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1   ///////////////////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3   // Copyright (C) 2001-2026 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.coding;
21  
22  import java.util.HashMap;
23  import java.util.Map;
24  
25  import com.puppycrawl.tools.checkstyle.StatelessCheck;
26  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
27  import com.puppycrawl.tools.checkstyle.api.DetailAST;
28  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
29  import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
30  
31  /**
32   * <div>
33   * Checks that overloaded methods are grouped together. Overloaded methods have the same
34   * name but different signatures where the signature can differ by the number of
35   * input parameters or type of input parameters or both.
36   * </div>
37   *
38   * @since 5.8
39   */
40  @StatelessCheck
41  public class OverloadMethodsDeclarationOrderCheck extends AbstractCheck {
42  
43      /**
44       * A key is pointing to the warning message text in "messages.properties"
45       * file.
46       */
47      public static final String MSG_KEY = "overload.methods.declaration";
48  
49      /**
50       * A key is pointing to the warning message text in "messages.properties"
51       * file.
52       */
53      public static final String MSG_ORDER = "overload.methods.declaration.order";
54  
55      /**
56       * Control whether to order overloaded methods by increasing parameter count.
57       */
58      private boolean orderByIncreasingParameterCount;
59  
60      /**
61       * Setter to control whether to enforce order by increasing parameter count (arity) or not.
62       *
63       * @param orderByIncreasingParameterCount true if order by increasing parameter
64       *               count is required.
65       * @since 13.7.0
66       */
67      public void setOrderByIncreasingParameterCount(boolean orderByIncreasingParameterCount) {
68          this.orderByIncreasingParameterCount = orderByIncreasingParameterCount;
69      }
70  
71      @Override
72      public int[] getDefaultTokens() {
73          return getRequiredTokens();
74      }
75  
76      @Override
77      public int[] getAcceptableTokens() {
78          return getRequiredTokens();
79      }
80  
81      @Override
82      public int[] getRequiredTokens() {
83          return new int[] {
84              TokenTypes.OBJBLOCK,
85          };
86      }
87  
88      @Override
89      public void visitToken(DetailAST ast) {
90          final int parentType = ast.getParent().getType();
91  
92          final int[] tokenTypes = {
93              TokenTypes.CLASS_DEF,
94              TokenTypes.ENUM_DEF,
95              TokenTypes.INTERFACE_DEF,
96              TokenTypes.LITERAL_NEW,
97              TokenTypes.RECORD_DEF,
98          };
99  
100         if (TokenUtil.isOfType(parentType, tokenTypes)) {
101             checkOverloadMethodsGrouping(ast);
102         }
103     }
104 
105     /**
106      * Checks that if overload methods are grouped together they should not be
107      * separated from each other.
108      *
109      * @param objectBlock
110      *        is a class, interface or enum object block.
111      */
112     private void checkOverloadMethodsGrouping(DetailAST objectBlock) {
113         final int allowedDistance = 1;
114         DetailAST currentToken = objectBlock.getFirstChild();
115         final Map<String, Integer> methodIndexMap = new HashMap<>();
116         final Map<String, Integer> methodLineNumberMap = new HashMap<>();
117 
118         final Map<String, Integer> methodParameterCountMap = new HashMap<>();
119         final Map<String, Boolean> methodIsOrderedMap = new HashMap<>();
120 
121         int currentIndex = 0;
122         while (currentToken != null) {
123             if (currentToken.getType() == TokenTypes.METHOD_DEF) {
124                 currentIndex++;
125                 final String methodName =
126                         currentToken.findFirstToken(TokenTypes.IDENT).getText();
127                 final Integer previousIndex = methodIndexMap.get(methodName);
128 
129                 if (previousIndex != null) {
130                     final DetailAST previousSibling = currentToken.getPreviousSibling();
131                     final boolean isMethod = previousSibling.getType() == TokenTypes.METHOD_DEF;
132 
133                     if (!isMethod || currentIndex - previousIndex > allowedDistance) {
134                         final int previousLineWithOverloadMethod =
135                                 methodLineNumberMap.get(methodName);
136                         log(currentToken, MSG_KEY,
137                                 previousLineWithOverloadMethod);
138                     }
139 
140                     if (orderByIncreasingParameterCount) {
141                         checkMethodOrdering(currentToken, methodName,
142                                 methodIsOrderedMap, methodParameterCountMap);
143                     }
144                 }
145                 methodIsOrderedMap.putIfAbsent(methodName, Boolean.TRUE);
146                 methodIndexMap.put(methodName, currentIndex);
147                 methodLineNumberMap.put(methodName, currentToken.getLineNo());
148                 methodParameterCountMap.put(methodName, getParameterCount(currentToken));
149             }
150             currentToken = currentToken.getNextSibling();
151         }
152     }
153 
154     /**
155      * Checks that overloaded methods are ordered with increasing parameter count
156      * or not.
157      *
158      * @param currentMethod ast of the method.
159      * @param methodName method name.
160      * @param methodIsOrderedMap
161      *        is a map of method names to booleans indicating whether the method is ordered.
162      * @param methodParameterCountMap
163      *        is a map of method names to integers indicating the parameter count of the previous
164      *        similar method.
165      */
166     private void checkMethodOrdering(DetailAST currentMethod, String methodName,
167         Map<String, Boolean> methodIsOrderedMap, Map<String, Integer> methodParameterCountMap) {
168 
169         final int currentParamCount = getParameterCount(currentMethod);
170         final boolean isOrdered = methodIsOrderedMap.get(methodName)
171                             && currentParamCount >= methodParameterCountMap.get(methodName);
172         if (!isOrdered) {
173             methodIsOrderedMap.put(methodName, Boolean.FALSE);
174             log(currentMethod, MSG_ORDER);
175         }
176     }
177 
178     /**
179      * Get the parameter count of a method.
180      *
181      * @param method the method AST
182      * @return the parameter count of the method
183      */
184     private static int getParameterCount(DetailAST method) {
185         final DetailAST params = method.findFirstToken(TokenTypes.PARAMETERS);
186         return params.getChildCount(TokenTypes.PARAMETER_DEF);
187     }
188 }