BaseTerm PrefixToTerm()
{
BaseTerm t0, t1;
BaseToken token = null;
try
{
token = PS.Pop();
}
catch // should not occur -- please report if it does
{
IO.Error("PrefixToTerm (): Unanticipated error in expression -- please report");
}
if (token is OperandToken)
{
return(((OperandToken)token).term);
}
OperatorToken oprToken = (OperatorToken)token;
if (oprToken.IsZerofix) // operator as operand; no arguments
{
return(new OperatorTerm(oprToken.triplet.Name));
}
t0 = PrefixToTerm();
if (oprToken.IsInfix)
{
t1 = PrefixToTerm(); // get the second operand from the PS-stack
return(new OperatorTerm(oprToken.od, t0, t1));
}
else // prefix or postfix
{
return(new OperatorTerm(oprToken.od, t0));
}
}