textio.java

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   /**
    * Skips whitespace characters and then reads a value of type byte from input.  Any additional characters on
    * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
    * this will not produce an error; the user will be prompted repeatedly for input until a legal value
    * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
    */
   public static byte getByte()   { 
      return (byte)readInteger(-128L,127L); 
   }

   /**
    * Skips whitespace characters and then reads a value of type short from input.  Any additional characters on
    * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
    * this will not produce an error; the user will be prompted repeatedly for input until a legal value
    * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
    */
   public static short getShort() { 
      return (short)readInteger(-32768L,32767L);
   }   
   
   /**
    * Skips whitespace characters and then reads a value of type int from input.  Any additional characters on
    * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
    * this will not produce an error; the user will be prompted repeatedly for input until a legal value
    * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
    */
   public static int getInt()     { 
      return (int)readInteger((long)Integer.MIN_VALUE, (long)Integer.MAX_VALUE);
   }
   
   /**
    * Skips whitespace characters and then reads a value of type long from input.  Any additional characters on
    * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
    * this will not produce an error; the user will be prompted repeatedly for input until a legal value
    * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
    */
   public static long getLong()   { 
      return readInteger(Long.MIN_VALUE, Long.MAX_VALUE); 
   }
   
   /**
    * Skips whitespace characters and then reads a single non-whitespace character from input.  Any additional characters on
    * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
    * this will not produce an error.  In other cases, an IllegalArgumentException will be thrown if an end-of-file
    * is encountered.
    */
   public static char getChar() { 
      skipWhitespace();
      return readChar();
   }
   
   /**
    * Skips whitespace characters and then reads a value of type float from input.  Any additional characters on
    * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
    * this will not produce an error; the user will be prompted repeatedly for input until a legal value
    * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
    */
   public static float getFloat() {
      float x = 0.0F;
      while (true) {
         String str = readRealString();
         if (str == null) {
            errorMessage("Floating point number not found.",
                  "Real number in the range " + (-Float.MAX_VALUE) + " to " + Float.MAX_VALUE);
         }
         else {
            try { 
               x = Float.parseFloat(str); 
            }
            catch (NumberFormatException e) {
               errorMessage("Illegal floating point input, " + str + ".",
                     "Real number in the range " + (-Float.MAX_VALUE) + " to " + Float.MAX_VALUE);
               continue;
            }
            if (Float.isInfinite(x)) {
               errorMessage("Floating point input outside of legal range, " + str + ".",
                     "Real number in the range " + (-Float.MAX_VALUE) + " to " + Float.MAX_VALUE);
               continue;
            }
            break;
         }
      }
      inputErrorCount = 0;
      return x;
   }
   
   /**
    * Skips whitespace characters and then reads a value of type double from input.  Any additional characters on
    * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
    * this will not produce an error; the user will be prompted repeatedly for input until a legal value
    * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
    */
   public static double getDouble() {
      double x = 0.0;
      while (true) {
         String str = readRealString();
         if (str == null) {
            errorMessage("Floating point number not found.",
                  "Real number in the range " + (-Double.MAX_VALUE) + " to " + Double.MAX_VALUE);
         }
         else {
            try { 
               x = Double.parseDouble(str); 
            }
            catch (NumberFormatException e) {
               errorMessage("Illegal floating point input, " + str + ".",
                     "Real number in the range " + (-Double.MAX_VALUE) + " to " + Double.MAX_VALUE);
               continue;
            }
            if (Double.isInfinite(x)) {
               errorMessage("Floating point input outside of legal range, " + str + ".",
                     "Real number in the range " + (-Double.MAX_VALUE) + " to " + Double.MAX_VALUE);
               continue;
            }
            break;
         }
      }
      inputErrorCount = 0;
      return x;
   }
   
   /**
    * Skips whitespace characters and then reads one "word" from input. Any additional characters on
    * the current line of input are retained, and will be read by the next input operation.  A word is defined as
    * a sequence of non-whitespace characters (not just letters!).   When using standard IO,
    * this will not produce an error.  In other cases, an IllegalArgumentException will be thrown
    * if an end-of-file is encountered.
    */
   public static String getWord() {
      skipWhitespace();
      StringBuffer str = new StringBuffer(50);
      char ch = lookChar();
      while (ch == EOF || !Character.isWhitespace(ch)) {
         str.append(readChar());
         ch = lookChar();
      }
      return str.toString();
   }
   
   /**
    * Skips whitespace characters and then reads a value of type boolean from input.  Any additional characters on
    * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
    * this will not produce an error; the user will be prompted repeatedly for input until a legal value
    * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
    * <p>Legal inputs for a boolean input are: true, t, yes, y, 1, false, f, no, n, and 0; letters can be
    * either upper case or lower case. One "word" of input is read, using the getWord() method, and it
    * must be one of these; note that the "word"  must be terminated by a whitespace character (or end-of-file).
    */
   public static boolean getBoolean() {
      boolean ans = false;
      while (true) {
         String s = getWord();
         if ( s.equalsIgnoreCase("true") || s.equalsIgnoreCase("t") ||
               s.equalsIgnoreCase("yes")  || s.equalsIgnoreCase("y") ||
               s.equals("1") ) {
            ans = true;
            break;
         }
         else if ( s.equalsIgnoreCase("false") || s.equalsIgnoreCase("f") ||
               s.equalsIgnoreCase("no")  || s.equalsIgnoreCase("n") ||
               s.equals("0") ) {
            ans = false;
            break;
         }
         else
            errorMessage("Illegal boolean input value.",
            "one of:  true, false, t, f, yes, no, y, n, 0, or 1");
      }
      inputErrorCount = 0;
      return ans;
   }
   
