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// Copyright 2015-2020 Denis Blank <denis.blank at outlook dot com>
// Distributed under the Boost Software License, Version 1.0
// (See accompanying file LICENSE_1_0.txt or copy at
#ifndef FU2_INCLUDED_FUNCTION2_HPP_
#define FU2_INCLUDED_FUNCTION2_HPP_
#include <cassert>
#include <cstddef>
#include <cstdlib>
#include <memory>
#include <tuple>
#include <type_traits>
#include <utility>
// Defines:
// - FU2_HAS_DISABLED_EXCEPTIONS
#if defined(FU2_WITH_DISABLED_EXCEPTIONS) || \
defined(FU2_MACRO_DISABLE_EXCEPTIONS)
#define FU2_HAS_DISABLED_EXCEPTIONS
#else // FU2_WITH_DISABLED_EXCEPTIONS
#if defined(_MSC_VER)
#if !defined(_HAS_EXCEPTIONS) || (_HAS_EXCEPTIONS == 0)
#define FU2_HAS_DISABLED_EXCEPTIONS
#endif
#elif defined(__clang__)
#if !(__EXCEPTIONS && __has_feature(cxx_exceptions))
#define FU2_HAS_DISABLED_EXCEPTIONS
#endif
#elif defined(__GNUC__)
#if !__EXCEPTIONS
#define FU2_HAS_DISABLED_EXCEPTIONS
#endif
#endif
#endif // FU2_WITH_DISABLED_EXCEPTIONS
// - FU2_HAS_LIMITED_EMPTY_PROPAGATION
#if defined(FU2_WITH_LIMITED_EMPTY_PROPAGATION)
#define FU2_HAS_LIMITED_EMPTY_PROPAGATION
#endif // FU2_WITH_NO_EMPTY_PROPAGATION
// - FU2_HAS_NO_FUNCTIONAL_HEADER
#if !defined(FU2_WITH_NO_FUNCTIONAL_HEADER) && \
!defined(FU2_NO_FUNCTIONAL_HEADER) && \
(!defined(FU2_HAS_DISABLED_EXCEPTIONS) || \
defined(FU2_HAS_LIMITED_EMPTY_PROPAGATION))
#include <functional>
#else
#define FU2_HAS_NO_FUNCTIONAL_HEADER
#endif
// - FU2_HAS_CXX17_NOEXCEPT_FUNCTION_TYPE
#if defined(FU2_WITH_CXX17_NOEXCEPT_FUNCTION_TYPE)
#define FU2_HAS_CXX17_NOEXCEPT_FUNCTION_TYPE
#else // FU2_WITH_CXX17_NOEXCEPT_FUNCTION_TYPE
#if defined(_MSC_VER)
#if defined(_HAS_CXX17) && _HAS_CXX17
#define FU2_HAS_CXX17_NOEXCEPT_FUNCTION_TYPE
#endif
#elif defined(__cpp_noexcept_function_type)
#define FU2_HAS_CXX17_NOEXCEPT_FUNCTION_TYPE
#elif defined(__cplusplus) && (__cplusplus >= 201703L)
#define FU2_HAS_CXX17_NOEXCEPT_FUNCTION_TYPE
#endif
#endif // FU2_WITH_CXX17_NOEXCEPT_FUNCTION_TYPE
// - FU2_HAS_NO_EMPTY_PROPAGATION
#if defined(FU2_WITH_NO_EMPTY_PROPAGATION)
#define FU2_HAS_NO_EMPTY_PROPAGATION
#endif // FU2_WITH_NO_EMPTY_PROPAGATION
#if !defined(FU2_HAS_DISABLED_EXCEPTIONS)
#include <exception>
#endif
#if defined(__cpp_constexpr) && (__cpp_constexpr >= 201304)
#define FU2_DETAIL_CXX14_CONSTEXPR constexpr
#elif defined(__clang__) && defined(__has_feature)
#if __has_feature(__cxx_generic_lambdas__) && \
__has_feature(__cxx_relaxed_constexpr__)
#define FU2_DETAIL_CXX14_CONSTEXPR constexpr
#endif
#elif defined(_MSC_VER) && (_MSC_VER >= 1915) && (_MSVC_LANG >= 201402)
#define FU2_DETAIL_CXX14_CONSTEXPR constexpr
#endif
#ifndef FU2_DETAIL_CXX14_CONSTEXPR
#define FU2_DETAIL_CXX14_CONSTEXPR
#endif
/// Hint for the compiler that this point should be unreachable
#if defined(_MSC_VER)
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_UNREACHABLE_INTRINSIC() __assume(false)
#elif defined(__GNUC__)
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_UNREACHABLE_INTRINSIC() __builtin_unreachable()
#elif defined(__has_builtin)
#if __has_builtin(__builtin_unreachable)
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_UNREACHABLE_INTRINSIC() __builtin_unreachable()
#endif
#endif
#ifndef FU2_DETAIL_UNREACHABLE_INTRINSIC
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_UNREACHABLE_INTRINSIC() abort()
#endif
/// Causes the application to exit abnormally
#if defined(_MSC_VER)
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_TRAP() __debugbreak()
#elif defined(__GNUC__)
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_TRAP() __builtin_trap()
#elif defined(__has_builtin)
#if __has_builtin(__builtin_trap)
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_TRAP() __builtin_trap()
#endif
#endif
#ifndef FU2_DETAIL_TRAP
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_TRAP() *(volatile int*)0x11 = 0
#endif
#ifndef NDEBUG
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_UNREACHABLE() ::fu2::detail::unreachable_debug()
#else
// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
#define FU2_DETAIL_UNREACHABLE() FU2_DETAIL_UNREACHABLE_INTRINSIC()
#endif
namespace fu2 {
inline namespace abi_400 {
namespace detail {
template <typename Config, typename Property>
class function;
template <typename...>
struct identity {};
// Equivalent to C++17's std::void_t which targets a bug in GCC,
// that prevents correct SFINAE behavior.
template <typename...>
struct deduce_to_void : std::common_type<void> {};
template <typename... T>
using void_t = typename deduce_to_void<T...>::type;
template <typename T>
using unrefcv_t = std::remove_cv_t<std::remove_reference_t<T>>;
template <typename...>
struct lazy_and;
template <typename B1>
struct lazy_and<B1> : B1 {};
template <typename B1, typename B2>
struct lazy_and<B1, B2> : std::conditional<B1::value, B2, B1>::type {};
// template <typename B1, typename B2, typename B3, typename... Bn>
// struct lazy_and<B1, B2, B3, Bn...>
// : std::conditional<B1::value, lazy_and<B2, B3, Bn...>, B1>::type {};
// Copy enabler helper class
template <bool /*Copyable*/>
struct copyable {};
template <>
struct copyable<false> {
copyable() = default;
~copyable() = default;
copyable(copyable const&) = delete;
copyable(copyable&&) = default;
copyable& operator=(copyable const&) = delete;
copyable& operator=(copyable&&) = default;
};
/// Configuration trait to configure the function_base class.
template <bool Owning, bool Copyable, typename Capacity>
struct config {
// Is true if the function is owning.
static constexpr auto const is_owning = Owning;
// Is true if the function is copyable.
static constexpr auto const is_copyable = Copyable;
// The internal capacity of the function
// used in small functor optimization.
// The object shall expose the real capacity through Capacity::capacity
// and the intended alignment through Capacity::alignment.
using capacity = Capacity;
};
/// A config which isn't compatible to other configs
template <bool Throws, bool HasStrongExceptGuarantee, typename... Args>
struct property {
// Is true when the function throws an exception on empty invocation.
static constexpr auto const is_throwing = Throws;
// Is true when the function throws an exception on empty invocation.
static constexpr auto const is_strong_exception_guaranteed =
HasStrongExceptGuarantee;
};
#ifndef NDEBUG
[[noreturn]] inline void unreachable_debug() {
FU2_DETAIL_TRAP();
std::abort();
}
#endif
/// Provides utilities for invocing callable objects
namespace invocation {
/// Invokes the given callable object with the given arguments
template <typename Callable, typename... Args>
constexpr auto invoke(Callable&& callable, Args&&... args) noexcept(
noexcept(std::forward<Callable>(callable)(std::forward<Args>(args)...)))
