1 files changed, 189 insertions, 0 deletions
diff --git a/src/DI/factory.hpp b/src/DI/factory.hpp
new file mode 100644
index 0000000..13d0eb5
--- /dev/null
+++ b/src/DI/factory.hpp
@@ -0,0 +1,189 @@
+#pragma once
+
+#include "DI/interfaces/copyable_functor.hpp"
+
+#include "DI/alloc_functor.hpp"
+#include "DI/allocation.hpp"
+#include "DI/copyable_functor.hpp"
+#include "DI/extra_concepts.hpp"
+#include "DI/strip_signature.hpp"
+#include "DI/value_functor.hpp"
+
+#include <type_traits>
+#include <utility>
+
+template <class>
+class Factory;
+
+template <class Return>
+// NOLINTNEXTLINE(readability-identifier-naming)
+struct maybe_derive_from_unary_function
+{
+};
+
+template <class Return, class Arg>
+struct maybe_derive_from_unary_function<Return(Arg)>
+	: public std::unary_function<Arg, Return>
+{
+};
+
+template <class Return>
+// NOLINTNEXTLINE(readability-identifier-naming)
+struct maybe_derive_from_binary_function
+{
+};
+
+template <class Return, class ArgOne, class ArgTwo>
+struct maybe_derive_from_binary_function<Return(ArgOne, ArgTwo)>
+	: public std::binary_function<ArgOne, ArgTwo, Return>
+{
+};
+
+template <class Function>
+auto not_null(Function const & /*unused*/) -> bool
+{
+	return true;
+}
+
+template <class Function>
+auto not_null(Function *function_ptr) -> bool
+{
+	return function_ptr;
+}
+
+template <class Return, class Class>
+auto not_null(Return Class::*method_ptr) -> bool
+{
+	return method_ptr;
+}
+
+template <class Function>
+auto not_null(Factory<Function> const &factory) -> bool
+{
+	return !!factory;
+}
+
+template <class Type>
+// NOLINTNEXTLINE(readability-identifier-naming)
+struct uncvref
+{
+	using type =
+		typename std::remove_cv<typename std::remove_reference<Type>::type>::type;
+};
+
+template <class Type>
+// NOLINTNEXTLINE(readability-identifier-naming)
+using uncvref_t = typename uncvref<Type>::type;
+
+template <class Tp, class Up, class = void>
+// NOLINTNEXTLINE(readability-identifier-naming)
+struct is_core_convertible : public std::false_type
+{
+};
+
+template <class Tp, class Up>
+struct is_core_convertible<
+	Tp, Up, decltype(static_cast<void (*)(Up)>(0)(static_cast<Tp (*)()>(0)()))>
+	: public std::true_type
+{
+};
+
+template <class Tp, class Up>
+constexpr bool is_core_convertible_v = is_core_convertible<Tp, Up>::value;
+
+template <typename Function, typename Return, typename... Args>
+concept Callable = !std::is_same_v<uncvref_t<Function>, Factory<Return(Args...)>> &&
+				   std::is_invocable_v<Function, Args...> &&
+				   is_core_convertible_v<std::invoke_result_t<Function, Args...>, Return>;
+
+template <class Return, class... Args>
+class Factory<Return(Args...)> : public maybe_derive_from_unary_function<Return(Args...)>,
+								 public maybe_derive_from_binary_function<Return(Args...)>
+{
+public:
+	using Result = Return;
+
+	Factory() noexcept = default;
+
+	explicit Factory(std::nullptr_t) noexcept {}
+
+	Factory(const Factory &factory);
+
+	Factory(Factory &&factory) noexcept;
+
+	template <class Function>
+	requires Callable<Function, Return, Args...>
+	// NOLINTNEXTLINE(google-explicit-constructor)
+	Factory(Function function) : _functor(std::move(function))
+	{
+	}
+
+	auto operator=(const Factory &factory) = delete;
+
+	auto operator=(Factory &&factory) noexcept -> Factory &;
+
+	auto operator=(std::nullptr_t) noexcept -> Factory &;
+
+	~Factory();
+
+	explicit operator bool() const noexcept;
+
+	// deleted overloads close possible hole in the type system
+	template <class RhsReturn, class... RhsArgs>
+	auto operator==(const Factory<RhsReturn(RhsArgs...)> &) const -> bool = delete;
+
+	template <class RhsReturn, class... RhsArgs>
+	auto operator!=(const Factory<RhsReturn(RhsArgs...)> &) const -> bool = delete;
+
+	auto operator()(Args... args) const -> Return;
+
+	[[nodiscard]] auto target_type() const noexcept -> const std::type_info &;
+
+	template <typename Tp>
+	auto target() noexcept -> Tp *;
+
+	template <typename Tp>
+	auto target() const noexcept -> const Tp *;
+
+private:
+	using ValFunctor = ValueFunctor<Return(Args...)>;
+
+	ValFunctor _functor;
+};
+
+template <class Return, class... Args>
+Factory(Return (*)(Args...)) -> Factory<Return(Args...)>;
+
+template <class Function,
+		  class Stripped = strip_signature_t<decltype(&Function::operator())>>
+Factory(Function) -> Factory<Stripped>;
+
+template <class Return, class... Args>
+inline auto operator==(const Factory<Return(Args...)> &factory, std::nullptr_t) noexcept
+	-> bool
+{
+	return !factory;
+}
+
+template <class Return, class... Args>
+inline auto operator==(std::nullptr_t, const Factory<Return(Args...)> &factory) noexcept
+	-> bool
+{
+	return !factory;
+}
+
+template <class Return, class... Args>
+inline auto operator!=(const Factory<Return(Args...)> &factory, std::nullptr_t) noexcept
+	-> bool
+{
+	return static_cast<bool>(factory);
+}
+
+template <class Return, class... Args>
+inline auto operator!=(std::nullptr_t, const Factory<Return(Args...)> &factory) noexcept
+	-> bool
+{
+	return static_cast<bool>(factory);
+}
+
+#include "factory.tpp"