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.util;
021
022import static java.util.Objects.requireNonNull;
023
024import java.util.Comparator;
025import java.util.Spliterator;
026import java.util.function.Consumer;
027import java.util.function.Predicate;
028
029/**
030 * Extends the {@link Spliterator} interface by an additional {@code proceed}
031 * predicate.
032 *
033 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
034 * @version 4.1
035 * @since 4.1
036 */
037public final class LimitSpliterator<T> implements Spliterator<T> {
038
039        private final Spliterator<T> _spliterator;
040        private final Predicate<? super T> _proceed;
041
042        private boolean _limited = false;
043
044        private LimitSpliterator(
045                final Spliterator<T> spliterator,
046                final Predicate<? super T> proceed
047        ) {
048                _spliterator = requireNonNull(spliterator);
049                _proceed = requireNonNull(proceed);
050        }
051
052        @Override
053        public boolean tryAdvance(final Consumer<? super T> action) {
054                final boolean hasNext = _spliterator.tryAdvance(element -> {
055                        if (_proceed.test(element)) {
056                                action.accept(element);
057                        } else {
058                                _limited = true;
059                        }
060                });
061
062                return hasNext && !_limited;
063        }
064
065        @Override
066        public Spliterator<T> trySplit() {
067                final Spliterator<T> split = _spliterator.trySplit();
068                return split == null ? null : new LimitSpliterator<>(split, _proceed);
069        }
070
071        @Override
072        public long estimateSize() {
073                return 0;
074        }
075
076        @Override
077        public int characteristics() {
078                return _spliterator.characteristics() & ~SIZED & ~SUBSIZED;
079        }
080
081        @Override
082        public Comparator<? super T> getComparator() {
083                return _spliterator.getComparator();
084        }
085
086
087        public static <T> LimitSpliterator<T> of(
088                final Spliterator<T> spliterator,
089                final Predicate<? super T> proceed
090        ) {
091                return new LimitSpliterator<>(spliterator, proceed);
092        }
093
094}