-> decltype(std::forward<Callable>(callable)(std::forward<Args>(args)...)) {
return std::forward<Callable>(callable)(std::forward<Args>(args)...);
}
/// Invokes the given member function pointer by reference
template <typename T, typename Type, typename Self, typename... Args>
constexpr auto invoke(Type T::*member, Self&& self, Args&&... args) noexcept(
noexcept((std::forward<Self>(self).*member)(std::forward<Args>(args)...)))
-> decltype((std::forward<Self>(self).*
member)(std::forward<Args>(args)...)) {
return (std::forward<Self>(self).*member)(std::forward<Args>(args)...);
}
/// Invokes the given member function pointer by pointer
template <typename T, typename Type, typename Self, typename... Args>
constexpr auto invoke(Type T::*member, Self&& self, Args&&... args) noexcept(
noexcept((std::forward<Self>(self)->*member)(std::forward<Args>(args)...)))
-> decltype((std::forward<Self>(self)->*member)(
std::forward<Args>(args)...)) {
return (std::forward<Self>(self)->*member)(std::forward<Args>(args)...);
}
/// Invokes the given pointer to a scalar member by reference
template <typename T, typename Type, typename Self>
constexpr auto
invoke(Type T::*member,
Self&& self) noexcept(noexcept(std::forward<Self>(self).*member))
-> decltype(std::forward<Self>(self).*member) {
return (std::forward<Self>(self).*member);
}
/// Invokes the given pointer to a scalar member by pointer
template <typename T, typename Type, typename Self>
constexpr auto
invoke(Type T::*member,
Self&& self) noexcept(noexcept(std::forward<Self>(self)->*member))
-> decltype(std::forward<Self>(self)->*member) {
return std::forward<Self>(self)->*member;
}
/// Deduces to a true type if the callable object can be invoked with
/// the given arguments.
/// We don't use invoke here because MSVC can't evaluate the nested expression
/// SFINAE here.
template <typename T, typename Args, typename = void>
struct can_invoke : std::false_type {};
template <typename T, typename... Args>
struct can_invoke<T, identity<Args...>,
decltype((void)std::declval<T>()(std::declval<Args>()...))>
: std::true_type {};
template <typename Pointer, typename T, typename... Args>
struct can_invoke<Pointer, identity<T&, Args...>,
decltype((void)((std::declval<T&>().*std::declval<Pointer>())(
std::declval<Args>()...)))> : std::true_type {};
template <typename Pointer, typename T, typename... Args>
struct can_invoke<Pointer, identity<T&&, Args...>,
decltype((
void)((std::declval<T&&>().*std::declval<Pointer>())(
std::declval<Args>()...)))> : std::true_type {};
template <typename Pointer, typename T, typename... Args>
struct can_invoke<Pointer, identity<T*, Args...>,
decltype((
void)((std::declval<T*>()->*std::declval<Pointer>())(
std::declval<Args>()...)))> : std::true_type {};
template <typename Pointer, typename T>
struct can_invoke<Pointer, identity<T&>,
decltype((void)(std::declval<T&>().*std::declval<Pointer>()))>
: std::true_type {};
template <typename Pointer, typename T>
struct can_invoke<Pointer, identity<T&&>,
decltype((void)(std::declval<T&&>().*
std::declval<Pointer>()))> : std::true_type {
};
template <typename Pointer, typename T>
struct can_invoke<Pointer, identity<T*>,
decltype((
void)(std::declval<T*>()->*std::declval<Pointer>()))>
: std::true_type {};
template <bool RequiresNoexcept, typename T, typename Args>
struct is_noexcept_correct : std::true_type {};
template <typename T, typename... Args>
struct is_noexcept_correct<true, T, identity<Args...>>
: std::integral_constant<bool,
noexcept(::fu2::detail::invocation::invoke(
std::declval<T>(), std::declval<Args>()...))> {
};
} // end namespace invocation
namespace overloading {
template <typename... Args>
struct overload_impl;
template <typename Current, typename Next, typename... Rest>
struct overload_impl<Current, Next, Rest...> : Current,
overload_impl<Next, Rest...> {
explicit overload_impl(Current current, Next next, Rest... rest)
: Current(std::move(current)),
overload_impl<Next, Rest...>(std::move(next), std::move(rest)...) {
}
using Current::operator();
using overload_impl<Next, Rest...>::operator();
};
template <typename Current>
struct overload_impl<Current> : Current {
explicit overload_impl(Current current) : Current(std::move(current)) {
}
using Current::operator();
};
template <typename... T>
constexpr auto overload(T&&... callables) {
return overload_impl<std::decay_t<T>...>{std::forward<T>(callables)...};
}
} // namespace overloading
/// Declares the namespace which provides the functionality to work with a
/// type-erased object.
namespace type_erasure {
/// Specialization to work with addresses of callable objects
template <typename T, typename = void>
struct address_taker {
template <typename O>
static auto take(O&& obj) {
return std::addressof(obj);
}
static T& restore(void* ptr) {
return *static_cast<T*>(ptr);
}
static T const& restore(void const* ptr) {
return *static_cast<T const*>(ptr);
}
static T volatile& restore(void volatile* ptr) {
return *static_cast<T volatile*>(ptr);
}
static T const volatile& restore(void const volatile* ptr) {
return *static_cast<T const volatile*>(ptr);
}
};
/// Specialization to work with addresses of raw function pointers
template <typename T>
struct address_taker<T, std::enable_if_t<std::is_pointer<T>::value>> {
template <typename O>
static void* take(O&& obj) {
return reinterpret_cast<void*>(obj);
}
template <typename O>
static T restore(O ptr) {
return reinterpret_cast<T>(const_cast<void*>(ptr));
}
};
template <typename Box>
struct box_factory;
/// Store the allocator inside the box
template <bool IsCopyable, typename T, typename Allocator>
struct box : private Allocator {
friend box_factory<box>;
T value_;
explicit box(T value, Allocator allocator_)
: Allocator(std::move(allocator_)), value_(std::move(value)) {
}
box(box&&) = default;
box(box const&) = default;
box& operator=(box&&) = default;
box& operator=(box const&) = default;
~box() = default;
};
template <typename T, typename Allocator>
struct box<false, T, Allocator> : private Allocator {
friend box_factory<box>;
T value_;
explicit box(T value, Allocator allocator_)
: Allocator(std::move(allocator_)), value_(std::move(value)) {
}
box(box&&) = default;
box(box const&) = delete;
box& operator=(box&&) = default;
box& operator=(box const&) = delete;
~box() = default;
};
template <bool IsCopyable, typename T, typename Allocator>
struct box_factory<box<IsCopyable, T, Allocator>> {
using real_allocator =
typename std::allocator_traits<std::decay_t<Allocator>>::
template rebind_alloc<box<IsCopyable, T, Allocator>>;
/// Allocates space through the boxed allocator
static box<IsCopyable, T, Allocator>*
box_allocate(box<IsCopyable, T, Allocator> const* me) {
real_allocator allocator_(*static_cast<Allocator const*>(me));
return static_cast<box<IsCopyable, T, Allocator>*>(
std::allocator_traits<real_allocator>::allocate(allocator_, 1U));
}
/// Destroys the box through the given allocator
static void box_deallocate(box<IsCopyable, T, Allocator>* me) {
real_allocator allocator_(*static_cast<Allocator const*>(me));
me->~box();
std::allocator_traits<real_allocator>::deallocate(allocator_, me, 1U);
}
};
/// Creates a box containing the given value and allocator
template <bool IsCopyable, typename T, typename Allocator>
auto make_box(std::integral_constant<bool, IsCopyable>, T&& value,
Allocator&& allocator_) {
return box<IsCopyable, std::decay_t<T>, std::decay_t<Allocator>>(
std::forward<T>(value), std::forward<Allocator>(allocator_));
}
template <typename T>
struct is_box : std::false_type {};
template <bool IsCopyable, typename T, typename Allocator>
struct is_box<box<IsCopyable, T, Allocator>> : std::true_type {};
/// Provides access to the pointer to a heal allocated erased object
/// as well to the inplace storage.
