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// Implementation of std::reference_wrapper -*- C++ -*-
// Copyright (C) 2004-2017 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/bind.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{functional}
*/
#ifndef _GLIBCXX_REFWRAP_H
#define _GLIBCXX_REFWRAP_H 1
#pragma GCC system_header
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
#include <bits/move.h>
#include <bits/invoke.h>
#include <bits/stl_function.h> // for unary_function and binary_function
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/// If we have found a result_type, extract it.
template<typename _Functor, typename = __void_t<>>
struct _Maybe_get_result_type
{ };
template<typename _Functor>
struct _Maybe_get_result_type<_Functor,
__void_t<typename _Functor::result_type>>
{ typedef typename _Functor::result_type result_type; };
/**
* Base class for any function object that has a weak result type, as
* defined in 20.8.2 [func.require] of C++11.
*/
template<typename _Functor>
struct _Weak_result_type_impl
: _Maybe_get_result_type<_Functor>
{ };
/// Retrieve the result type for a function type.
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(_ArgTypes...)>
{ typedef _Res result_type; };
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(_ArgTypes......)>
{ typedef _Res result_type; };
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(_ArgTypes...) const>
{ typedef _Res result_type; };
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(_ArgTypes......) const>
{ typedef _Res result_type; };
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(_ArgTypes...) volatile>
{ typedef _Res result_type; };
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(_ArgTypes......) volatile>
{ typedef _Res result_type; };
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(_ArgTypes...) const volatile>
{ typedef _Res result_type; };
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(_ArgTypes......) const volatile>
{ typedef _Res result_type; };
/// Retrieve the result type for a function reference.
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(&)(_ArgTypes...)>
{ typedef _Res result_type; };
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(&)(_ArgTypes......)>
{ typedef _Res result_type; };
/// Retrieve the result type for a function pointer.
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(*)(_ArgTypes...)>
{ typedef _Res result_type; };
template<typename _Res, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res(*)(_ArgTypes......)>
{ typedef _Res result_type; };
/// Retrieve result type for a member function pointer.
template<typename _Res, typename _Class, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res (_Class::*)(_ArgTypes...)>
{ typedef _Res result_type; };
template<typename _Res, typename _Class, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res (_Class::*)(_ArgTypes......)>
{ typedef _Res result_type; };
/// Retrieve result type for a const member function pointer.
template<typename _Res, typename _Class, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res (_Class::*)(_ArgTypes...) const>
{ typedef _Res result_type; };
template<typename _Res, typename _Class, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res (_Class::*)(_ArgTypes......) const>
{ typedef _Res result_type; };
/// Retrieve result type for a volatile member function pointer.
template<typename _Res, typename _Class, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res (_Class::*)(_ArgTypes...) volatile>
{ typedef _Res result_type; };
template<typename _Res, typename _Class, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res (_Class::*)(_ArgTypes......) volatile>
{ typedef _Res result_type; };
/// Retrieve result type for a const volatile member function pointer.
template<typename _Res, typename _Class, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res (_Class::*)(_ArgTypes...)
const volatile>
{ typedef _Res result_type; };
template<typename _Res, typename _Class, typename... _ArgTypes>
struct _Weak_result_type_impl<_Res (_Class::*)(_ArgTypes......)
const volatile>
{ typedef _Res result_type; };
/**
* Strip top-level cv-qualifiers from the function object and let
* _Weak_result_type_impl perform the real work.
*/
template<typename _Functor>
struct _Weak_result_type
: _Weak_result_type_impl<typename remove_cv<_Functor>::type>
{ };
// Detect nested argument_type.
template<typename _Tp, typename = __void_t<>>
struct _Refwrap_base_arg1
{ };
// Nested argument_type.
template<typename _Tp>
struct _Refwrap_base_arg1<_Tp,
__void_t<typename _Tp::argument_type>>
{
typedef typename _Tp::argument_type argument_type;
};
// Detect nested first_argument_type and second_argument_type.
template<typename _Tp, typename = __void_t<>>
struct _Refwrap_base_arg2
{ };
// Nested first_argument_type and second_argument_type.
template<typename _Tp>
struct _Refwrap_base_arg2<_Tp,
__void_t<typename _Tp::first_argument_type,
typename _Tp::second_argument_type>>
{
typedef typename _Tp::first_argument_type first_argument_type;
typedef typename _Tp::second_argument_type second_argument_type;
};
/**
* Derives from unary_function or binary_function when it
* can. Specializations handle all of the easy cases. The primary
* template determines what to do with a class type, which may
* derive from both unary_function and binary_function.
