| 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 | } |