001//////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code for adherence to a set of rules. 003// Copyright (C) 2001-2014 Oliver Burn 004// 005// This library is free software; you can redistribute it and/or 006// modify it under the terms of the GNU Lesser General Public 007// License as published by the Free Software Foundation; either 008// version 2.1 of the License, or (at your option) any later version. 009// 010// This library is distributed in the hope that it will be useful, 011// but WITHOUT ANY WARRANTY; without even the implied warranty of 012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013// Lesser General Public License for more details. 014// 015// You should have received a copy of the GNU Lesser General Public 016// License along with this library; if not, write to the Free Software 017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 018//////////////////////////////////////////////////////////////////////////////// 019package com.puppycrawl.tools.checkstyle.checks.coding; 020 021import com.google.common.collect.Sets; 022import com.puppycrawl.tools.checkstyle.api.Check; 023import com.puppycrawl.tools.checkstyle.api.DetailAST; 024import com.puppycrawl.tools.checkstyle.api.FastStack; 025import com.puppycrawl.tools.checkstyle.api.TokenTypes; 026import java.util.Set; 027 028/** 029 * <p> 030 * Disallow assignment of parameters. 031 * </p> 032 * <p> 033 * Rationale: 034 * Parameter assignment is often considered poor 035 * programming practice. Forcing developers to declare 036 * parameters as final is often onerous. Having a check 037 * ensure that parameters are never assigned would give 038 * the best of both worlds. 039 * </p> 040 * @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a> 041 */ 042public final class ParameterAssignmentCheck extends Check 043{ 044 /** Stack of methods' parameters. */ 045 private final FastStack<Set<String>> parameterNamesStack = 046 FastStack.newInstance(); 047 /** Current set of perameters. */ 048 private Set<String> parameterNames; 049 050 @Override 051 public int[] getDefaultTokens() 052 { 053 return new int[] { 054 TokenTypes.CTOR_DEF, 055 TokenTypes.METHOD_DEF, 056 TokenTypes.ASSIGN, 057 TokenTypes.PLUS_ASSIGN, 058 TokenTypes.MINUS_ASSIGN, 059 TokenTypes.STAR_ASSIGN, 060 TokenTypes.DIV_ASSIGN, 061 TokenTypes.MOD_ASSIGN, 062 TokenTypes.SR_ASSIGN, 063 TokenTypes.BSR_ASSIGN, 064 TokenTypes.SL_ASSIGN, 065 TokenTypes.BAND_ASSIGN, 066 TokenTypes.BXOR_ASSIGN, 067 TokenTypes.BOR_ASSIGN, 068 TokenTypes.INC, 069 TokenTypes.POST_INC, 070 TokenTypes.DEC, 071 TokenTypes.POST_DEC, 072 }; 073 } 074 075 @Override 076 public int[] getRequiredTokens() 077 { 078 return getDefaultTokens(); 079 } 080 081 @Override 082 public void beginTree(DetailAST rootAST) 083 { 084 // clear data 085 parameterNamesStack.clear(); 086 parameterNames = null; 087 } 088 089 @Override 090 public void visitToken(DetailAST ast) 091 { 092 switch (ast.getType()) { 093 case TokenTypes.CTOR_DEF: 094 case TokenTypes.METHOD_DEF: 095 visitMethodDef(ast); 096 break; 097 case TokenTypes.ASSIGN: 098 case TokenTypes.PLUS_ASSIGN: 099 case TokenTypes.MINUS_ASSIGN: 100 case TokenTypes.STAR_ASSIGN: 101 case TokenTypes.DIV_ASSIGN: 