/**
* Remember that we are trying to cast something of type {@code supertype} to {@code subtype}.
*
* <p>Since at runtime we can only check the class (type constructor), the rest of the subtype
* should be known statically, from supertype. This method reconstructs all static information
* that can be obtained from supertype.
*
* <p>Example 1: supertype = Collection<String> subtype = List<...> result = List<String>, all
* arguments are inferred
*
* <p>Example 2: supertype = Any subtype = List<...> result = List<*>, some arguments were not
* inferred, replaced with '*'
*/
public static TypeReconstructionResult findStaticallyKnownSubtype(
@NotNull KotlinType supertype, @NotNull TypeConstructor subtypeConstructor) {
assert !supertype.isMarkedNullable() : "This method only makes sense for non-nullable types";
// Assume we are casting an expression of type Collection<Foo> to List<Bar>
// First, let's make List<T>, where T is a type variable
ClassifierDescriptor descriptor = subtypeConstructor.getDeclarationDescriptor();
assert descriptor != null : "Can't create default type for " + subtypeConstructor;
KotlinType subtypeWithVariables = descriptor.getDefaultType();
// Now, let's find a supertype of List<T> that is a Collection of something,
// in this case it will be Collection<T>
KotlinType supertypeWithVariables =
TypeCheckingProcedure.findCorrespondingSupertype(subtypeWithVariables, supertype);
final List<TypeParameterDescriptor> variables =
subtypeWithVariables.getConstructor().getParameters();
Map<TypeConstructor, TypeProjection> substitution;
if (supertypeWithVariables != null) {
// Now, let's try to unify Collection<T> and Collection<Foo> solution is a map from T to Foo
TypeUnifier.UnificationResult solution =
TypeUnifier.unify(
new TypeProjectionImpl(supertype),
new TypeProjectionImpl(supertypeWithVariables),
new Predicate<TypeConstructor>() {
@Override
public boolean apply(TypeConstructor typeConstructor) {
ClassifierDescriptor descriptor = typeConstructor.getDeclarationDescriptor();
return descriptor instanceof TypeParameterDescriptor
&& variables.contains(descriptor);
}
});
substitution = Maps.newHashMap(solution.getSubstitution());
} else {
// If there's no corresponding supertype, no variables are determined
// This may be OK, e.g. in case 'Any as List<*>'
substitution = Maps.newHashMapWithExpectedSize(variables.size());
}
// If some of the parameters are not determined by unification, it means that these parameters
// are lost,
// let's put stars instead, so that we can only cast to something like List<*>, e.g. (a: Any) as
// List<*>
boolean allArgumentsInferred = true;
for (TypeParameterDescriptor variable : variables) {
TypeProjection value = substitution.get(variable.getTypeConstructor());
if (value == null) {
substitution.put(variable.getTypeConstructor(), TypeUtils.makeStarProjection(variable));
allArgumentsInferred = false;
}
}
// At this point we have values for all type parameters of List
// Let's make a type by substituting them: List<T> -> List<Foo>
KotlinType substituted =
TypeSubstitutor.create(substitution).substitute(subtypeWithVariables, Variance.INVARIANT);
return new TypeReconstructionResult(substituted, allArgumentsInferred);
}
@Override
public void setUp() throws Exception {
super.setUp();
ModuleDescriptorImpl module = JetTestUtils.createEmptyModule();
builtIns = module.getBuiltIns();
typeResolver = InjectionKt.createContainerForTests(getProject(), module).getTypeResolver();
x = createTypeVariable("X");
y = createTypeVariable("Y");
variables = Sets.newHashSet(x.getTypeConstructor(), y.getTypeConstructor());
}
@NotNull
private OverrideCompatibilityInfo isOverridableBy(
@NotNull CallableDescriptor superDescriptor,
@NotNull CallableDescriptor subDescriptor,
boolean checkReturnType) {
if (superDescriptor instanceof FunctionDescriptor) {
if (!(subDescriptor instanceof FunctionDescriptor))
return OverrideCompatibilityInfo.memberKindMismatch();
} else if (superDescriptor instanceof PropertyDescriptor) {
if (!(subDescriptor instanceof PropertyDescriptor))