union data_accessor {
data_accessor() = default;
explicit constexpr data_accessor(std::nullptr_t) noexcept : ptr_(nullptr) {
}
explicit constexpr data_accessor(void* ptr) noexcept : ptr_(ptr) {
}
explicit constexpr data_accessor(void const* ptr) noexcept
: data_accessor(const_cast<void*>(ptr)) {
}
constexpr void assign_ptr(void* ptr) noexcept {
ptr_ = ptr;
}
constexpr void assign_ptr(void const* ptr) noexcept {
ptr_ = const_cast<void*>(ptr);
}
/// The pointer we use if the object is on the heap
void* ptr_;
/// The first field of the inplace storage
std::size_t inplace_storage_;
};
/// See opcode::op_fetch_empty
static FU2_DETAIL_CXX14_CONSTEXPR void write_empty(data_accessor* accessor,
bool empty) noexcept {
accessor->inplace_storage_ = std::size_t(empty);
}
template <typename From, typename To>
using transfer_const_t =
std::conditional_t<std::is_const<std::remove_pointer_t<From>>::value,
std::add_const_t<To>, To>;
template <typename From, typename To>
using transfer_volatile_t =
std::conditional_t<std::is_volatile<std::remove_pointer_t<From>>::value,
std::add_volatile_t<To>, To>;
/// The retriever when the object is allocated inplace
template <typename T, typename Accessor>
FU2_DETAIL_CXX14_CONSTEXPR auto retrieve(std::true_type /*is_inplace*/,
Accessor from,
std::size_t from_capacity) {
using type = transfer_const_t<Accessor, transfer_volatile_t<Accessor, void>>*;
/// Process the command by using the data inside the internal capacity
auto storage = &(from->inplace_storage_);
auto inplace = const_cast<void*>(static_cast<type>(storage));
return type(std::align(alignof(T), sizeof(T), inplace, from_capacity));
}
/// The retriever which is used when the object is allocated
/// through the allocator
template <typename T, typename Accessor>
constexpr auto retrieve(std::false_type /*is_inplace*/, Accessor from,
std::size_t /*from_capacity*/) {
return from->ptr_;
}
namespace invocation_table {
#if !defined(FU2_HAS_DISABLED_EXCEPTIONS)
#if defined(FU2_HAS_NO_FUNCTIONAL_HEADER)
struct bad_function_call : std::exception {
bad_function_call() noexcept {
}
char const* what() const noexcept override {
return "bad function call";
}
};
#else
using std::bad_function_call;
#endif
#endif
#ifdef FU2_HAS_CXX17_NOEXCEPT_FUNCTION_TYPE
#define FU2_DETAIL_EXPAND_QUALIFIERS_NOEXCEPT(F) \
F(, , noexcept, , &) \
F(const, , noexcept, , &) \
F(, volatile, noexcept, , &) \
F(const, volatile, noexcept, , &) \
F(, , noexcept, &, &) \
F(const, , noexcept, &, &) \
F(, volatile, noexcept, &, &) \
F(const, volatile, noexcept, &, &) \
F(, , noexcept, &&, &&) \
F(const, , noexcept, &&, &&) \
F(, volatile, noexcept, &&, &&) \
F(const, volatile, noexcept, &&, &&)
#define FU2_DETAIL_EXPAND_CV_NOEXCEPT(F) \
F(, , noexcept) \
F(const, , noexcept) \
F(, volatile, noexcept) \
F(const, volatile, noexcept)
#else // FU2_HAS_CXX17_NOEXCEPT_FUNCTION_TYPE
#define FU2_DETAIL_EXPAND_QUALIFIERS_NOEXCEPT(F)
#define FU2_DETAIL_EXPAND_CV_NOEXCEPT(F)
#endif // FU2_HAS_CXX17_NOEXCEPT_FUNCTION_TYPE
#define FU2_DETAIL_EXPAND_QUALIFIERS(F) \
F(, , , , &) \
F(const, , , , &) \
F(, volatile, , , &) \
F(const, volatile, , , &) \
F(, , , &, &) \
F(const, , , &, &) \
F(, volatile, , &, &) \
F(const, volatile, , &, &) \
F(, , , &&, &&) \
F(const, , , &&, &&) \
F(, volatile, , &&, &&) \
F(const, volatile, , &&, &&) \
FU2_DETAIL_EXPAND_QUALIFIERS_NOEXCEPT(F)
#define FU2_DETAIL_EXPAND_CV(F) \
F(, , ) \
F(const, , ) \
F(, volatile, ) \
F(const, volatile, ) \
FU2_DETAIL_EXPAND_CV_NOEXCEPT(F)
/// If the function is qualified as noexcept, the call will never throw
template <bool IsNoexcept>
[[noreturn]] void throw_or_abortnoexcept(
std::integral_constant<bool, IsNoexcept> /*is_throwing*/) noexcept {
std::abort();
}
/// Calls std::abort on empty function calls
[[noreturn]] inline void
throw_or_abort(std::false_type /*is_throwing*/) noexcept {
std::abort();
}
/// Throws bad_function_call on empty funciton calls
[[noreturn]] inline void throw_or_abort(std::true_type /*is_throwing*/) {
#ifdef FU2_HAS_DISABLED_EXCEPTIONS
throw_or_abort(std::false_type{});
#else
throw bad_function_call{};
#endif
}
template <typename T>
struct function_trait;
using is_noexcept_ = std::false_type;
using is_noexcept_noexcept = std::true_type;
#define FU2_DEFINE_FUNCTION_TRAIT(CONST, VOLATILE, NOEXCEPT, OVL_REF, REF) \
template <typename Ret, typename... Args> \
struct function_trait<Ret(Args...) CONST VOLATILE OVL_REF NOEXCEPT> { \
using pointer_type = Ret (*)(data_accessor CONST VOLATILE*, \
std::size_t capacity, Args...); \
template <typename T, bool IsInplace> \
struct internal_invoker { \
static Ret invoke(data_accessor CONST VOLATILE* data, \
std::size_t capacity, Args... args) NOEXCEPT { \
auto obj = retrieve<T>(std::integral_constant<bool, IsInplace>{}, \
data, capacity); \
auto box = static_cast<T CONST VOLATILE*>(obj); \
return invocation::invoke( \
static_cast<std::decay_t<decltype(box->value_)> CONST VOLATILE \
REF>(box->value_), \
std::forward<Args>(args)...); \
} \
}; \
\
template <typename T> \
struct view_invoker { \
static Ret invoke(data_accessor CONST VOLATILE* data, std::size_t, \
Args... args) NOEXCEPT { \
\
auto ptr = static_cast<void CONST VOLATILE*>(data->ptr_); \
return invocation::invoke(address_taker<T>::restore(ptr), \
std::forward<Args>(args)...); \
} \
}; \
\
template <typename T> \
using callable = T CONST VOLATILE REF; \
\
using arguments = identity<Args...>; \
\
using is_noexcept = is_noexcept_##NOEXCEPT; \
\
template <bool Throws> \
struct empty_invoker { \
static Ret invoke(data_accessor CONST VOLATILE* /*data*/, \
std::size_t /*capacity*/, Args... /*args*/) NOEXCEPT { \
throw_or_abort##NOEXCEPT(std::integral_constant<bool, Throws>{}); \
} \
}; \
};
FU2_DETAIL_EXPAND_QUALIFIERS(FU2_DEFINE_FUNCTION_TRAIT)
#undef FU2_DEFINE_FUNCTION_TRAIT
/// Deduces to the function pointer to the given signature
template <typename Signature>
using function_pointer_of = typename function_trait<Signature>::pointer_type;
template <typename... Args>
struct invoke_table;
/// We optimize the vtable_t in case there is a single function overload
template <typename First>
struct invoke_table<First> {
using type = function_pointer_of<First>;
/// Return the function pointer itself
template <std::size_t Index>
static constexpr auto fetch(type pointer) noexcept {
static_assert(Index == 0U, "The index should be 0 here!");
return pointer;
}
/// Returns the thunk of an single overloaded callable
template <typename T, bool IsInplace>
static constexpr type get_invocation_table_of() noexcept {
return &function_trait<First>::template internal_invoker<T,
IsInplace>::invoke;
}
/// Returns the thunk of an single overloaded callable
template <typename T>
static constexpr type get_invocation_view_table_of() noexcept {
return &function_trait<First>::template view_invoker<T>::invoke;
}
/// Returns the thunk of an empty single overloaded callable
template <bool IsThrowing>
static constexpr type get_empty_invocation_table() noexcept {
return &function_trait<First>::template empty_invoker<IsThrowing>::invoke;
}
};
/// We generate a table in case of multiple function overloads
template <typename First, typename Second, typename... Args>
struct invoke_table<First, Second, Args...> {
using type =
