FinalLocalVariableCheck


1   ////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code for adherence to a set of rules.
3   // Copyright (C) 2001-2005  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  package com.puppycrawl.tools.checkstyle.checks.coding;
20  
21  import java.util.HashMap  ;
22  import java.util.Iterator  ;
23  import java.util.Stack  ;
24  
25  import com.puppycrawl.tools.checkstyle.api.Check;
26  import com.puppycrawl.tools.checkstyle.api.DetailAST;
27  import com.puppycrawl.tools.checkstyle.api.ScopeUtils;
28  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
29  
30  /**
31   * <p>
32   * Ensures that local variables that never get their values changed,
33   * must be declared final.
34   * </p>
35   * <p>
36   * An example of how to configure the check is:
37   * </p>
38   * <pre>
39   * &lt;module name="FinalLocalVariable"&gt;
40   *     &lt;property name="token" value="VARIABLE_DEF"/&gt;
41   * &lt;/module&gt;
42   * </pre>
43   * @author k_gibbs, r_auckenthaler
44   */
45  public class FinalLocalVariableCheck extends Check
46  {
47      /** Scope Stack */
48      private final Stack   mScopeStack = new Stack  ();
49  
50      /**
51       * {@inheritDoc}
52       */
53      public int[] getDefaultTokens()
54      {
55          return new int[] {
56              TokenTypes.IDENT,
57              TokenTypes.CTOR_DEF,
58              TokenTypes.METHOD_DEF,
59              TokenTypes.VARIABLE_DEF,
60              TokenTypes.INSTANCE_INIT,
61              TokenTypes.STATIC_INIT,
62              TokenTypes.LITERAL_FOR,
63              TokenTypes.SLIST,
64              TokenTypes.OBJBLOCK,
65          };
66      }
67  
68      /** {@inheritDoc} */
69      public int[] getAcceptableTokens()
70      {
71          return new int[] {
72              TokenTypes.VARIABLE_DEF,
73              TokenTypes.PARAMETER_DEF,
74          };
75      }
76  
77      /** {@inheritDoc} */
78      public int[] getRequiredTokens()
79      {
80          return new int[] {
81              TokenTypes.IDENT,
82              TokenTypes.CTOR_DEF,
83              TokenTypes.METHOD_DEF,
84              TokenTypes.INSTANCE_INIT,
85              TokenTypes.STATIC_INIT,
86              TokenTypes.LITERAL_FOR,
87              TokenTypes.SLIST,
88              TokenTypes.OBJBLOCK,
89          };
90      }
91  
92      /**
93       * {@inheritDoc}
94       */
95      public void visitToken(DetailAST aAST)
96      {
97          switch(aAST.getType()) {
98          case TokenTypes.OBJBLOCK:
99          case TokenTypes.SLIST:
100         case TokenTypes.LITERAL_FOR:
101         case TokenTypes.METHOD_DEF:
102         case TokenTypes.CTOR_DEF:
103         case TokenTypes.STATIC_INIT:
104         case TokenTypes.INSTANCE_INIT:
105             mScopeStack.push(new HashMap  ());
106             break;
107 
108         case TokenTypes.PARAMETER_DEF:
109             if (ScopeUtils.inInterfaceBlock(aAST)
110                 || inAbstractMethod(aAST))
111             {
112                 break;
113             }
114         case TokenTypes.VARIABLE_DEF:
115             if ((aAST.getParent().getType() != TokenTypes.OBJBLOCK)
116                 && (aAST.getParent().getType() != TokenTypes.FOR_EACH_CLAUSE))
117             {
118                 insertVariable(aAST);
119             }
120             break;
121 
122         case TokenTypes.IDENT:
123             final int parentType = aAST.getParent().getType();
124             if ((TokenTypes.POST_DEC        == parentType)
125                 || (TokenTypes.DEC          == parentType)
126                 || (TokenTypes.POST_INC     == parentType)
127                 || (TokenTypes.INC          == parentType)
128                 || (TokenTypes.ASSIGN       == parentType)
129                 || (TokenTypes.PLUS_ASSIGN  == parentType)
130                 || (TokenTypes.MINUS_ASSIGN == parentType)
131                 || (TokenTypes.DIV_ASSIGN   == parentType)
132                 || (TokenTypes.STAR_ASSIGN  == parentType)
133                 || (TokenTypes.MOD_ASSIGN   == parentType)
134                 || (TokenTypes.SR_ASSIGN    == parentType)
135                 || (TokenTypes.BSR_ASSIGN   == parentType)
136                 || (TokenTypes.SL_ASSIGN    == parentType)
137                 || (TokenTypes.BXOR_ASSIGN  == parentType)
138                 || (TokenTypes.BOR_ASSIGN   == parentType)
139                 || (TokenTypes.BAND_ASSIGN  == parentType))
140             {
141                 // TODO: is there better way to check is aAST
142                 // in left part of assignment?
143                 if (aAST.getParent().getFirstChild() == aAST) {
144                     removeVariable(aAST);
145                 }
146             }
147             break;
148 
149         default:
150         }
151     }
152 
153     /**
154      * Determines whether an AST is a descentant of an abstract method.
155      * @param aAST the AST to check.
156      * @return true if aAST is a descentant of an abstract method.
157      */
158     private boolean inAbstractMethod(DetailAST aAST)
159     {
160         DetailAST parent = aAST.getParent();
161         while (parent != null) {
162             if (parent.getType() == TokenTypes.METHOD_DEF) {
163                 final DetailAST modifiers =
164                     parent.findFirstToken(TokenTypes.MODIFIERS);
165                 return modifiers.branchContains(TokenTypes.ABSTRACT);
166             }
167             parent = parent.getParent();
168         }
169         return false;
170     }
171 
172     /**
173      * Inserts a variable at the topmost scope stack
174      * @param aAST the variable to insert
175      */
176     private void insertVariable(DetailAST aAST)
177     {
178         if (!aAST.branchContains(TokenTypes.FINAL)) {
179             final HashMap   state = (HashMap  ) mScopeStack.peek();
180             final DetailAST ast = aAST.findFirstToken(TokenTypes.IDENT);
181             state.put(ast.getText(), ast);
182         }
183     }
184 
185     /**
186      * Removes the variable from the Stacks
187      * @param aAST Variable to remove
188      */
189     private void removeVariable(DetailAST aAST)
190     {
191         for (int i = mScopeStack.size() - 1; i >= 0; i--) {
192             final HashMap   state = (HashMap  ) mScopeStack.get(i);
193             final Object   obj = state.remove(aAST.getText());
194             if (obj != null) {
195                 break;
196             }
197         }
198     }
199 
200     /**
201      * {@inheritDoc}
202      */
203     public void leaveToken(DetailAST aAST)
204     {
205         super.leaveToken(aAST);
206 
207         switch(aAST.getType()) {
208         case TokenTypes.OBJBLOCK:
209         case TokenTypes.SLIST:
210         case TokenTypes.LITERAL_FOR:
211         case TokenTypes.CTOR_DEF:
212         case TokenTypes.STATIC_INIT:
213         case TokenTypes.INSTANCE_INIT:
214         case TokenTypes.METHOD_DEF:
215             final HashMap   state = (HashMap  ) mScopeStack.pop();
216             final Iterator   finalVars = state.values().iterator();
217 
218             while (finalVars.hasNext()) {
219                 final DetailAST var = (DetailAST) finalVars.next();
220                 log(var.getLineNo(), var.getColumnNo(),
221                     "final.variable", var.getText());
222             }
223             break;
224 
225         default:
226         }
227     }
228 }
229
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