private DataType InferUnaryExpressionType(UnaryExpressionSyntax unaryExpression)
{
var operandType = InferExpressionType(unaryExpression.Operand);
var @operator = unaryExpression.Operator;
// If either is unknown, then we can't know whether there is a a problem
// (technically not true, for example, we could know that one arg should
// be a bool and isn't)
if (operandType == DataType.Unknown)
{
return(unaryExpression.Type = DataType.Unknown);
}
bool typeError;
switch (@operator)
{
case UnaryOperator.Not:
typeError = operandType != DataType.Bool;
unaryExpression.Type = DataType.Bool;
break;
case UnaryOperator.At:
typeError = false; // TODO check that the expression can have a pointer taken
if (operandType is Metatype)
{
unaryExpression.Type = DataType.Type; // constructing a type
}
else
{
unaryExpression.Type = new PointerType(operandType); // taking the address of something
}
break;
case UnaryOperator.Question:
typeError = false; // TODO check that the expression can have a pointer taken
unaryExpression.Type = new PointerType(operandType);
break;
case UnaryOperator.Caret:
switch (operandType)
{
case PointerType pointerType:
unaryExpression.Type = pointerType.Referent;
typeError = false;
break;
default:
unaryExpression.Type = DataType.Unknown;
typeError = true;
break;
}
break;
case UnaryOperator.Minus:
switch (operandType)
{
case IntegerConstantType integerType:
typeError = false;
unaryExpression.Type = integerType;
break;
case SizedIntegerType sizedIntegerType:
typeError = false;
unaryExpression.Type = sizedIntegerType;
break;
default:
unaryExpression.Type = DataType.Unknown;
typeError = true;
break;
}
break;
default:
throw NonExhaustiveMatchException.ForEnum(@operator);
}
if (typeError)
{
diagnostics.Add(TypeError.OperatorCannotBeAppliedToOperandOfType(file,
unaryExpression.Span, @operator, operandType));
}
return(unaryExpression.Type);
}
