001/*
002 * Java Genetic Algorithm Library (jenetics-8.1.0).
003 * Copyright (c) 2007-2024 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 */
020package io.jenetics.ext.rewriting;
021
022import static java.util.Objects.requireNonNull;
023
024import java.util.stream.Stream;
025
026import 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 * {@snippet lang="java":
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 * }
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 */
048public 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 subtrees
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}