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;
  
  import java.nio.charset.StandardCharsets;
  import java.util.Arrays;
  
  /**
   * Represents the options for line separator settings.
   *
   * @see NewlineAtEndOfFileCheck
   */
  public enum LineSeparatorOption {
  
      /** Windows-style line separators. **/
      CRLF("\r\n"),
  
      /** Mac-style line separators. **/
      CR("\r"),
  
      /** Unix-style line separators. **/
      LF("\n"),
  
      /**
       * Matches CR, LF and CRLF line separators.
       * Only the length is used - the actual value is ignored.
       */
      LF_CR_CRLF("#"),
  
      /** System default line separators. **/
      SYSTEM(System.getProperty("line.separator"));
  
      /** The line separator representation. */
      private final byte[] lineSeparator;
  
      /**
       * Creates a new {@code LineSeparatorOption} instance.
       *
       * @param sep the line separator, e.g. "\r\n"
       */
      LineSeparatorOption(String sep) {
          lineSeparator = sep.getBytes(StandardCharsets.US_ASCII);
      }
  
      /**
       * Checks that bytes is equal to the byte representation of this line separator.
       *
       * @param bytes a bytes array to check
       * @return if bytes is equal to the byte representation
       *     of this line separator
       */
      public boolean matches(byte... bytes) {
          final boolean result;
          if (this == LF_CR_CRLF) {
              // this silently assumes LF and CR are of length 1
              // CRLF always matches LF, so CRLF isn't tested
              result = LF.matches(bytes) || CR.matches(bytes);
          }
          else {
              result = Arrays.equals(bytes, lineSeparator);
          }
          return result;
      }
  
      /**
       * Returns length of file separator in bytes.
       *
       * @return the length of the file separator in bytes,
       *     e.g. 1 for CR, 2 for CRLF, ...
       */
      public int length() {
          return lineSeparator.length;
      }
  
  }
  