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>> mScopeStack = 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 aAST) 092 { 093 switch (aAST.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 mScopeStack.push(new HashMap<String, DetailAST>()); 102 break; 103 104 case TokenTypes.PARAMETER_DEF: 105 if (ScopeUtils.inInterfaceBlock(aAST) 106 || inAbstractMethod(aAST)) 107 { 108 break; 109 } 110 case TokenTypes.VARIABLE_DEF: 111 if ((aAST.getParent().getType() != TokenTypes.OBJBLOCK) 112 && (aAST.getParent().getType() != TokenTypes.FOR_EACH_CLAUSE)) 113 { 114 insertVariable(aAST); 115 } 116 break; 117 118 case TokenTypes.IDENT: 119 final int parentType = aAST.getParent().getType(); 120 if ((TokenTypes.POST_DEC == parentType) 121 || (TokenTypes.DEC == parentType) 122 || (TokenTypes.POST_INC == parentType) 123 || (TokenTypes.INC == parentType) 124 || (TokenTypes.ASSIGN == parentType) 125 || (TokenTypes.PLUS_ASSIGN == parentType) 126 || (TokenTypes.MINUS_ASSIGN == parentType) 127 || (TokenTypes.DIV_ASSIGN == parentType) 128 || (TokenTypes.STAR_ASSIGN == parentType) 129 || (TokenTypes.MOD_ASSIGN == parentType) 130 || (TokenTypes.SR_ASSIGN == parentType) 131 || (TokenTypes.BSR_ASSIGN == parentType) 132 || (TokenTypes.SL_ASSIGN == parentType) 133 || (TokenTypes.BXOR_ASSIGN == parentType) 134 || (TokenTypes.BOR_ASSIGN == parentType) 135 || (TokenTypes.BAND_ASSIGN == parentType)) 136 { 137 // TODO: is there better way to check is aAST 138 // in left part of assignment? 139 if (aAST.getParent().getFirstChild() == aAST) { 140 removeVariable(aAST); 141 } 142 } 143 break; 144 145 default: 146 } 147 } 148 149 /** 150 * Determines whether an AST is a descentant of an abstract method. 151 * @param aAST the AST to check. 152 * @return true if aAST is a descentant of an abstract method. 153 */ 154 private boolean inAbstractMethod(DetailAST aAST) 155 { 156 DetailAST parent = aAST.getParent(); 157 while (parent != null) { 158 if (parent.getType() == TokenTypes.METHOD_DEF) { 159 final DetailAST modifiers = 160 parent.findFirstToken(TokenTypes.MODIFIERS); 161 return modifiers.branchContains(TokenTypes.ABSTRACT); 162 } 163 parent = parent.getParent(); 164 } 165 return false; 166 } 167 168 /** 169 * Inserts a variable at the topmost scope stack 170 * @param aAST the variable to insert 171 */ 172 private void insertVariable(DetailAST aAST) 173 { 174 if (!aAST.branchContains(TokenTypes.FINAL)) { 175 final Map<String, DetailAST> state = mScopeStack.peek(); 176 final DetailAST ast = aAST.findFirstToken(TokenTypes.IDENT); 177 state.put(ast.getText(), ast); 178 } 179 } 180 181 /** 182 * Removes the variable from the Stacks 183 * @param aAST Variable to remove 184 */ 185 private void removeVariable(DetailAST aAST) 186 { 187 for (int i = mScopeStack.size() - 1; i >= 0; i--) { 188 final Map<String, DetailAST> state = mScopeStack.peek(i); 189 final Object obj = state.remove(aAST.getText()); 190 if (obj != null) { 191 break; 192 } 193 } 194 } 195 196 @Override 197 public void leaveToken(DetailAST aAST) 198 { 199 super.leaveToken(aAST); 200 201 switch (aAST.getType()) { 202 case TokenTypes.OBJBLOCK: 203 case TokenTypes.SLIST: 204 case TokenTypes.LITERAL_FOR: 205 case TokenTypes.CTOR_DEF: 206 case TokenTypes.STATIC_INIT: 207 case TokenTypes.INSTANCE_INIT: 208 case TokenTypes.METHOD_DEF: 209 final Map<String, DetailAST> state = mScopeStack.pop(); 210 for (DetailAST var : state.values()) { 211 log(var.getLineNo(), var.getColumnNo(), "final.variable", var 212 .getText()); 213 } 214 break; 215 216 default: 217 } 218 } 219}