protected override Expression DoResolve(ResolveContext rc)
{
base.DoResolve(rc);
if (type != null)
{
type = NullableInfo.GetUnderlyingType(type);
}
return(this);
}
public static Expression Create(Expression expr, TypeSpec type)
{
//
// Avoid unwraping and wraping of the same type
//
Unwrap unwrap = expr as Unwrap;
if (unwrap != null && expr.Type == NullableInfo.GetUnderlyingType(type))
{
return(unwrap.Original);
}
return(new Wrap(expr, type));
}
protected override void EmitOperator(EmitContext ec, TypeSpec l)
{
if (user_operator != null)
{
user_operator.Emit(ec);
return;
}
if (left.Type.IsNullableType)
{
l = NullableInfo.GetUnderlyingType(left.Type);
left = EmptyCast.Create(left, l);
}
if (right.Type.IsNullableType)
{
right = EmptyCast.Create(right, NullableInfo.GetUnderlyingType(right.Type));
}
base.EmitOperator(ec, l);
}
Expression LiftResult(ResolveContext ec, Expression res_expr)
{
TypeSpec lifted_type;
//
// Avoid double conversion
//
if (left_unwrap == null || IsLeftNullLifted || left_unwrap.Type != left.Type || (left_unwrap != null && IsRightNullLifted))
{
lifted_type = new NullableType(left.Type, loc).ResolveAsType(ec);
if (lifted_type == null)
{
return(null);
}
if (left is UserCast || left is EmptyCast || left is OpcodeCast)
{
left.Type = lifted_type;
}
else
{
left = EmptyCast.Create(left, lifted_type);
}
}
if (left != right && (right_unwrap == null || IsRightNullLifted || right_unwrap.Type != right.Type || (right_unwrap != null && IsLeftNullLifted)))
{
lifted_type = new NullableType(right.Type, loc).ResolveAsType(ec);
if (lifted_type == null)
{
return(null);
}
var r = right;
if (r is ReducedExpression)
{
r = ((ReducedExpression)r).OriginalExpression;
}
if (r is UserCast || r is EmptyCast || r is OpcodeCast)
{
r.Type = lifted_type;
}
else
{
right = EmptyCast.Create(right, lifted_type);
}
}
if ((Oper & Operator.ComparisonMask) == 0)
{
lifted_type = new NullableType(res_expr.Type, loc).ResolveAsType(ec);
if (lifted_type == null)
{
return(null);
}
wrap_ctor = NullableInfo.GetConstructor(lifted_type);
type = res_expr.Type = lifted_type;
}
if (IsLeftNullLifted)
{
left = LiftedNull.Create(right.Type, left.Location);
//
// Special case for bool?, the result depends on both null right side and left side value
//
if ((Oper == Operator.BitwiseAnd || Oper == Operator.BitwiseOr) && NullableInfo.GetUnderlyingType(type).BuiltinType == BuiltinTypeSpec.Type.Bool)
{
return(res_expr);
}
if ((Oper & (Operator.ArithmeticMask | Operator.ShiftMask | Operator.BitwiseMask)) != 0)
{
return(LiftedNull.CreateFromExpression(ec, res_expr));
}
//
// Value types and null comparison
//
if (right_unwrap == null || (Oper & Operator.RelationalMask) != 0)
{
return(CreateNullConstant(ec, right_orig));
}
}
if (IsRightNullLifted)
{
right = LiftedNull.Create(left.Type, right.Location);
//
// Special case for bool?, the result depends on both null right side and left side value
//
if ((Oper == Operator.BitwiseAnd || Oper == Operator.BitwiseOr) && NullableInfo.GetUnderlyingType(type).BuiltinType == BuiltinTypeSpec.Type.Bool)
{
return(res_expr);
}
if ((Oper & (Operator.ArithmeticMask | Operator.ShiftMask | Operator.BitwiseMask)) != 0)
{
return(LiftedNull.CreateFromExpression(ec, res_expr));
}
//
// Value types and null comparison
//
if (left_unwrap == null || (Oper & Operator.RelationalMask) != 0)
{
return(CreateNullConstant(ec, left_orig));
}
}
return(res_expr);
}
