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.coding;
  
  import com.puppycrawl.tools.checkstyle.FileStatefulCheck;
  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  
  /**
   * <p>
   * Restricts nested try-catch-finally blocks to a specified depth.
   * </p>
   * <ul>
   * <li>
   * Property {@code max} - Specify maximum allowed nesting depth.
   * Type is {@code int}.
   * Default value is {@code 1}.
   * </li>
   * </ul>
   * <p>
   * To configure the check:
   * </p>
   * <pre>
   * &lt;module name=&quot;NestedTryDepth&quot;/&gt;
   * </pre>
   * <p>
   *     case 1: Example of code with violation:
   * </p>
   * <pre>
   * try {
   *     try {
   *         try { // violation, current depth is 2, default max allowed depth is 1
   *         } catch (Exception e) {
   *         }
   *     } catch (Exception e) {
   *     }
   * } catch (Exception e) {
   * }
   * </pre>
   * <p>
   *     case 1: Example of compliant code:
   * </p>
   * <pre>
   * try {
   *     try { // OK, current depth is 1, default max allowed depth is also 1
   *     } catch (Exception e) {
   *     }
   * } catch (Exception e) {
   * }
   *         </pre>
   *         <p>case 2: Example of code for handling unique and general exceptions</p>
   *         <pre>
   * try {
   *     try { // OK, current depth is 1, default max allowed depth is also 1
   *             // any more nesting could cause code violation!
   *             throw ArithmeticException();
   *     } catch (ArithmeticException e) { // catches arithmetic exceptions
   *     } catch (NumberFormatException e) { // catches number-format exceptions
   *     } catch (Exception e) { // catches general exceptions other than stated above
   *     }
   * } catch (
   *   ArithmeticException
   *   | NumberFormatException
   *   | ArrayIndexOutOfBoundsException e) { // catches any of the 3 exception
   * } catch (Exception e) { // catches general exception
   * } finally { // do something when try-catch block finished execution
   * }
   * </pre>
   * <p>
   * To configure the check to allow nesting depth 3:
   * </p>
   * <pre>
   * &lt;module name=&quot;NestedTryDepth&quot;&gt;
   *   &lt;property name=&quot;max&quot; value=&quot;3&quot;/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>
   *     Example of code with violation:
   * </p>
   * <pre>
   * try {
   *     try {
   *         try {
   *             try {
   *                 try { // violation, current depth is 4, max allowed depth is 3
   *                 } catch (Exception e) {
   *                 }
   *             } catch (Exception e) {
   *             }
   *         } catch (Exception e) {
   *         }
   *     } catch (Exception e) {
   *     }
   * } catch (Exception e) {
   * }
   * </pre>
   * <p>
   *      Example of compliant code:
   * </p>
   * <pre>
   * try {
   *     try {
   *         try {
   *             try { // OK, current depth is 3, max allowed depth is also 3
   *             } catch (Exception e) {
   *             }
   *         } catch (Exception e) {
   *         }
   *     } catch (Exception e) {
   *     }
   * } catch (Exception e) {
   * }
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code nested.try.depth}
   * </li>
   * </ul>
   *
   * @since 3.2
   */
  @FileStatefulCheck
  public final class NestedTryDepthCheck extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "nested.try.depth";
  
      /** Specify maximum allowed nesting depth. */
      private int max = 1;
      /** Current nesting depth. */
      private int depth;
  
      /**
       * Setter to specify maximum allowed nesting depth.
       *
       * @param max maximum allowed nesting depth.
       */
      public void setMax(int max) {
          this.max = max;
      }
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getRequiredTokens() {
          return new int[] {TokenTypes.LITERAL_TRY};
      }
  
      @Override
      public void visitToken(DetailAST literalTry) {
          if (depth > max) {
              log(literalTry, MSG_KEY, depth, max);
          }
          ++depth;
      }
  
      @Override
      public void leaveToken(DetailAST literalTry) {
          --depth;
      }
  
  }
  