| // Implementation of std::function -*- C++ -*- |
| |
| // Copyright (C) 2004-2020 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library is free |
| // software; you can redistribute it and/or modify it under the |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) |
| // any later version. |
| |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // Under Section 7 of GPL version 3, you are granted additional |
| // permissions described in the GCC Runtime Library Exception, version |
| // 3.1, as published by the Free Software Foundation. |
| |
| // You should have received a copy of the GNU General Public License and |
| // a copy of the GCC Runtime Library Exception along with this program; |
| // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| // <http://www.gnu.org/licenses/>. |
| |
| /** @file include/bits/std_function.h |
| * This is an internal header file, included by other library headers. |
| * Do not attempt to use it directly. @headername{functional} |
| */ |
| |
| #ifndef _GLIBCXX_STD_FUNCTION_H |
| #define _GLIBCXX_STD_FUNCTION_H 1 |
| |
| #pragma GCC system_header |
| |
| #if __cplusplus < 201103L |
| # include <bits/c++0x_warning.h> |
| #else |
| |
| #if __cpp_rtti |
| # include <typeinfo> |
| #endif |
| #include <bits/stl_function.h> |
| #include <bits/invoke.h> |
| #include <bits/refwrap.h> |
| #include <bits/functexcept.h> |
| |
| namespace std _GLIBCXX_VISIBILITY(default) |
| { |
| _GLIBCXX_BEGIN_NAMESPACE_VERSION |
| |
| /** |
| * @brief Exception class thrown when class template function's |
| * operator() is called with an empty target. |
| * @ingroup exceptions |
| */ |
| class bad_function_call : public std::exception |
| { |
| public: |
| virtual ~bad_function_call() noexcept; |
| |
| const char* what() const noexcept; |
| }; |
| |
| /** |
| * Trait identifying "location-invariant" types, meaning that the |
| * address of the object (or any of its members) will not escape. |
| * Trivially copyable types are location-invariant and users can |
| * specialize this trait for other types. |
| */ |
| template<typename _Tp> |
| struct __is_location_invariant |
| : is_trivially_copyable<_Tp>::type |
| { }; |
| |
| class _Undefined_class; |
| |
| union _Nocopy_types |
| { |
| void* _M_object; |
| const void* _M_const_object; |
| void (*_M_function_pointer)(); |
| void (_Undefined_class::*_M_member_pointer)(); |
| }; |
| |
| union [[gnu::may_alias]] _Any_data |
| { |
| void* _M_access() { return &_M_pod_data[0]; } |
| const void* _M_access() const { return &_M_pod_data[0]; } |
| |
| template<typename _Tp> |
| _Tp& |
| _M_access() |
| { return *static_cast<_Tp*>(_M_access()); } |
| |
| template<typename _Tp> |
| const _Tp& |
| _M_access() const |
| { return *static_cast<const _Tp*>(_M_access()); } |
| |
| _Nocopy_types _M_unused; |
| char _M_pod_data[sizeof(_Nocopy_types)]; |
| }; |
| |
| enum _Manager_operation |
| { |
| __get_type_info, |
| __get_functor_ptr, |
| __clone_functor, |
| __destroy_functor |
| }; |
| |
| template<typename _Signature> |
| class function; |
| |
| /// Base class of all polymorphic function object wrappers. |
| class _Function_base |
| { |
| public: |
| static const size_t _M_max_size = sizeof(_Nocopy_types); |
| static const size_t _M_max_align = __alignof__(_Nocopy_types); |
| |
| template<typename _Functor> |
| class _Base_manager |
| { |
| protected: |
| static const bool __stored_locally = |
| (__is_location_invariant<_Functor>::value |
| && sizeof(_Functor) <= _M_max_size |
| && __alignof__(_Functor) <= _M_max_align |
| && (_M_max_align % __alignof__(_Functor) == 0)); |
