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// Implementation of std::function -*- C++ -*-
// Copyright (C) 2004-2019 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); }
/// @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); }
// [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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