textio.java

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import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

import java.util.IllegalFormatException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


/**
 * TextIO provides a set of static methods for reading and writing text.  This version of TextIO
 * is an alternative to the basic version (which uses standard input and standard output for its
 * basic IO operations).  When this version is used, a window appears on the screen. This window
 * simulates standard IO when it is used by TextIO:  When TextIO writes to "standard output", the 
 * output actually goes to the window.  When TextIO reads from "standard input", the input actually
 * comes from input typed into the window by the user.  This is the default behavior, but it is
 * possible to redirect the IO to files or to other input and output streams.  When the (simulated)
 * standard input and output streams are being used, the input methods will not produce an error; 
 * instead, the user is repeatedly prompted for input until a legal input is entered.   For the most part,
 * any other error will be translated into an IllegalArguementException.  Note that when this version of
 * TextIO is used, calls to the output methods in TextIO are not equivalent to calls to methods in 
 * System.out; output to System.out still goes to the usual standard output.
 * <p>The window in which IO takes place remains open until it is closed by the user, even after
 * the program that used TextIO ends.
 * <p>This class does not use optimal Java programming practices.  It is designed specifically to be easily
 * usable even by a beginning programmer who has not yet learned about objects and exceptions.  Therefore, 
 * everything is in a single source file, all the methods are static methods, and none of the methods throw 
 * exceptions that would require try...catch statements.  Also for this reason, all exceptions are converted 
 * into IllegalArgumentExceptions, even when this exception type doesn't really make sense.
 * <p>When this version of TextIO is compiled, a rather large number of .class files are produced.  The
 * class files all have names beginning with "TextIO".  All of the class files are required for TextIO
 * to run successfully.
 * <p>This class requires Java 5.0 or higher. (A previous version of TextIO required only Java 1.1;
 * this version should work with any source code that used the previous version, but it has some new
 * features, including the type of formatted output that was introduced in Java 5 and the ability to
 * use files and streams.)
 */
public class TextIO {

   /* Modified November 2007 to empty the TextIO input buffer when switching from one
    * input source to another. This fixes a bug that allows input from the previous input
    * source to be read after the new source has been selected.
    */

   /**
    * The value returned by the peek() method when the input is at end-of-file.
    * (The value of this constant is (char)0xFFFF.)
    */
   public final static char EOF = (char)0xFFFF; 

   /**
    * The value returned by the peek() method when the input is at end-of-line.
    * The value of this constant is the character '\n'.
    */
   public final static char EOLN = '\n';          // The value returned by peek() when at end-of-line.
   

   /**
    * After this method is called, input will be read from standard input (as it 
    * is in the default state).  If a file or stream was previously the input source, that file
    * or stream is closed.
    */
   public static void readStandardInput() {
      if (readingStandardInput)
         return;
      try {
         in.close();
      }
      catch (Exception e) {
      }
      emptyBuffer();  // Added November 2007
      in = standardInput;
      inputFileName = null;
      readingStandardInput = true;
      inputErrorCount = 0;
   }
   
   /**
    * After this method is called, input will be read from inputStream, provided it
    * is non-null.  If inputStream is null, then this method has the same effect
    * as calling readStandardInput(); that is, future input will come from the
    * standard input stream.
    */
   public static void readStream(InputStream inputStream) {
      if (inputStream == null)
         readStandardInput();
      else
         readStream(new InputStreamReader(inputStream));
   }
   
   /**
    * After this method is called, input will be read from inputStream, provided it
    * is non-null.  If inputStream is null, then this method has the same effect
    * as calling readStandardInput(); that is, future input will come from the
    * standard input stream.
    */
   public static void readStream(Reader inputStream) {
      if (inputStream == null)
         readStandardInput();
      else {
         if ( inputStream instanceof BufferedReader)
            in = (BufferedReader)inputStream;
         else
            in = new BufferedReader(inputStream);
         emptyBuffer();  // Added November 2007
         inputFileName = null;
         readingStandardInput = false;
         inputErrorCount = 0;
      }
   }
   
   /**
    * Opens a file with a specified name for input.  If the file name is null, this has
    * the same effect as calling readStandardInput(); that is, input will be read from standard
    * input.  If an
    * error occurs while trying to open the file, an exception of type IllegalArgumentException
    * is thrown, and the input source is not changed.  If the file is opened 
    * successfully, then after this method is called, all of the input routines will read 
    * from the file, instead of from standard input.
    */
   public static void readFile(String fileName) {
      if (fileName == null) // Go back to reading standard input
         readStandardInput();
      else {
         BufferedReader newin;
         try {
            newin = new BufferedReader( new FileReader(fileName) );
         }
         catch (Exception e) {
            throw new IllegalArgumentException("Can't open file \"" + fileName + "\" for input.\n"
                           + "(Error :" + e + ")");
         }
         if (! readingStandardInput) { // close current input stream
            try {
               in.close();
            }
            catch (Exception e) {
            }
         }
         emptyBuffer();  // Added November 2007
         in = newin;
         readingStandardInput = false;
         inputErrorCount = 0;
         inputFileName = fileName;
      }
   }