*/
template<typename _Tp>
struct _Reference_wrapper_base
: _Weak_result_type<_Tp>, _Refwrap_base_arg1<_Tp>, _Refwrap_base_arg2<_Tp>
{ };
// - a function type (unary)
template<typename _Res, typename _T1>
struct _Reference_wrapper_base<_Res(_T1)>
: unary_function<_T1, _Res>
{ };
template<typename _Res, typename _T1>
struct _Reference_wrapper_base<_Res(_T1) const>
: unary_function<_T1, _Res>
{ };
template<typename _Res, typename _T1>
struct _Reference_wrapper_base<_Res(_T1) volatile>
: unary_function<_T1, _Res>
{ };
template<typename _Res, typename _T1>
struct _Reference_wrapper_base<_Res(_T1) const volatile>
: unary_function<_T1, _Res>
{ };
// - a function type (binary)
template<typename _Res, typename _T1, typename _T2>
struct _Reference_wrapper_base<_Res(_T1, _T2)>
: binary_function<_T1, _T2, _Res>
{ };
template<typename _Res, typename _T1, typename _T2>
struct _Reference_wrapper_base<_Res(_T1, _T2) const>
: binary_function<_T1, _T2, _Res>
{ };
template<typename _Res, typename _T1, typename _T2>
struct _Reference_wrapper_base<_Res(_T1, _T2) volatile>
: binary_function<_T1, _T2, _Res>
{ };
template<typename _Res, typename _T1, typename _T2>
struct _Reference_wrapper_base<_Res(_T1, _T2) const volatile>
: binary_function<_T1, _T2, _Res>
{ };
// - a function pointer type (unary)
template<typename _Res, typename _T1>
struct _Reference_wrapper_base<_Res(*)(_T1)>
: unary_function<_T1, _Res>
{ };
// - a function pointer type (binary)
template<typename _Res, typename _T1, typename _T2>
struct _Reference_wrapper_base<_Res(*)(_T1, _T2)>
: binary_function<_T1, _T2, _Res>
{ };
// - a pointer to member function type (unary, no qualifiers)
template<typename _Res, typename _T1>
struct _Reference_wrapper_base<_Res (_T1::*)()>
: unary_function<_T1*, _Res>
{ };
// - a pointer to member function type (binary, no qualifiers)
template<typename _Res, typename _T1, typename _T2>
struct _Reference_wrapper_base<_Res (_T1::*)(_T2)>
: binary_function<_T1*, _T2, _Res>
{ };
// - a pointer to member function type (unary, const)
template<typename _Res, typename _T1>
struct _Reference_wrapper_base<_Res (_T1::*)() const>
: unary_function<const _T1*, _Res>
{ };
// - a pointer to member function type (binary, const)
template<typename _Res, typename _T1, typename _T2>
struct _Reference_wrapper_base<_Res (_T1::*)(_T2) const>
: binary_function<const _T1*, _T2, _Res>
{ };
// - a pointer to member function type (unary, volatile)
template<typename _Res, typename _T1>
struct _Reference_wrapper_base<_Res (_T1::*)() volatile>
: unary_function<volatile _T1*, _Res>
{ };
// - a pointer to member function type (binary, volatile)
template<typename _Res, typename _T1, typename _T2>
struct _Reference_wrapper_base<_Res (_T1::*)(_T2) volatile>
: binary_function<volatile _T1*, _T2, _Res>
{ };
// - a pointer to member function type (unary, const volatile)
template<typename _Res, typename _T1>
struct _Reference_wrapper_base<_Res (_T1::*)() const volatile>
: unary_function<const volatile _T1*, _Res>
{ };
// - a pointer to member function type (binary, const volatile)
template<typename _Res, typename _T1, typename _T2>
struct _Reference_wrapper_base<_Res (_T1::*)(_T2) const volatile>
: binary_function<const volatile _T1*, _T2, _Res>
{ };
/**
* @brief Primary class template for reference_wrapper.
* @ingroup functors
* @{
*/
template<typename _Tp>
class reference_wrapper
: public _Reference_wrapper_base<typename remove_cv<_Tp>::type>
{
_Tp* _M_data;
public:
typedef _Tp type;
reference_wrapper(_Tp& __indata) noexcept
: _M_data(std::__addressof(__indata))
{ }
reference_wrapper(_Tp&&) = delete;
reference_wrapper(const reference_wrapper&) = default;
reference_wrapper&
operator=(const reference_wrapper&) = default;
operator _Tp&() const noexcept
{ return this->get(); }
_Tp&
get() const noexcept
{ return *_M_data; }
template<typename... _Args>
typename result_of<_Tp&(_Args&&...)>::type
operator()(_Args&&... __args) const
{
return std::__invoke(get(), std::forward<_Args>(__args)...);
}
};
/// Denotes a reference should be taken to a variable.
template<typename _Tp>
inline reference_wrapper<_Tp>
ref(_Tp& __t) noexcept
{ return reference_wrapper<_Tp>(__t); }
/// Denotes a const reference should be taken to a variable.
template<typename _Tp>
inline reference_wrapper<const _Tp>
cref(const _Tp& __t) noexcept
{ return reference_wrapper<const _Tp>(__t); }
template<typename _Tp>
void ref(const _Tp&&) = delete;
template<typename _Tp>
void cref(const _Tp&&) = delete;
/// Partial specialization.
template<typename _Tp>
inline reference_wrapper<_Tp>
ref(reference_wrapper<_Tp> __t) noexcept
{ return ref(__t.get()); }
/// Partial specialization.
template<typename _Tp>
inline reference_wrapper<const _Tp>
cref(reference_wrapper<_Tp> __t) noexcept
{ return cref(__t.get()); }
// @} group functors
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++11
#endif // _GLIBCXX_REFWRAP_H
|