std::tuple<function_pointer_of<First>, function_pointer_of<Second>,
function_pointer_of<Args>...> const*;
/// Return the function pointer at the particular index
template <std::size_t Index>
static constexpr auto fetch(type table) noexcept {
return std::get<Index>(*table);
}
/// The invocation vtable for a present object
template <typename T, bool IsInplace>
struct invocation_vtable : public std::tuple<function_pointer_of<First>,
function_pointer_of<Second>,
function_pointer_of<Args>...> {
constexpr invocation_vtable() noexcept
: std::tuple<function_pointer_of<First>, function_pointer_of<Second>,
function_pointer_of<Args>...>(std::make_tuple(
&function_trait<First>::template internal_invoker<
T, IsInplace>::invoke,
&function_trait<Second>::template internal_invoker<
T, IsInplace>::invoke,
&function_trait<Args>::template internal_invoker<
T, IsInplace>::invoke...)) {
}
};
/// Returns the thunk of an multi overloaded callable
template <typename T, bool IsInplace>
static type get_invocation_table_of() noexcept {
static invocation_vtable<T, IsInplace> const table;
return &table;
}
/// The invocation vtable for a present object
template <typename T>
struct invocation_view_vtable
: public std::tuple<function_pointer_of<First>,
function_pointer_of<Second>,
function_pointer_of<Args>...> {
constexpr invocation_view_vtable() noexcept
: std::tuple<function_pointer_of<First>, function_pointer_of<Second>,
function_pointer_of<Args>...>(std::make_tuple(
&function_trait<First>::template view_invoker<T>::invoke,
&function_trait<Second>::template view_invoker<T>::invoke,
&function_trait<Args>::template view_invoker<T>::invoke...)) {
}
};
/// Returns the thunk of an multi overloaded callable
template <typename T>
static type get_invocation_view_table_of() noexcept {
static invocation_view_vtable<T> const table;
return &table;
}
/// The invocation table for an empty wrapper
template <bool IsThrowing>
struct empty_vtable : public std::tuple<function_pointer_of<First>,
function_pointer_of<Second>,
function_pointer_of<Args>...> {
constexpr empty_vtable() noexcept
: std::tuple<function_pointer_of<First>, function_pointer_of<Second>,
function_pointer_of<Args>...>(
std::make_tuple(&function_trait<First>::template empty_invoker<
IsThrowing>::invoke,
&function_trait<Second>::template empty_invoker<
IsThrowing>::invoke,
&function_trait<Args>::template empty_invoker<
IsThrowing>::invoke...)) {
}
};
/// Returns the thunk of an multi single overloaded callable
template <bool IsThrowing>
static type get_empty_invocation_table() noexcept {
static empty_vtable<IsThrowing> const table;
return &table;
}
};
template <std::size_t Index, typename Function, typename... Signatures>
class operator_impl;
#define FU2_DEFINE_FUNCTION_TRAIT(CONST, VOLATILE, NOEXCEPT, OVL_REF, REF) \
template <std::size_t Index, typename Function, typename Ret, \
typename... Args, typename Next, typename... Signatures> \
class operator_impl<Index, Function, \
Ret(Args...) CONST VOLATILE OVL_REF NOEXCEPT, Next, \
Signatures...> \
: operator_impl<Index + 1, Function, Next, Signatures...> { \
\
template <std::size_t, typename, typename...> \
friend class operator_impl; \
\
protected: \
operator_impl() = default; \
~operator_impl() = default; \
operator_impl(operator_impl const&) = default; \
operator_impl(operator_impl&&) = default; \
operator_impl& operator=(operator_impl const&) = default; \
operator_impl& operator=(operator_impl&&) = default; \
\
using operator_impl<Index + 1, Function, Next, Signatures...>::operator(); \
\
Ret operator()(Args... args) CONST VOLATILE OVL_REF NOEXCEPT { \
auto parent = static_cast<Function CONST VOLATILE*>(this); \
using erasure_t = std::decay_t<decltype(parent->erasure_)>; \
\
/* `std::decay_t<decltype(parent->erasure_)>` is a workaround for a */ \
/* compiler regression of MSVC 16.3.1, see #29 for details. */ \
return std::decay_t<decltype(parent->erasure_)>::template invoke<Index>( \
static_cast<erasure_t CONST VOLATILE REF>(parent->erasure_), \
std::forward<Args>(args)...); \
} \
}; \
template <std::size_t Index, typename Config, typename Property, \
typename Ret, typename... Args> \
class operator_impl<Index, function<Config, Property>, \
Ret(Args...) CONST VOLATILE OVL_REF NOEXCEPT> \
: copyable<!Config::is_owning || Config::is_copyable> { \
\
template <std::size_t, typename, typename...> \
friend class operator_impl; \
\
protected: \
operator_impl() = default; \
~operator_impl() = default; \
operator_impl(operator_impl const&) = default; \
operator_impl(operator_impl&&) = default; \
operator_impl& operator=(operator_impl const&) = default; \
operator_impl& operator=(operator_impl&&) = default; \
\
Ret operator()(Args... args) CONST VOLATILE OVL_REF NOEXCEPT { \
auto parent = \
static_cast<function<Config, Property> CONST VOLATILE*>(this); \
using erasure_t = std::decay_t<decltype(parent->erasure_)>; \
\
/* `std::decay_t<decltype(parent->erasure_)>` is a workaround for a */ \
/* compiler regression of MSVC 16.3.1, see #29 for details. */ \
return std::decay_t<decltype(parent->erasure_)>::template invoke<Index>( \
static_cast<erasure_t CONST VOLATILE REF>(parent->erasure_), \
std::forward<Args>(args)...); \
} \
};
FU2_DETAIL_EXPAND_QUALIFIERS(FU2_DEFINE_FUNCTION_TRAIT)
#undef FU2_DEFINE_FUNCTION_TRAIT
} // namespace invocation_table
namespace tables {
/// Identifies the action which is dispatched on the erased object
enum class opcode {
op_move, ///< Move the object and set the vtable
op_copy, ///< Copy the object and set the vtable
op_destroy, ///< Destroy the object and reset the vtable
op_weak_destroy, ///< Destroy the object without resetting the vtable
op_fetch_empty, ///< Stores true or false into the to storage
///< to indicate emptiness
};
/// Abstraction for a vtable together with a command table
/// TODO Add optimization for a single formal argument
/// TODO Add optimization to merge both tables if the function is size
/// optimized
template <typename Property>
class vtable;
template <bool IsThrowing, bool HasStrongExceptGuarantee,
typename... FormalArgs>
class vtable<property<IsThrowing, HasStrongExceptGuarantee, FormalArgs...>> {
using command_function_t = void (*)(vtable* /*this*/, opcode /*op*/,
data_accessor* /*from*/,
std::size_t /*from_capacity*/,
data_accessor* /*to*/,
std::size_t /*to_capacity*/);
using invoke_table_t = invocation_table::invoke_table<FormalArgs...>;
command_function_t cmd_;
typename invoke_table_t::type vtable_;
template <typename T>
struct trait {
static_assert(is_box<T>::value,
"The trait must be specialized with a box!");
/// The command table
template <bool IsInplace>
static void process_cmd(vtable* to_table, opcode op, data_accessor* from,
std::size_t from_capacity, data_accessor* to,
std::size_t to_capacity) {
switch (op) {
case opcode::op_move: {
/// Retrieve the pointer to the object
auto box = static_cast<T*>(retrieve<T>(
std::integral_constant<bool, IsInplace>{}, from, from_capacity));
assert(box && "The object must not be over aligned or null!");
if (!IsInplace) {
// Just swap both pointers if we allocated on the heap
to->ptr_ = from->ptr_;
#ifndef NDEBUG
// We don't need to null the pointer since we know that
// we don't own the data anymore through the vtable
// which is set to empty.
