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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) 2001-2024 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.naming;
21  
22  import java.util.Objects;
23  
24  import com.puppycrawl.tools.checkstyle.api.DetailAST;
25  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
26  import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
27  
28  /**
29   * <p>
30   * Checks lambda parameter names.
31   * </p>
32   * <ul>
33   * <li>
34   * Property {@code format} - Sets the pattern to match valid identifiers.
35   * Type is {@code java.util.regex.Pattern}.
36   * Default value is {@code "^[a-z][a-zA-Z0-9]*$"}.
37   * </li>
38   * </ul>
39   * <p>
40   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
41   * </p>
42   * <p>
43   * Violation Message Keys:
44   * </p>
45   * <ul>
46   * <li>
47   * {@code name.invalidPattern}
48   * </li>
49   * </ul>
50   *
51   * @since 8.11
52   */
53  public class LambdaParameterNameCheck extends AbstractNameCheck {
54  
55      /** Creates new instance of {@code LambdaParameterNameCheck}. */
56      public LambdaParameterNameCheck() {
57          super("^[a-z][a-zA-Z0-9]*$");
58      }
59  
60      @Override
61      public int[] getDefaultTokens() {
62          return getRequiredTokens();
63      }
64  
65      @Override
66      public int[] getAcceptableTokens() {
67          return getRequiredTokens();
68      }
69  
70      @Override
71      public int[] getRequiredTokens() {
72          return new int[] {
73              TokenTypes.LAMBDA,
74          };
75      }
76  
77      @Override
78      public void visitToken(DetailAST ast) {
79          final boolean isInSwitchRule = ast.getParent().getType() == TokenTypes.SWITCH_RULE;
80  
81          if (Objects.nonNull(ast.findFirstToken(TokenTypes.PARAMETERS))) {
82              final DetailAST parametersNode = ast.findFirstToken(TokenTypes.PARAMETERS);
83              TokenUtil.forEachChild(parametersNode, TokenTypes.PARAMETER_DEF, super::visitToken);
84          }
85          else if (!isInSwitchRule) {
86              super.visitToken(ast);
87          }
88      }
89  
90      @Override
91      protected boolean mustCheckName(DetailAST ast) {
92          return true;
93      }
94  
95  }