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/*
    This file is part of JLog.

    Created by Glendon Holst for Alan Mackworth and the 
    "Computational Intelligence: A Logical Approach" text.
    
    Copyright 1998, 2000, 2002 by University of British Columbia and 
    Alan Mackworth.
    
    This notice must remain in all files which belong to, or are derived 
    from JLog.
    
    Check  or 
     for further information
    about JLog, or to contact the authors.
     
    JLog 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.

    JLog 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 JLog; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    URLs:  or 
*/
//#########################################################################
//	Arithmetic
//#########################################################################
 
package ubc.cs.JLog.Builtins;

import java.lang.*;
import java.util.*;
import ubc.cs.JLog.Terms.*;
import ubc.cs.JLog.Foundation.*;
import ubc.cs.JLog.Terms.Goals.*;

/**
* The abstract class for binary arithmetic operators.
*
* @author       Glendon Holst
* @version      %I%, %G%
*/
abstract class jArithmetic extends jBinaryBuiltinPredicate implements iArithmetic
{
 public jArithmetic(jTerm l,jTerm r)
 {
  super(l,r,TYPE_ARITHMETIC);
 };
  
 public  jTerm 		getValue()
 {jTerm 		l,r;
  
  l = lhs.getValue();
  r = rhs.getValue();

  if (l.type == TYPE_INTEGER && r.type == TYPE_INTEGER)
   return new jInteger(operatorInt(((jInteger) l).getIntegerValue(),
                                   ((jInteger) r).getIntegerValue()));
  else
  {float 		rl,rr;

   if (l.type == TYPE_INTEGER)
    rl = (float) ((jInteger) l).getIntegerValue();
   else if (l.type == TYPE_REAL)
    rl = ((jReal) l).getRealValue();
   else
    throw new InvalidArithmeticOperationException();
  
   if (r.type == TYPE_INTEGER)
    rr = (float) ((jInteger) r).getIntegerValue();
   else if (r.type == TYPE_REAL)
    rr = ((jReal) r).getRealValue();
   else
    throw new InvalidArithmeticOperationException();
 
   return new jReal(operatorReal(rl,rr));
  }
 };
 
 /**
  * Perform the integer operations specified by this instance on the two
  * given integers, and return the integer result.
  *
  * @param l 		The left operand.
  * @param r 		The right operand.
  *
  * @return 		The result of l op r 
  * 			where op is specified by this instance.
  */
 abstract protected int 	operatorInt(int l,int r);

 /**
  * Perform the float operations specified by this instance on the two
  * given floats, and return the float result.
  *
  * @param l 		The left operand.
  * @param r 		The right operand.
  *
  * @return 		The result of l op r 
  * 			where op is specified by this instance.
  */
 abstract protected float 	operatorReal(float l,float r);
 
 /**
  * Arithmetics are intended as expressions for is, 
  * if used a predicate they fail.
  */
 public void 		addGoals(jGoal g,jVariable[] vars,iGoalStack goals)
 {
  goals.push(new jFailGoal());
 }; 

 /**
  * Arithmetics are intended as expressions for is, 
  * if used a predicate they fail.
  */
 public void 		addGoals(jGoal g,iGoalStack goals)
 {
  goals.push(new jFailGoal());
 }; 

 public String 		toString(boolean usename)
 {jTerm 	l,r;
  boolean 	bracket_l = false,bracket_r = false;
  
  l = lhs.getTerm();
  r = rhs.getTerm();
  
  if (l instanceof iArithmetic)
   bracket_l = ((iArithmetic) l).getPriority() > getPriority();
  if (r instanceof iArithmetic)
   bracket_r = ((iArithmetic) r).getPriority() > getPriority();
  
  return (bracket_l ? "(" : "") + lhs.toString(usename) + (bracket_l ? ") " : " ") + 
          getName() + 
         (bracket_r ? " (" : " ") + rhs.toString(usename) + (bracket_r ? ")" : "");
 };
};