from->ptr_ = nullptr;
#endif
to_table->template set_allocated<T>();
}
// The object is allocated inplace
else {
construct(std::true_type{}, std::move(*box), to_table, to,
to_capacity);
box->~T();
}
return;
}
case opcode::op_copy: {
auto box = static_cast<T const*>(retrieve<T>(
std::integral_constant<bool, IsInplace>{}, from, from_capacity));
assert(box && "The object must not be over aligned or null!");
assert(std::is_copy_constructible<T>::value &&
"The box is required to be copyable here!");
// Try to allocate the object inplace
construct(std::is_copy_constructible<T>{}, *box, to_table, to,
to_capacity);
return;
}
case opcode::op_destroy:
case opcode::op_weak_destroy: {
assert(!to && !to_capacity && "Arg overflow!");
auto box = static_cast<T*>(retrieve<T>(
std::integral_constant<bool, IsInplace>{}, from, from_capacity));
if (IsInplace) {
box->~T();
} else {
box_factory<T>::box_deallocate(box);
}
if (op == opcode::op_destroy) {
to_table->set_empty();
}
return;
}
case opcode::op_fetch_empty: {
write_empty(to, false);
return;
}
}
FU2_DETAIL_UNREACHABLE();
}
template <typename Box>
static void
construct(std::true_type /*apply*/, Box&& box, vtable* to_table,
data_accessor* to,
std::size_t to_capacity) noexcept(HasStrongExceptGuarantee) {
// Try to allocate the object inplace
void* storage = retrieve<T>(std::true_type{}, to, to_capacity);
if (storage) {
to_table->template set_inplace<T>();
} else {
// Allocate the object through the allocator
to->ptr_ = storage =
box_factory<std::decay_t<Box>>::box_allocate(std::addressof(box));
to_table->template set_allocated<T>();
}
new (storage) T(std::forward<Box>(box));
}
template <typename Box>
static void
construct(std::false_type /*apply*/, Box&& /*box*/, vtable* /*to_table*/,
data_accessor* /*to*/,
std::size_t /*to_capacity*/) noexcept(HasStrongExceptGuarantee) {
}
};
/// The command table
static void empty_cmd(vtable* to_table, opcode op, data_accessor* /*from*/,
std::size_t /*from_capacity*/, data_accessor* to,
std::size_t /*to_capacity*/) {
switch (op) {
case opcode::op_move:
case opcode::op_copy: {
to_table->set_empty();
break;
}
case opcode::op_destroy:
case opcode::op_weak_destroy: {
// Do nothing
break;
}
case opcode::op_fetch_empty: {
write_empty(to, true);
break;
}
default: {
FU2_DETAIL_UNREACHABLE();
}
}
}
public:
vtable() noexcept = default;
/// Initialize an object at the given position
template <typename T>
static void init(vtable& table, T&& object, data_accessor* to,
std::size_t to_capacity) {
trait<std::decay_t<T>>::construct(std::true_type{}, std::forward<T>(object),
&table, to, to_capacity);
}
/// Moves the object at the given position
void move(vtable& to_table, data_accessor* from, std::size_t from_capacity,
data_accessor* to,
std::size_t to_capacity) noexcept(HasStrongExceptGuarantee) {
cmd_(&to_table, opcode::op_move, from, from_capacity, to, to_capacity);
set_empty();
}
/// Destroys the object at the given position
void copy(vtable& to_table, data_accessor const* from,
std::size_t from_capacity, data_accessor* to,
std::size_t to_capacity) const {
cmd_(&to_table, opcode::op_copy, const_cast<data_accessor*>(from),
from_capacity, to, to_capacity);
}
/// Destroys the object at the given position
void destroy(data_accessor* from,
std::size_t from_capacity) noexcept(HasStrongExceptGuarantee) {
cmd_(this, opcode::op_destroy, from, from_capacity, nullptr, 0U);
}
/// Destroys the object at the given position without invalidating the
/// vtable
void
weak_destroy(data_accessor* from,
std::size_t from_capacity) noexcept(HasStrongExceptGuarantee) {
cmd_(this, opcode::op_weak_destroy, from, from_capacity, nullptr, 0U);
}
/// Returns true when the vtable doesn't hold any erased object
bool empty() const noexcept {
data_accessor data;
cmd_(nullptr, opcode::op_fetch_empty, nullptr, 0U, &data, 0U);
return bool(data.inplace_storage_);
}
/// Invoke the function at the given index
template <std::size_t Index, typename... Args>
constexpr decltype(auto) invoke(Args&&... args) const {
auto thunk = invoke_table_t::template fetch<Index>(vtable_);
return thunk(std::forward<Args>(args)...);
}
/// Invoke the function at the given index
template <std::size_t Index, typename... Args>
constexpr decltype(auto) invoke(Args&&... args) const volatile {
auto thunk = invoke_table_t::template fetch<Index>(vtable_);
return thunk(std::forward<Args>(args)...);
}
template <typename T>
void set_inplace() noexcept {
using type = std::decay_t<T>;
vtable_ = invoke_table_t::template get_invocation_table_of<type, true>();
cmd_ = &trait<type>::template process_cmd<true>;
}
template <typename T>
void set_allocated() noexcept {
using type = std::decay_t<T>;
vtable_ = invoke_table_t::template get_invocation_table_of<type, false>();
cmd_ = &trait<type>::template process_cmd<false>;
}
void set_empty() noexcept {
vtable_ = invoke_table_t::template get_empty_invocation_table<IsThrowing>();
cmd_ = &empty_cmd;
}
};
} // namespace tables
/// A union which makes the pointer to the heap object share the
/// same space with the internal capacity.
/// The storage type is distinguished by multiple versions of the
/// control and vtable.
template <typename Capacity, typename = void>
struct internal_capacity {
/// We extend the union through a technique similar to the tail object hack
typedef union {
/// Tag to access the structure in a type-safe way
data_accessor accessor_;
/// The internal capacity we use to allocate in-place
std::aligned_storage_t<Capacity::capacity, Capacity::alignment> capacity_;
} type;
};
template <typename Capacity>
struct internal_capacity<
Capacity, std::enable_if_t<(Capacity::capacity < sizeof(void*))>> {
typedef struct {
/// Tag to access the structure in a type-safe way
data_accessor accessor_;
} type;
};
template <typename Capacity>
class internal_capacity_holder {
// Tag to access the structure in a type-safe way
typename internal_capacity<Capacity>::type storage_;
public:
constexpr internal_capacity_holder() = default;
FU2_DETAIL_CXX14_CONSTEXPR data_accessor* opaque_ptr() noexcept {
return &storage_.accessor_;
}
constexpr data_accessor const* opaque_ptr() const noexcept {
return &storage_.accessor_;
}
FU2_DETAIL_CXX14_CONSTEXPR data_accessor volatile*
opaque_ptr() volatile noexcept {
return &storage_.accessor_;
}
constexpr data_accessor const volatile* opaque_ptr() const volatile noexcept {
return &storage_.accessor_;
}
static constexpr std::size_t capacity() noexcept {
return sizeof(storage_);
}
};
/// An owning erasure
template <bool IsOwning /* = true*/, typename Config, typename Property>
class erasure : internal_capacity_holder<typename Config::capacity> {
template <bool, typename, typename>
friend class erasure;
template <std::size_t, typename, typename...>
friend class operator_impl;
using vtable_t = tables::vtable<Property>;
vtable_t vtable_;
public:
/// Returns the capacity of this erasure
static constexpr std::size_t capacity() noexcept {
return internal_capacity_holder<typename Config::capacity>::capacity();
}
FU2_DETAIL_CXX14_CONSTEXPR erasure() noexcept {
vtable_.set_empty();
}
FU2_DETAIL_CXX14_CONSTEXPR erasure(std::nullptr_t) noexcept {
vtable_.set_empty();
}
FU2_DETAIL_CXX14_CONSTEXPR
erasure(erasure&& right) noexcept(Property::is_strong_exception_guaranteed) {
right.vtable_.move(vtable_, right.opaque_ptr(), right.capacity(),
this->opaque_ptr(), capacity());
}
