/**
* Differs from `isNullableType` only by treating type parameters: acceptsNullable(T) <=> T has
* nullable lower bound Semantics should be the same as `isSubtype(Nothing?, T)`
*
* @return true if `null` can be assigned to storage of this type
*/
public static boolean acceptsNullable(@NotNull KotlinType type) {
if (type.isMarkedNullable()) {
return true;
}
if (FlexibleTypesKt.isFlexible(type)
&& acceptsNullable(FlexibleTypesKt.flexibility(type).getUpperBound())) {
return true;
}
return false;
}
@Nullable
public static KotlinType createSubstitutedSupertype(
@NotNull KotlinType subType,
@NotNull KotlinType superType,
@NotNull TypeSubstitutor substitutor) {
KotlinType substitutedType = substitutor.substitute(superType, Variance.INVARIANT);
if (substitutedType != null) {
return makeNullableIfNeeded(substitutedType, subType.isMarkedNullable());
}
return null;
}
public static boolean hasNullableSuperType(@NotNull KotlinType type) {
if (type.getConstructor().getDeclarationDescriptor() instanceof ClassDescriptor) {
// A class/trait cannot have a nullable supertype
return false;
}
for (KotlinType supertype : getImmediateSupertypes(type)) {
if (supertype.isMarkedNullable()) return true;
if (hasNullableSuperType(supertype)) return true;
}
return false;
}
/**
* A work-around of the generic nullability problem in the type checker Semantics should be the
* same as `!isSubtype(T, Any)`
*
* @return true if a value of this type can be null
*/
public static boolean isNullableType(@NotNull KotlinType type) {
if (type.isMarkedNullable()) {
return true;
}
if (FlexibleTypesKt.isFlexible(type)
&& isNullableType(FlexibleTypesKt.flexibility(type).getUpperBound())) {
return true;
}
if (isTypeParameter(type)) {
return hasNullableSuperType(type);
}
return false;
}
@NotNull
public static KotlinType makeNullableAsSpecified(@NotNull KotlinType type, boolean nullable) {
Flexibility flexibility = type.getCapability(Flexibility.class);
if (flexibility != null) {
return flexibility.makeNullableAsSpecified(nullable);
}
// Wrapping serves two purposes here
// 1. It's requires less memory than copying with a changed nullability flag: a copy has many
// fields, while a wrapper has only one
// 2. It preserves laziness of types
// Unwrap to avoid long delegation call chains
if (type instanceof AbstractTypeWithKnownNullability) {
return makeNullableAsSpecified(((AbstractTypeWithKnownNullability) type).delegate, nullable);
}
// checking to preserve laziness
if (!(type instanceof LazyType) && type.isMarkedNullable() == nullable) {
return type;
}
return nullable ? new NullableType(type) : new NotNullType(type);
}
private static boolean isNotNullConstructedFromGivenClass(
@NotNull KotlinType type, @NotNull FqNameUnsafe fqName) {
return !type.isMarkedNullable() && isConstructedFromGivenClass(type, fqName);
}
public static boolean isPrimitiveType(@NotNull KotlinType type) {
ClassifierDescriptor descriptor = type.getConstructor().getDeclarationDescriptor();
return !type.isMarkedNullable()
&& descriptor instanceof ClassDescriptor
&& isPrimitiveClass((ClassDescriptor) descriptor);
}
public static boolean isNullableAny(@NotNull KotlinType type) {
return isAnyOrNullableAny(type) && type.isMarkedNullable();
}
public static boolean isNullableNothing(@NotNull KotlinType type) {
return isNothingOrNullableNothing(type) && type.isMarkedNullable();
}
public static boolean canHaveSubtypes(KotlinTypeChecker typeChecker, @NotNull KotlinType type) {
if (type.isMarkedNullable()) {
return true;
}
if (!type.getConstructor().isFinal()) {
return true;
}
List<TypeParameterDescriptor> parameters = type.getConstructor().getParameters();
List<TypeProjection> arguments = type.getArguments();
for (int i = 0, parametersSize = parameters.size(); i < parametersSize; i++) {
TypeParameterDescriptor parameterDescriptor = parameters.get(i);
TypeProjection typeProjection = arguments.get(i);
if (typeProjection.isStarProjection()) return true;
Variance projectionKind = typeProjection.getProjectionKind();
KotlinType argument = typeProjection.getType();
switch (parameterDescriptor.getVariance()) {
case INVARIANT:
switch (projectionKind) {
case INVARIANT:
if (lowerThanBound(typeChecker, argument, parameterDescriptor)
|| canHaveSubtypes(typeChecker, argument)) {
return true;
}
break;
case IN_VARIANCE:
if (lowerThanBound(typeChecker, argument, parameterDescriptor)) {
return true;
}
break;
case OUT_VARIANCE:
if (canHaveSubtypes(typeChecker, argument)) {
return true;
}
break;
}
break;
case IN_VARIANCE:
if (projectionKind != Variance.OUT_VARIANCE) {
if (lowerThanBound(typeChecker, argument, parameterDescriptor)) {
return true;
}
} else {
if (canHaveSubtypes(typeChecker, argument)) {
return true;
}
}
break;
case OUT_VARIANCE:
if (projectionKind != Variance.IN_VARIANCE) {
if (canHaveSubtypes(typeChecker, argument)) {
return true;
}
} else {
if (lowerThanBound(typeChecker, argument, parameterDescriptor)) {
return true;
}
}
break;
}
}
return false;
}