public override void Emit(EmitContext ec)
{
Label is_null_label = ec.DefineLabel();
Label end_label = ec.DefineLabel();
unwrap.EmitCheck(ec);
ec.Emit(OpCodes.Brfalse, is_null_label);
if (user_operator != null)
{
user_operator.Emit(ec);
}
else
{
EmitOperator(ec, NullableInfo.GetUnderlyingType(type));
}
ec.Emit(OpCodes.Newobj, NullableInfo.GetConstructor(type));
ec.Emit(OpCodes.Br_S, end_label);
ec.MarkLabel(is_null_label);
LiftedNull.Create(type, loc).Emit(ec);
ec.MarkLabel(end_label);
}
protected override void EmitOperation(EmitContext ec)
{
Label is_null_label = ec.DefineLabel();
Label end_label = ec.DefineLabel();
LocalTemporary lt = new LocalTemporary(type);
// Value is on the stack
lt.Store(ec);
var call = new CallEmitter();
call.InstanceExpression = lt;
call.EmitPredefined(ec, NullableInfo.GetHasValue(expr.Type), null);
ec.Emit(OpCodes.Brfalse, is_null_label);
call = new CallEmitter();
call.InstanceExpression = lt;
call.EmitPredefined(ec, NullableInfo.GetGetValueOrDefault(expr.Type), null);
lt.Release(ec);
base.EmitOperation(ec);
ec.Emit(OpCodes.Newobj, NullableInfo.GetConstructor(type));
ec.Emit(OpCodes.Br_S, end_label);
ec.MarkLabel(is_null_label);
LiftedNull.Create(type, loc).Emit(ec);
ec.MarkLabel(end_label);
}
protected override Expression DoResolve(ResolveContext ec)
{
//
// It's null when lifting non-nullable type
//
if (unwrap == null)
{
// S -> T? is wrap only
if (type.IsNullableType)
{
return(Wrap.Create(expr, type));
}
// S -> T can be simplified
return(expr);
}
// Wrap target for T?
if (type.IsNullableType)
{
expr = Wrap.Create(expr, type);
if (expr == null)
{
return(null);
}
null_value = LiftedNull.Create(type, loc);
}
else if (TypeSpec.IsValueType(type))
{
null_value = LiftedNull.Create(type, loc);
}
else
{
null_value = new NullConstant(type, loc);
}
eclass = ExprClass.Value;
return(this);
}
public override void Emit(EmitContext ec)
{
//
// Optimize same expression operation
//
if (right_unwrap != null && right.Equals(left))
{
right_unwrap = left_unwrap;
}
if (user_operator == null && IsBitwiseBoolean)
{
EmitBitwiseBoolean(ec);
return;
}
if ((Oper & Operator.EqualityMask) != 0)
{
EmitEquality(ec);
return;
}
Label is_null_label = ec.DefineLabel();
Label end_label = ec.DefineLabel();
if (left_unwrap != null)
{
left_unwrap.EmitCheck(ec);
ec.Emit(OpCodes.Brfalse, is_null_label);
}
//
// Don't emit HasValue check when left and right expressions are same
//
if (right_unwrap != null && !left.Equals(right))
{
right_unwrap.EmitCheck(ec);
ec.Emit(OpCodes.Brfalse, is_null_label);
}
EmitOperator(ec, left.Type);
if (wrap_ctor != null)
{
ec.Emit(OpCodes.Newobj, wrap_ctor);
}
ec.Emit(OpCodes.Br_S, end_label);
ec.MarkLabel(is_null_label);
if ((Oper & Operator.ComparisonMask) != 0)
{
ec.EmitInt(0);
}
else
{
LiftedNull.Create(type, loc).Emit(ec);
}
ec.MarkLabel(end_label);
}
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);
}