   // ***************** Everything beyond this point is private implementation detail *******************
   
   private static String inputFileName;  // Name of file that is the current input source, or null if the source is not a file.
   private static String outputFileName; // Name of file that is the current output destination, or null if the destination is not a file.
   
   private static JFileChooser fileDialog; // Dialog used by readUserSelectedFile() and writeUserSelectedFile()
   
   private final static BufferedReader standardInput;  // wraps the input stream from Console. (Set in static initializer.)
   private final static PrintWriter standardOutput;  // wraps the output stream. (Set in static initializer.)

   private static BufferedReader in;  // Stream that data is read from; the current input source. (Set in static initializer.)
   private static PrintWriter out;   // Stream that data is written to; the current output destination. (Set in static initializer.)
   
   private static boolean readingStandardInput = true;
   private static boolean writingStandardOutput = true;
   
   private static int inputErrorCount;  // Number of consecutive errors on standard input; reset to 0 when a successful read occurs.
   private static int outputErrorCount;  // Number of errors on standard output since it was selected as the output destination.
   
   private static Matcher integerMatcher;  // Used for reading integer numbers; created from the integer Regex Pattern.
   private static Matcher floatMatcher;   // Used for reading floating point numbers; created from the floatRegex Pattern.
   private final static Pattern integerRegex = Pattern.compile("(\\+|-)?[0-9]+");
   private final static Pattern floatRegex = Pattern.compile("(\\+|-)?(([0-9]+(\\.[0-9]*)?)|(\\.[0-9]+))((e|E)(\\+|-)?[0-9]+)?");
   
   private static String buffer = null;  // One line read from input.
   private static int pos = 0;           // Position of next char in input line that has not yet been processed.
   
   private static Console console;  // The GUI IO widget used for simulated input/output.
   
   private static String readRealString() {   // read chars from input following syntax of real numbers
      skipWhitespace();
      if (lookChar() == EOF)
         return null;
      if (floatMatcher == null)
         floatMatcher = floatRegex.matcher(buffer);
      floatMatcher.region(pos,buffer.length());
      if (floatMatcher.lookingAt()) {
         String str = floatMatcher.group();
         pos = floatMatcher.end();
         return str;
      }
      else 
         return null;
   }
   
   private static String readIntegerString() {  // read chars from input following syntax of integers
      skipWhitespace();
      if (lookChar() == EOF)
         return null;
      if (integerMatcher == null)
         integerMatcher = integerRegex.matcher(buffer);
      integerMatcher.region(pos,buffer.length());
      if (integerMatcher.lookingAt()) {
         String str = integerMatcher.group();
         pos = integerMatcher.end();
         return str;
      }
      else 
         return null;
   }
   
   private static long readInteger(long min, long max) {  // read long integer, limited to specified range
      long x=0;
      while (true) {
         String s = readIntegerString();
         if (s == null){
            errorMessage("Integer value not found in input.",
                  "Integer in the range " + min + " to " + max);
         }
         else {
            String str = s.toString();
            try { 
               x = Long.parseLong(str);
            }
            catch (NumberFormatException e) {
               errorMessage("Illegal integer input, " + str + ".",
                     "Integer in the range " + min + " to " + max);
               continue;
            }
            if (x < min || x > max) {
               errorMessage("Integer input outside of legal range, " + str + ".",
                     "Integer in the range " + min + " to " + max);
               continue;
            }
            break;
         }
      }
      inputErrorCount = 0;
      return x;
   }
   
   
   private static void errorMessage(String message, String expecting) {  // Report error on input.
      console.clearTypeAhead();
      if (readingStandardInput && writingStandardOutput) {
             // inform user of error and force user to re-enter.
         out.println();
         out.print("  *** Error in input: " + message + "\n");
         out.print("  *** Expecting: " + expecting + "\n");
         out.print("  *** Discarding Input: ");
         if (lookChar() == '\n')
            out.print("(end-of-line)\n\n");
         else {
            while (lookChar() != '\n')    // Discard and echo remaining chars on the current line of input.
               out.print(readChar());
            out.print("\n\n");
         }
         out.print("Please re-enter: ");
         out.flush();
         readChar();  // discard the end-of-line character
         inputErrorCount++;
         if (inputErrorCount >= 10)
            throw new IllegalArgumentException("Too many input consecutive input errors on standard input.");
      }
      else if (inputFileName != null)
         throw new IllegalArgumentException("Error while reading from file \"" + inputFileName + "\":\n" 
               + message + "\nExpecting " + expecting);
      else
         throw new IllegalArgumentException("Error while reading from input stream:\n" 
               + message + "\nExpecting " + expecting);
   }
   
   private static char lookChar() {  // return next character from input
      if (buffer == null || pos > buffer.length())
         fillBuffer();
      if (buffer == null)
         return EOF;
      else if (pos == buffer.length())
         return '\n';
      else 
         return buffer.charAt(pos);
   }
   
   private static char readChar() {  // return and discard next character from input
      char ch = lookChar();
      if (buffer == null) {
         if (readingStandardInput)
            throw new IllegalArgumentException("Attempt to read past end-of-file in standard input???");
         else
            throw new IllegalArgumentException("Attempt to read past end-of-file in file \"" + inputFileName + "\".");
      }
      pos++;
      return ch;
   }
      
   private static void fillBuffer() {    // Wait for user to type a line and press return,
      try {
         buffer = in.readLine();
      }
      catch (Exception e) {
         if (readingStandardInput)
            throw new IllegalArgumentException("Error while reading standard input???");
         else if (inputFileName != null)
            throw new IllegalArgumentException("Error while attempting to read from file \"" + inputFileName + "\".");
         else
            throw new IllegalArgumentException("Errow while attempting to read form an input stream.");
      }
      pos = 0;
      floatMatcher = null;