Add possibleTypes to interfaces in Introspection

Author: wravery

include/graphqlservice/Introspection.h

@@ -113,17 +113,20 @@ class InterfaceType : public BaseType
 public:
 	explicit InterfaceType(response::StringType&& name, response::StringType&& description);
 
+	void AddPossibleType(std::weak_ptr<ObjectType> possibleType);
 	void AddFields(std::vector<std::shared_ptr<Field>> fields);
 
 	// Accessors
 	service::FieldResult<TypeKind> getKind(service::FieldParams&& params) const override;
 	service::FieldResult<std::optional<response::StringType>> getName(service::FieldParams&& params) const override;
 	service::FieldResult<std::optional<std::vector<std::shared_ptr<object::Field>>>> getFields(service::FieldParams&& params, std::optional<response::BooleanType>&& includeDeprecatedArg) const override;
+	service::FieldResult<std::optional<std::vector<std::shared_ptr<object::Type>>>> getPossibleTypes(service::FieldParams&& params) const override;
 
 private:
 	const response::StringType _name;
 
 	std::vector<std::shared_ptr<Field>> _fields;
+	std::vector<std::weak_ptr<ObjectType>> _possibleTypes;
 };
 
 class UnionType : public BaseType

src/Introspection.cpp

@@ -186,6 +186,11 @@ ObjectType::ObjectType(response::StringType&& name, response::StringType&& descr
 void ObjectType::AddInterfaces(std::vector<std::shared_ptr<InterfaceType>> interfaces)
 {
 	_interfaces = std::move(interfaces);
+
+	for (const auto& interface : _interfaces)
+	{
+		interface->AddPossibleType(std::static_pointer_cast<ObjectType>(shared_from_this()));
+	}
 }
 
 void ObjectType::AddFields(std::vector<std::shared_ptr<Field>> fields)
@@ -234,6 +239,11 @@ InterfaceType::InterfaceType(response::StringType&& name, response::StringType&&
 {
 }
 
+void InterfaceType::AddPossibleType(std::weak_ptr<ObjectType> possibleType)
+{
+	_possibleTypes.push_back(possibleType);
+}
+
 void InterfaceType::AddFields(std::vector<std::shared_ptr<Field>> fields)
 {
 	_fields = std::move(fields);
@@ -265,6 +275,19 @@ service::FieldResult<std::optional<std::vector<std::shared_ptr<object::Field>>>>
 	return { std::move(result) };
 }
 
+service::FieldResult<std::optional<std::vector<std::shared_ptr<object::Type>>>> InterfaceType::getPossibleTypes(service::FieldParams&&) const
+{
+	auto result = std::make_optional<std::vector<std::shared_ptr<object::Type>>>(_possibleTypes.size());
+
+	std::transform(_possibleTypes.cbegin(), _possibleTypes.cend(), result->begin(),
+		[](const std::weak_ptr<object::Type>& weak)
+	{
+		return weak.lock();
+	});
+
+	return { std::move(result) };
+}
+
 UnionType::UnionType(response::StringType&& name, response::StringType&& description)
 	: BaseType(std::move(description))
 	, _name(std::move(name))