1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2026 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 * Creates a new {@code NestedIfDepthCheck} instance.
50 */
51 public NestedIfDepthCheck() {
52 // no code by default
53 }
54
55 /**
56 * Setter to specify maximum allowed nesting depth.
57 *
58 * @param max maximum allowed nesting depth.
59 * @since 3.2
60 */
61 public void setMax(int max) {
62 this.max = max;
63 }
64
65 @Override
66 public int[] getDefaultTokens() {
67 return getRequiredTokens();
68 }
69
70 @Override
71 public int[] getAcceptableTokens() {
72 return getRequiredTokens();
73 }
74
75 @Override
76 public int[] getRequiredTokens() {
77 return new int[] {TokenTypes.LITERAL_IF};
78 }
79
80 @Override
81 public void visitToken(DetailAST literalIf) {
82 if (!isElseIf(literalIf)) {
83 if (depth > max) {
84 log(literalIf, MSG_KEY, depth, max);
85 }
86 ++depth;
87 }
88 }
89
90 @Override
91 public void leaveToken(DetailAST literalIf) {
92 if (!isElseIf(literalIf)) {
93 --depth;
94 }
95 }
96
97 /**
98 * Returns whether a token represents an ELSE as part of an ELSE / IF set.
99 *
100 * @param ast the token to check
101 * @return whether it is
102 */
103 private static boolean isElseIf(DetailAST ast) {
104 final DetailAST parentAST = ast.getParent();
105
106 return isElse(parentAST) || isElseWithCurlyBraces(parentAST);
107 }
108
109 /**
110 * Returns whether a token represents an ELSE.
111 *
112 * @param ast the token to check
113 * @return whether the token represents an ELSE
114 */
115 private static boolean isElse(DetailAST ast) {
116 return ast.getType() == TokenTypes.LITERAL_ELSE;
117 }
118
119 /**
120 * Returns whether a token represents an SLIST as part of an ELSE
121 * statement.
122 *
123 * @param ast the token to check
124 * @return whether the toke does represent an SLIST as part of an ELSE
125 */
126 private static boolean isElseWithCurlyBraces(DetailAST ast) {
127 return ast.getChildCount() == 2 && isElse(ast.getParent());
128 }
129
130 }