001 /*
002 * Java Genetic Algorithm Library (jenetics-5.1.0).
003 * Copyright (c) 2007-2019 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 @SuppressWarnings("unchecked")
036 static <V, T extends Tree<V, T>> T self(final Tree<?, ?> tree) {
037 return (T)tree;
038 }
039
040 /**
041 * Builds the parents of node up to and including the root node, where the
042 * original node is the last element in the returned array. The length of
043 * the returned array gives the node's depth in the tree.
044 *
045 * @param node the node to get the path for
046 * @param depth an int giving the number of steps already taken towards
047 * the root (on recursive calls), used to size the returned array
048 * @return an array of nodes giving the path from the root to the specified
049 * node
050 */
051 static <V, T extends Tree<V, T>> MSeq<T> pathElementsFromRoot(
052 final T node,
053 final int depth
054 ) {
055 final MSeq<T> path;
056 if (node == null) {
057 path = MSeq.ofLength(depth);
058 } else {
059 path = pathElementsFromRoot(
060 node.getParent().orElse(null),
061 depth + 1
062 );
063 path.set(path.length() - depth - 1, node);
064 }
065
066 return path;
067 }
068
069 static <V, T extends Tree<V, T>> int[] pathFromRoot(
070 final T node,
071 final int depth
072 ) {
073 final int[] path;
074 if (node == null) {
075 path = new int[depth - 1];
076 } else {
077 final T parent = node.getParent().orElse(null);
078 path = pathFromRoot(parent, depth + 1);
079
080 if (parent != null) {
081 final int index = node.getParent()
082 .map(p -> p.indexOf(node))
083 .orElseThrow(AssertionError::new);
084
085 path[path.length - depth - 1] = index;
086 }
087 }
088
089 return path;
090 }
091
092 /**
093 * Checks if the two given trees has the same structure with the same values.
094 *
095 * @param a the first tree
096 * @param b the second tree
097 * @return {@code true} if the two given trees are structurally equals,
098 * {@code false} otherwise
099 */
100 static boolean equals(final Tree<?, ?> a, final Tree<?, ?> b) {
101 boolean equals = a == b;
102 if (!equals && a != null && b != null) {
103 equals = a.childCount() == b.childCount();
104 if (equals) {
105 equals = Objects.equals(a.getValue(), b.getValue());
106 if (equals && a.childCount() > 0) {
107 equals = equals(a.childIterator(), b.childIterator());
108 }
109 }
110 }
111
112 return equals;
113 }
114
115 private static boolean equals(
116 final Iterator<? extends Tree<?, ?>> a,
117 final Iterator<? extends Tree<?, ?>> b
118 ) {
119 boolean equals = true;
120 while (a.hasNext() && equals) {
121 equals = equals(a.next(), b.next());
122 }
123
124 return equals;
125 }
126
127 static int countChildren(final Tree<?, ?> tree) {
128 int cnt = tree.childCount();
129 for (int i = 0; i < tree.childCount(); ++i) {
130 cnt += countChildren(tree.childAt(i));
131 }
132 return cnt;
133 }
134
135 }
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