public bool IsAssignableFrom(Type target, NullabilityTypeKind targetNullability, Type from, NullabilityTypeKind fromNullability)
{
if (from == null)
{
throw new ArgumentNullException(nameof(from));
}
if (target == null)
{
throw new ArgumentNullException(nameof(target));
}
// A non nullable cannot be assigned from a nullable.
if (!targetNullability.IsNullable() && fromNullability.IsNullable())
{
return(false);
}
return(target == from ||
target.IsAssignableFrom(from) ||
(AllInterfaces.TryGetValue(target, out var tP) &&
AllInterfaces.TryGetValue(from, out var fP) &&
tP.Root == fP.Root));
}
static NullableTypeTree GetNullableTypeTreeWithProfile(Type t, IEnumerator <byte> annotations, NullabilityTypeKind known, INullableTypeTreeBuilder?builder)
{
if (t.DeclaringType != null && t.DeclaringType.IsGenericType)
{
throw new ArgumentException($"Type '{t.Name}' is nested in a generic type ({t.DeclaringType.ToCSharpName()}). Only nested types in non generic types are supported.", nameof(t));
}
NullableTypeTree[] sub = Array.Empty <NullableTypeTree>();
bool isInside;
if (isInside = (known == NullabilityTypeKind.None))
{
known = t.GetNullabilityKind();
}
if (known.IsNullableValueType())
{
// Lift the Nullable<T>.
t = Nullable.GetUnderlyingType(t) !;
}
if (isInside && !known.IsNonGenericValueType())
{
// Consume our annotation.
if (!annotations.MoveNext())
{
throw new InvalidOperationException($"Byte annotations too short.");
}
var thisOne = annotations.Current;
// Annotations only apply to reference types. Only 1 (not null!) is of interest.
if (thisOne == 1 && known.IsReferenceType())
{
Debug.Assert(known.IsNullable());
known &= ~NullabilityTypeKind.IsNullable;
}
}
Type[]? genArgs = null;
if (t.HasElementType)
{
Debug.Assert(known.IsReferenceType());
sub = new[] { GetNullableTypeTreeWithProfile(t.GetElementType() !, annotations, default, builder) };