| |
| typedef integral_constant<bool, __stored_locally> _Local_storage; |
| |
| // Retrieve a pointer to the function object |
| static _Functor* |
| _M_get_pointer(const _Any_data& __source) |
| { |
| if _GLIBCXX17_CONSTEXPR (__stored_locally) |
| { |
| const _Functor& __f = __source._M_access<_Functor>(); |
| return const_cast<_Functor*>(std::__addressof(__f)); |
| } |
| else // have stored a pointer |
| return __source._M_access<_Functor*>(); |
| } |
| |
| // Clone a location-invariant function object that fits within |
| // an _Any_data structure. |
| static void |
| _M_clone(_Any_data& __dest, const _Any_data& __source, true_type) |
| { |
| ::new (__dest._M_access()) _Functor(__source._M_access<_Functor>()); |
| } |
| |
| // Clone a function object that is not location-invariant or |
| // that cannot fit into an _Any_data structure. |
| static void |
| _M_clone(_Any_data& __dest, const _Any_data& __source, false_type) |
| { |
| __dest._M_access<_Functor*>() = |
| new _Functor(*__source._M_access<const _Functor*>()); |
| } |
| |
| // Destroying a location-invariant object may still require |
| // destruction. |
| static void |
| _M_destroy(_Any_data& __victim, true_type) |
| { |
| __victim._M_access<_Functor>().~_Functor(); |
| } |
| |
| // Destroying an object located on the heap. |
| static void |
| _M_destroy(_Any_data& __victim, false_type) |
| { |
| delete __victim._M_access<_Functor*>(); |
| } |
| |
| public: |
| static bool |
| _M_manager(_Any_data& __dest, const _Any_data& __source, |
| _Manager_operation __op) |
| { |
| switch (__op) |
| { |
| #if __cpp_rtti |
| case __get_type_info: |
| __dest._M_access<const type_info*>() = &typeid(_Functor); |
| break; |
| #endif |
| case __get_functor_ptr: |
| __dest._M_access<_Functor*>() = _M_get_pointer(__source); |
| break; |
| |
| case __clone_functor: |
| _M_clone(__dest, __source, _Local_storage()); |
| break; |
| |
| case __destroy_functor: |
| _M_destroy(__dest, _Local_storage()); |
| break; |
| } |
| return false; |
| } |
| |
| static void |
| _M_init_functor(_Any_data& __functor, _Functor&& __f) |
| { _M_init_functor(__functor, std::move(__f), _Local_storage()); } |
| |
| template<typename _Signature> |
| static bool |
| _M_not_empty_function(const function<_Signature>& __f) |
| { return static_cast<bool>(__f); } |
| |
| template<typename _Tp> |
| static bool |
| _M_not_empty_function(_Tp* __fp) |
| { return __fp != nullptr; } |
| |
| template<typename _Class, typename _Tp> |
| static bool |
| _M_not_empty_function(_Tp _Class::* __mp) |
| { return __mp != nullptr; } |
| |
| template<typename _Tp> |
| static bool |
| _M_not_empty_function(const _Tp&) |
| { return true; } |
| |
| private: |
| static void |
| _M_init_functor(_Any_data& __functor, _Functor&& __f, true_type) |
| { ::new (__functor._M_access()) _Functor(std::move(__f)); } |
| |
| static void |
| _M_init_functor(_Any_data& __functor, _Functor&& __f, false_type) |
| { __functor._M_access<_Functor*>() = new _Functor(std::move(__f)); } |
| }; |
| |
| _Function_base() : _M_manager(nullptr) { } |
| |
| ~_Function_base() |
| { |
| if (_M_manager) |
| _M_manager(_M_functor, _M_functor, __destroy_functor); |
| } |
| |
| bool _M_empty() const { return !_M_manager; } |
| |
| typedef bool (*_Manager_type)(_Any_data&, const _Any_data&, |
| _Manager_operation); |
| |
| _Any_data _M_functor; |
| _Manager_type _M_manager; |
| }; |
| |
| template<typename _Signature, typename _Functor> |
| class _Function_handler; |
| |
| template<typename _Res, typename _Functor, typename... _ArgTypes> |
