1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2024 the original author or authors.
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 ///////////////////////////////////////////////////////////////////////////////////////////////
19
20 package com.puppycrawl.tools.checkstyle.checks.coding;
21
22 import com.puppycrawl.tools.checkstyle.StatelessCheck;
23 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
24 import com.puppycrawl.tools.checkstyle.api.DetailAST;
25 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
26 import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
27
28 /**
29 * <p>
30 * Checks for over-complicated boolean expressions. Currently, it finds code like
31 * {@code if (b == true)}, {@code b || true}, {@code !false},
32 * {@code boolean a = q > 12 ? true : false},
33 * etc.
34 * </p>
35 * <p>
36 * Rationale: Complex boolean logic makes code hard to understand and maintain.
37 * </p>
38 * <p>
39 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
40 * </p>
41 * <p>
42 * Violation Message Keys:
43 * </p>
44 * <ul>
45 * <li>
46 * {@code simplify.expression}
47 * </li>
48 * </ul>
49 *
50 * @since 3.0
51 */
52 @StatelessCheck
53 public class SimplifyBooleanExpressionCheck
54 extends AbstractCheck {
55
56 /**
57 * A key is pointing to the warning message text in "messages.properties"
58 * file.
59 */
60 public static final String MSG_KEY = "simplify.expression";
61
62 @Override
63 public int[] getDefaultTokens() {
64 return getRequiredTokens();
65 }
66
67 @Override
68 public int[] getAcceptableTokens() {
69 return getRequiredTokens();
70 }
71
72 @Override
73 public int[] getRequiredTokens() {
74 return new int[] {TokenTypes.LITERAL_TRUE, TokenTypes.LITERAL_FALSE};
75 }
76
77 @Override
78 public void visitToken(DetailAST ast) {
79 final DetailAST parent = ast.getParent();
80 switch (parent.getType()) {
81 case TokenTypes.NOT_EQUAL:
82 case TokenTypes.EQUAL:
83 case TokenTypes.LNOT:
84 case TokenTypes.LOR:
85 case TokenTypes.LAND:
86 log(parent, MSG_KEY);
87 break;
88 case TokenTypes.QUESTION:
89 final DetailAST nextSibling = ast.getNextSibling();
90 if (TokenUtil.isBooleanLiteralType(parent.getFirstChild().getType())
91 || nextSibling != null && nextSibling.getNextSibling() != null
92 && TokenUtil.isBooleanLiteralType(
93 nextSibling.getNextSibling().getType())) {
94 log(parent, MSG_KEY);
95 }
96 break;
97 default:
98 break;
99 }
100 }
101
102 }