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1   ////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code for adherence to a set of rules.
3   // Copyright (C) 2001-2017 the original author or authors.
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;
21  
22  import java.util.Arrays;
23  import java.util.Collections;
24  import java.util.Set;
25  import java.util.stream.Collectors;
26  
27  import com.puppycrawl.tools.checkstyle.StatelessCheck;
28  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
29  import com.puppycrawl.tools.checkstyle.api.DetailAST;
30  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
31  import com.puppycrawl.tools.checkstyle.utils.CheckUtils;
32  import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
33  
34  /**
35   * Check that method/constructor/catch/foreach parameters are final.
36   * The user can set the token set to METHOD_DEF, CONSTRUCTOR_DEF,
37   * LITERAL_CATCH, FOR_EACH_CLAUSE or any combination of these token
38   * types, to control the scope of this check.
39   * Default scope is both METHOD_DEF and CONSTRUCTOR_DEF.
40   * <p>
41   * Check has an option <b>ignorePrimitiveTypes</b> which allows ignoring lack of
42   * final modifier at
43   * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html">
44   *  primitive data type</a> parameter. Default value <b>false</b>.
45   * </p>
46   * E.g.:
47   * <p>
48   * {@code
49   * private void foo(int x) { ... } //parameter is of primitive type
50   * }
51   * </p>
52   *
53   * @author lkuehne
54   * @author o_sukhodolsky
55   * @author Michael Studman
56   * @author <a href="mailto:nesterenko-aleksey@list.ru">Aleksey Nesterenko</a>
57   */
58  @StatelessCheck
59  public class FinalParametersCheck extends AbstractCheck {
60  
61      /**
62       * A key is pointing to the warning message text in "messages.properties"
63       * file.
64       */
65      public static final String MSG_KEY = "final.parameter";
66  
67      /**
68       * Contains
69       * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html">
70       * primitive datatypes</a>.
71       */
72      private final Set<Integer> primitiveDataTypes = Collections.unmodifiableSet(
73          Arrays.stream(new Integer[] {
74              TokenTypes.LITERAL_BYTE,
75              TokenTypes.LITERAL_SHORT,
76              TokenTypes.LITERAL_INT,
77              TokenTypes.LITERAL_LONG,
78              TokenTypes.LITERAL_FLOAT,
79              TokenTypes.LITERAL_DOUBLE,
80              TokenTypes.LITERAL_BOOLEAN,
81              TokenTypes.LITERAL_CHAR, })
82          .collect(Collectors.toSet()));
83  
84      /**
85       * Option to ignore primitive types as params.
86       */
87      private boolean ignorePrimitiveTypes;
88  
89      /**
90       * Sets ignoring primitive types as params.
91       * @param ignorePrimitiveTypes true or false.
92       */
93      public void setIgnorePrimitiveTypes(boolean ignorePrimitiveTypes) {
94          this.ignorePrimitiveTypes = ignorePrimitiveTypes;
95      }
96  
97      @Override
98      public int[] getDefaultTokens() {
99          return new int[] {
100             TokenTypes.METHOD_DEF,
101             TokenTypes.CTOR_DEF,
102         };
103     }
104 
105     @Override
106     public int[] getAcceptableTokens() {
107         return new int[] {
108             TokenTypes.METHOD_DEF,
109             TokenTypes.CTOR_DEF,
110             TokenTypes.LITERAL_CATCH,
111             TokenTypes.FOR_EACH_CLAUSE,
112         };
113     }
114 
115     @Override
116     public int[] getRequiredTokens() {
117         return CommonUtils.EMPTY_INT_ARRAY;
118     }
119 
120     @Override
121     public void visitToken(DetailAST ast) {
122         // don't flag interfaces
123         final DetailAST container = ast.getParent().getParent();
124         if (container.getType() != TokenTypes.INTERFACE_DEF) {
125             if (ast.getType() == TokenTypes.LITERAL_CATCH) {
126                 visitCatch(ast);
127             }
128             else if (ast.getType() == TokenTypes.FOR_EACH_CLAUSE) {
129                 visitForEachClause(ast);
130             }
131             else {
132                 visitMethod(ast);
133             }
134         }
135     }
136 
137     /**
138      * Checks parameters of the method or ctor.
139      * @param method method or ctor to check.
140      */
141     private void visitMethod(final DetailAST method) {
142         final DetailAST modifiers =
143             method.findFirstToken(TokenTypes.MODIFIERS);
144         // exit on fast lane if there is nothing to check here
145 
146         if (method.findFirstToken(TokenTypes.PARAMETERS)
147                 .findFirstToken(TokenTypes.PARAMETER_DEF) != null
148                 // ignore abstract and native methods
149                 && modifiers.findFirstToken(TokenTypes.ABSTRACT) == null
150                 && modifiers.findFirstToken(TokenTypes.LITERAL_NATIVE) == null) {
151             // we can now be sure that there is at least one parameter
152             final DetailAST parameters =
153                 method.findFirstToken(TokenTypes.PARAMETERS);
154             DetailAST child = parameters.getFirstChild();
155             while (child != null) {
156                 // children are PARAMETER_DEF and COMMA
157                 if (child.getType() == TokenTypes.PARAMETER_DEF) {
158                     checkParam(child);
159                 }
160                 child = child.getNextSibling();
161             }
162         }
163     }
164 
165     /**
166      * Checks parameter of the catch block.
167      * @param catchClause catch block to check.
168      */
169     private void visitCatch(final DetailAST catchClause) {
170         checkParam(catchClause.findFirstToken(TokenTypes.PARAMETER_DEF));
171     }
172 
173     /**
174      * Checks parameter of the for each clause.
175      * @param forEachClause for each clause to check.
176      */
177     private void visitForEachClause(final DetailAST forEachClause) {
178         checkParam(forEachClause.findFirstToken(TokenTypes.VARIABLE_DEF));
179     }
180 
181     /**
182      * Checks if the given parameter is final.
183      * @param param parameter to check.
184      */
185     private void checkParam(final DetailAST param) {
186         if (param.findFirstToken(TokenTypes.MODIFIERS).findFirstToken(TokenTypes.FINAL) == null
187                 && !isIgnoredParam(param)
188                 && !CheckUtils.isReceiverParameter(param)) {
189             final DetailAST paramName = param.findFirstToken(TokenTypes.IDENT);
190             final DetailAST firstNode = CheckUtils.getFirstNode(param);
191             log(firstNode.getLineNo(), firstNode.getColumnNo(),
192                 MSG_KEY, paramName.getText());
193         }
194     }
195 
196     /**
197      * Checks for skip current param due to <b>ignorePrimitiveTypes</b> option.
198      * @param paramDef {@link TokenTypes#PARAMETER_DEF PARAMETER_DEF}
199      * @return true if param has to be skipped.
200      */
201     private boolean isIgnoredParam(DetailAST paramDef) {
202         boolean result = false;
203         if (ignorePrimitiveTypes) {
204             final DetailAST parameterType = paramDef
205                 .findFirstToken(TokenTypes.TYPE).getFirstChild();
206             if (primitiveDataTypes.contains(parameterType.getType())) {
207                 result = true;
208             }
209         }
210         return result;
211     }
212 }