102 case TokenTypes.MOD_ASSIGN: 103 case TokenTypes.SR_ASSIGN: 104 case TokenTypes.BSR_ASSIGN: 105 case TokenTypes.SL_ASSIGN: 106 case TokenTypes.BAND_ASSIGN: 107 case TokenTypes.BXOR_ASSIGN: 108 case TokenTypes.BOR_ASSIGN: 109 visitAssign(ast); 110 break; 111 case TokenTypes.INC: 112 case TokenTypes.POST_INC: 113 case TokenTypes.DEC: 114 case TokenTypes.POST_DEC: 115 visitIncDec(ast); 116 break; 117 default: 118 throw new IllegalStateException(ast.toString()); 119 } 120 } 121 122 @Override 123 public void leaveToken(DetailAST ast) 124 { 125 switch (ast.getType()) { 126 case TokenTypes.CTOR_DEF: 127 case TokenTypes.METHOD_DEF: 128 leaveMethodDef(); 129 break; 130 case TokenTypes.ASSIGN: 131 case TokenTypes.PLUS_ASSIGN: 132 case TokenTypes.MINUS_ASSIGN: 133 case TokenTypes.STAR_ASSIGN: 134 case TokenTypes.DIV_ASSIGN: 135 case TokenTypes.MOD_ASSIGN: 136 case TokenTypes.SR_ASSIGN: 137 case TokenTypes.BSR_ASSIGN: 138 case TokenTypes.SL_ASSIGN: 139 case TokenTypes.BAND_ASSIGN: 140 case TokenTypes.BXOR_ASSIGN: 141 case TokenTypes.BOR_ASSIGN: 142 case TokenTypes.INC: 143 case TokenTypes.POST_INC: 144 case TokenTypes.DEC: 145 case TokenTypes.POST_DEC: 146 // Do nothing 147 break; 148 default: 149 throw new IllegalStateException(ast.toString()); 150 } 151 } 152 153 /** 154 * Ckecks if this is assignments of parameter. 155 * @param ast assignment to check. 156 */ 157 private void visitAssign(DetailAST ast) 158 { 159 checkIdent(ast); 160 } 161 162 /** 163 * Checks if this is increment/decrement of parameter. 164 * @param ast dec/inc to check. 165 */ 166 private void visitIncDec(DetailAST ast) 167 { 168 checkIdent(ast); 169 } 170 171 /** 172 * Check if ident is parameter. 173 * @param ast ident to check. 174 */ 175 private void checkIdent(DetailAST ast) 176 { 177 if ((parameterNames != null) && !parameterNames.isEmpty()) { 178 final DetailAST identAST = ast.getFirstChild(); 179 180 if ((identAST != null) 181 && (identAST.getType() == TokenTypes.IDENT) 182 && parameterNames.contains(identAST.getText())) 183 { 184 log(ast.getLineNo(), ast.getColumnNo(), 185 "parameter.assignment", identAST.getText()); 186 } 187 } 188 } 189 190 /** 191 * Creates new set of parameters and store old one in stack. 192 * @param ast a method to process. 193 */ 194 private void visitMethodDef(DetailAST ast) 195 { 196 parameterNamesStack.push(parameterNames); 197 parameterNames = Sets.newHashSet(); 198 199 visitMethodParameters(ast.findFirstToken(TokenTypes.PARAMETERS)); 200 } 201 202 /** Restores old set of parameters. */ 203 private void leaveMethodDef() 204 { 205 parameterNames = parameterNamesStack.pop(); 206 } 207 208 /** 209 * Creates new parameter set for given method. 210 * @param ast a method for process. 211 */ 212 private void visitMethodParameters(DetailAST ast) 213 { 214 DetailAST parameterDefAST = 215 ast.findFirstToken(TokenTypes.PARAMETER_DEF); 216 217 for (; parameterDefAST != null; 218 parameterDefAST = parameterDefAST.getNextSibling()) 219 { 220 if (parameterDefAST.getType() == TokenTypes.PARAMETER_DEF) { 221 final DetailAST param = 222 parameterDefAST.findFirstToken(TokenTypes.IDENT); 223 parameterNames.add(param.getText()); 224 } 225 } 226 } 227}