| class _Function_handler<_Res(_ArgTypes...), _Functor> |
| : public _Function_base::_Base_manager<_Functor> |
| { |
| typedef _Function_base::_Base_manager<_Functor> _Base; |
| |
| public: |
| static bool |
| _M_manager(_Any_data& __dest, const _Any_data& __source, |
| _Manager_operation __op) |
| { |
| switch (__op) |
| { |
| #if __cpp_rtti |
| case __get_type_info: |
| __dest._M_access<const type_info*>() = &typeid(_Functor); |
| break; |
| #endif |
| case __get_functor_ptr: |
| __dest._M_access<_Functor*>() = _Base::_M_get_pointer(__source); |
| break; |
| |
| default: |
| _Base::_M_manager(__dest, __source, __op); |
| } |
| return false; |
| } |
| |
| static _Res |
| _M_invoke(const _Any_data& __functor, _ArgTypes&&... __args) |
| { |
| return std::__invoke_r<_Res>(*_Base::_M_get_pointer(__functor), |
| std::forward<_ArgTypes>(__args)...); |
| } |
| }; |
| |
| /** |
| * @brief Primary class template for std::function. |
| * @ingroup functors |
| * |
| * Polymorphic function wrapper. |
| */ |
| template<typename _Res, typename... _ArgTypes> |
| class function<_Res(_ArgTypes...)> |
| : public _Maybe_unary_or_binary_function<_Res, _ArgTypes...>, |
| private _Function_base |
| { |
| template<typename _Func, |
| typename _Res2 = __invoke_result<_Func&, _ArgTypes...>> |
| struct _Callable |
| : __is_invocable_impl<_Res2, _Res>::type |
| { }; |
| |
| // Used so the return type convertibility checks aren't done when |
| // performing overload resolution for copy construction/assignment. |
| template<typename _Tp> |
| struct _Callable<function, _Tp> : false_type { }; |
| |
| template<typename _Cond, typename _Tp> |
| using _Requires = typename enable_if<_Cond::value, _Tp>::type; |
| |
| public: |
| typedef _Res result_type; |
| |
| // [3.7.2.1] construct/copy/destroy |
| |
| /** |
| * @brief Default construct creates an empty function call wrapper. |
| * @post @c !(bool)*this |
| */ |
| function() noexcept |
| : _Function_base() { } |
| |
| /** |
| * @brief Creates an empty function call wrapper. |
| * @post @c !(bool)*this |
| */ |
| function(nullptr_t) noexcept |
| : _Function_base() { } |
| |
| /** |
| * @brief %Function copy constructor. |
| * @param __x A %function object with identical call signature. |
| * @post @c bool(*this) == bool(__x) |
| * |
| * The newly-created %function contains a copy of the target of @a |
| * __x (if it has one). |
| */ |
| function(const function& __x); |
| |
| /** |
| * @brief %Function move constructor. |
| * @param __x A %function object rvalue with identical call signature. |
| * |
| * The newly-created %function contains the target of @a __x |
| * (if it has one). |
| */ |
| function(function&& __x) noexcept : _Function_base() |
| { |
| __x.swap(*this); |
| } |
| |
| /** |
| * @brief Builds a %function that targets a copy of the incoming |
| * function object. |
| * @param __f A %function object that is callable with parameters of |
| * type @c T1, @c T2, ..., @c TN and returns a value convertible |
| * to @c Res. |
| * |
| * The newly-created %function object will target a copy of |
| * @a __f. If @a __f is @c reference_wrapper<F>, then this function |
| * object will contain a reference to the function object @c |
| * __f.get(). If @a __f is a NULL function pointer or NULL |
| * pointer-to-member, the newly-created object will be empty. |
| * |
| * If @a __f is a non-NULL function pointer or an object of type @c |
| * reference_wrapper<F>, this function will not throw. |
| */ |
| template<typename _Functor, |
| typename = _Requires<__not_<is_same<_Functor, function>>, void>, |
