001 /*
002 * Java Genetic Algorithm Library (jenetics-7.1.2).
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 */
020 package io.jenetics.ext.util;
021
022 import java.util.Iterator;
023 import java.util.Objects;
024
025 import io.jenetics.util.MSeq;
026
027 /**
028 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
029 * @version 5.0
030 * @since 3.9
031 */
032 final class Trees {
033 private Trees() {}
034
035 /**
036 * Builds the parents of node up to and including the root node, where the
037 * original node is the last element in the returned array. The length of
038 * the returned array gives the node's depth in the tree.
039 *
040 * @param node the node to get the path for
041 * @param depth an int giving the number of steps already taken towards
042 * the root (on recursive calls), used to size the returned array
043 * @return an array of nodes giving the path from the root to the specified
044 * node
045 */
046 static <V, T extends Tree<V, T>> MSeq<T> pathElementsFromRoot(
047 final T node,
048 final int depth
049 ) {
050 final MSeq<T> path;
051 if (node == null) {
052 path = MSeq.ofLength(depth);
053 } else {
054 path = pathElementsFromRoot(
055 node.parent().orElse(null),
056 depth + 1
057 );
058 path.set(path.length() - depth - 1, node);
059 }
060
061 return path;
062 }
063
064 static <V, T extends Tree<V, T>> int[] pathFromRoot(
065 final T node,
066 final int depth
067 ) {
068 final int[] path;
069 if (node == null) {
070 path = new int[depth - 1];
071 } else {
072 final T parent = node.parent().orElse(null);
073 path = pathFromRoot(parent, depth + 1);
074
075 if (parent != null) {
076 final int index = node.parent()
077 .map(p -> p.indexOf(node))
078 .orElseThrow(AssertionError::new);
079
080 path[path.length - depth - 1] = index;
081 }
082 }
083
084 return path;
085 }
086
087 /**
088 * Checks if the two given trees has the same structure with the same values.
089 *
090 * @param a the first tree
091 * @param b the second tree
092 * @return {@code true} if the two given trees are structurally equals,
093 * {@code false} otherwise
094 */
095 static boolean equals(final Tree<?, ?> a, final Tree<?, ?> b) {
096 boolean equals = a == b;
097 if (!equals && a != null && b != null) {
098 equals = a.childCount() == b.childCount();
099 if (equals) {
100 equals = Objects.equals(a.value(), b.value());
101 if (equals && a.childCount() > 0) {
102 equals = equals(a.childIterator(), b.childIterator());
103 }
104 }
105 }
106
107 return equals;
108 }
109
110 private static boolean equals(
111 final Iterator<? extends Tree<?, ?>> a,
112 final Iterator<? extends Tree<?, ?>> b
113 ) {
114 boolean equals = true;
115 while (a.hasNext() && equals) {
116 equals = equals(a.next(), b.next());
117 }
118
119 return equals;
120 }
121
122 static int countChildren(final Tree<?, ?> tree) {
123 int cnt = tree.childCount();
124 for (int i = 0; i < tree.childCount(); ++i) {
125 cnt += countChildren(tree.childAt(i));
126 }
127 return cnt;
128 }
129
130 }
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