@Nullable
private static JetType computeUnsafeReturnType(
@NotNull JetFunctionLiteralExpression expression,
@NotNull ExpressionTypingContext context,
@NotNull SimpleFunctionDescriptorImpl functionDescriptor,
@Nullable JetType expectedReturnType) {
JetFunctionLiteral functionLiteral = expression.getFunctionLiteral();
JetBlockExpression bodyExpression = functionLiteral.getBodyExpression();
assert bodyExpression != null;
JetScope functionInnerScope =
FunctionDescriptorUtil.getFunctionInnerScope(
context.scope, functionDescriptor, context.trace);
JetTypeReference returnTypeRef = functionLiteral.getReturnTypeRef();
JetType declaredReturnType = null;
if (returnTypeRef != null) {
declaredReturnType =
context
.expressionTypingServices
.getTypeResolver()
.resolveType(context.scope, returnTypeRef, context.trace, true);
// This is needed for ControlStructureTypingVisitor#visitReturnExpression() to properly
// type-check returned expressions
functionDescriptor.setReturnType(declaredReturnType);
if (expectedReturnType != null) {
if (!JetTypeChecker.INSTANCE.isSubtypeOf(declaredReturnType, expectedReturnType)) {
context.trace.report(EXPECTED_RETURN_TYPE_MISMATCH.on(returnTypeRef, expectedReturnType));
}
}
}
// Type-check the body
ExpressionTypingContext newContext =
context
.replaceScope(functionInnerScope)
.replaceExpectedType(
declaredReturnType != null
? declaredReturnType
: (expectedReturnType != null ? expectedReturnType : NO_EXPECTED_TYPE));
JetType typeOfBodyExpression =
context
.expressionTypingServices
.getBlockReturnedType(bodyExpression, COERCION_TO_UNIT, newContext)
.getType();
List<JetType> returnedExpressionTypes =
Lists.newArrayList(
getTypesOfLocallyReturnedExpressions(
functionLiteral, context.trace, collectReturns(bodyExpression)));
ContainerUtil.addIfNotNull(returnedExpressionTypes, typeOfBodyExpression);
if (declaredReturnType != null) return declaredReturnType;
if (returnedExpressionTypes.isEmpty()) return null;
return CommonSupertypes.commonSupertype(returnedExpressionTypes);
}
@Override
public JetTypeInfo visitFunctionLiteralExpression(
@NotNull JetFunctionLiteralExpression expression, ExpressionTypingContext context) {
JetBlockExpression bodyExpression = expression.getFunctionLiteral().getBodyExpression();
if (bodyExpression == null) return null;
Name callerName = getCallerName(expression);
if (callerName != null) {
context.labelResolver.enterLabeledElement(new LabelName(callerName.asString()), expression);
}
JetType expectedType = context.expectedType;
boolean functionTypeExpected =
!noExpectedType(expectedType)
&& KotlinBuiltIns.getInstance().isFunctionOrExtensionFunctionType(expectedType);
AnonymousFunctionDescriptor functionDescriptor =
createFunctionDescriptor(expression, context, functionTypeExpected);
JetType safeReturnType =
computeReturnType(expression, context, functionDescriptor, functionTypeExpected);
functionDescriptor.setReturnType(safeReturnType);
JetType receiver =
DescriptorUtils.getReceiverParameterType(functionDescriptor.getReceiverParameter());
List<JetType> valueParametersTypes =
DescriptorUtils.getValueParametersTypes(functionDescriptor.getValueParameters());
JetType resultType =
KotlinBuiltIns.getInstance()
.getFunctionType(
Collections.<AnnotationDescriptor>emptyList(),
receiver,
valueParametersTypes,
safeReturnType);
if (!noExpectedType(expectedType)
&& KotlinBuiltIns.getInstance().isFunctionOrExtensionFunctionType(expectedType)) {
// all checks were done before
return JetTypeInfo.create(resultType, context.dataFlowInfo);
}
if (callerName != null) {
context.labelResolver.exitLabeledElement(expression);
}
return DataFlowUtils.checkType(resultType, expression, context, context.dataFlowInfo);
}
@NotNull
private static AnonymousFunctionDescriptor createFunctionDescriptor(
@NotNull JetFunctionLiteralExpression expression,
@NotNull ExpressionTypingContext context,
boolean functionTypeExpected) {
JetFunctionLiteral functionLiteral = expression.getFunctionLiteral();
JetTypeReference receiverTypeRef = functionLiteral.getReceiverTypeRef();
AnonymousFunctionDescriptor functionDescriptor =
new AnonymousFunctionDescriptor(
context.scope.getContainingDeclaration(),
Collections.<AnnotationDescriptor>emptyList(),
CallableMemberDescriptor.Kind.DECLARATION);
List<ValueParameterDescriptor> valueParameterDescriptors =
createValueParameterDescriptors(
context, functionLiteral,
functionDescriptor, functionTypeExpected);
JetType effectiveReceiverType;
if (receiverTypeRef == null) {
if (functionTypeExpected) {
effectiveReceiverType = KotlinBuiltIns.getInstance().getReceiverType(context.expectedType);
} else {
effectiveReceiverType = null;
}
} else {
effectiveReceiverType =
context
.expressionTypingServices
.getTypeResolver()
.resolveType(context.scope, receiverTypeRef, context.trace, true);
}
functionDescriptor.initialize(
effectiveReceiverType,
ReceiverParameterDescriptor.NO_RECEIVER_PARAMETER,
Collections.<TypeParameterDescriptorImpl>emptyList(),
valueParameterDescriptors,
/*unsubstitutedReturnType = */ null,
Modality.FINAL,
Visibilities.LOCAL);
BindingContextUtils.recordFunctionDeclarationToDescriptor(
context.trace, functionLiteral, functionDescriptor);
return functionDescriptor;
}
@NotNull
private static JetType computeReturnType(
@NotNull JetFunctionLiteralExpression expression,
@NotNull ExpressionTypingContext context,
@NotNull SimpleFunctionDescriptorImpl functionDescriptor,
boolean functionTypeExpected) {
JetType expectedReturnType =
functionTypeExpected
? KotlinBuiltIns.getInstance().getReturnTypeFromFunctionType(context.expectedType)
: null;
JetType returnType =
computeUnsafeReturnType(expression, context, functionDescriptor, expectedReturnType);
if (!expression.getFunctionLiteral().hasDeclaredReturnType() && functionTypeExpected) {
if (KotlinBuiltIns.getInstance().isUnit(expectedReturnType)) {
return KotlinBuiltIns.getInstance().getUnitType();
}
}
return returnType == null ? CANT_INFER_LAMBDA_PARAM_TYPE : returnType;
}
@Nullable
private static JetCallExpression getContainingCallExpression(
JetFunctionLiteralExpression expression) {
PsiElement parent = expression.getParent();
if (parent instanceof JetCallExpression) {
// f {}
return (JetCallExpression) parent;
}
if (parent instanceof JetValueArgument) {
// f ({}) or f(p = {})
JetValueArgument argument = (JetValueArgument) parent;
PsiElement argList = argument.getParent();
if (argList == null) return null;
PsiElement call = argList.getParent();
if (call instanceof JetCallExpression) {
return (JetCallExpression) call;
}
}
return null;
}