| typename = _Requires<_Callable<_Functor>, void>> |
| function(_Functor); |
| |
| /** |
| * @brief %Function assignment operator. |
| * @param __x A %function with identical call signature. |
| * @post @c (bool)*this == (bool)x |
| * @returns @c *this |
| * |
| * The target of @a __x is copied to @c *this. If @a __x has no |
| * target, then @c *this will be empty. |
| * |
| * If @a __x targets a function pointer or a reference to a function |
| * object, then this operation will not throw an %exception. |
| */ |
| function& |
| operator=(const function& __x) |
| { |
| function(__x).swap(*this); |
| return *this; |
| } |
| |
| /** |
| * @brief %Function move-assignment operator. |
| * @param __x A %function rvalue with identical call signature. |
| * @returns @c *this |
| * |
| * The target of @a __x is moved to @c *this. If @a __x has no |
| * target, then @c *this will be empty. |
| * |
| * If @a __x targets a function pointer or a reference to a function |
| * object, then this operation will not throw an %exception. |
| */ |
| function& |
| operator=(function&& __x) noexcept |
| { |
| function(std::move(__x)).swap(*this); |
| return *this; |
| } |
| |
| /** |
| * @brief %Function assignment to zero. |
| * @post @c !(bool)*this |
| * @returns @c *this |
| * |
| * The target of @c *this is deallocated, leaving it empty. |
| */ |
| function& |
| operator=(nullptr_t) noexcept |
| { |
| if (_M_manager) |
| { |
| _M_manager(_M_functor, _M_functor, __destroy_functor); |
| _M_manager = nullptr; |
| _M_invoker = nullptr; |
| } |
| return *this; |
| } |
| |
| /** |
| * @brief %Function assignment to a new target. |
| * @param __f A %function object that is callable with parameters of |
| * type @c T1, @c T2, ..., @c TN and returns a value convertible |
| * to @c Res. |
| * @return @c *this |
| * |
| * This %function object wrapper will target a copy of @a |
| * __f. If @a __f is @c reference_wrapper<F>, then this function |
| * object will contain a reference to the function object @c |
| * __f.get(). If @a __f is a NULL function pointer or NULL |
| * pointer-to-member, @c this object will be empty. |
| * |
| * If @a __f is a non-NULL function pointer or an object of type @c |
| * reference_wrapper<F>, this function will not throw. |
| */ |
| template<typename _Functor> |
| _Requires<_Callable<typename decay<_Functor>::type>, function&> |
| operator=(_Functor&& __f) |
| { |
| function(std::forward<_Functor>(__f)).swap(*this); |
| return *this; |
| } |
| |
| /// @overload |
| template<typename _Functor> |
| function& |
| operator=(reference_wrapper<_Functor> __f) noexcept |
| { |
| function(__f).swap(*this); |
| return *this; |
| } |
| |
| // [3.7.2.2] function modifiers |
| |
| /** |
| * @brief Swap the targets of two %function objects. |
| * @param __x A %function with identical call signature. |
| * |
| * Swap the targets of @c this function object and @a __f. This |
| * function will not throw an %exception. |
| */ |
| void swap(function& __x) noexcept |
| { |
| std::swap(_M_functor, __x._M_functor); |
| std::swap(_M_manager, __x._M_manager); |
| std::swap(_M_invoker, __x._M_invoker); |
| } |
| |
| // [3.7.2.3] function capacity |
| |
| /** |
| * @brief Determine if the %function wrapper has a target. |
| * |
| * @return @c true when this %function object contains a target, |
| * or @c false when it is empty. |
| * |
| * This function will not throw an %exception. |
| */ |
| explicit operator bool() const noexcept |
| { return !_M_empty(); } |
| |
| // [3.7.2.4] function invocation |
| |
| /** |
