code: ///////////////////////////////////////////////////////////////////////////////////////////////
  // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
  // Copyright (C) 2001-2023 the original author or authors.
  //
  // This library is free software; you can redistribute it and/or
  // modify it under the terms of the GNU Lesser General Public
  // License as published by the Free Software Foundation; either
  // version 2.1 of the License, or (at your option) any later version.
  //
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  // Lesser General Public License for more details.
  //
  // You should have received a copy of the GNU Lesser General Public
  // License along with this library; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  ///////////////////////////////////////////////////////////////////////////////////////////////
  
  package com.puppycrawl.tools.checkstyle.checks.naming;
  
  import com.puppycrawl.tools.checkstyle.StatelessCheck;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  /**
   * <p>
   * Checks identifiers with a pattern for a set of illegal names, such as those
   * that are restricted or contextual keywords. Examples include "yield", "record", "_", and
   * "var". Please read more at
   * <a href="https://docs.oracle.com/javase/specs/jls/se14/html/jls-3.html#jls-3.9">
   * Java Language Specification</a> to get to know more about restricted keywords. Since this
   * check uses a pattern to specify valid identifiers, users can also prohibit the usage
   * of certain symbols, such as "$", or any non-ascii character.
   * </p>
   * <ul>
   * <li>
   * Property {@code format} - Specifies valid identifiers.
   * Type is {@code java.util.regex.Pattern}.
   * Default value is {@code "(?i)^(?!(record|yield|var|permits|sealed|_)$).+$"}.
   * </li>
   * <li>
   * Property {@code tokens} - tokens to check
   * Type is {@code java.lang.String[]}.
   * Validation type is {@code tokenSet}.
   * Default value is:
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#CLASS_DEF">
   * CLASS_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INTERFACE_DEF">
   * INTERFACE_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ENUM_DEF">
   * ENUM_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ANNOTATION_DEF">
   * ANNOTATION_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ANNOTATION_FIELD_DEF">
   * ANNOTATION_FIELD_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#PARAMETER_DEF">
   * PARAMETER_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#VARIABLE_DEF">
   * VARIABLE_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#METHOD_DEF">
   * METHOD_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ENUM_CONSTANT_DEF">
   * ENUM_CONSTANT_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#PATTERN_VARIABLE_DEF">
   * PATTERN_VARIABLE_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#RECORD_DEF">
   * RECORD_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#RECORD_COMPONENT_DEF">
   * RECORD_COMPONENT_DEF</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LAMBDA">
   * LAMBDA</a>.
   * </li>
   * </ul>
   * <p>
   * To configure the check:
   * </p>
   * <p>Configuration:</p>
   * <pre>
   * &lt;module name="IllegalIdentifierName"/&gt;
   * </pre>
   * <p>
   * Example:
   * </p>
   * <pre>
   * public class TestClass {
   *     public static void main(String... args) {
   *         var var = 4; // violation, "var" should not be used as an identifier.
   *         int record = 15; // violation, "record" should not be used as an identifier.
   *         String yield = "yield"; // violation, "yield" should not be used as an identifier.
   *
   *         record Record // violation, "Record" should not be used as an identifier.
   *             (Record record) { // violation, "record" should not be used as an identifier.
   *         }
   *
   *         String yieldString = "yieldString"; // ok, part of another word
   *         record MyRecord(){} // ok, part of another word
   *         var variable = 2; // ok, part of another word
   *         String _; // violation, underscore should not be used as an identifier.
   *     }
   * }
   * </pre>
   * <p>
   * To configure the check to include "open" and "transitive" in the set of illegal identifiers:
   * </p>
   * <p>Configuration:</p>
   * <pre>
   * &lt;module name="IllegalIdentifierName"&gt;
   *     &lt;property name="format" value="(?i)^(?!(record|yield|var
   *                        |permits|sealed|open|transitive|_)$).+$"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Example:</p>
   * <pre>
   * public class TestClass {
   *     public static void main(String... args) {
   *
   *         int open = 4; // violation, "open" should not be used as an identifier
   *         Object transitive = "transitive"; // violation, "transitive" should not
   *                                                // be used as an identifier
   *
   *         int openInt = 4; // ok, "open" is part of another word
   *         Object transitiveObject = "transitiveObject"; // ok, "transitive" is part of another word
   *     }
   * }
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code name.invalidPattern}
   * </li>
   * </ul>
   *
   * @since 8.36
   */
  @StatelessCheck
  public class IllegalIdentifierNameCheck extends AbstractNameCheck {
  
      /**
       * Creates a new {@code IllegalIdentifierNameCheck} instance.
       */
      public IllegalIdentifierNameCheck() {
          super("(?i)^(?!(record|yield|var|permits|sealed|_)$).+$");
      }
  
      @Override
      public int[] getDefaultTokens() {
          return getAcceptableTokens();
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return new int[] {
              TokenTypes.CLASS_DEF,
              TokenTypes.INTERFACE_DEF,
              TokenTypes.ENUM_DEF,
              TokenTypes.ANNOTATION_DEF,
              TokenTypes.ANNOTATION_FIELD_DEF,
              TokenTypes.PARAMETER_DEF,
              TokenTypes.VARIABLE_DEF,
              TokenTypes.METHOD_DEF,
              TokenTypes.ENUM_CONSTANT_DEF,
              TokenTypes.PATTERN_VARIABLE_DEF,
              TokenTypes.RECORD_DEF,
              TokenTypes.RECORD_COMPONENT_DEF,
              TokenTypes.LAMBDA,
          };
      }
  
      @Override
      public int[] getRequiredTokens() {
          return CommonUtil.EMPTY_INT_ARRAY;
      }
  
      @Override
      protected boolean mustCheckName(DetailAST ast) {
          return ast.findFirstToken(TokenTypes.IDENT) != null;
      }
  
  }
  