Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
SimplifyBooleanReturnCheck |
|
| 3.6;3.6 |
1 | //////////////////////////////////////////////////////////////////////////////// | |
2 | // checkstyle: Checks Java source code for adherence to a set of rules. | |
3 | // Copyright (C) 2001-2014 Oliver Burn | |
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 antlr.collections.AST; | |
23 | import com.puppycrawl.tools.checkstyle.api.Check; | |
24 | import com.puppycrawl.tools.checkstyle.api.TokenTypes; | |
25 | import com.puppycrawl.tools.checkstyle.api.DetailAST; | |
26 | ||
27 | ||
28 | /** | |
29 | * <p> | |
30 | * Checks for overly complicated boolean return statements. | |
31 | * Idea shamelessly stolen from the equivalent PMD rule (pmd.sourceforge.net). | |
32 | * </p> | |
33 | * <p> | |
34 | * An example of how to configure the check is: | |
35 | * </p> | |
36 | * <pre> | |
37 | * <module name="SimplifyBooleanReturn"/> | |
38 | * </pre> | |
39 | * @author Lars Kühne | |
40 | */ | |
41 | 1 | public class SimplifyBooleanReturnCheck |
42 | extends Check | |
43 | { | |
44 | @Override | |
45 | public int[] getDefaultTokens() | |
46 | { | |
47 | 1 | return new int[] {TokenTypes.LITERAL_IF}; |
48 | } | |
49 | ||
50 | @Override | |
51 | public void visitToken(DetailAST aAST) | |
52 | { | |
53 | // LITERAL_IF has the following four or five children: | |
54 | // '(' | |
55 | // condition | |
56 | // ')' | |
57 | // thenStatement | |
58 | // [ LITERAL_ELSE (with the elseStatement as a child) ] | |
59 | ||
60 | // don't bother if this is not if then else | |
61 | 5 | final AST elseLiteral = |
62 | aAST.findFirstToken(TokenTypes.LITERAL_ELSE); | |
63 | 5 | if (elseLiteral == null) { |
64 | 1 | return; |
65 | } | |
66 | 4 | final AST elseStatement = elseLiteral.getFirstChild(); |
67 | ||
68 | // skip '(' and ')' | |
69 | // TODO: Introduce helpers in DetailAST | |
70 | 4 | final AST condition = aAST.getFirstChild().getNextSibling(); |
71 | 4 | final AST thenStatement = condition.getNextSibling().getNextSibling(); |
72 | ||
73 | 4 | if (returnsOnlyBooleanLiteral(thenStatement) |
74 | && returnsOnlyBooleanLiteral(elseStatement)) | |
75 | { | |
76 | 2 | log(aAST.getLineNo(), aAST.getColumnNo(), "simplify.boolreturn"); |
77 | } | |
78 | 4 | } |
79 | ||
80 | /** | |
81 | * Returns if an AST is a return statment with a boolean literal | |
82 | * or a compound statement that contains only such a return statement. | |
83 | * | |
84 | * Returns <code>true</code> iff aAST represents | |
85 | * <br> | |
86 | * <pre> | |
87 | * return true/false; | |
88 | * <pre> | |
89 | * or | |
90 | * <br> | |
91 | * <pre> | |
92 | * { | |
93 | * return true/false; | |
94 | * } | |
95 | * <pre> | |
96 | * | |
97 | * @param aAST the sytax tree to check | |
98 | * @return if aAST is a return statment with a boolean literal. | |
99 | */ | |
100 | private static boolean returnsOnlyBooleanLiteral(AST aAST) | |
101 | { | |
102 | 6 | if (isBooleanLiteralReturnStatement(aAST)) { |
103 | 2 | return true; |
104 | } | |
105 | ||
106 | 4 | final AST firstStmnt = aAST.getFirstChild(); |
107 | 4 | return isBooleanLiteralReturnStatement(firstStmnt); |
108 | } | |
109 | ||
110 | /** | |
111 | * Returns if an AST is a return statment with a boolean literal. | |
112 | * | |
113 | * Returns <code>true</code> iff aAST represents | |
114 | * <br> | |
115 | * <pre> | |
116 | * return true/false; | |
117 | * <pre> | |
118 | * | |
119 | * @param aAST the sytax tree to check | |
120 | * @return if aAST is a return statment with a boolean literal. | |
121 | */ | |
122 | private static boolean isBooleanLiteralReturnStatement(AST aAST) | |
123 | { | |
124 | 10 | if ((aAST == null) || (aAST.getType() != TokenTypes.LITERAL_RETURN)) { |
125 | 5 | return false; |
126 | } | |
127 | ||
128 | 5 | final AST expr = aAST.getFirstChild(); |
129 | ||
130 | 5 | if ((expr == null) || (expr.getType() == TokenTypes.SEMI)) { |
131 | 1 | return false; |
132 | } | |
133 | ||
134 | 4 | final AST value = expr.getFirstChild(); |
135 | 4 | return isBooleanLiteralType(value.getType()); |
136 | } | |
137 | ||
138 | /** | |
139 | * Checks if a token type is a literal true or false. | |
140 | * @param aTokenType the TokenType | |
141 | * @return true iff aTokenType is LITERAL_TRUE or LITERAL_FALSE | |
142 | */ | |
143 | private static boolean isBooleanLiteralType(final int aTokenType) | |
144 | { | |
145 | 4 | final boolean isTrue = (aTokenType == TokenTypes.LITERAL_TRUE); |
146 | 4 | final boolean isFalse = (aTokenType == TokenTypes.LITERAL_FALSE); |
147 | 4 | return isTrue || isFalse; |
148 | } | |
149 | } |