| * @brief Invokes the function targeted by @c *this. |
| * @returns the result of the target. |
| * @throws bad_function_call when @c !(bool)*this |
| * |
| * The function call operator invokes the target function object |
| * stored by @c this. |
| */ |
| _Res operator()(_ArgTypes... __args) const; |
| |
| #if __cpp_rtti |
| // [3.7.2.5] function target access |
| /** |
| * @brief Determine the type of the target of this function object |
| * wrapper. |
| * |
| * @returns the type identifier of the target function object, or |
| * @c typeid(void) if @c !(bool)*this. |
| * |
| * This function will not throw an %exception. |
| */ |
| const type_info& target_type() const noexcept; |
| |
| /** |
| * @brief Access the stored target function object. |
| * |
| * @return Returns a pointer to the stored target function object, |
| * if @c typeid(_Functor).equals(target_type()); otherwise, a NULL |
| * pointer. |
| * |
| * This function does not throw exceptions. |
| * |
| * @{ |
| */ |
| template<typename _Functor> _Functor* target() noexcept; |
| |
| template<typename _Functor> const _Functor* target() const noexcept; |
| // @} |
| #endif |
| |
| private: |
| using _Invoker_type = _Res (*)(const _Any_data&, _ArgTypes&&...); |
| _Invoker_type _M_invoker; |
| }; |
| |
| #if __cpp_deduction_guides >= 201606 |
| template<typename> |
| struct __function_guide_helper |
| { }; |
| |
| template<typename _Res, typename _Tp, bool _Nx, typename... _Args> |
| struct __function_guide_helper< |
| _Res (_Tp::*) (_Args...) noexcept(_Nx) |
| > |
| { using type = _Res(_Args...); }; |
| |
| template<typename _Res, typename _Tp, bool _Nx, typename... _Args> |
| struct __function_guide_helper< |
| _Res (_Tp::*) (_Args...) & noexcept(_Nx) |
| > |
| { using type = _Res(_Args...); }; |
| |
| template<typename _Res, typename _Tp, bool _Nx, typename... _Args> |
| struct __function_guide_helper< |
| _Res (_Tp::*) (_Args...) const noexcept(_Nx) |
| > |
| { using type = _Res(_Args...); }; |
| |
| template<typename _Res, typename _Tp, bool _Nx, typename... _Args> |
| struct __function_guide_helper< |
| _Res (_Tp::*) (_Args...) const & noexcept(_Nx) |
| > |
| { using type = _Res(_Args...); }; |
| |
| template<typename _Res, typename... _ArgTypes> |
| function(_Res(*)(_ArgTypes...)) -> function<_Res(_ArgTypes...)>; |
| |
| template<typename _Functor, typename _Signature = typename |
| __function_guide_helper<decltype(&_Functor::operator())>::type> |
| function(_Functor) -> function<_Signature>; |
| #endif |
| |
| // Out-of-line member definitions. |
| template<typename _Res, typename... _ArgTypes> |
| function<_Res(_ArgTypes...)>:: |
| function(const function& __x) |
| : _Function_base() |
| { |
| if (static_cast<bool>(__x)) |
| { |
| __x._M_manager(_M_functor, __x._M_functor, __clone_functor); |
| _M_invoker = __x._M_invoker; |
| _M_manager = __x._M_manager; |
| } |
| } |
| |
| template<typename _Res, typename... _ArgTypes> |
| template<typename _Functor, typename, typename> |
| function<_Res(_ArgTypes...)>:: |
| function(_Functor __f) |
| : _Function_base() |
| { |
| typedef _Function_handler<_Res(_ArgTypes...), _Functor> _My_handler; |
| |
| if (_My_handler::_M_not_empty_function(__f)) |
| { |
| _My_handler::_M_init_functor(_M_functor, std::move(__f)); |
| _M_invoker = &_My_handler::_M_invoke; |
| _M_manager = &_My_handler::_M_manager; |
| } |
| } |
| |
| template<typename _Res, typename... _ArgTypes> |
| _Res |
| function<_Res(_ArgTypes...)>:: |
| operator()(_ArgTypes... __args) const |
| { |
| if (_M_empty()) |
| __throw_bad_function_call(); |
