gcc/libstdc++-v3/include/bits/std_function.h

713 lines
20 KiB
C
Raw Normal View History

// 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)
: _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;
}
}
/**
* @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 __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;
}
}
/**
* @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 (_M_empty())
__throw_bad_function_call();
return _M_invoker(_M_functor, std::forward<_ArgTypes>(__args)...);
}
#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
{
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);
}
/**
* @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
{
const function* __const_this = this;
const _Functor* __func = __const_this->template target<_Functor>();
return const_cast<_Functor*>(__func);
}
template<typename _Functor>
const _Functor*
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
private:
using _Invoker_type = _Res (*)(const _Any_data&, _ArgTypes&&...);
_Invoker_type _M_invoker;
};
Add deduction guides for C++17 (P0433R2, partial) * include/bits/shared_ptr.h (shared_ptr, weak_ptr): Add deduction guides for C++17. * include/bits/std_function.h (function): Likewise. * include/bits/stl_pair.h (pair): Likewise. * include/debug/array (__gnu_debug::array): Likewise. * include/std/array (array): Likewise. * include/std/functional (make_default_searcher) (make_boyer_moore_searcher, make_boyer_moore_horspool_searcher): Remove generator functions. * include/std/tuple (tuple): Add deduction guides. * include/std/valarray (valarray): Likewise. * testsuite/20_util/function_objects/searchers.cc: Adjust to use class template argument deduction instead of generator functions. * testsuite/20_util/function/cons/deduction.cc: New test. * testsuite/20_util/optional/cons/deduction_guide.cc: Rename to ... * testsuite/20_util/optional/cons/deduction.cc: ... here. * testsuite/20_util/pair/cons/deduction.cc: New test. * testsuite/20_util/shared_ptr/cons/deduction.cc: New test. * testsuite/20_util/tuple/cons/deduction.cc: New test. * testsuite/20_util/tuple/element_access/get_neg.cc: Adjust dg-error. * testsuite/20_util/unique_ptr/cons/deduction_neg.cc: New test. * testsuite/20_util/weak_ptr/cons/deduction.cc: New test. * testsuite/23_containers/array/cons/deduction.cc: New test. * testsuite/23_containers/array/cons/deduction_neg.cc: New test. * testsuite/23_containers/array/tuple_interface/get_debug_neg.cc: Adjust dg-error. * testsuite/23_containers/array/tuple_interface/get_neg.cc: Likewise. * testsuite/23_containers/array/tuple_interface/tuple_element_neg.cc: Likewise. * testsuite/26_numerics/valarray/deduction.cc: New test. * testsuite/30_threads/lock_guard/cons/deduction.cc: New test. * testsuite/30_threads/scoped_lock/cons/deduction.cc: New test. * testsuite/30_threads/unique_lock/cons/deduction.cc: New test. From-SVN: r246389
2017-03-22 16:58:35 +01:00
#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
// [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); }
PR libstdc++/87431 re-adjust never-valueless optimizations Avoid creating arbitrarily large objects on the stack when emplacing trivially copyable objects into a variant. Currently we provide the strong exception-safety guarantee for all trivially copyable types, by constructing a second variant and then doing a non-throwing move assignment from the temporary. This patch restricts that behaviour to trivially copyable types that are no larger than 256 bytes. For larger types the object will be emplaced directly into the variant, and if its initialization throws then the variant becomes valueless. Also implement Antony Polukhin's suggestion to whitelist specific types that are not trivially copyable but can be efficiently move-assigned. Emplacing those types will never cause a variant to become valueless. The whitelisted types are: std::shared_ptr, std::weak_ptr, std::unique_ptr, std::function, and std::any. Additionally, std::basic_string, std::vector, and __gnu_debug::vector are whitelisted if their allocator traits give them a non-throwing move assignment operator. Specifically, this means std::string is whitelisted, but std::pmr::string is not. As part of this patch, additional if-constexpr branches are added for the cases where the initialization is known to be non-throwing (so the overhead of the try-catch block can be avoided) and where a scalar is being produced by a potentially-throwing conversion operator (so that the overhead of constructing and move-assigning a variant is avoided). These changes should have no semantic effect, just better codegen. PR libstdc++/87431 (again) * include/bits/basic_string.h (__variant::_Never_valueless_alt): Define partial specialization for basic_string. * include/bits/shared_ptr.h (_Never_valueless_alt): Likewise for shared_ptr and weak_ptr. * include/bits/std_function.h (_Never_valueless_alt): Likewise for function. * include/bits/stl_vector.h (_Never_valueless_alt): Likewise for vector. * include/bits/unique_ptr.h (_Never_valueless_alt): Likewise for unique_ptr. * include/debug/vector (_Never_valueless_alt): Likewise for debug vector. * include/std/any (_Never_valueless_alt): Define explicit specialization for any. * include/std/variant (_Never_valueless_alt): Define primary template. (__never_valueless): Use _Never_valueless_alt instead of is_trivially_copyable. (variant::emplace<N>(Args&&...)): Add special case for non-throwing initializations to avoid try-catch overhead. Add special case for scalars produced by potentially-throwing conversions. Use _Never_valueless_alt instead of is_trivially_copyable for the remaining strong exception-safety cases. (variant::emplace<N>(initializer_list<U>, Args&&...)): Likewise. * testsuite/20_util/variant/87431.cc: Run both test functions. * testsuite/20_util/variant/exception_safety.cc: New test. * testsuite/20_util/variant/run.cc: Use pmr::string instead of string, so the variant becomes valueless. From-SVN: r270170
2019-04-05 18:56:09 +02:00
#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