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.utils;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import com.puppycrawl.tools.checkstyle.api.LineColumn;
  
  /**
   * Tools for parsing block tags from a Javadoc comment.
   *
   */
  public final class BlockTagUtil {
  
      /** Block tag pattern for a first line. */
      private static final Pattern BLOCK_TAG_PATTERN_FIRST_LINE = Pattern.compile(
          "/\\*{2,}\\s*@(\\p{Alpha}+)\\s");
  
      /** Block tag pattern. */
      private static final Pattern BLOCK_TAG_PATTERN = Pattern.compile(
          "^\\s*\\**\\s*@(\\p{Alpha}+)\\s");
  
      /** Closing tag. */
      private static final String JAVADOC_CLOSING_TAG = "*/";
  
      /** Prevent instantiation. */
      private BlockTagUtil() {
      }
  
      /**
       * Extract the block tags from a Javadoc comment.
       *
       * @param lines The text of the comment, as separate lines.
       * @return The tags extracted from the block.
       */
      public static List<TagInfo> extractBlockTags(String... lines) {
          final List<TagInfo> tags = new ArrayList<>();
  
          for (int i = 0; i < lines.length; i++) {
              // Starting lines of a comment have a different first line pattern.
              final boolean isFirstLine = i == 0;
              final Pattern pattern;
              if (isFirstLine) {
                  pattern = BLOCK_TAG_PATTERN_FIRST_LINE;
              }
              else {
                  pattern = BLOCK_TAG_PATTERN;
              }
  
              final String line = lines[i];
              final Matcher tagMatcher = pattern.matcher(line);
  
              if (tagMatcher.find()) {
                  final String tagName = tagMatcher.group(1);
  
                  // offset of one for the @ character
                  final int colNum = tagMatcher.start(1) - 1;
                  final int lineNum = i + 1;
  
                  final String remainder = line.substring(tagMatcher.end(1));
                  String tagValue = remainder.trim();
  
                  // Handle the case where we're on the last line of a Javadoc comment.
                  if (tagValue.endsWith(JAVADOC_CLOSING_TAG)) {
                      final int endIndex = tagValue.length() - JAVADOC_CLOSING_TAG.length();
                      tagValue = tagValue.substring(0, endIndex).trim();
                  }
  
                  final LineColumn position = new LineColumn(lineNum, colNum);
                  tags.add(new TagInfo(tagName, tagValue, position));
              }
          }
  
          return tags;
      }
  
  }
  