FM / bits

/usr/include/c++/9/bits

Name	Size	Mode	Actions
algorithmfwd.h	21737	0644	edit dl rm
allocated_ptr.h	3293	0644	edit dl rm
allocator.h	7942	0644	edit dl rm
alloc_traits.h	21481	0644	edit dl rm
atomic_base.h	24993	0644	edit dl rm
atomic_futex.h	9499	0644	edit dl rm
atomic_lockfree_defines.h	2353	0644	edit dl rm
basic_ios.h	16080	0644	edit dl rm
basic_ios.tcc	6083	0644	edit dl rm
basic_string.h	247075	0644	edit dl rm
basic_string.tcc	53891	0644	edit dl rm
boost_concept_check.h	27161	0644	edit dl rm
c++0x_warning.h	1474	0644	edit dl rm
char_traits.h	24828	0644	edit dl rm
codecvt.h	25429	0644	edit dl rm
concept_check.h	3423	0644	edit dl rm
cpp_type_traits.h	9947	0644	edit dl rm
cxxabi_forced.h	1811	0644	edit dl rm
cxxabi_init_exception.h	2220	0644	edit dl rm
deque.tcc	34404	0644	edit dl rm
enable_special_members.h	12387	0644	edit dl rm
erase_if.h	2037	0644	edit dl rm
exception.h	2486	0644	edit dl rm
exception_defines.h	1645	0644	edit dl rm
exception_ptr.h	5982	0644	edit dl rm
forward_list.h	49405	0644	edit dl rm
forward_list.tcc	13871	0644	edit dl rm
fstream.tcc	33663	0644	edit dl rm
fs_dir.h	15168	0644	edit dl rm
fs_fwd.h	11687	0644	edit dl rm
fs_ops.h	9731	0644	edit dl rm
fs_path.h	36954	0644	edit dl rm
functexcept.h	3433	0644	edit dl rm
functional_hash.h	8568	0644	edit dl rm
gslice.h	5519	0644	edit dl rm
gslice_array.h	7852	0644	edit dl rm
hashtable.h	74814	0644	edit dl rm
hashtable_policy.h	68109	0644	edit dl rm
hash_bytes.h	2146	0644	edit dl rm
indirect_array.h	7862	0644	edit dl rm
invoke.h	3657	0644	edit dl rm
ios_base.h	31434	0644	edit dl rm
istream.tcc	31093	0644	edit dl rm
list.tcc	16968	0644	edit dl rm
localefwd.h	5941	0644	edit dl rm
locale_classes.h	24903	0644	edit dl rm
locale_classes.tcc	8375	0644	edit dl rm
locale_conv.h	18801	0644	edit dl rm
locale_facets.h	92339	0644	edit dl rm
locale_facets.tcc	39548	0644	edit dl rm
locale_facets_nonio.h	68994	0644	edit dl rm
locale_facets_nonio.tcc	45280	0644	edit dl rm
mask_array.h	7676	0644	edit dl rm
memoryfwd.h	2453	0644	edit dl rm
move.h	6529	0644	edit dl rm
nested_exception.h	4803	0644	edit dl rm
node_handle.h	8216	0644	edit dl rm
ostream.tcc	12315	0644	edit dl rm
ostream_insert.h	4002	0644	edit dl rm
parse_numbers.h	7944	0644	edit dl rm
postypes.h	8465	0644	edit dl rm
predefined_ops.h	9083	0644	edit dl rm
ptr_traits.h	6728	0644	edit dl rm
quoted_string.h	5053	0644	edit dl rm
random.h	178041	0644	edit dl rm
random.tcc	105619	0644	edit dl rm
range_access.h	10084	0644	edit dl rm
refwrap.h	12927	0644	edit dl rm
regex.h	98707	0644	edit dl rm
regex.tcc	16574	0644	edit dl rm
regex_automaton.h	10739	0644	edit dl rm
regex_automaton.tcc	7722	0644	edit dl rm
regex_compiler.h	16482	0644	edit dl rm
regex_compiler.tcc	18929	0644	edit dl rm
regex_constants.h	14707	0644	edit dl rm
regex_error.h	4907	0644	edit dl rm
regex_executor.h	7489	0644	edit dl rm
regex_executor.tcc	18841	0644	edit dl rm
regex_scanner.h	7089	0644	edit dl rm
regex_scanner.tcc	15009	0644	edit dl rm
shared_ptr.h	24221	0644	edit dl rm
shared_ptr_atomic.h	9775	0644	edit dl rm
shared_ptr_base.h	53771	0644	edit dl rm
slice_array.h	9430	0644	edit dl rm
specfun.h	47052	0644	edit dl rm
sstream.tcc	10142	0644	edit dl rm
std_abs.h	3384	0644	edit dl rm
std_function.h	23566	0644	edit dl rm
std_mutex.h	4768	0644	edit dl rm
stl_algo.h	215416	0644	edit dl rm
stl_algobase.h	51417	0644	edit dl rm
stl_bvector.h	33888	0644	edit dl rm
stl_construct.h	7397	0644	edit dl rm
stl_deque.h	80116	0644	edit dl rm
stl_function.h	42293	0644	edit dl rm
stl_heap.h	20206	0644	edit dl rm
stl_iterator.h	42755	0644	edit dl rm
stl_iterator_base_funcs.h	8178	0644	edit dl rm
stl_iterator_base_types.h	8682	0644	edit dl rm
stl_list.h	67809	0644	edit dl rm
stl_map.h	53495	0644	edit dl rm
stl_multimap.h	42240	0644	edit dl rm
stl_multiset.h	36486	0644	edit dl rm
stl_numeric.h	14376	0644	edit dl rm
stl_pair.h	18642	0644	edit dl rm
stl_queue.h	24580	0644	edit dl rm
stl_raw_storage_iter.h	3830	0644	edit dl rm
stl_relops.h	4594	0644	edit dl rm
stl_set.h	36790	0644	edit dl rm
stl_stack.h	12228	0644	edit dl rm
stl_tempbuf.h	8287	0644	edit dl rm
stl_tree.h	75018	0644	edit dl rm
stl_uninitialized.h	31455	0644	edit dl rm
stl_vector.h	64968	0644	edit dl rm
streambuf.tcc	4929	0644	edit dl rm
streambuf_iterator.h	13889	0644	edit dl rm
stream_iterator.h	6867	0644	edit dl rm
stringfwd.h	2690	0644	edit dl rm
string_view.tcc	6698	0644	edit dl rm
uniform_int_dist.h	10248	0644	edit dl rm
unique_lock.h	6102	0644	edit dl rm
unique_ptr.h	27564	0644	edit dl rm
unordered_map.h	76884	0644	edit dl rm
unordered_set.h	60677	0644	edit dl rm
uses_allocator.h	6824	0644	edit dl rm
valarray_after.h	22839	0644	edit dl rm
valarray_array.h	21295	0644	edit dl rm
valarray_array.tcc	7254	0644	edit dl rm
valarray_before.h	19142	0644	edit dl rm
vector.tcc	30870	0644	edit dl rm

