01 /*
02 * Java Genetic Algorithm Library (jenetics-7.1.1).
03 * Copyright (c) 2007-2022 Franz Wilhelmstötter
04 *
05 * Licensed under the Apache License, Version 2.0 (the "License");
06 * you may not use this file except in compliance with the License.
07 * You may obtain a copy of the License at
08 *
09 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 * Author:
18 * Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
19 */
20 package io.jenetics.prog.op;
21
22 import java.util.Map;
23
24 import io.jenetics.ext.util.Tree;
25
26 /**
27 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
28 * @version 4.3
29 * @since 4.3
30 */
31 final class MathExprFormatter {
32 private MathExprFormatter() {}
33
34 private static final Map<Op<Double>, String> INFIX_OPS = Map.of(
35 MathOp.ADD, " + ",
36 MathOp.SUB, " - ",
37 MathOp.MUL, "*",
38 MathOp.DIV, "/",
39 MathOp.MOD, "%",
40 MathOp.POW, "^"
41 );
42
43 private static final Map<Op<Double>, Integer> PRECEDENCE = Map.of(
44 MathOp.ADD, 6,
45 MathOp.SUB, 6,
46 MathOp.MUL, 5,
47 MathOp.DIV, 5,
48 MathOp.MOD, 5,
49 MathOp.POW, 4
50 );
51
52 static String format(final Tree<? extends Op<Double>, ?> tree) {
53 final StringBuilder out = new StringBuilder();
54 format(tree, out);
55 return out.toString();
56 }
57
58 private static void format(
59 final Tree<? extends Op<Double>, ?> tree,
60 final StringBuilder out
61 ) {
62 final Op<Double> op = tree.value();
63 if (INFIX_OPS.containsKey(op)) {
64 infix(tree, out);
65 } else {
66 out.append(op);
67 if (!tree.isLeaf()) {
68 out.append("(");
69 format(tree.childAt(0), out);
70 for (int i = 1; i < tree.childCount(); ++i) {
71 out.append(", ");
72 format(tree.childAt(i), out);
73 }
74 out.append(")");
75 }
76 }
77 }
78
79 private static void infix(
80 final Tree<? extends Op<Double>, ?> tree,
81 final StringBuilder out
82 ) {
83 assert tree.childCount() == 2;
84
85 final int precedence = PRECEDENCE.getOrDefault(tree.value(), 100);
86 final int parentPrecedence = tree.parent()
87 .map(p -> PRECEDENCE.getOrDefault(p.value(), 100))
88 .orElse(100);
89
90 final boolean brackets = !tree.isRoot() && precedence >= parentPrecedence;
91
92 if (brackets) out.append("(");
93 format(tree.childAt(0), out);
94 out.append(INFIX_OPS.get(tree.value()));
95 format(tree.childAt(1), out);
96 if (brackets) out.append(")");
97 }
98
99 }
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