Download | Plain Text | Line Numbers
/*
* Copyright (c) 2008, Manuel Mausz <manuel at mausz.at>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the copyright holders nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
import java.util.Scanner;
/**
* Implements a simple RPN (UPN) Calculator
* - Parses the given input syntax
* - passes them to the RPN Calculator
* - and prints the specified (tho completely non-informative) error messages
*
* @version 1.0
* @author Manuel Mausz (manuel at mausz.at)
* @author http://manuel.mausz.at/
*/
class UpnApplication
{
private static UpnCalculator calc = new UpnCalculator();
/**
* read operands and operator from first line of src
* parses RPN syntax; only allows integers as operands
* prints "?" to stdout if calculations fails
*
* @param src input stream
* @return boolean true on success, false otherwise
*/
private static boolean parse(java.io.InputStream src)
{
Scanner scan;
/* get first line only */
scan = new Scanner(src);
if (!scan.hasNextLine())
{
scan.close();
return false;
}
String line1 = scan.nextLine();
scan.close();
/* parse first line */
scan = new Scanner(line1);
boolean err = false;
while(!err && scan.hasNext())
{
/* pass operand or operator to UpnCalculator */
if (scan.hasNextInt())
calc.addOperand(scan.nextInt());
else if (scan.hasNext())
{
String op = scan.next();
if (!calc.supportsOperator(op))
err = true;
else if (!calc.addOperator(op))
System.out.println("?");
}
else
err = true;
}
scan.close();
return !err;
}
/**
* main method
*
* @param args not used
*/
public static void main(String args[])
{
/* try-catch for the sake of safety */
try
{
/* dump RPN stack of everything was ok */
if (parse(System.in))
System.out.print(calc);
else
System.out.println("FALSCHE EINGABE");
}
catch(Throwable e)
{
System.out.println("FALSCHE EINGABE");
}
}
}