//  This may look like C code, but it is really -*- C++ -*-

//  ------------------------------------------------------------------
//  The Goldware Library
//  Copyright (C) 1990-1999 Odinn Sorensen
//  ------------------------------------------------------------------
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Library General Public
//  License as published by the Free Software Foundation; either
//  version 2 of the License, or (at your option) any later version.
//
//  This library 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
//  Library General Public License for more details.
//
//  You should have received a copy of the GNU Library General Public
//  License along with this program; if not, write to the Free
//  Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
//  MA 02111-1307, USA
//  ------------------------------------------------------------------
//  $Id$
//  ------------------------------------------------------------------
//  Expression evaluator classes.
//  ------------------------------------------------------------------

#ifndef __geval_h
#define __geval_h


//  ------------------------------------------------------------------

#include <vector>
#include <gdefs.h>


//  ------------------------------------------------------------------
//  Base class

class geval {

public:

  enum ops {
    lowest,
    logic_or,
    logic_and,
    logic_xor,
    not_equal,
    equal,
    greater_or_equal,
    greater,
    lesser_or_equal,
    lesser,
    subtraction,
    addition,
    modulus,
    division,
    multiplication,
    negation,
    logic_not,
    parenthesis_right,
    parenthesis_left,
    highest
  };

protected:

  std::vector<ops> ostk;
  std::vector<int> vstk;

  ops pop_operator();
  int pop_value();

public:

  geval();
  ~geval();

  void push_value(int v);
  void push_operator(ops o);

  int evaluate_op(ops o, int y, int x);
  int evaluate_ops(std::vector<ops>::iterator o, std::vector<int>::iterator y, std::vector<int>::iterator x);

};


//  ------------------------------------------------------------------

inline int geval::evaluate_ops(std::vector<ops>::iterator o, std::vector<int>::iterator y, std::vector<int>::iterator x) {

  return evaluate_op(*o, *y, *x);
}


//  ------------------------------------------------------------------
//  Reverse Polish Notation expression evaluator.

class gevalrpn : public geval {

public:

  gevalrpn();
  ~gevalrpn();

  int evaluate();

};


//  ------------------------------------------------------------------
//  Human (left-to-right) expression evaluator.

class gevalhum : public geval {

public:

  gevalhum();
  ~gevalhum();

  int evaluate();

};


//  ------------------------------------------------------------------

#endif

//  ------------------------------------------------------------------
