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.javadoc;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.BitSet;
  import java.util.List;
  
  import com.puppycrawl.tools.checkstyle.PropertyType;
  import com.puppycrawl.tools.checkstyle.StatelessCheck;
  import com.puppycrawl.tools.checkstyle.XdocsPropertyType;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.DetailNode;
  import com.puppycrawl.tools.checkstyle.api.JavadocTokenTypes;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.JavadocUtil;
  import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
  
  /**
   * <p>
   * Checks the order of
   * <a href="https://docs.oracle.com/javase/8/docs/technotes/tools/windows/javadoc.html#CHDBEFIF">
   * javadoc block-tags or javadoc tags</a>.
   * </p>
   * <p>
   * Note: Google used the term "at-clauses" for block tags in their guide till 2017-02-28.
   * </p>
   *
   * <ul>
   * <li>
   * Property {@code violateExecutionOnNonTightHtml} - Control when to print violations if the
   * Javadoc being examined by this check violates the tight html rules defined at
   * <a href="https://checkstyle.org/writingjavadocchecks.html#Tight-HTML_rules">Tight-HTML Rules</a>.
   * Type is {@code boolean}.
   * Default value is {@code false}.
   * </li>
   * <li>
   * Property {@code target} - Specify block tags targeted.
   * Type is {@code java.lang.String[]}.
   * Validation type is {@code tokenTypesSet}.
   * 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#COMPACT_CTOR_DEF">
   * COMPACT_CTOR_DEF</a>,
   * <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#ENUM_DEF">
   * ENUM_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#METHOD_DEF">
   * METHOD_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#VARIABLE_DEF">
   * VARIABLE_DEF</a>.
   * </li>
   * <li>
   * Property {@code tagOrder} - Specify the order by tags.
   * Type is {@code java.lang.String[]}.
   * Default value is
   * {@code @author, @deprecated, @exception, @param, @return, @see, @serial, @serialData, @serialField, @since, @throws, @version}.
   * </li>
   * </ul>
   * <p>
   * To configure the default check:
   * </p>
   * <pre>
   * &lt;module name=&quot;AtclauseOrder&quot;/&gt;
   * </pre>
   * <p>
   * Example:
   * </p>
   * <pre>
   * &#47;**
   * * Some javadoc. // OK
   * *
   * * &#64;author Some javadoc. // OK
   * * &#64;version Some javadoc. // OK
   * * &#64;param Some javadoc. // OK
   * * &#64;return Some javadoc. // OK
   * * &#64;throws Some javadoc. // OK
   * * &#64;exception Some javadoc. // OK
   * * &#64;see Some javadoc. // OK
   * * &#64;since Some javadoc. // OK
   * * &#64;serial Some javadoc. // OK
   * * &#64;serialField // OK
   * * &#64;serialData // OK
   * * &#64;deprecated Some javadoc. // OK
   * *&#47;
   *
   * class Valid implements Serializable
   * {
   * }
   *
   * &#47;**
   * * Some javadoc.
   * *
   * * &#64;since Some javadoc. // OK
   * * &#64;version Some javadoc. // Violation - wrong order
   * * &#64;deprecated
   * * &#64;see Some javadoc. // Violation - wrong order
   * * &#64;author Some javadoc. // Violation - wrong order
   * *&#47;
   *
   * class Invalid implements Serializable
   * {
   * }
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code at.clause.order}
   * </li>
   * <li>
   * {@code javadoc.missed.html.close}
   * </li>
   * <li>
   * {@code javadoc.parse.rule.error}
   * </li>
   * <li>
   * {@code javadoc.wrong.singleton.html.tag}
   * </li>
   * </ul>
   *
   * @since 6.0
   */
  @StatelessCheck
  public class AtclauseOrderCheck extends AbstractJavadocCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "at.clause.order";
  
      /**
       * Default order of atclauses.
       */
      private static final String[] DEFAULT_ORDER = {
          "@author", "@version",
          "@param", "@return",
          "@throws", "@exception",
          "@see", "@since",
          "@serial", "@serialField",
          "@serialData", "@deprecated",
      };
  
      /**
       * Specify block tags targeted.
       */
      @XdocsPropertyType(PropertyType.TOKEN_ARRAY)
      private BitSet target = TokenUtil.asBitSet(
          TokenTypes.CLASS_DEF,
          TokenTypes.INTERFACE_DEF,
          TokenTypes.ENUM_DEF,
          TokenTypes.METHOD_DEF,
          TokenTypes.CTOR_DEF,
          TokenTypes.VARIABLE_DEF,
          TokenTypes.RECORD_DEF,
          TokenTypes.COMPACT_CTOR_DEF
      );
  
      /**
       * Specify the order by tags.
       */
      private List<String> tagOrder = Arrays.asList(DEFAULT_ORDER);
  
      /**
       * Setter to specify block tags targeted.
       *
       * @param targets user's targets.
       */
      public void setTarget(String... targets) {
          target = TokenUtil.asBitSet(targets);
      }
  
      /**
       * Setter to specify the order by tags.
       *
       * @param orders user's orders.
       */
      public void setTagOrder(String... orders) {
          final List<String> customOrder = new ArrayList<>(orders.length);
          for (String order : orders) {
              customOrder.add(order.trim());
          }
          tagOrder = customOrder;
      }
  
      @Override
      public int[] getDefaultJavadocTokens() {
          return new int[] {
              JavadocTokenTypes.JAVADOC,
          };
      }
  
      @Override
      public int[] getRequiredJavadocTokens() {
          return getAcceptableJavadocTokens();
      }
  
      @Override
      public void visitJavadocToken(DetailNode ast) {
          final int parentType = getParentType(getBlockCommentAst());
  
          if (target.get(parentType)) {
              checkOrderInTagSection(ast);
          }
      }
  
      /**
       * Checks order of atclauses in tag section node.
       *
       * @param javadoc Javadoc root node.
       */
      private void checkOrderInTagSection(DetailNode javadoc) {
          int maxIndexOfPreviousTag = 0;
  
          for (DetailNode node : javadoc.getChildren()) {
              if (node.getType() == JavadocTokenTypes.JAVADOC_TAG) {
                  final String tagText = JavadocUtil.getFirstChild(node).getText();
                  final int indexOfCurrentTag = tagOrder.indexOf(tagText);
  
                  if (indexOfCurrentTag != -1) {
                      if (indexOfCurrentTag < maxIndexOfPreviousTag) {
                          log(node.getLineNumber(), MSG_KEY, tagOrder.toString());
                      }
                      else {
                          maxIndexOfPreviousTag = indexOfCurrentTag;
                      }
                  }
              }
          }
      }
  
      /**
       * Returns type of parent node.
       *
       * @param commentBlock child node.
       * @return parent type.
       */
      private static int getParentType(DetailAST commentBlock) {
          final DetailAST parentNode = commentBlock.getParent();
          int result = parentNode.getType();
          if (result == TokenTypes.TYPE || result == TokenTypes.MODIFIERS) {
              result = parentNode.getParent().getType();
          }
          else if (parentNode.getParent() != null
                  && parentNode.getParent().getType() == TokenTypes.MODIFIERS) {
              result = parentNode.getParent().getParent().getType();
          }
          return result;
      }
  
  }
  