolution = requireNonNull(evolution);
063                _start = requireNonNull(start);
064                _estimate = estimate;
065        }
066
067        /**
068         * Create a new evolution spliterator with the given {@code start} element
069         * and the {@code evolution} function.
070         *
071         *
072         * @param start the start element
073         * @param evolution the evolution function
074         * @throws NullPointerException if one of the arguments is {@code null}
075         */
076        public EvolutionSpliterator(
077                final Supplier<EvolutionStart<G, C>> start,
078                final Evolution<G, C> evolution
079        ) {
080                this(start, evolution, Long.MAX_VALUE);
081        }
082
083        @Override
084        public boolean
085        tryAdvance(final Consumer<? super EvolutionResult<G, C>> action) {
086                if (_next == null) {
087                        _next = _start.get();
088                }
089
090                final EvolutionResult<G, C> result = _evolution.evolve(_next);
091                action.accept(result);
092                _next = result.next();
093                return true;
094        }
095
096        @Override
097        public Spliterator<EvolutionResult<G, C>> trySplit() {
098                return _estimate > 0
099                        ? new EvolutionSpliterator<>(_start, _evolution, _estimate >>>= 1)
100                        : null;
101        }
102
103        @Override
104        public long estimateSize() {
105                return _estimate;
106        }
107
108        @Override
109        public int characteristics() {
110                return NONNULL | IMMUTABLE | ORDERED;
111        }
112
113        /**
114         * Create a new spliterator with the given {@code start} element and the
115         * {@code evolution} function-function.
116         *
117         * @since 5.1
118         *
119         * @param start the start element
120         * @param evolution the evolution function-function
121         * @param <G> the gene type
122         * @param <C> the evolution result type
123         * @return a new evolution spliterator
124         */
125        public static <G extends Gene<?, G>, C extends Comparable<? super C>>
126        EvolutionSpliterator<G, C> of(
127                final Supplier<EvolutionStart<G, C>> start,
128                final Function<
129                        ? super EvolutionStart<G, C>,
130                        ? extends Evolution<G, C>> evolution
131        ) {
132                return new EvolutionSpliterator<>(
133                        start,
134                        result -> evolution.apply(result).evolve(result)
135                );
136        }
137
138}