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.regexp;
  
  import com.puppycrawl.tools.checkstyle.PropertyType;
  import com.puppycrawl.tools.checkstyle.StatelessCheck;
  import com.puppycrawl.tools.checkstyle.XdocsPropertyType;
  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  /**
   * <p>
   * Checks that a specified pattern matches a single-line in Java files.
   * </p>
   * <p>
   * This class is variation on
   * <a href="https://checkstyle.org/checks/regexp/regexpsingleline.html#RegexpSingleline">
   * RegexpSingleline</a>
   * for detecting single-lines that match a supplied regular expression in Java files.
   * It supports suppressing matches in Java comments.
   * </p>
   * <ul>
   * <li>
   * Property {@code format} - Specify the format of the regular expression to match.
   * Type is {@code java.util.regex.Pattern}.
   * Default value is {@code "$."}.
   * </li>
   * <li>
   * Property {@code message} - Specify the message which is used to notify about
   * violations, if empty then default (hard-coded) message is used.
   * Type is {@code java.lang.String}.
   * Default value is {@code null}.
   * </li>
   * <li>
   * Property {@code ignoreCase} - Control whether to ignore case when searching.
   * Type is {@code boolean}.
   * Default value is {@code false}.
   * </li>
   * <li>
   * Property {@code minimum} - Specify the minimum number of matches required in each file.
   * Type is {@code int}.
   * Default value is {@code 0}.
   * </li>
   * <li>
   * Property {@code maximum} - Specify the maximum number of matches required in each file.
   * Type is {@code int}.
   * Default value is {@code 0}.
   * </li>
   * <li>
   * Property {@code ignoreComments} - Control whether to ignore text in comments when searching.
   * Type is {@code boolean}.
   * Default value is {@code false}.
   * </li>
   * </ul>
   * <p>
   *   To configure the default check:
   * </p>
   * <pre>
   * &lt;module name=&quot;RegexpSinglelineJava&quot;/&gt;
   * </pre>
   * <p>
   *   This configuration does not match to anything,
   *   so we do not provide any code example for it
   *   as no violation will ever be reported.
   * </p>
   * <p>
   * To configure the check for calls to {@code System.out.println}, except in comments:
   * </p>
   * <pre>
   * &lt;module name="RegexpSinglelineJava"&gt;
   *   &lt;!-- . matches any character, so we need to
   *        escape it and use \. to match dots. --&gt;
   *   &lt;property name="format" value="System\.out\.println"/&gt;
   *   &lt;property name="ignoreComments" value="true"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Example:</p>
   * <pre>
   * System.out.println(""); // violation, instruction matches illegal pattern
   * System.out.
   *   println(""); // OK
   * &#47;* System.out.println *&#47; // OK, comments are ignored
   * </pre>
   * <p>
   * To configure the check to find case-insensitive occurrences of "debug":
   * </p>
   * <pre>
   * &lt;module name="RegexpSinglelineJava"&gt;
   *   &lt;property name="format" value="debug"/&gt;
   *   &lt;property name="ignoreCase" value="true"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Example:</p>
   * <pre>
   * int debug = 0; // violation, variable name matches illegal pattern
   * public class Debug { // violation, class name matches illegal pattern
   * &#47;* this is for de
   *   bug only; *&#47; // OK
   * </pre>
   * <p>
   * To configure the check to find occurrences of
   * &quot;\.read(.*)|\.write(.*)&quot;
   * and display &quot;IO found&quot; for each violation.
   * </p>
   * <pre>
   * &lt;module name=&quot;RegexpSinglelineJava&quot;&gt;
   *   &lt;property name=&quot;format&quot; value=&quot;\.read(.*)|\.write(.*)&quot;/&gt;
   *   &lt;property name=&quot;message&quot; value=&quot;IO found&quot;/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Example:</p>
   * <pre>
   * FileReader in = new FileReader("path/to/input");
   * int ch = in.read(); // violation
   * while(ch != -1) {
   *   System.out.print((char)ch);
   *   ch = in.read(); // violation
   * }
   *
   * FileWriter out = new FileWriter("path/to/output");
   * out.write("something"); // violation
   * </pre>
   * <p>
   * To configure the check to find occurrences of
   * &quot;\.log(.*)&quot;. We want to allow a maximum of 2 occurrences.
   * </p>
   * <pre>
   * &lt;module name=&quot;RegexpSinglelineJava&quot;&gt;
   *   &lt;property name=&quot;format&quot; value=&quot;\.log(.*)&quot;/&gt;
   *   &lt;property name=&quot;maximum&quot; value=&quot;2&quot;/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Example:</p>
   * <pre>
   * public class Foo{
   *   public void bar(){
   *     Logger.log("first"); // OK, first occurrence is allowed
   *     Logger.log("second"); // OK, second occurrence is allowed
   *     Logger.log("third"); // violation
   *     System.out.println("fourth");
   *     Logger.log("fifth"); // violation
   *   }
   * }
   * </pre>
   * <p>
   * To configure the check to find all occurrences of
   * &quot;public&quot;. We want to ignore comments,
   * display &quot;public member found&quot; for each violation
   * and say if less than 2 occurrences.
   * </p>
   * <pre>
   * &lt;module name=&quot;RegexpSinglelineJava&quot;&gt;
   *   &lt;property name=&quot;format&quot; value=&quot;public&quot;/&gt;
   *   &lt;property name=&quot;minimum&quot; value=&quot;2&quot;/&gt;
   *   &lt;property name=&quot;message&quot; value=&quot;public member found&quot;/&gt;
   *   &lt;property name=&quot;ignoreComments&quot; value=&quot;true&quot;/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Example:</p>
   * <pre>
   * class Foo{ // violation, file contains less than 2 occurrences of "public"
   *   private int a;
   *   &#47;* public comment *&#47; // OK, comment is ignored
   *   private void bar1() {}
   *   public void bar2() {} // violation
   * }
   * </pre>
   * <p>Example:</p>
   * <pre>
   * class Foo{
   *   private int a;
   *  &#47;* public comment *&#47; // OK, comment is ignored
   *   public void bar1() {} // violation
   *   public void bar2() {} // violation
   * }
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code regexp.exceeded}
   * </li>
   * <li>
   * {@code regexp.minimum}
   * </li>
   * </ul>
   *
   * @since 6.0
   */
  @StatelessCheck
  public class RegexpSinglelineJavaCheck extends AbstractCheck {
  