   /**
    * Puts a GUI file-selection dialog box on the screen in which the user can select
    * an input file.  If the user cancels the dialog instead of selecting a file, it is
    * not considered an error, but the return value of the subroutine is false.
    * If the user does select a file, but there is an error while trying to open the
    * file, then an exception of type IllegalArgumentException is thrown.  Finally, if
    * the user selects a file and it is successfully opened, then the return value of the
    * subroutine is true, and  the input routines will read from the file, instead of 
    * from standard input.   If the user cancels, or if any error occurs, then the
    * previous input source is not changed.
    * <p>NOTE: Calling this method starts a GUI user interface thread, which can continue
    * to run even if the thread that runs the main program ends.  If you use this method
    * in a non-GUI program, it might be necessary to call System.exit(0) at the end of the main() 
    * routine to shut down the Java virtual machine completely.
    */
   public static boolean readUserSelectedFile() {
      if (fileDialog == null)
         fileDialog = new JFileChooser();
      fileDialog.setDialogTitle("Select File for Input");
      int option = fileDialog.showOpenDialog(console);
      if (option != JFileChooser.APPROVE_OPTION)
         return false;
      File selectedFile = fileDialog.getSelectedFile();
      BufferedReader newin;
      try {
         newin = new BufferedReader( new FileReader(selectedFile) );
      }
      catch (Exception e) {
         throw new IllegalArgumentException("Can't open file \"" + selectedFile.getName() + "\" for input.\n"
                        + "(Error :" + e + ")");
      }
      if (!readingStandardInput) { // close current file
         try {
            in.close();
         }
         catch (Exception e) {
         }
      }
      emptyBuffer();  // Added November 2007
      in = newin;
      inputFileName = selectedFile.getName();
      readingStandardInput = false;
      inputErrorCount = 0;
      return true;
   }
   
   /**
    * After this method is called, output will be written to standard output (as it 
    * is in the default state).  If a file or stream was previously open for output, it
    * will be closed.
    */
   public static void writeStandardOutput() {
      if (writingStandardOutput)
         return;
      try {
         out.close();
      }
      catch (Exception e) {
      }
      outputFileName = null;
      outputErrorCount = 0;
      out = standardOutput;
      writingStandardOutput = true;
   }
   

   /**
    * After this method is called, output will be sent to outputStream, provided it
    * is non-null.  If outputStream is null, then this method has the same effect
    * as calling writeStandardOutput(); that is, future output will be sent to the
    * standard output stream.
    */
   public static void writeStream(OutputStream outputStream) {
      if (outputStream == null)
         writeStandardOutput();
      else
         writeStream(new PrintWriter(outputStream));
   }
   
   /**
    * After this method is called, output will be sent to outputStream, provided it
    * is non-null.  If outputStream is null, then this method has the same effect
    * as calling writeStandardOutput(); that is, future output will be sent to the
    * standard output stream.
    */
   public static void writeStream(PrintWriter outputStream) {
      if (outputStream == null)
         writeStandardOutput();
      else {
         out = outputStream;
         outputFileName = null;
         outputErrorCount = 0;
         writingStandardOutput = false;
      }
   }
   

   /**
    * Opens a file with a specified name for output.  If the file name is null, this has
    * the same effect as calling writeStandardOutput(); that is, output will be sent to standard
    * output.  If an
    * error occurs while trying to open the file, an exception of type IllegalArgumentException
    * is thrown.  If the file is opened successfully, then after this method is called,
    * all of the output routines will write to the file, instead of to  standard output.
    * If an error occurs, the output destination is not changed.
    * <p>NOTE: Calling this method starts a GUI user interface thread, which can continue
    * to run even if the thread that runs the main program ends.  If you use this method
    * in a non-GUI program, it might be necessary to call System.exit(0) at the end of the main() 
    * routine to shut down the Java virtual machine completely.
    */
   public static void writeFile(String fileName) {
      if (fileName == null)  // Go back to reading standard output
         writeStandardOutput();
      else {
         PrintWriter newout;
         try {
            newout = new PrintWriter(new FileWriter(fileName));
         }
         catch (Exception e) {
            throw new IllegalArgumentException("Can't open file \"" + fileName + "\" for output.\n"
                           + "(Error :" + e + ")");
         }
         if (!writingStandardOutput) {
            try {
               out.close();
            }
            catch (Exception e) {
            }
         }
         out = newout;
         writingStandardOutput = false;
         outputFileName = fileName;
         outputErrorCount = 0;
      }
   }
   
   /**
    * Puts a GUI file-selection dialog box on the screen in which the user can select
    * an output file.  If the user cancels the dialog instead of selecting a file, it is
    * not considered an error, but the return value of the subroutine is false.
    * If the user does select a file, but there is an error while trying to open the
    * file, then an exception of type IllegalArgumentException is thrown.  Finally, if
    * the user selects a file and it is successfully opened, then the return value of the
    * subroutine is true, and  the output routines will write to the file, instead of 
    * to standard output.  If the user cancels, or if an error occurs, then the current
    * output destination is not changed.
    */
   public static boolean writeUserSelectedFile() {
      if (fileDialog == null)
         fileDialog = new JFileChooser();
      fileDialog.setDialogTitle("Select File for Output");
      File selectedFile;
      while (true) {
         int option = fileDialog.showSaveDialog(console);
         if (option != JFileChooser.APPROVE_OPTION)
            return false;  // user canceled
         selectedFile = fileDialog.getSelectedFile();
         if (selectedFile.exists()) {
            int response = JOptionPane.showConfirmDialog(console,
                  "The file \"" + selectedFile.getName() + "\" already exists.  Do you want to replace it?",
                  "Replace existing file?",
                  JOptionPane.YES_NO_OPTION, JOptionPane.WARNING_MESSAGE);
            if (response == JOptionPane.YES_OPTION)
               break;
         }
         else {
            break;
         }
      }
      PrintWriter newout;
      try {
         newout = new PrintWriter(new FileWriter(selectedFile));
      }
      catch (Exception e) {
         throw new IllegalArgumentException("Can't open file \"" + selectedFile.getName() + "\" for output.\n"
                        + "(Error :" + e + ")");
      }
      if (!writingStandardOutput) {
         try {
            out.close();
         }