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.puppycrawl.tools.checkstyle.api.Check; 022import com.puppycrawl.tools.checkstyle.api.DetailAST; 023import com.puppycrawl.tools.checkstyle.api.FastStack; 024import com.puppycrawl.tools.checkstyle.api.ScopeUtils; 025import com.puppycrawl.tools.checkstyle.api.TokenTypes; 026import java.util.HashMap; 027import java.util.Map; 028 029/** 030 * <p> 031 * Ensures that local variables that never get their values changed, 032 * must be declared final. 033 * </p> 034 * <p> 035 * An example of how to configure the check is: 036 * </p> 037 * <pre> 038 * <module name="FinalLocalVariable"> 039 * <property name="token" value="VARIABLE_DEF"/> 040 * </module> 041 * </pre> 042 * @author k_gibbs, r_auckenthaler 043 */ 044public class FinalLocalVariableCheck extends Check 045{ 046 /** Scope Stack */ 047 private final FastStack<Map<String, DetailAST>> scopeStack = 048 FastStack.newInstance(); 049 050 @Override 051 public int[] getDefaultTokens() 052 { 053 return new int[] { 054 TokenTypes.IDENT, 055 TokenTypes.CTOR_DEF, 056 TokenTypes.METHOD_DEF, 057 TokenTypes.VARIABLE_DEF, 058 TokenTypes.INSTANCE_INIT, 059 TokenTypes.STATIC_INIT, 060 TokenTypes.LITERAL_FOR, 061 TokenTypes.SLIST, 062 TokenTypes.OBJBLOCK, 063 }; 064 } 065 066 @Override 067 public int[] getAcceptableTokens() 068 { 069 return new int[] { 070 TokenTypes.VARIABLE_DEF, 071 TokenTypes.PARAMETER_DEF, 072 }; 073 } 074 075 @Override 076 public int[] getRequiredTokens() 077 { 078 return new int[] { 079 TokenTypes.IDENT, 080 TokenTypes.CTOR_DEF, 081 TokenTypes.METHOD_DEF, 082 TokenTypes.INSTANCE_INIT, 083 TokenTypes.STATIC_INIT, 084 TokenTypes.LITERAL_FOR, 085 TokenTypes.SLIST, 086 TokenTypes.OBJBLOCK, 087 }; 088 } 089 090 @Override 091 public void visitToken(DetailAST ast) 092 { 093 switch (ast.getType()) { 094 case TokenTypes.OBJBLOCK: 095 case TokenTypes.SLIST: 096 case TokenTypes.LITERAL_FOR: 097 case TokenTypes.METHOD_DEF: 098 case TokenTypes.CTOR_DEF: 099 case TokenTypes.STATIC_INIT: 100 case TokenTypes.INSTANCE_INIT: 101 scopeStack.push(new HashMap<String, DetailAST>()); 102 break; 103 104 case TokenTypes.PARAMETER_DEF: 105 if (ScopeUtils.inInterfaceBlock(ast) 106 || inAbstractOrNativeMethod(ast)) 107 { 108 break; 109 } 110 case TokenTypes.VARIABLE_DEF: 111 if ((ast.getParent().getType() != TokenTypes.OBJBLOCK) 112 && (ast.getParent().getType() != TokenTypes.FOR_EACH_CLAUSE) 113 && isFirstVariableInForInit(ast)) 114 { 115 insertVariable(ast); 116 } 117 break; 118 119 case TokenTypes.IDENT: 120 final int parentType = ast.getParent().getType(); 121 if ((TokenTypes.POST_DEC == parentType) 122 || (TokenTypes.DEC == parentType) 123 || (TokenTypes.POST_INC == parentType) 124 || (TokenTypes.INC == parentType) 125 || (TokenTypes.ASSIGN == parentType) 126 || (TokenTypes.PLUS_ASSIGN == parentType) 127 || (TokenTypes.MINUS_ASSIGN == parentType) 128 || (TokenTypes.DIV_ASSIGN == parentType) 129 || (TokenTypes.STAR_ASSIGN == parentType) 130 || (TokenTypes.MOD_ASSIGN == parentType) 131 || (TokenTypes.SR_ASSIGN == parentType) 132 || (TokenTypes.BSR_ASSIGN == parentType) 133 || (TokenTypes.SL_ASSIGN == parentType) 134 || (TokenTypes.BXOR_ASSIGN == parentType) 135 || (TokenTypes.BOR_ASSIGN == parentType) 136 || (TokenTypes.BAND_ASSIGN == parentType)) 137 { 138 // TODO: is there better way to check is ast 139 // in left part of assignment? 