01 /*
02 * Java Genetic Algorithm Library (jenetics-5.1.0).
03 * Copyright (c) 2007-2019 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.util;
21
22 import static java.lang.String.format;
23 import static java.util.Objects.requireNonNull;
24
25 import java.util.ArrayDeque;
26 import java.util.Deque;
27 import java.util.Iterator;
28
29 /**
30 * Path (between nodes) iterator.
31 *
32 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
33 * @version 5.1
34 * @since 3.9
35 */
36 final class TreeNodePathIterator<V, T extends Tree<V, T>>
37 implements Iterator<T>
38 {
39 private final Deque<T> _stack = new ArrayDeque<>();
40
41 /**
42 * Create an iterator between two tree nodes.
43 *
44 * @param ancestor the ancestor tree node
45 * @param descendant the descendant tree node
46 * @throws NullPointerException if one of the nodes is {@code null}
47 */
48 TreeNodePathIterator(
49 final Tree<?, ?> ancestor,
50 final T descendant
51 ) {
52 requireNonNull(ancestor);
53 _stack.push(requireNonNull(descendant));
54
55 T current = descendant;
56 while (!current.identical(ancestor)) {
57 current = current.getParent().orElseThrow(() ->
58 new IllegalArgumentException(format(
59 "Node %s is not an ancestor of %s.",
60 ancestor.getValue(), descendant.getValue()
61 ))
62 );
63
64 _stack.push(current);
65 }
66 }
67
68 @Override
69 public boolean hasNext() {
70 return !_stack.isEmpty();
71 }
72
73 @Override
74 public T next() {
75 return _stack.pop();
76 }
77
78 }
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