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.whitespace;
  
  import java.util.Locale;
  
  import com.puppycrawl.tools.checkstyle.StatelessCheck;
  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.CommonUtil;
  
  /**
   * <p>
   * Checks the padding of an empty for iterator; that is whether a white
   * space is required at an empty for iterator, or such white space is
   * forbidden. No check occurs if there is a line wrap at the iterator, as in
   * </p>
   * <pre>
   * for (Iterator foo = very.long.line.iterator();
   *     foo.hasNext();
   *    )
   * </pre>
   * <ul>
   * <li>
   * Property {@code option} - Specify policy on how to pad an empty for iterator.
   * Type is {@code com.puppycrawl.tools.checkstyle.checks.whitespace.PadOption}.
   * Default value is {@code nospace}.
   * </li>
   * </ul>
   * <p>
   * To configure the check:
   * </p>
   * <pre>
   * &lt;module name=&quot;EmptyForIteratorPad&quot;/&gt;
   * </pre>
   * <p>
   * Example:
   * </p>
   * <pre>
   * for (Iterator it = map.entrySet().iterator();  it.hasNext(););  // ok
   * for (Iterator it = map.entrySet().iterator();  it.hasNext(); ); // violation since whitespace
   *                                                                 //after semicolon
   *
   * for (Iterator foo = very.long.line.iterator();
   *       foo.hasNext();
   *      ); // ok
   * </pre>
   * <p>
   * To configure the check to require white space at an empty for iterator:
   * </p>
   * <pre>
   * &lt;module name=&quot;EmptyForIteratorPad&quot;&gt;
   *   &lt;property name=&quot;option&quot; value=&quot;space&quot;/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>
   * Example:
   * </p>
   * <pre>
   * for (Iterator it = map.entrySet().iterator();  it.hasNext();); // violation as there is no
   *                                                                // whitespace after semicolon
   *
   * for (Iterator it = map.entrySet().iterator();  it.hasNext(); ); // ok
   *
   * for (Iterator foo = very.long.line.iterator();
   *       foo.hasNext();
   *      ); // violation as there  is no whitespace after semicolon
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code ws.followed}
   * </li>
   * <li>
   * {@code ws.notFollowed}
   * </li>
   * </ul>
   *
   * @since 3.0
   */
  @StatelessCheck
  public class EmptyForIteratorPadCheck
      extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_WS_FOLLOWED = "ws.followed";
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_WS_NOT_FOLLOWED = "ws.notFollowed";
  
      /** Semicolon literal. */
      private static final String SEMICOLON = ";";
  
      /** Specify policy on how to pad an empty for iterator. */
      private PadOption option = PadOption.NOSPACE;
  
      /**
       * Setter to specify policy on how to pad an empty for iterator.
       *
       * @param optionStr string to decode option from
       * @throws IllegalArgumentException if unable to decode
       */
      public void setOption(String optionStr) {
          option = PadOption.valueOf(optionStr.trim().toUpperCase(Locale.ENGLISH));
      }
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getRequiredTokens() {
          return new int[] {TokenTypes.FOR_ITERATOR};
      }
  
      @Override
      public void visitToken(DetailAST ast) {
          if (!ast.hasChildren()) {
              // empty for iterator. test pad after semi.
              final DetailAST semi = ast.getPreviousSibling();
              final int[] line = getLineCodePoints(semi.getLineNo() - 1);
              final int after = semi.getColumnNo() + 1;
              // don't check if at end of line
              if (after < line.length) {
                  if (option == PadOption.NOSPACE
                      && CommonUtil.isCodePointWhitespace(line, after)) {
                      log(ast, MSG_WS_FOLLOWED, SEMICOLON);
                  }
                  else if (option == PadOption.SPACE
                           && !CommonUtil.isCodePointWhitespace(line, after)) {
                      log(ast, MSG_WS_NOT_FOLLOWED, SEMICOLON);
                  }
              }
          }
      }
  
  }
  