01 /*
02 * Java Genetic Algorithm Library (jenetics-7.1.1).
03 * Copyright (c) 2007-2022 Franz Wilhelmstötter
04 *
05 * Licensed under the Apache License, Version 2.0 (the "License");
06 * you may not use this file except in compliance with the License.
07 * You may obtain a copy of the License at
08 *
09 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 * Author:
18 * Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
19 */
20 package io.jenetics.ext.internal.util;
21
22 import java.util.ArrayList;
23 import java.util.List;
24 import java.util.Objects;
25 import java.util.Spliterator;
26 import java.util.function.Consumer;
27 import java.util.function.Supplier;
28
29 /**
30 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
31 * @version 4.1
32 * @since 4.1
33 */
34 public class CyclicSpliterator<T> implements Spliterator<T> {
35
36 private final List<Supplier<Spliterator<T>>> _spliterators;
37
38 private ConcatSpliterator<T> _concat = null;
39
40 public CyclicSpliterator(final List<Supplier<Spliterator<T>>> spliterators) {
41 spliterators.forEach(Objects::requireNonNull);
42 _spliterators = new ArrayList<>(spliterators);
43 }
44
45 @Override
46 public boolean tryAdvance(final Consumer<? super T> action) {
47 boolean advance = true;
48 if (_spliterators.isEmpty()) {
49 advance = false;
50 } else {
51 if (!spliterator().tryAdvance(action)) {
52 _concat = null;
53 }
54 }
55
56 return advance;
57 }
58
59 @Override
60 public Spliterator<T> trySplit() {
61 return new CyclicSpliterator<>(_spliterators);
62 }
63
64 @Override
65 public long estimateSize() {
66 return Long.MAX_VALUE;
67 }
68
69 @Override
70 public int characteristics() {
71 return Spliterator.ORDERED;
72 }
73
74 private ConcatSpliterator<T> spliterator() {
75 if (_concat == null) {
76 _concat = new ConcatSpliterator<>(
77 _spliterators.stream()
78 .map(Supplier::get)
79 .toList()
80 );
81 }
82
83 return _concat;
84 }
85
86 }
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