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.sizes;
  
  import java.util.ArrayDeque;
  import java.util.Deque;
  
  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;
  import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
  
  /**
   * <p>
   * Restricts the number of executable statements to a specified limit.
   * </p>
   * <ul>
   * <li>
   * Property {@code max} - Specify the maximum threshold allowed.
   * Type is {@code int}.
   * Default value is {@code 30}.
   * </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#CTOR_DEF">
   * CTOR_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#INSTANCE_INIT">
   * INSTANCE_INIT</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#STATIC_INIT">
   * STATIC_INIT</a>,
   * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#COMPACT_CTOR_DEF">
   * COMPACT_CTOR_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>
   * <pre>
   * &lt;module name="ExecutableStatementCount"/&gt;
   * </pre>
   * <p>
   * To configure the check with a threshold of 20 for constructor and method definitions:
   * </p>
   * <pre>
   * &lt;module name="ExecutableStatementCount"&gt;
   *   &lt;property name="max" value="20"/&gt;
   *   &lt;property name="tokens" value="CTOR_DEF,METHOD_DEF"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code executableStatementCount}
   * </li>
   * </ul>
   *
   * @since 3.2
   */
  @FileStatefulCheck
  public final class ExecutableStatementCountCheck
      extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "executableStatementCount";
  
      /** Default threshold. */
      private static final int DEFAULT_MAX = 30;
  
      /** Stack of method contexts. */
      private final Deque<Context> contextStack = new ArrayDeque<>();
  
      /** Specify the maximum threshold allowed. */
      private int max;
  
      /** Current method context. */
      private Context context;
  
      /** Constructs a {@code ExecutableStatementCountCheck}. */
      public ExecutableStatementCountCheck() {
          max = DEFAULT_MAX;
      }
  
      @Override
      public int[] getDefaultTokens() {
          return new int[] {
              TokenTypes.CTOR_DEF,
              TokenTypes.METHOD_DEF,
              TokenTypes.INSTANCE_INIT,
              TokenTypes.STATIC_INIT,
              TokenTypes.SLIST,
              TokenTypes.COMPACT_CTOR_DEF,
              TokenTypes.LAMBDA,
          };
      }
  
      @Override
      public int[] getRequiredTokens() {
          return new int[] {TokenTypes.SLIST};
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return new int[] {
              TokenTypes.CTOR_DEF,
              TokenTypes.METHOD_DEF,
              TokenTypes.INSTANCE_INIT,
              TokenTypes.STATIC_INIT,
              TokenTypes.SLIST,
              TokenTypes.COMPACT_CTOR_DEF,
              TokenTypes.LAMBDA,
          };
      }
  
      /**
       * Setter to specify the maximum threshold allowed.
       *
       * @param max the maximum threshold.
       */
      public void setMax(int max) {
          this.max = max;
      }
  
      @Override
      public void beginTree(DetailAST rootAST) {
          context = new Context(null);
          contextStack.clear();
      }
  
      @Override
      public void visitToken(DetailAST ast) {
          if (isContainerNode(ast)) {
              visitContainerNode(ast);
          }
          else if (TokenUtil.isOfType(ast, TokenTypes.SLIST)) {
              visitSlist(ast);
          }
          else {
              throw new IllegalStateException(ast.toString());
          }
      }
  
      @Override
      public void leaveToken(DetailAST ast) {
          if (isContainerNode(ast)) {
              leaveContainerNode(ast);
          }
          else if (!TokenUtil.isOfType(ast, TokenTypes.SLIST)) {
              throw new IllegalStateException(ast.toString());
          }
      }
  
      /**
       * Process the start of the container node.
       *
       * @param ast the token representing the container node.
       */
      private void visitContainerNode(DetailAST ast) {
          contextStack.push(context);
          context = new Context(ast);
      }
  
      /**
       * Process the end of a container node.
       *
       * @param ast the token representing the container node.
       */
      private void leaveContainerNode(DetailAST ast) {
          final int count = context.getCount();
          if (count > max) {
              log(ast, MSG_KEY, count, max);
          }
          context = contextStack.pop();
      }
  
      /**
       * Process the end of a statement list.
       *
       * @param ast the token representing the statement list.
       */
      private void visitSlist(DetailAST ast) {
          final DetailAST contextAST = context.getAST();
          DetailAST parent = ast;
          while (parent != null && !isContainerNode(parent)) {
              parent = parent.getParent();
          }
          if (parent == contextAST) {
              context.addCount(ast.getChildCount() / 2);
          }
      }
  
      /**
       * Check if the node is of type ctor (compact or canonical),
       * instance/ static initializer, method definition or lambda.
       *
       * @param node AST node we are checking
       * @return true if node is of the given types
       */
      private static boolean isContainerNode(DetailAST node) {
          return TokenUtil.isOfType(node, TokenTypes.METHOD_DEF,
                  TokenTypes.LAMBDA, TokenTypes.CTOR_DEF, TokenTypes.INSTANCE_INIT,
                  TokenTypes.STATIC_INIT, TokenTypes.COMPACT_CTOR_DEF);
      }
  
      /**
       * Class to encapsulate counting information about one member.
       */
      private static final class Context {
  
          /** Member AST node. */
          private final DetailAST ast;
  
          /** Counter for context elements. */
          private int count;
  
          /**
           * Creates new member context.
           *
           * @param ast member AST node.
           */
          private Context(DetailAST ast) {
              this.ast = ast;
          }
  
          /**
           * Increase count.
           *
           * @param addition the count increment.
           */
          public void addCount(int addition) {
              count += addition;
          }
  
          /**
           * Gets the member AST node.
           *
           * @return the member AST node.
           */
          public DetailAST getAST() {
              return ast;
          }
  
          /**
           * Gets the count.
           *
           * @return the count.
           */
          public int getCount() {
              return count;
          }
  
      }
  
  }
  