FU2_DETAIL_CXX14_CONSTEXPR erasure(erasure const& right) {
right.vtable_.copy(vtable_, right.opaque_ptr(), right.capacity(),
this->opaque_ptr(), capacity());
}
template <typename OtherConfig>
FU2_DETAIL_CXX14_CONSTEXPR
erasure(erasure<true, OtherConfig, Property> right) noexcept(
Property::is_strong_exception_guaranteed) {
right.vtable_.move(vtable_, right.opaque_ptr(), right.capacity(),
this->opaque_ptr(), capacity());
}
template <typename T, typename Allocator = std::allocator<std::decay_t<T>>>
FU2_DETAIL_CXX14_CONSTEXPR erasure(std::false_type /*use_bool_op*/,
T&& callable,
Allocator&& allocator_ = Allocator{}) {
vtable_t::init(vtable_,
type_erasure::make_box(
std::integral_constant<bool, Config::is_copyable>{},
std::forward<T>(callable),
std::forward<Allocator>(allocator_)),
this->opaque_ptr(), capacity());
}
template <typename T, typename Allocator = std::allocator<std::decay_t<T>>>
FU2_DETAIL_CXX14_CONSTEXPR erasure(std::true_type /*use_bool_op*/,
T&& callable,
Allocator&& allocator_ = Allocator{}) {
if (!!callable) {
vtable_t::init(vtable_,
type_erasure::make_box(
std::integral_constant<bool, Config::is_copyable>{},
std::forward<T>(callable),
std::forward<Allocator>(allocator_)),
this->opaque_ptr(), capacity());
} else {
vtable_.set_empty();
}
}
~erasure() {
vtable_.weak_destroy(this->opaque_ptr(), capacity());
}
FU2_DETAIL_CXX14_CONSTEXPR erasure&
operator=(std::nullptr_t) noexcept(Property::is_strong_exception_guaranteed) {
vtable_.destroy(this->opaque_ptr(), capacity());
return *this;
}
FU2_DETAIL_CXX14_CONSTEXPR erasure& operator=(erasure&& right) noexcept(
Property::is_strong_exception_guaranteed) {
vtable_.weak_destroy(this->opaque_ptr(), capacity());
right.vtable_.move(vtable_, right.opaque_ptr(), right.capacity(),
this->opaque_ptr(), capacity());
return *this;
}
FU2_DETAIL_CXX14_CONSTEXPR erasure& operator=(erasure const& right) {
vtable_.weak_destroy(this->opaque_ptr(), capacity());
right.vtable_.copy(vtable_, right.opaque_ptr(), right.capacity(),
this->opaque_ptr(), capacity());
return *this;
}
template <typename OtherConfig>
FU2_DETAIL_CXX14_CONSTEXPR erasure&
operator=(erasure<true, OtherConfig, Property> right) noexcept(
Property::is_strong_exception_guaranteed) {
vtable_.weak_destroy(this->opaque_ptr(), capacity());
right.vtable_.move(vtable_, right.opaque_ptr(), right.capacity(),
this->opaque_ptr(), capacity());
return *this;
}
template <typename T, typename Allocator = std::allocator<std::decay_t<T>>>
void assign(std::false_type /*use_bool_op*/, T&& callable,
Allocator&& allocator_ = {}) {
vtable_.weak_destroy(this->opaque_ptr(), capacity());
vtable_t::init(vtable_,
type_erasure::make_box(
std::integral_constant<bool, Config::is_copyable>{},
std::forward<T>(callable),
std::forward<Allocator>(allocator_)),
this->opaque_ptr(), capacity());
}
template <typename T, typename Allocator = std::allocator<std::decay_t<T>>>
void assign(std::true_type /*use_bool_op*/, T&& callable,
Allocator&& allocator_ = {}) {
if (!!callable) {
assign(std::false_type{}, std::forward<T>(callable),
std::forward<Allocator>(allocator_));
} else {
operator=(nullptr);
}
}
/// Returns true when the erasure doesn't hold any erased object
constexpr bool empty() const noexcept {
return vtable_.empty();
}
/// Invoke the function of the erasure at the given index
///
/// We define this out of class to be able to forward the qualified
/// erasure correctly.
template <std::size_t Index, typename Erasure, typename... Args>
static constexpr decltype(auto) invoke(Erasure&& erasure, Args&&... args) {
auto const capacity = erasure.capacity();
return erasure.vtable_.template invoke<Index>(
std::forward<Erasure>(erasure).opaque_ptr(), capacity,
std::forward<Args>(args)...);
}
};
// A non owning erasure
template </*bool IsOwning = false, */ typename Config, bool IsThrowing,
bool HasStrongExceptGuarantee, typename... Args>
class erasure<false, Config,
property<IsThrowing, HasStrongExceptGuarantee, Args...>> {
template <bool, typename, typename>
friend class erasure;
template <std::size_t, typename, typename...>
friend class operator_impl;
using property_t = property<IsThrowing, HasStrongExceptGuarantee, Args...>;
using invoke_table_t = invocation_table::invoke_table<Args...>;
typename invoke_table_t::type invoke_table_;
/// The internal pointer to the non owned object
data_accessor view_;
public:
// NOLINTNEXTLINE(cppcoreguidlines-pro-type-member-init)
constexpr erasure() noexcept
: invoke_table_(
invoke_table_t::template get_empty_invocation_table<IsThrowing>()),
view_(nullptr) {
}
// NOLINTNEXTLINE(cppcoreguidlines-pro-type-member-init)
constexpr erasure(std::nullptr_t) noexcept
: invoke_table_(
invoke_table_t::template get_empty_invocation_table<IsThrowing>()),
view_(nullptr) {
}
// NOLINTNEXTLINE(cppcoreguidlines-pro-type-member-init)
constexpr erasure(erasure&& right) noexcept
: invoke_table_(right.invoke_table_), view_(right.view_) {
}
constexpr erasure(erasure const& /*right*/) = default;
template <typename OtherConfig>
// NOLINTNEXTLINE(cppcoreguidlines-pro-type-member-init)
constexpr erasure(erasure<false, OtherConfig, property_t> right) noexcept
: invoke_table_(right.invoke_table_), view_(right.view_) {
}
template <typename T>
// NOLINTNEXTLINE(cppcoreguidlines-pro-type-member-init)
constexpr erasure(std::false_type /*use_bool_op*/, T&& object)
: invoke_table_(invoke_table_t::template get_invocation_view_table_of<
std::decay_t<T>>()),
view_(address_taker<std::decay_t<T>>::take(std::forward<T>(object))) {
}
template <typename T>
// NOLINTNEXTLINE(cppcoreguidlines-pro-type-member-init)
FU2_DETAIL_CXX14_CONSTEXPR erasure(std::true_type use_bool_op, T&& object) {
this->assign(use_bool_op, std::forward<T>(object));
}
~erasure() = default;
constexpr erasure&
operator=(std::nullptr_t) noexcept(HasStrongExceptGuarantee) {
invoke_table_ =
invoke_table_t::template get_empty_invocation_table<IsThrowing>();
view_.ptr_ = nullptr;
return *this;
}
constexpr erasure& operator=(erasure&& right) noexcept {
invoke_table_ = right.invoke_table_;
view_ = right.view_;
right = nullptr;
return *this;
}
constexpr erasure& operator=(erasure const& /*right*/) = default;
template <typename OtherConfig>
constexpr erasure&
operator=(erasure<true, OtherConfig, property_t> right) noexcept {
invoke_table_ = right.invoke_table_;
view_ = right.view_;
return *this;
}
template <typename T>
constexpr void assign(std::false_type /*use_bool_op*/, T&& callable) {
invoke_table_ = invoke_table_t::template get_invocation_view_table_of<
std::decay_t<T>>();
view_.assign_ptr(
address_taker<std::decay_t<T>>::take(std::forward<T>(callable)));
}
template <typename T>
constexpr void assign(std::true_type /*use_bool_op*/, T&& callable) {
if (!!callable) {
assign(std::false_type{}, std::forward<T>(callable));
} else {
operator=(nullptr);
}
}
/// Returns true when the erasure doesn't hold any erased object
constexpr bool empty() const noexcept {
return view_.ptr_ == nullptr;
}
template <std::size_t Index, typename Erasure, typename... T>
static constexpr decltype(auto) invoke(Erasure&& erasure, T&&... args) {
auto thunk = invoke_table_t::template fetch<Index>(erasure.invoke_table_);
return thunk(&(erasure.view_), 0UL, std::forward<T>(args)...);
}
};
} // namespace type_erasure
/// Deduces to a true_type if the type T provides the given signature and the
/// signature is noexcept correct callable.
