//  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 base class.
//  ------------------------------------------------------------------

#include <gdefs.h>
#include <geval.h>


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

geval::geval()
{

    // nothing to do
}


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

geval::~geval()
{

    // nothing
}


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

geval::ops geval::pop_operator()
{

    ops o = ostk.back();
    ostk.pop_back();
    return o;
}


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

int geval::pop_value()
{

    int v = vstk.back();
    vstk.pop_back();
    return v;
}


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

void geval::push_value(int v)
{

    vstk.push_back(v);
}


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

void geval::push_operator(geval::ops o)
{

    ostk.push_back(o);
}


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

int geval::evaluate_op(geval::ops o, int y, int x)
{

    switch(o)
    {
    case addition:
        return y + x;
    case subtraction:
        return y - x;
    case multiplication:
        return y * x;
    case division:
        return y / x;
    case modulus:
        return y % x;
    case negation:
        return -x;
    case logic_not:
        return (not x) ? 1 : 0;
    case logic_and:
        return (y and x) ? 1 : 0;
    case logic_xor:
        return (y ^ x) ? 1 : 0;
    case equal:
        return (y == x) ? 1 : 0;
    case not_equal:
        return (y != x) ? 1 : 0;
    case greater:
        return (y > x) ? 1 : 0;
    case greater_or_equal:
        return (y >= x) ? 1 : 0;
    case lesser:
        return (y < x) ? 1 : 0;
    case lesser_or_equal:
        return (y <= x) ? 1 : 0;
    default:
        ;
    }

    return 0;
}


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