001 /*
002 * Java Genetic Algorithm Library (jenetics-6.3.0).
003 * Copyright (c) 2007-2021 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.rewriting;
021
022 import static java.util.Objects.requireNonNull;
023 import static io.jenetics.internal.util.Hashes.hash;
024
025 import java.util.Map;
026
027 import io.jenetics.ext.rewriting.TreePattern.Var;
028 import io.jenetics.ext.util.Tree;
029
030 /**
031 * The result of a tree match operation. It contains the matching tree and the
032 * tree variables which matches the matching tree.
033 *
034 * <pre>{@code
035 * final Tree<String, ?> tree = ...;
036 * final TreePattern<String> pattern = ...;
037 * final Optional<TreeMatchResult<String>> result = pattern.match(tree);
038 * result.ifPresent(r -> {assert r.tree() == tree;});
039 * }</pre>
040 *
041 * @see TreePattern#match(Tree)
042 *
043 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
044 * @version 5.0
045 * @since 5.0
046 */
047 public final class TreeMatchResult<V> {
048
049 private final Tree<V, ?> _tree;
050 private final Map<Var<V>, Tree<V, ?>> _vars;
051
052 private TreeMatchResult(
053 final Tree<V, ?> tree,
054 final Map<Var<V>, Tree<V, ?>> vars
055 ) {
056 _tree = requireNonNull(tree);
057 _vars = Map.copyOf(vars);
058 }
059
060 /**
061 * The node (tree), which has been matched by some pattern. This tree is the
062 * argument of the {@link TreePattern#match(Tree)} call, in the case of a
063 * match.
064 *
065 * <pre>{@code
066 * final Tree<String, ?> tree = ...;
067 * final TreePattern<String> pattern = ...;
068 * final Optional<TreeMatchResult<String>> result = pattern.match(tree);
069 * result.ifPresent(r -> {assert r.tree() == tree;});
070 * }</pre>
071 *
072 * @return node (tree), which has been matched by some pattern
073 */
074 public Tree<V, ?> tree() {
075 return _tree;
076 }
077
078 /**
079 * The variables involved while matching the tree {@link #tree()}.
080 *
081 * @return variables involved while matching the tree {@link #tree()}.
082 */
083 public Map<Var<V>, Tree<V, ?>> vars() {
084 return _vars;
085 }
086
087 @Override
088 public int hashCode() {
089 return hash(_tree, hash(_vars));
090 }
091
092 @Override
093 public boolean equals(final Object obj) {
094 return obj == this ||
095 obj instanceof TreeMatchResult<?> &&
096 _tree.equals(((TreeMatchResult<?>)obj)._tree) &&
097 _vars.equals(((TreeMatchResult<?>)obj)._vars);
098 }
099
100 @Override
101 public String toString() {
102 return _tree.toParenthesesString();
103 }
104
105 static <V> TreeMatchResult<V> of(
106 final Tree<V, ?> tree,
107 final Map<Var<V>, Tree<V, ?>> vars
108 ) {
109 return new TreeMatchResult<>(tree, vars);
110 }
111
112 }
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