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.annotation;
  
  import java.util.BitSet;
  
  import com.puppycrawl.tools.checkstyle.StatelessCheck;
  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.checks.javadoc.AbstractJavadocCheck;
  import com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocTagInfo;
  import com.puppycrawl.tools.checkstyle.utils.AnnotationUtil;
  import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
  
  /**
   * <p>
   * Verifies that the annotation {@code @Deprecated} and the Javadoc tag
   * {@code @deprecated} are both present when either of them is present.
   * </p>
   * <p>
   * Both ways of flagging deprecation serve their own purpose.
   * The &#64;Deprecated annotation is used for compilers and development tools.
   * The &#64;deprecated javadoc tag is used to document why something is deprecated
   * and what, if any, alternatives exist.
   * </p>
   * <p>
   * In order to properly mark something as deprecated both forms of
   * deprecation should be present.
   * </p>
   * <p>
   * Package deprecation is an exception to the rule of always using the
   * javadoc tag and annotation to deprecate.  It is not clear if the javadoc
   * tool will support it or not as newer versions keep flip-flopping on if
   * it is supported or will cause an error. See
   * <a href="https://bugs.openjdk.org/browse/JDK-8160601">JDK-8160601</a>.
   * The deprecated javadoc tag is currently the only way to say why the package
   * is deprecated and what to use instead.  Until this is resolved, if you don't
   * want to print violations on package-info, you can use a
   * <a href="https://checkstyle.org/filters/index.html">filter</a> to ignore
   * these files until the javadoc tool faithfully supports it. An example config
   * using SuppressionSingleFilter is:
   * </p>
   * <pre>
   * &lt;!-- required till https://bugs.openjdk.org/browse/JDK-8160601 --&gt;
   * &lt;module name="SuppressionSingleFilter"&gt;
   *     &lt;property name="checks" value="MissingDeprecatedCheck"/&gt;
   *     &lt;property name="files" value="package-info\.java"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <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>
   * </ul>
   * <p>
   * To configure the check:
   * </p>
   * <pre>
   * &lt;module name=&quot;MissingDeprecated&quot;/&gt;
   * </pre>
   * <p>
   * Example:
   * </p>
   * <pre>
   * &#64;Deprecated
   * public static final int MY_CONST = 13; // ok
   *
   * &#47;** This javadoc is missing deprecated tag. *&#47;
   * &#64;Deprecated
   * public static final int COUNTER = 10; // violation
   *
   * &#47;**
   *  * &#64;deprecated
   *  * &lt;p&gt;&lt;/p&gt;
   *  *&#47;
   * &#64;Deprecated
   * public static final int NUM = 123456; // ok
   *
   * &#47;**
   *  * &#64;deprecated
   *  * &lt;p&gt;
   *  *&#47;
   * &#64;Deprecated
   * public static final int CONST = 12; // ok
   * </pre>
   * <p>
   * To configure the check such that it prints violation
   * messages if tight HTML rules are not obeyed
   * </p>
   * <pre>
   * &lt;module name="MissingDeprecated"&gt;
   *   &lt;property name="violateExecutionOnNonTightHtml" value="true"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>
   * Example:
   * </p>
   * <pre>
   * &#64;Deprecated
   * public static final int MY_CONST = 13; // ok
   *
   * &#47;** This javadoc is missing deprecated tag. *&#47;
   * &#64;Deprecated
   * public static final int COUNTER = 10; // violation
   *
   * &#47;**
   *  * &#64;deprecated
   *  * &lt;p&gt;&lt;/p&gt;
   *  *&#47;
   * &#64;Deprecated
   * public static final int NUM = 123456; // ok
   *
   * &#47;**
   *  * &#64;deprecated
   *  * &lt;p&gt;
   *  *&#47;
   * &#64;Deprecated
   * public static final int CONST = 12; // violation, tight HTML rules not obeyed
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code annotation.missing.deprecated}
   * </li>
   * <li>
   * {@code javadoc.duplicateTag}
   * </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 5.0
   */
  @StatelessCheck
  public final class MissingDeprecatedCheck extends AbstractJavadocCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY_ANNOTATION_MISSING_DEPRECATED =
              "annotation.missing.deprecated";
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY_JAVADOC_DUPLICATE_TAG =
              "javadoc.duplicateTag";
  
      /** {@link Deprecated Deprecated} annotation name. */
      private static final String DEPRECATED = "Deprecated";
  
      /** Fully-qualified {@link Deprecated Deprecated} annotation name. */
      private static final String FQ_DEPRECATED = "java.lang." + DEPRECATED;
  
      /** Token types to find parent of. */
      private static final BitSet TYPES_HASH_SET = TokenUtil.asBitSet(
              TokenTypes.TYPE, TokenTypes.MODIFIERS, TokenTypes.ANNOTATION,
              TokenTypes.ANNOTATIONS, TokenTypes.ARRAY_DECLARATOR,
              TokenTypes.TYPE_PARAMETERS, TokenTypes.DOT);
  
      @Override
      public int[] getDefaultJavadocTokens() {
          return getRequiredJavadocTokens();
      }
  
      @Override
      public int[] getRequiredJavadocTokens() {
          return new int[] {
              JavadocTokenTypes.JAVADOC,
          };
      }
  
      @Override
      public void visitJavadocToken(DetailNode ast) {
          final DetailAST parentAst = getParent(getBlockCommentAst());
  
          final boolean containsAnnotation =
              AnnotationUtil.containsAnnotation(parentAst, DEPRECATED)
              || AnnotationUtil.containsAnnotation(parentAst, FQ_DEPRECATED);
  
          final boolean containsJavadocTag = containsDeprecatedTag(ast);
  
          if (containsAnnotation ^ containsJavadocTag) {
              log(parentAst.getLineNo(), MSG_KEY_ANNOTATION_MISSING_DEPRECATED);
          }
      }
  
      /**
       * Checks to see if the javadoc contains a deprecated tag.
       *
       * @param javadoc the javadoc of the AST
       * @return true if contains the tag
       */
      private boolean containsDeprecatedTag(DetailNode javadoc) {
          boolean found = false;
          for (DetailNode child : javadoc.getChildren()) {
              if (child.getType() == JavadocTokenTypes.JAVADOC_TAG
                      && child.getChildren()[0].getType() == JavadocTokenTypes.DEPRECATED_LITERAL) {
                  if (found) {
                      log(child.getLineNumber(), MSG_KEY_JAVADOC_DUPLICATE_TAG,
                              JavadocTagInfo.DEPRECATED.getText());
                  }
                  found = true;
              }
          }
          return found;
      }
  
      /**
       * Returns the parent node of the comment.
       *
       * @param commentBlock child node.
       * @return parent node.
       */
      private static DetailAST getParent(DetailAST commentBlock) {
          DetailAST result = commentBlock.getParent();
  
          if (TokenUtil.isRootNode(result)) {
              result = commentBlock.getNextSibling();
          }
  
          while (true) {
              final int type = result.getType();
              if (TYPES_HASH_SET.get(type)) {
                  result = result.getParent();
              }
              else if (type == TokenTypes.SINGLE_LINE_COMMENT) {
                  result = result.getNextSibling();
              }
              else {
                  break;
              }
          }
  
          return result;
      }
  
  }
  