template <typename T, typename Signature,
typename Trait =
type_erasure::invocation_table::function_trait<Signature>>
struct accepts_one
: detail::lazy_and< // both are std::integral_constant
invocation::can_invoke<typename Trait::template callable<T>,
typename Trait::arguments>,
invocation::is_noexcept_correct<Trait::is_noexcept::value,
typename Trait::template callable<T>,
typename Trait::arguments>> {};
/// Deduces to a true_type if the type T provides all signatures
template <typename T, typename Signatures, typename = void>
struct accepts_all : std::false_type {};
template <typename T, typename... Signatures>
struct accepts_all<
T, identity<Signatures...>,
void_t<std::enable_if_t<accepts_one<T, Signatures>::value>...>>
: std::true_type {};
#if defined(FU2_HAS_NO_EMPTY_PROPAGATION)
template <typename T>
struct use_bool_op : std::false_type {};
#elif defined(FU2_HAS_LIMITED_EMPTY_PROPAGATION)
/// Implementation for use_bool_op based on the behaviour of std::function,
/// propagating empty state for pointers, `std::function` and
/// `fu2::detail::function` types only.
template <typename T>
struct use_bool_op : std::false_type {};
#if !defined(FU2_HAS_NO_FUNCTIONAL_HEADER)
template <typename Signature>
struct use_bool_op<std::function<Signature>> : std::true_type {};
#endif
template <typename Config, typename Property>
struct use_bool_op<function<Config, Property>> : std::true_type {};
template <typename T>
struct use_bool_op<T*> : std::true_type {};
template <typename Class, typename T>
struct use_bool_op<T Class::*> : std::true_type {};
#else
template <typename T, typename = void>
struct has_bool_op : std::false_type {};
template <typename T>
struct has_bool_op<T, void_t<decltype(bool(std::declval<T>()))>>
: std::true_type {
#ifndef NDEBUG
static_assert(!std::is_pointer<T>::value,
"Missing deduction for function pointer!");
#endif
};
/// Deduces to a true_type if the type T is implementing operator bool()
/// or if the type is convertible to bool directly, this also implements an
/// optimizations for function references `void(&)()` which are can never
/// be null and for such a conversion to bool would never return false.
template <typename T>
struct use_bool_op : has_bool_op<T> {};
#define FU2_DEFINE_USE_OP_TRAIT(CONST, VOLATILE, NOEXCEPT) \
template <typename Ret, typename... Args> \
struct use_bool_op<Ret (*CONST VOLATILE)(Args...) NOEXCEPT> \
: std::true_type {};
FU2_DETAIL_EXPAND_CV(FU2_DEFINE_USE_OP_TRAIT)
#undef FU2_DEFINE_USE_OP_TRAIT
template <typename Ret, typename... Args>
struct use_bool_op<Ret(Args...)> : std::false_type {};
#if defined(FU2_HAS_CXX17_NOEXCEPT_FUNCTION_TYPE)
template <typename Ret, typename... Args>
struct use_bool_op<Ret(Args...) noexcept> : std::false_type {};
#endif
#endif // FU2_HAS_NO_EMPTY_PROPAGATION
template <typename Config, typename T>
struct assert_wrong_copy_assign {
static_assert(!Config::is_owning || !Config::is_copyable ||
std::is_copy_constructible<std::decay_t<T>>::value,
"Can't wrap a non copyable object into a unique function!");
using type = void;
};
template <bool IsStrongExceptGuaranteed, typename T>
struct assert_no_strong_except_guarantee {
static_assert(
!IsStrongExceptGuaranteed ||
(std::is_nothrow_move_constructible<T>::value &&
std::is_nothrow_destructible<T>::value),
"Can't wrap a object an object that has no strong exception guarantees "
"if this is required by the wrapper!");
using type = void;
};
/// SFINAES out if the given callable is not copyable correct to the left one.
template <typename LeftConfig, typename RightConfig>
using enable_if_copyable_correct_t =
std::enable_if_t<(!LeftConfig::is_copyable || RightConfig::is_copyable)>;
template <typename LeftConfig, typename RightConfig>
using is_owning_correct =
std::integral_constant<bool,
(LeftConfig::is_owning == RightConfig::is_owning)>;
/// SFINAES out if the given function2 is not owning correct to this one
template <typename LeftConfig, typename RightConfig>
using enable_if_owning_correct_t =
std::enable_if_t<is_owning_correct<LeftConfig, RightConfig>::value>;
template <typename Config, bool IsThrowing, bool HasStrongExceptGuarantee,
typename... Args>
class function<Config, property<IsThrowing, HasStrongExceptGuarantee, Args...>>
: type_erasure::invocation_table::operator_impl<
0U,
function<Config,
property<IsThrowing, HasStrongExceptGuarantee, Args...>>,
Args...> {
template <typename, typename>
friend class function;
template <std::size_t, typename, typename...>
friend class type_erasure::invocation_table::operator_impl;
using property_t = property<IsThrowing, HasStrongExceptGuarantee, Args...>;
using erasure_t =
type_erasure::erasure<Config::is_owning, Config, property_t>;
template <typename T>
using enable_if_can_accept_all_t =
std::enable_if_t<accepts_all<std::decay_t<T>, identity<Args...>>::value>;
template <typename Function, typename = void>
struct is_convertible_to_this : std::false_type {};
template <typename RightConfig>
struct is_convertible_to_this<
function<RightConfig, property_t>,
void_t<enable_if_copyable_correct_t<Config, RightConfig>,
enable_if_owning_correct_t<Config, RightConfig>>>
: std::true_type {};
template <typename T>
using enable_if_not_convertible_to_this =
std::enable_if_t<!is_convertible_to_this<std::decay_t<T>>::value>;
template <typename T>
using enable_if_owning_t =
std::enable_if_t<std::is_same<T, T>::value && Config::is_owning>;
template <typename T>
using assert_wrong_copy_assign_t =
typename assert_wrong_copy_assign<Config, std::decay_t<T>>::type;
template <typename T>
using assert_no_strong_except_guarantee_t =
typename assert_no_strong_except_guarantee<HasStrongExceptGuarantee,
std::decay_t<T>>::type;
erasure_t erasure_;
public:
/// Default constructor which empty constructs the function
function() = default;
~function() = default;
explicit FU2_DETAIL_CXX14_CONSTEXPR
function(function const& /*right*/) = default;
explicit FU2_DETAIL_CXX14_CONSTEXPR function(function&& /*right*/) = default;
/// Copy construction from another copyable function
template <typename RightConfig,
std::enable_if_t<RightConfig::is_copyable>* = nullptr,
enable_if_copyable_correct_t<Config, RightConfig>* = nullptr,
enable_if_owning_correct_t<Config, RightConfig>* = nullptr>
FU2_DETAIL_CXX14_CONSTEXPR
function(function<RightConfig, property_t> const& right)
: erasure_(right.erasure_) {
}
/// Move construction from another function
template <typename RightConfig,
enable_if_copyable_correct_t<Config, RightConfig>* = nullptr,
enable_if_owning_correct_t<Config, RightConfig>* = nullptr>
FU2_DETAIL_CXX14_CONSTEXPR function(function<RightConfig, property_t>&& right)
: erasure_(std::move(right.erasure_)) {
}
/// Construction from a callable object which overloads the `()` operator
template <typename T, //
enable_if_not_convertible_to_this<T>* = nullptr,
enable_if_can_accept_all_t<T>* = nullptr,
assert_wrong_copy_assign_t<T>* = nullptr,
assert_no_strong_except_guarantee_t<T>* = nullptr>
FU2_DETAIL_CXX14_CONSTEXPR function(T&& callable)
: erasure_(use_bool_op<unrefcv_t<T>>{}, std::forward<T>(callable)) {
}
template <typename T, typename Allocator, //
enable_if_not_convertible_to_this<T>* = nullptr,
enable_if_can_accept_all_t<T>* = nullptr,
enable_if_owning_t<T>* = nullptr,
assert_wrong_copy_assign_t<T>* = nullptr,
assert_no_strong_except_guarantee_t<T>* = nullptr>
FU2_DETAIL_CXX14_CONSTEXPR function(T&& callable, Allocator&& allocator_)
: erasure_(use_bool_op<unrefcv_t<T>>{}, std::forward<T>(callable),
std::forward<Allocator>(allocator_)) {
}
/// Empty constructs the function
FU2_DETAIL_CXX14_CONSTEXPR function(std::nullptr_t np) : erasure_(np) {
}
function& operator=(function const& /*right*/) = default;
function& operator=(function&& /*right*/) = default;
/// Copy assigning from another copyable function
template <typename RightConfig,
std::enable_if_t<RightConfig::is_copyable>* = nullptr,
enable_if_copyable_correct_t<Config, RightConfig>* = nullptr,
enable_if_owning_correct_t<Config, RightConfig>* = nullptr>
function& operator=(function<RightConfig, property_t> const& right) {
erasure_ = right.erasure_;
return *this;
}
/// Move assigning from another function
template <typename RightConfig,
enable_if_copyable_correct_t<Config, RightConfig>* = nullptr,
enable_if_owning_correct_t<Config, RightConfig>* = nullptr>
function& operator=(function<RightConfig, property_t>&& right) {
erasure_ = std::move(right.erasure_);
return *this;
}
/// Move assigning from a callable object
template <typename T, // ...
