| 1 | //////////////////////////////////////////////////////////////////////////////// | |
| 2 | // checkstyle: Checks Java source code for adherence to a set of rules. | |
| 3 | // Copyright (C) 2001-2018 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 antlr.collections.AST; | |
| 23 | import com.puppycrawl.tools.checkstyle.StatelessCheck; | |
| 24 | import com.puppycrawl.tools.checkstyle.api.AbstractCheck; | |
| 25 | import com.puppycrawl.tools.checkstyle.api.DetailAST; | |
| 26 | import com.puppycrawl.tools.checkstyle.api.TokenTypes; | |
| 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 | @StatelessCheck | |
| 42 | public class SimplifyBooleanReturnCheck | |
| 43 | extends AbstractCheck { | |
| 44 | ||
| 45 | /** | |
| 46 | * A key is pointing to the warning message text in "messages.properties" | |
| 47 | * file. | |
| 48 | */ | |
| 49 | public static final String MSG_KEY = "simplify.boolReturn"; | |
| 50 | ||
| 51 | @Override | |
| 52 | public int[] getAcceptableTokens() { | |
| 53 |
1
1. getAcceptableTokens : mutated return of Object value for com/puppycrawl/tools/checkstyle/checks/coding/SimplifyBooleanReturnCheck::getAcceptableTokens to ( if (x != null) null else throw new RuntimeException ) → KILLED |
return getRequiredTokens(); |
| 54 | } | |
| 55 | ||
| 56 | @Override | |
| 57 | public int[] getDefaultTokens() { | |
| 58 |
1
1. getDefaultTokens : mutated return of Object value for com/puppycrawl/tools/checkstyle/checks/coding/SimplifyBooleanReturnCheck::getDefaultTokens to ( if (x != null) null else throw new RuntimeException ) → KILLED |
return getRequiredTokens(); |
| 59 | } | |
| 60 | ||
| 61 | @Override | |
| 62 | public int[] getRequiredTokens() { | |
| 63 |
1
1. getRequiredTokens : mutated return of Object value for com/puppycrawl/tools/checkstyle/checks/coding/SimplifyBooleanReturnCheck::getRequiredTokens to ( if (x != null) null else throw new RuntimeException ) → KILLED |
return new int[] {TokenTypes.LITERAL_IF}; |
| 64 | } | |
| 65 | ||
| 66 | @Override | |
| 67 | public void visitToken(DetailAST ast) { | |
| 68 | // LITERAL_IF has the following four or five children: | |
| 69 | // '(' | |
| 70 | // condition | |
| 71 | // ')' | |
| 72 | // thenStatement | |
| 73 | // [ LITERAL_ELSE (with the elseStatement as a child) ] | |
| 74 | ||
| 75 | // don't bother if this is not if then else | |
| 76 | final AST elseLiteral = | |
| 77 | ast.findFirstToken(TokenTypes.LITERAL_ELSE); | |
| 78 |
1
1. visitToken : negated conditional → KILLED |
if (elseLiteral != null) { |
| 79 | final AST elseStatement = elseLiteral.getFirstChild(); | |
| 80 | ||
| 81 | // skip '(' and ')' | |
| 82 | final AST condition = ast.getFirstChild().getNextSibling(); | |
| 83 | final AST thenStatement = condition.getNextSibling().getNextSibling(); | |
| 84 | ||
| 85 |
1
1. visitToken : negated conditional → KILLED |
if (canReturnOnlyBooleanLiteral(thenStatement) |
| 86 |
1
1. visitToken : negated conditional → KILLED |
&& canReturnOnlyBooleanLiteral(elseStatement)) { |
| 87 |
1
1. visitToken : removed call to com/puppycrawl/tools/checkstyle/checks/coding/SimplifyBooleanReturnCheck::log → KILLED |
log(ast.getLineNo(), ast.getColumnNo(), MSG_KEY); |
| 88 | } | |
| 89 | } | |
| 90 | } | |
| 91 | ||
| 92 | /** | |