      /** Specify the format of the regular expression to match. */
      @XdocsPropertyType(PropertyType.PATTERN)
      private String format = "$.";
      /**
       * Specify the message which is used to notify about violations,
       * if empty then default (hard-coded) message is used.
       */
      private String message;
      /** Specify the minimum number of matches required in each file. */
      private int minimum;
      /** Specify the maximum number of matches required in each file. */
      private int maximum;
      /** Control whether to ignore case when searching. */
      private boolean ignoreCase;
      /** Control whether to ignore text in comments when searching. */
      private boolean ignoreComments;
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getRequiredTokens() {
          return CommonUtil.EMPTY_INT_ARRAY;
      }
  
      // suppress deprecation until https://github.com/checkstyle/checkstyle/issues/11166
      @SuppressWarnings("deprecation")
      @Override
      public void beginTree(DetailAST rootAST) {
          MatchSuppressor suppressor = null;
          if (ignoreComments) {
              suppressor = new CommentSuppressor(getFileContents());
          }
  
          final DetectorOptions options = DetectorOptions.newBuilder()
              .reporter(this)
              .suppressor(suppressor)
              .format(format)
              .message(message)
              .minimum(minimum)
              .maximum(maximum)
              .ignoreCase(ignoreCase)
              .build();
          final SinglelineDetector detector = new SinglelineDetector(options);
          detector.processLines(getFileContents().getText());
      }
  
      /**
       * Setter to specify the format of the regular expression to match.
       *
       * @param format the format of the regular expression to match.
       */
      public void setFormat(String format) {
          this.format = format;
      }
  
      /**
       * Setter to specify the message which is used to notify about violations,
       * if empty then default (hard-coded) message is used.
       *
       * @param message the message to report for a match.
       */
      public void setMessage(String message) {
          this.message = message;
      }
  
      /**
       * Setter to specify the minimum number of matches required in each file.
       *
       * @param minimum the minimum number of matches required in each file.
       */
      public void setMinimum(int minimum) {
          this.minimum = minimum;
      }
  
      /**
       * Setter to specify the maximum number of matches required in each file.
       *
       * @param maximum the maximum number of matches required in each file.
       */
      public void setMaximum(int maximum) {
          this.maximum = maximum;
      }
  
      /**
       * Setter to control whether to ignore case when searching.
       *
       * @param ignoreCase whether to ignore case when searching.
       */
      public void setIgnoreCase(boolean ignoreCase) {
          this.ignoreCase = ignoreCase;
      }
  
      /**
       * Setter to control whether to ignore text in comments when searching.
       *
       * @param ignore whether to ignore text in comments when searching.
       */
      public void setIgnoreComments(boolean ignore) {
          ignoreComments = ignore;
      }
  
  }
  