// ** object model
override public object Evaluate(Dictionary <string, double> operands)
{
switch (_token.ID)
{
case TKID.ADD:
return(+_expr.toDouble(operands));
case TKID.SUB:
return(-_expr.toDouble(operands));
case TKID.ABS:
return(Math.Abs(_expr.toDouble(operands)));
case TKID.NOT:
return(!_expr.toBool(operands));
}
throw new ArgumentException("Bad expression.");
}
// ** object model
override public object Evaluate(Dictionary <string, double> operands)
{
// handle comparisons
if (_token.Type == TKTYPE.COMPARE)
{
var cmp = _lft.CompareTo(_rgt, operands);
if (cmp == int.MinValue)
{
return(false); // one of the operands was NaN
}
switch (_token.ID)
{
case TKID.GT: return(cmp > 0);
case TKID.LT: return(cmp < 0);
case TKID.GE: return(cmp >= 0);
case TKID.LE: return(cmp <= 0);
case TKID.EQ: return(cmp == 0);
case TKID.NE: return(cmp != 0);
}
}
// handle everything else
switch (_token.ID)
{
case TKID.ADD:
return(_lft.toDouble(operands) + _rgt.toDouble(operands));
case TKID.SUB:
return(_lft.toDouble(operands) - _rgt.toDouble(operands));
case TKID.MUL:
return(_lft.toDouble(operands) * _rgt.toDouble(operands));
case TKID.DIV:
double r = _rgt.toDouble(operands);
if (r == 0)
{
return(double.NaN); // division by 0
}
else
{
return(_lft.toDouble(operands) / r);
}
case TKID.DIVINT:
return((double)(int)(_lft.toDouble(operands) / _rgt.toDouble(operands)));
case TKID.MOD:
return((double)(int)(_lft.toDouble(operands) % _rgt.toDouble(operands)));
case TKID.POWER:
var a = _lft.toDouble(operands);
var b = _rgt.toDouble(operands);
if (b == 0.0)
{
return(1.0);
}
if (b == 0.5)
{
return(Math.Sqrt(a));
}
if (b == 1.0)
{
return(a);
}
if (b == 2.0)
{
return(a * a);
}
if (b == 3.0)
{
return(a * a * a);
}
if (b == 4.0)
{
return(a * a * a * a);
}
return(Math.Pow(_lft.toDouble(operands), _rgt.toDouble(operands)));
case TKID.MAX:
return(Math.Max(_lft.toDouble(operands), _rgt.toDouble(operands)));
case TKID.MIN:
return(Math.Min(_lft.toDouble(operands), _rgt.toDouble(operands)));
case TKID.AND:
return(_lft.toBool(operands) && _rgt.toBool(operands));
case TKID.OR:
return(_lft.toBool(operands) || _rgt.toBool(operands));
}
throw new ArgumentException("Bad expression.");
}
