Filename: //usr/include/c++//10/bits/std_function.h

// 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

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