1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2025 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.FileStatefulCheck;
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
27 /**
28 * <div>
29 * Restricts nested if-else blocks to a specified depth.
30 * </div>
31 *
32 * @since 3.2
33 */
34 @FileStatefulCheck
35 public final class NestedIfDepthCheck extends AbstractCheck {
36
37 /**
38 * A key is pointing to the warning message text in "messages.properties"
39 * file.
40 */
41 public static final String MSG_KEY = "nested.if.depth";
42
43 /** Specify maximum allowed nesting depth. */
44 private int max = 1;
45 /** Current nesting depth. */
46 private int depth;
47
48 /**
49 * Setter to specify maximum allowed nesting depth.
50 *
51 * @param max maximum allowed nesting depth.
52 * @since 3.2
53 */
54 public void setMax(int max) {
55 this.max = max;
56 }
57
58 @Override
59 public int[] getDefaultTokens() {
60 return getRequiredTokens();
61 }
62
63 @Override
64 public int[] getAcceptableTokens() {
65 return getRequiredTokens();
66 }
67
68 @Override
69 public int[] getRequiredTokens() {
70 return new int[] {TokenTypes.LITERAL_IF};
71 }
72
73 @Override
74 public void visitToken(DetailAST literalIf) {
75 if (!isElseIf(literalIf)) {
76 if (depth > max) {
77 log(literalIf, MSG_KEY, depth, max);
78 }
79 ++depth;
80 }
81 }
82
83 @Override
84 public void leaveToken(DetailAST literalIf) {
85 if (!isElseIf(literalIf)) {
86 --depth;
87 }
88 }
89
90 /**
91 * Returns whether a token represents an ELSE as part of an ELSE / IF set.
92 *
93 * @param ast the token to check
94 * @return whether it is
95 */
96 private static boolean isElseIf(DetailAST ast) {
97 final DetailAST parentAST = ast.getParent();
98
99 return isElse(parentAST) || isElseWithCurlyBraces(parentAST);
100 }
101
102 /**
103 * Returns whether a token represents an ELSE.
104 *
105 * @param ast the token to check
106 * @return whether the token represents an ELSE
107 */
108 private static boolean isElse(DetailAST ast) {
109 return ast.getType() == TokenTypes.LITERAL_ELSE;
110 }
111
112 /**
113 * Returns whether a token represents an SLIST as part of an ELSE
114 * statement.
115 *
116 * @param ast the token to check
117 * @return whether the toke does represent an SLIST as part of an ELSE
118 */
119 private static boolean isElseWithCurlyBraces(DetailAST ast) {
120 return ast.getChildCount() == 2 && isElse(ast.getParent());
121 }
122 }