public override Type Typecheck(TypecheckingState state)
{
var type1 = Expression1.Typecheck(state);
var type2 = Expression2.Typecheck(state);
OperandType = type1;
switch (Operator)
{
case BinaryOperator.Add:
if (type1 != Type.NumType && type2 != Type.NumType)
{
TypeError("+ expects number operands");
}
return(Type.NumType);
case BinaryOperator.Sub:
if (type1 != Type.NumType && type2 != Type.NumType)
{
TypeError("- expects number operands");
}
return(Type.NumType);
case BinaryOperator.Eq:
if (type1 != type2)
{
TypeError("== expects operands of the same type");
}
return(Type.BoolType);
case BinaryOperator.Lt:
if (type1 != Type.NumType && type2 != Type.NumType)
{
TypeError("- expects number operands");
}
return(Type.BoolType);
}
throw new ImpossibleException();
}
// public Expression Expression1;
// public Expression Expression2;
public override Type Typecheck(TypecheckingState state)
{
Expression1.Typecheck(state);
return(Expression2.Typecheck(state));
}