return OverrideCompatibilityInfo.memberKindMismatch();
} else {
throw new IllegalArgumentException(
"This type of CallableDescriptor cannot be checked for overridability: "
+ superDescriptor);
}
// TODO: check outside of this method
if (!superDescriptor.getName().equals(subDescriptor.getName())) {
return OverrideCompatibilityInfo.nameMismatch();
}
OverrideCompatibilityInfo receiverAndParameterResult =
checkReceiverAndParameterCount(superDescriptor, subDescriptor);
if (receiverAndParameterResult != null) {
return receiverAndParameterResult;
}
List<JetType> superValueParameters = compiledValueParameters(superDescriptor);
List<JetType> subValueParameters = compiledValueParameters(subDescriptor);
List<TypeParameterDescriptor> superTypeParameters = superDescriptor.getTypeParameters();
List<TypeParameterDescriptor> subTypeParameters = subDescriptor.getTypeParameters();
if (superTypeParameters.size() != subTypeParameters.size()) {
for (int i = 0; i < superValueParameters.size(); ++i) {
JetType superValueParameterType = getUpperBound(superValueParameters.get(i));
JetType subValueParameterType = getUpperBound(subValueParameters.get(i));
// TODO: compare erasure
if (!JetTypeChecker.DEFAULT.equalTypes(superValueParameterType, subValueParameterType)) {
return OverrideCompatibilityInfo.typeParameterNumberMismatch();
}
}
return OverrideCompatibilityInfo.valueParameterTypeMismatch(
null, null, OverrideCompatibilityInfo.Result.CONFLICT);
}
final Map<TypeConstructor, TypeConstructor> matchingTypeConstructors =
new HashMap<TypeConstructor, TypeConstructor>();
for (int i = 0, typeParametersSize = superTypeParameters.size(); i < typeParametersSize; i++) {
TypeParameterDescriptor superTypeParameter = superTypeParameters.get(i);
TypeParameterDescriptor subTypeParameter = subTypeParameters.get(i);
matchingTypeConstructors.put(
superTypeParameter.getTypeConstructor(), subTypeParameter.getTypeConstructor());
}
JetTypeChecker.TypeConstructorEquality localEqualityAxioms =
new JetTypeChecker.TypeConstructorEquality() {
@Override
public boolean equals(@NotNull TypeConstructor a, @NotNull TypeConstructor b) {
if (equalityAxioms.equals(a, b)) return true;
TypeConstructor img1 = matchingTypeConstructors.get(a);
TypeConstructor img2 = matchingTypeConstructors.get(b);
if (!(img1 != null && img1.equals(b)) && !(img2 != null && img2.equals(a))) {
return false;
}
return true;
}
};
for (int i = 0, typeParametersSize = superTypeParameters.size(); i < typeParametersSize; i++) {
TypeParameterDescriptor superTypeParameter = superTypeParameters.get(i);
TypeParameterDescriptor subTypeParameter = subTypeParameters.get(i);
if (!areTypesEquivalent(
superTypeParameter.getUpperBoundsAsType(),
subTypeParameter.getUpperBoundsAsType(),
localEqualityAxioms)) {
return OverrideCompatibilityInfo.boundsMismatch(superTypeParameter, subTypeParameter);
}
}
for (int i = 0, unsubstitutedValueParametersSize = superValueParameters.size();
i < unsubstitutedValueParametersSize;
i++) {
JetType superValueParameter = superValueParameters.get(i);
JetType subValueParameter = subValueParameters.get(i);
if (!areTypesEquivalent(superValueParameter, subValueParameter, localEqualityAxioms)) {
return OverrideCompatibilityInfo.valueParameterTypeMismatch(
superValueParameter, subValueParameter, INCOMPATIBLE);
}
}
if (checkReturnType) {
JetType superReturnType = superDescriptor.getReturnType();
JetType subReturnType = subDescriptor.getReturnType();
if (superReturnType != null && subReturnType != null) {
boolean bothErrors = subReturnType.isError() && superReturnType.isError();
if (!bothErrors
&& !JetTypeChecker.withAxioms(localEqualityAxioms)
.isSubtypeOf(subReturnType, superReturnType)) {
return OverrideCompatibilityInfo.returnTypeMismatch(superReturnType, subReturnType);
}
}
}
for (ExternalOverridabilityCondition externalCondition : EXTERNAL_CONDITIONS) {
if (!externalCondition.isOverridable(superDescriptor, subDescriptor)) {
return OverrideCompatibilityInfo.externalConditionFailed(externalCondition.getClass());
}
}
return OverrideCompatibilityInfo.success();
}