140 if (ast.getParent().getFirstChild() == ast) { 141 removeVariable(ast); 142 } 143 } 144 break; 145 146 default: 147 } 148 } 149 150 /** 151 * Checks if current variable is defined first in 152 * {@link TokenTypes#FOR_INIT for-loop init}, e.g.: 153 * <p> 154 * <code> 155 * for (int i = 0, j = 0; i < j; i++) { . . . } 156 * </code> 157 * </p> 158 * <code>i</code> is first variable in {@link TokenTypes#FOR_INIT for-loop init} 159 * @param variableDef variable definition node. 160 * @return true if variableDef is first variable in {@link TokenTypes#FOR_INIT for-loop init} 161 */ 162 private static boolean isFirstVariableInForInit(DetailAST variableDef) 163 { 164 return variableDef.getParent().getType() != TokenTypes.FOR_INIT 165 || variableDef.getPreviousSibling() == null 166 || variableDef.getPreviousSibling().getType() != TokenTypes.COMMA; 167 } 168 169 /** 170 * Determines whether an AST is a descendant of an abstract or native method. 171 * @param ast the AST to check. 172 * @return true if ast is a descendant of an abstract or native method. 173 */ 174 private static boolean inAbstractOrNativeMethod(DetailAST ast) 175 { 176 DetailAST parent = ast.getParent(); 177 while (parent != null) { 178 if (parent.getType() == TokenTypes.METHOD_DEF) { 179 final DetailAST modifiers = 180 parent.findFirstToken(TokenTypes.MODIFIERS); 181 return modifiers.branchContains(TokenTypes.ABSTRACT) 182 || modifiers.branchContains(TokenTypes.LITERAL_NATIVE); 183 } 184 parent = parent.getParent(); 185 } 186 return false; 187 } 188 189 /** 190 * Inserts a variable at the topmost scope stack 191 * @param ast the variable to insert 192 */ 193 private void insertVariable(DetailAST ast) 194 { 195 if (!ast.branchContains(TokenTypes.FINAL)) { 196 final Map<String, DetailAST> state = scopeStack.peek(); 197 final DetailAST astNode = ast.findFirstToken(TokenTypes.IDENT); 198 state.put(astNode.getText(), astNode); 199 } 200 } 201 202 /** 203 * Removes the variable from the Stacks 204 * @param ast Variable to remove 205 */ 206 private void removeVariable(DetailAST ast) 207 { 208 for (int i = scopeStack.size() - 1; i >= 0; i--) { 209 final Map<String, DetailAST> state = scopeStack.peek(i); 210 final Object obj = state.remove(ast.getText()); 211 if (obj != null) { 212 break; 213 } 214 } 215 } 216 217 @Override 218 public void leaveToken(DetailAST ast) 219 { 220 super.leaveToken(ast); 221 222 switch (ast.getType()) { 223 case TokenTypes.OBJBLOCK: 224 case TokenTypes.SLIST: 225 case TokenTypes.LITERAL_FOR: 226 case TokenTypes.CTOR_DEF: 227 case TokenTypes.STATIC_INIT: 228 case TokenTypes.INSTANCE_INIT: 229 case TokenTypes.METHOD_DEF: 230 final Map<String, DetailAST> state = scopeStack.pop(); 231 for (DetailAST var : state.values()) { 232 log(var.getLineNo(), var.getColumnNo(), "final.variable", var 233 .getText()); 234 } 235 break; 236 237 default: 238 } 239 } 240}