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.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.AnnotationUtil;
  
  /**
   * <p>
   * Checks that method names conform to a specified pattern.
   * </p>
   *
   * <p>Also, checks if a method name has the same name as the residing class.
   * The default is false (it is not allowed). It is legal in Java to have
   * method with the same name as a class. As long as a return type is specified
   * it is a method and not a constructor which it could be easily confused as.
   * Does not check-style the name of an overridden methods because the developer does not
   * have a choice in renaming such methods.
   * </p>
   *
   * <ul>
   * <li>
   * Property {@code format} - Specifies valid identifiers.
   * Type is {@code java.util.regex.Pattern}.
   * Default value is {@code "^[a-z][a-zA-Z0-9]*$"}.
   * </li>
   * <li>
   * Property {@code allowClassName} - Controls whether to allow a method name to have the same name
   * as the residing class name. This is not to be confused with a constructor. An easy mistake is
   * to place a return type on a constructor declaration which turns it into a method. For example:
   * <pre>
   * class MyClass {
   *     public void MyClass() {} //this is a method
   *     public MyClass() {} //this is a constructor
   * }
   * </pre>
   * Type is {@code boolean}.
   * Default value is {@code false}.
   * </li>
   * <li>
   * Property {@code applyToPublic} - Controls whether to apply the check to public member.
   * Type is {@code boolean}.
   * Default value is {@code true}.
   * </li>
   * <li>
   * Property {@code applyToProtected} - Controls whether to apply the check to protected member.
   * Type is {@code boolean}.
   * Default value is {@code true}.
   * </li>
   * <li>
   * Property {@code applyToPackage} - Controls whether to apply the check to package-private member.
   * Type is {@code boolean}.
   * Default value is {@code true}.
   * </li>
   * <li>
   * Property {@code applyToPrivate} - Controls whether to apply the check to private member.
   * Type is {@code boolean}.
   * Default value is {@code true}.
   * </li>
   * </ul>
   *
   * <p>
   * To configure the check:
   * </p>
   * <pre>
   * &lt;module name="MethodName"/&gt;
   * </pre>
   * <p>Code Example:</p>
   * <pre>
   * class MyClass {
   *   public void firstMethod1() {} // OK
   *   protected void secondMethod() {} // OK
   *   private void ThirdMethod() {} // violation, method name must match to the
   *                                 // default pattern '^[a-z][a-zA-Z0-9]*$'
   *   public void fourth_Method4() {} // violation, method name must match to the
   *                                  // default pattern '^[a-z][a-zA-Z0-9]*$'
   * }
   * </pre>
   * <p>
   * An example of how to configure the check for names that begin with
   * a lower case letter, followed by letters, digits, and underscores is:
   * </p>
   * <pre>
   * &lt;module name="MethodName"&gt;
   *    &lt;property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Code Example:</p>
   * <pre>
   * class MyClass {
   *   public void myMethod() {} // OK
   *   public void MyMethod() {} // violation, name "MyMethod"
   *                             // should match the pattern "^[a-z](_?[a-zA-Z0-9]+)*$"
   * }
   * </pre>
   * <p>
   * An example of how to configure the check to allow method names to be equal to the
   * residing class name is:
   * </p>
   * <pre>
   * &lt;module name="MethodName"&gt;
   *    &lt;property name="format" value="^[a-zA-Z](_?[a-zA-Z0-9]+)*$"/&gt;
   *    &lt;property name="allowClassName" value="true"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Code Example:</p>
   * <pre>
   * class MyClass {
   *   public MyClass() {} // OK
   *   public void MyClass() {} // OK, method Name 'MyClass' is allowed to be
   *                            // equal to the enclosing class name
   * }
   * </pre>
   * <p>
   * An example of how to configure the check to disallow method names to be equal to the
   * residing class name is:
   * </p>
   * <pre>
   * &lt;module name="MethodName"&gt;
   *    &lt;property name="format" value="^[a-zA-Z](_?[a-zA-Z0-9]+)*$"/&gt;
   *    &lt;property name="allowClassName" value="false"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Code Example:</p>
   * <pre>
   * class MyClass {
   *   public MyClass() {} // OK
   *   public void MyClass() {} // violation, method Name 'MyClass' must not
   *                            // equal the enclosing class name
   * }
   * </pre>
   * <p>
   * An example of how to suppress the check to public and protected methods:
   * </p>
   * <pre>
   * &lt;module name="MethodName"&gt;
   *    &lt;property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/&gt;
   *    &lt;property name="applyToPublic" value="false"/&gt;
   *    &lt;property name="applyToProtected" value="false"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Code Example:</p>
   * <pre>
   * class MyClass {
   *   public void FirstMethod() {} // OK
   *   protected void SecondMethod() {} // OK
   *   private void ThirdMethod() {} // violation, name 'ThirdMethod' must match
   *                                 // pattern '^[a-z](_?[a-zA-Z0-9]+)*$'
   *   void FourthMethod() {} // violation, name 'FourthMethod' must match
   *                          // pattern '^[a-z](_?[a-zA-Z0-9]+)*$'
   * }
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code method.name.equals.class.name}
   * </li>
   * <li>
   * {@code name.invalidPattern}
   * </li>
   * </ul>
   *
   * @since 3.0
   */
  public class MethodNameCheck
      extends AbstractAccessControlNameCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "method.name.equals.class.name";
  
      /**
       * Controls whether to allow a method name to have the same name as the residing class name.
       * This is not to be confused with a constructor. An easy mistake is to place a return type on
       * a constructor declaration which turns it into a method. For example:
       * <pre>
       * class MyClass {
       *     public void MyClass() {} //this is a method
       *     public MyClass() {} //this is a constructor
       * }
       * </pre>
       */
      private boolean allowClassName;
  
      /** Creates a new {@code MethodNameCheck} instance. */
      public MethodNameCheck() {
          super("^[a-z][a-zA-Z0-9]*$");
      }
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getRequiredTokens() {
          return new int[] {TokenTypes.METHOD_DEF, };
      }
  
      @Override
      public void visitToken(DetailAST ast) {
          if (!AnnotationUtil.hasOverrideAnnotation(ast)) {
              // Will check the name against the format.
              super.visitToken(ast);
          }
  
          if (!allowClassName) {
              final DetailAST method =
                  ast.findFirstToken(TokenTypes.IDENT);
              // in all cases this will be the classDef type except anon inner
              // with anon inner classes this will be the Literal_New keyword
              final DetailAST classDefOrNew = ast.getParent().getParent();
              final DetailAST classIdent =
                  classDefOrNew.findFirstToken(TokenTypes.IDENT);
              // Following logic is to handle when a classIdent can not be
              // found. This is when you have a Literal_New keyword followed
              // a DOT, which is when you have:
              // new Outclass.InnerInterface(x) { ... }
              // Such a rare case, will not have the logic to handle parsing
              // down the tree looking for the first ident.
              if (classIdent != null
                  && method.getText().equals(classIdent.getText())) {
                  log(method, MSG_KEY, method.getText());
              }
          }
      }
  
      /**
       * Setter to controls whether to allow a method name to have the same name as the residing
       * class name. This is not to be confused with a constructor. An easy mistake is to place
       * a return type on a constructor declaration which turns it into a method. For example:
       * <pre>
       * class MyClass {
       *     public void MyClass() {} //this is a method
       *     public MyClass() {} //this is a constructor
       * }
       * </pre>
       *
       * @param allowClassName true to allow false to disallow
       */
      public void setAllowClassName(boolean allowClassName) {
          this.allowClassName = allowClassName;
      }
  
  }
  