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
024 import java.util.stream.Stream;
025
026 import io.jenetics.ext.util.Tree;
027
028 /**
029 * Implementation of a pattern based tree matcher. It allows you to iterate over
030 * all matches of a tree for a given pattern.
031 *
032 * <pre>{@code
033 * final TreePattern<String> pattern = TreePattern.compile("add($x,$y)");
034 * final Tree<String, ?> tree = TreeNode.parse("add(1,add(2,3))");
035 * final TreeMatcher<String> matcher = pattern.matcher(tree);
036 * matcher.results().forEach(r -> System.out.println(r.tree().toParenthesesString()));
037 * // Prints:
038 * // add(1,add(2,3))
039 * // add(2,3)
040 * }</pre>
041 *
042 * @see TreePattern#matcher(Tree)
043 *
044 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
045 * @version 5.0
046 * @since 5.0
047 */
048 public final class TreeMatcher<V> {
049
050 private final TreePattern<V> _pattern;
051 private final Tree<V, ?> _tree;
052
053 private TreeMatcher(final TreePattern<V> pattern, final Tree<V, ?> tree) {
054 _pattern = requireNonNull(pattern);
055 _tree = requireNonNull(tree);
056 }
057
058 /**
059 * Return the underlying pattern of {@code this} matcher.
060 *
061 * @return the underlying tree pattern
062 */
063 public TreePattern<V> pattern() {
064 return _pattern;
065 }
066
067 /**
068 * Return the matching tree.
069 *
070 * @return the matching tree
071 */
072 public Tree<V, ?> tree() {
073 return _tree;
074 }
075
076 /**
077 * Tests if the tree matches the pattern.
078 *
079 * @return {@code true} if the tree matches against the pattern,
080 * {@code false} otherwise
081 * @throws NullPointerException if the given predicate is {@code null}
082 */
083 public boolean matches() {
084 return _pattern.matches(_tree);
085 }
086
087 /**
088 * Return all matching <em>sub</em>-trees.
089 *
090 * @return all matching sub-trees
091 * @throws NullPointerException if the given predicate is {@code null}
092 */
093 public Stream<TreeMatchResult<V>> results() {
094 return _tree.stream()
095 .flatMap(tree -> _pattern.match(tree).stream());
096 }
097
098 static <V> TreeMatcher<V> of(
099 final TreePattern<V> pattern,
100 final Tree<V, ?> tree
101 ) {
102 return new TreeMatcher<>(pattern, tree);
103 }
104
105 }
|