| return _M_invoker(_M_functor, std::forward<_ArgTypes>(__args)...); |
| } |
| |
| #if __cpp_rtti |
| template<typename _Res, typename... _ArgTypes> |
| const type_info& |
| function<_Res(_ArgTypes...)>:: |
| target_type() const noexcept |
| { |
| if (_M_manager) |
| { |
| _Any_data __typeinfo_result; |
| _M_manager(__typeinfo_result, _M_functor, __get_type_info); |
| return *__typeinfo_result._M_access<const type_info*>(); |
| } |
| else |
| return typeid(void); |
| } |
| |
| template<typename _Res, typename... _ArgTypes> |
| template<typename _Functor> |
| _Functor* |
| function<_Res(_ArgTypes...)>:: |
| target() noexcept |
| { |
| const function* __const_this = this; |
| const _Functor* __func = __const_this->template target<_Functor>(); |
| return const_cast<_Functor*>(__func); |
| } |
| |
| template<typename _Res, typename... _ArgTypes> |
| template<typename _Functor> |
| const _Functor* |
| function<_Res(_ArgTypes...)>:: |
| target() const noexcept |
| { |
| if (typeid(_Functor) == target_type() && _M_manager) |
| { |
| _Any_data __ptr; |
| _M_manager(__ptr, _M_functor, __get_functor_ptr); |
| return __ptr._M_access<const _Functor*>(); |
| } |
| else |
| return nullptr; |
| } |
| #endif |
| |
| // [20.7.15.2.6] null pointer comparisons |
| |
| /** |
| * @brief Compares a polymorphic function object wrapper against 0 |
| * (the NULL pointer). |
| * @returns @c true if the wrapper has no target, @c false otherwise |
| * |
| * This function will not throw an %exception. |
| */ |
| template<typename _Res, typename... _Args> |
| inline bool |
| operator==(const function<_Res(_Args...)>& __f, nullptr_t) noexcept |
| { return !static_cast<bool>(__f); } |
| |
| #if __cpp_impl_three_way_comparison < 201907L |
| /// @overload |
| template<typename _Res, typename... _Args> |
| inline bool |
| operator==(nullptr_t, const function<_Res(_Args...)>& __f) noexcept |
| { return !static_cast<bool>(__f); } |
| |
| /** |
| * @brief Compares a polymorphic function object wrapper against 0 |
| * (the NULL pointer). |
| * @returns @c false if the wrapper has no target, @c true otherwise |
| * |
| * This function will not throw an %exception. |
| */ |
| template<typename _Res, typename... _Args> |
| inline bool |
| operator!=(const function<_Res(_Args...)>& __f, nullptr_t) noexcept |
| { return static_cast<bool>(__f); } |
| |
| /// @overload |
| template<typename _Res, typename... _Args> |
| inline bool |
| operator!=(nullptr_t, const function<_Res(_Args...)>& __f) noexcept |
| { return static_cast<bool>(__f); } |
| #endif |
| |
| // [20.7.15.2.7] specialized algorithms |
| |
| /** |
| * @brief Swap the targets of two polymorphic function object wrappers. |
| * |
| * This function will not throw an %exception. |
| */ |
| // _GLIBCXX_RESOLVE_LIB_DEFECTS |
| // 2062. Effect contradictions w/o no-throw guarantee of std::function swaps |
| template<typename _Res, typename... _Args> |
| inline void |
| swap(function<_Res(_Args...)>& __x, function<_Res(_Args...)>& __y) noexcept |
| { __x.swap(__y); } |
| |
| #if __cplusplus >= 201703L |
| namespace __detail::__variant |
| { |
| template<typename> struct _Never_valueless_alt; // see <variant> |
| |
| // Provide the strong exception-safety guarantee when emplacing a |
| // function into a variant. |
| template<typename _Signature> |
| struct _Never_valueless_alt<std::function<_Signature>> |
| : std::true_type |
| { }; |
| } // namespace __detail::__variant |
| #endif // C++17 |
| |
| _GLIBCXX_END_NAMESPACE_VERSION |
| } // namespace std |
| |
| #endif // C++11 |
| #endif // _GLIBCXX_STD_FUNCTION_H |