code: ///////////////////////////////////////////////////////////////////////////////
  // For information as to what this class does, see the Javadoc, below.       //
  // Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,       //
  // 2007, 2008, 2009, 2010, 2014, 2015 by Peter Spirtes, Richard Scheines, Joseph   //
  // Ramsey, and Clark Glymour.                                                //
  //                                                                           //
  // This program is free software; you can redistribute it and/or modify      //
  // it under the terms of the GNU General Public License as published by      //
  // the Free Software Foundation; either version 2 of the License, or         //
  // (at your option) any later version.                                       //
  //                                                                           //
  // This program 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 General Public License for more details.                              //
  //                                                                           //
  // You should have received a copy of the GNU General Public License         //
  // along with this program; if not, write to the Free Software               //
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA //
  ///////////////////////////////////////////////////////////////////////////////
  
  package edu.cmu.tetrad.data;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.Reader;
  
  /**
   * @author Joseph Ramsey
   *         Returns one line at a time, with a method to determine whether another
   *         line is available. Blank lines and lines beginning with the given comment
   *         marker are skipped.
   */
  final class Lineizer {
  
      /**
       * The character sequence being tokenized.
       */
      private final BufferedReader reader;
  
      /**
       * Stores the line read by hasMoreLines, until it is retrieved by nextLine,
       * at which point it is null.
       */
      private String tempLine = null;
  
      /**
       * The comment marker.
       */
      private String commentMarker;
  
      /**
       * The line number of the line most recently read.
       */
      private int lineNumber = 0;
  
      /**
       * Constructs a tokenizer for the given input line, using the given Pattern
       * as delimiter.
       */
      public Lineizer(Reader reader, String commentMarker) {
          if (reader == null) {
              throw new NullPointerException();
          }
  
          if (commentMarker == null) {
              throw new NullPointerException();
          }
  
          this.reader = new BufferedReader(reader);
          this.commentMarker = commentMarker;
      }
  
      /**
       * @return true iff more tokens exist in the line.
       */
      public final boolean hasMoreLines() {
          if (tempLine == null) {
              try {
                  tempLine = readLine();
                  return tempLine != null;
              } catch (IOException e) {
                  return false;
              }
          } else {
              return true;
          }
      }
  
      /**
       * Return the next token in the line.
       */
      public final String nextLine() {
          lineNumber++;
  
          if (tempLine == null) {
              try {
                  return readLine();
              } catch (IOException e) {
                  throw new RuntimeException(e);
              }
          } else {
              String line = tempLine;
              tempLine = null;
              return line;
          }
      }
  
      private String readLine() throws IOException {
          String line;
  
          while ((line = reader.readLine()) != null) {
              if ("".equals(line)) {
                  continue;
              }
  
              if (line.startsWith(commentMarker)) {
                  continue;
              }
  
              return line;
          }
  
          return null;
      }
  
      public int getLineNumber() {
          return lineNumber;
      }
  }
  
  
  
  