| 93 | * Returns if an AST is a return statement with a boolean literal | |
| 94 | * or a compound statement that contains only such a return statement. | |
| 95 | * | |
| 96 | * <p>Returns {@code true} iff ast represents | |
| 97 | * <br/> | |
| 98 | * <pre> | |
| 99 | * return true/false; | |
| 100 | * </pre> | |
| 101 | * or | |
| 102 | * <br/> | |
| 103 | * <pre> | |
| 104 | * { | |
| 105 | * return true/false; | |
| 106 | * } | |
| 107 | * </pre> | |
| 108 | * | |
| 109 | * @param ast the syntax tree to check | |
| 110 | * @return if ast is a return statement with a boolean literal. | |
| 111 | */ | |
| 112 | private static boolean canReturnOnlyBooleanLiteral(AST ast) { | |
| 113 | boolean result = true; | |
| 114 |
1
1. canReturnOnlyBooleanLiteral : negated conditional → KILLED |
if (!isBooleanLiteralReturnStatement(ast)) { |
| 115 | final AST firstStatement = ast.getFirstChild(); | |
| 116 | result = isBooleanLiteralReturnStatement(firstStatement); | |
| 117 | } | |
| 118 |
1
1. canReturnOnlyBooleanLiteral : replaced return of integer sized value with (x == 0 ? 1 : 0) → KILLED |
return result; |
| 119 | } | |
| 120 | ||
| 121 | /** | |
| 122 | * Returns if an AST is a return statement with a boolean literal. | |
| 123 | * | |
| 124 | * <p>Returns {@code true} iff ast represents | |
| 125 | * <br/> | |
| 126 | * <pre> | |
| 127 | * return true/false; | |
| 128 | * </pre> | |
| 129 | * | |
| 130 | * @param ast the syntax tree to check | |
| 131 | * @return if ast is a return statement with a boolean literal. | |
| 132 | */ | |
| 133 | private static boolean isBooleanLiteralReturnStatement(AST ast) { | |
| 134 | boolean booleanReturnStatement = false; | |
| 135 | ||
| 136 |
2
1. isBooleanLiteralReturnStatement : negated conditional → KILLED 2. isBooleanLiteralReturnStatement : negated conditional → KILLED |
if (ast != null && ast.getType() == TokenTypes.LITERAL_RETURN) { |
| 137 | final AST expr = ast.getFirstChild(); | |
| 138 | ||
| 139 |
1
1. isBooleanLiteralReturnStatement : negated conditional → KILLED |
if (expr.getType() != TokenTypes.SEMI) { |
| 140 | final AST value = expr.getFirstChild(); | |
| 141 | booleanReturnStatement = isBooleanLiteralType(value.getType()); | |
| 142 | } | |
| 143 | } | |
| 144 |
1
1. isBooleanLiteralReturnStatement : replaced return of integer sized value with (x == 0 ? 1 : 0) → KILLED |
return booleanReturnStatement; |
| 145 | } | |
| 146 | ||
| 147 | /** | |
| 148 | * Checks if a token type is a literal true or false. | |
| 149 | * @param tokenType the TokenType | |
| 150 | * @return true iff tokenType is LITERAL_TRUE or LITERAL_FALSE | |
| 151 | */ | |
| 152 | private static boolean isBooleanLiteralType(final int tokenType) { | |
| 153 |
1
1. isBooleanLiteralType : negated conditional → KILLED |
final boolean isTrue = tokenType == TokenTypes.LITERAL_TRUE; |
| 154 |
1
1. isBooleanLiteralType : negated conditional → KILLED |
final boolean isFalse = tokenType == TokenTypes.LITERAL_FALSE; |
| 155 |
3
1. isBooleanLiteralType : negated conditional → KILLED 2. isBooleanLiteralType : negated conditional → KILLED 3. isBooleanLiteralType : replaced return of integer sized value with (x == 0 ? 1 : 0) → KILLED |
return isTrue || isFalse; |
| 156 | } | |
| 157 | ||
| 158 | } | |
Mutations | ||
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