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.Stack;
import java.util.HashMap;
import java.util.Iterator;
/**
* Implements a RPN Calculator (stack based)
* See http://en.wikipedia.org/wiki/Reverse_Polish_notation for more info
*
* @version 1.0
* @author Manuel Mausz (manuel at mausz.at)
* @author http://manuel.mausz.at/
*/
class Rechner implements UPNRechner
{
private Stack<Double> stack = new Stack<Double>();
private HashMap<String, UPNOperation> operations = new HashMap<String, UPNOperation>();
/**
* add operation to "supported operations"-list
*
* @param op operation object
*/
public void addOperation(UPNOperation op)
{
operations.put(op.getOperationSymbol(), op);
}
/**
* get operation mapped to the specified operation-symbol
*
* @param op operation symbol
* @return operation object or null
*/
public UPNOperation getOperation(String op)
{
return (operations.containsKey(op)) ? operations.get(op) : null;
}
/**
* push operand onto internal stack
*
* @param val value
*/
public void enterNumber(Double val)
{
stack.push(val);
}
/**
* executes operation assigned to operation symbol
*
* @param opstr operation symbol
* @throws InvalidOperationException if operation isn't supported
* @throws InvalidParameterException
*/
public void enterOperation(String opstr)
throws InvalidOperationException, InvalidParameterException
{
UPNOperation op = getOperation(opstr);
if (op == null)
throw new InvalidOperationException("Operator doesn't exist");
op.execute(stack);
}
/**
* returns internal stack converted to string
*
* @return string
*/
public String toString()
{
String str = "";
Iterator it = stack.iterator();
while(it.hasNext())
str += it.next() + " ";
return str;
}
}