001 /*
002 * Java Genetic Algorithm Library (jenetics-7.1.1).
003 * Copyright (c) 2007-2022 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 static java.util.Objects.requireNonNull;
023
024 import java.util.function.Function;
025
026 import io.jenetics.ext.internal.util.Escaper;
027
028 /**
029 * Helper methods for creating parentheses tree strings.
030 *
031 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
032 * @version 4.3
033 * @since 4.3
034 */
035 final class ParenthesesTrees {
036 private ParenthesesTrees() {}
037
038 private static final char[] PROTECTED_CHARS = { '(', ')', ',' };
039 static final char ESCAPE_CHAR = '\\';
040
041 private static final Escaper ESCAPER = new Escaper(ESCAPE_CHAR, PROTECTED_CHARS);
042
043 static String escape(final CharSequence value) {
044 return ESCAPER.escape(value);
045 }
046
047 static String unescape(final CharSequence value) {
048 return ESCAPER.unescape(value);
049 }
050
051 /* *************************************************************************
052 * To string methods.
053 **************************************************************************/
054
055 /**
056 * Return a compact string representation of the given tree.
057 * <pre>
058 * mul(div(cos(1.0), cos(π)), sin(mul(1.0, z)))
059 * </pre>
060 *
061 * @param tree the input tree
062 * @param mapper the string mapper function
063 * @return the string representation of the given tree
064 */
065 static <V> String toString(
066 final Tree<V, ?> tree,
067 final Function<? super V, ? extends CharSequence> mapper
068 ) {
069 requireNonNull(mapper);
070
071 if (tree != null) {
072 final StringBuilder out = new StringBuilder();
073 toString(out, tree, mapper);
074 return out.toString();
075 } else {
076 return "null";
077 }
078 }
079
080 private static <V> void toString(
081 final StringBuilder out,
082 final Tree<V, ?> tree,
083 final Function<? super V, ? extends CharSequence> mapper
084 ) {
085 out.append(escape(mapper.apply(tree.value())));
086 if (!tree.isLeaf()) {
087 out.append("(");
088 toString(out, tree.childAt(0), mapper);
089 for (int i = 1; i < tree.childCount(); ++i) {
090 out.append(",");
091 toString(out, tree.childAt(i), mapper);
092 }
093 out.append(")");
094 }
095 }
096
097 }
098
099
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