enable_if_not_convertible_to_this<T>* = nullptr,
enable_if_can_accept_all_t<T>* = nullptr,
assert_wrong_copy_assign_t<T>* = nullptr,
assert_no_strong_except_guarantee_t<T>* = nullptr>
function& operator=(T&& callable) {
erasure_.assign(use_bool_op<unrefcv_t<T>>{}, std::forward<T>(callable));
return *this;
}
/// Clears the function
function& operator=(std::nullptr_t np) {
erasure_ = np;
return *this;
}
/// Returns true when the function is empty
bool empty() const noexcept {
return erasure_.empty();
}
/// Returns true when the function isn't empty
explicit operator bool() const noexcept {
return !empty();
}
/// Assigns a new target with an optional allocator
template <typename T, typename Allocator = std::allocator<std::decay_t<T>>,
enable_if_not_convertible_to_this<T>* = nullptr,
enable_if_can_accept_all_t<T>* = nullptr,
assert_wrong_copy_assign_t<T>* = nullptr,
assert_no_strong_except_guarantee_t<T>* = nullptr>
void assign(T&& callable, Allocator&& allocator_ = Allocator{}) {
erasure_.assign(use_bool_op<unrefcv_t<T>>{}, std::forward<T>(callable),
std::forward<Allocator>(allocator_));
}
/// Swaps this function with the given function
void swap(function& other) noexcept(HasStrongExceptGuarantee) {
if (&other == this) {
return;
}
function cache = std::move(other);
other = std::move(*this);
*this = std::move(cache);
}
/// Swaps the left function with the right one
friend void swap(function& left,
function& right) noexcept(HasStrongExceptGuarantee) {
left.swap(right);
}
/// Calls the wrapped callable object
using type_erasure::invocation_table::operator_impl<
0U, function<Config, property_t>, Args...>::operator();
};
template <typename Config, typename Property>
bool operator==(function<Config, Property> const& f, std::nullptr_t) {
return !bool(f);
}
template <typename Config, typename Property>
bool operator!=(function<Config, Property> const& f, std::nullptr_t) {
return bool(f);
}
template <typename Config, typename Property>
bool operator==(std::nullptr_t, function<Config, Property> const& f) {
return !bool(f);
}
template <typename Config, typename Property>
bool operator!=(std::nullptr_t, function<Config, Property> const& f) {
return bool(f);
}
// Default intended object size of the function
using object_size = std::integral_constant<std::size_t, 32U>;
} // namespace detail
} // namespace abi_400
/// Can be passed to function_base as template argument which causes
/// the internal small buffer to be sized according to the given size,
/// and aligned with the given alignment.
template <std::size_t Capacity,
std::size_t Alignment = alignof(std::max_align_t)>
struct capacity_fixed {
static constexpr std::size_t capacity = Capacity;
static constexpr std::size_t alignment = Alignment;
};
/// Default capacity for small functor optimization
struct capacity_default
: capacity_fixed<detail::object_size::value - (2 * sizeof(void*))> {};
/// Can be passed to function_base as template argument which causes
/// the internal small buffer to be removed from the callable wrapper.
/// The owning function_base will then allocate memory for every object
/// it applies a type erasure on.
struct capacity_none : capacity_fixed<0UL> {};
/// Can be passed to function_base as template argument which causes
/// the internal small buffer to be sized such that it can hold
/// the given object without allocating memory for an applied type erasure.
template <typename T>
struct capacity_can_hold {
static constexpr std::size_t capacity = sizeof(T);
static constexpr std::size_t alignment = alignof(T);
};
/// An adaptable function wrapper base for arbitrary functional types.
///
/// \tparam IsOwning Is true when the type erasure shall be owning the object.
///
/// \tparam IsCopyable Defines whether the function is copyable or not
///
/// \tparam Capacity Defines the internal capacity of the function
/// for small functor optimization.
/// The size of the whole function object will be the capacity
/// plus the size of two pointers. If the capacity is zero,
/// the size will increase through one additional pointer
/// so the whole object has the size of 3 * sizeof(void*).
/// The type which is passed to the Capacity template parameter
/// shall provide a capacity and alignment member which
/// looks like the following example:
/// ```cpp
/// struct my_capacity {
/// static constexpr std::size_t capacity = sizeof(my_type);
/// static constexpr std::size_t alignment = alignof(my_type);
/// };
/// ```
///
/// \tparam IsThrowing Defines whether the function throws an exception on
/// empty function call, `std::abort` is called otherwise.
///
/// \tparam HasStrongExceptGuarantee Defines whether all objects satisfy the
/// strong exception guarantees,
/// which means the function type will satisfy
/// the strong exception guarantees too.
///
/// \tparam Signatures Defines the signature of the callable wrapper
///
template <bool IsOwning, bool IsCopyable, typename Capacity, bool IsThrowing,
bool HasStrongExceptGuarantee, typename... Signatures>
using function_base = detail::function<
detail::config<IsOwning, IsCopyable, Capacity>,
detail::property<IsThrowing, HasStrongExceptGuarantee, Signatures...>>;
/// An owning copyable function wrapper for arbitrary callable types.
template <typename... Signatures>
using function = function_base<true, true, capacity_default, //
true, false, Signatures...>;
/// An owning non copyable function wrapper for arbitrary callable types.
template <typename... Signatures>
using unique_function = function_base<true, false, capacity_default, //
true, false, Signatures...>;
/// A non owning copyable function wrapper for arbitrary callable types.
template <typename... Signatures>
using function_view = function_base<false, true, capacity_default, //
true, false, Signatures...>;
#if !defined(FU2_HAS_DISABLED_EXCEPTIONS)
/// Exception type that is thrown when invoking empty function objects
/// and exception support isn't disabled.
///
/// Exception support is enabled if
/// the template parameter 'Throwing' is set to true (default).
///
/// This type will default to std::bad_function_call if the
/// functional header is used, otherwise the library provides its own type.
///
/// You may disable the inclusion of the functional header
/// through defining `FU2_WITH_NO_FUNCTIONAL_HEADER`.
///
using detail::type_erasure::invocation_table::bad_function_call;
#endif
/// Returns a callable object, which unifies all callable objects
/// that were passed to this function.
///
/// ```cpp
/// auto overloaded = fu2::overload([](std::true_type) { return true; },
/// [](std::false_type) { return false; });
/// ```
///
/// \param callables A pack of callable objects with arbitrary signatures.
///
/// \returns A callable object which exposes the
///
template <typename... T>
constexpr auto overload(T&&... callables) {
return detail::overloading::overload(std::forward<T>(callables)...);
}
} // namespace fu2
namespace std{
template <typename Config, typename Property, typename Alloc>
struct uses_allocator<
::fu2::detail::function<Config, Property>,
Alloc
> : std::true_type {};
} // namespace std
#undef FU2_DETAIL_EXPAND_QUALIFIERS
#undef FU2_DETAIL_EXPAND_QUALIFIERS_NOEXCEPT
#undef FU2_DETAIL_EXPAND_CV
#undef FU2_DETAIL_EXPAND_CV_NOEXCEPT
#undef FU2_DETAIL_UNREACHABLE_INTRINSIC
#undef FU2_DETAIL_TRAP
#undef FU2_DETAIL_CXX14_CONSTEXPR
#endif // FU2_INCLUDED_FUNCTION2_HPP_