Edit: /usr/include/c++/9/bits/refwrap.h (12927B)

// Implementation of std::reference_wrapper -*- 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/refwrap.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

/**
   * Derives from @c unary_function or @c binary_function, or perhaps
   * nothing, depending on the number of arguments provided. The
   * primary template is the basis case, which derives nothing.
   */
  template<typename _Res, typename... _ArgTypes>
    struct _Maybe_unary_or_binary_function { };

/// Derives from @c unary_function, as appropriate.
  template<typename _Res, typename _T1>
    struct _Maybe_unary_or_binary_function<_Res, _T1>
    : std::unary_function<_T1, _Res> { };

/// Derives from @c binary_function, as appropriate.
  template<typename _Res, typename _T1, typename _T2>
    struct _Maybe_unary_or_binary_function<_Res, _T1, _T2>
    : std::binary_function<_T1, _T2, _Res> { };

template<typename _Signature>
    struct _Mem_fn_traits;

template<typename _Res, typename _Class, typename... _ArgTypes>
    struct _Mem_fn_traits_base
    {
      using __result_type = _Res;
      using __maybe_type
	= _Maybe_unary_or_binary_function<_Res, _Class*, _ArgTypes...>;
      using __arity = integral_constant<size_t, sizeof...(_ArgTypes)>;
    };

#define _GLIBCXX_MEM_FN_TRAITS2(_CV, _REF, _LVAL, _RVAL)		\
  template<typename _Res, typename _Class, typename... _ArgTypes>	\
    struct _Mem_fn_traits<_Res (_Class::*)(_ArgTypes...) _CV _REF>	\
    : _Mem_fn_traits_base<_Res, _CV _Class, _ArgTypes...>		\
    {									\
      using __vararg = false_type;					\
    };									\
  template<typename _Res, typename _Class, typename... _ArgTypes>	\
    struct _Mem_fn_traits<_Res (_Class::*)(_ArgTypes... ...) _CV _REF>	\
    : _Mem_fn_traits_base<_Res, _CV _Class, _ArgTypes...>		\
    {									\
      using __vararg = true_type;					\
    };

#define _GLIBCXX_MEM_FN_TRAITS(_REF, _LVAL, _RVAL)		\
  _GLIBCXX_MEM_FN_TRAITS2(		, _REF, _LVAL, _RVAL)	\
  _GLIBCXX_MEM_FN_TRAITS2(const		, _REF, _LVAL, _RVAL)	\
  _GLIBCXX_MEM_FN_TRAITS2(volatile	, _REF, _LVAL, _RVAL)	\
  _GLIBCXX_MEM_FN_TRAITS2(const volatile, _REF, _LVAL, _RVAL)

_GLIBCXX_MEM_FN_TRAITS( , true_type, true_type)
_GLIBCXX_MEM_FN_TRAITS(&, true_type, false_type)
_GLIBCXX_MEM_FN_TRAITS(&&, false_type, true_type)

#if __cplusplus > 201402L
_GLIBCXX_MEM_FN_TRAITS(noexcept, true_type, true_type)
_GLIBCXX_MEM_FN_TRAITS(& noexcept, true_type, false_type)
_GLIBCXX_MEM_FN_TRAITS(&& noexcept, false_type, true_type)
#endif

#undef _GLIBCXX_MEM_FN_TRAITS
#undef _GLIBCXX_MEM_FN_TRAITS2

/// 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 _GLIBCXX_NOEXCEPT_PARM>
    struct _Weak_result_type_impl<_Res(_ArgTypes...) _GLIBCXX_NOEXCEPT_QUAL>
    { typedef _Res result_type; };

/// Retrieve the result type for a varargs function type.
  template<typename _Res, typename... _ArgTypes _GLIBCXX_NOEXCEPT_PARM>
    struct _Weak_result_type_impl<_Res(_ArgTypes......) _GLIBCXX_NOEXCEPT_QUAL>
    { typedef _Res result_type; };

/// Retrieve the result type for a function pointer.
  template<typename _Res, typename... _ArgTypes _GLIBCXX_NOEXCEPT_PARM>
    struct _Weak_result_type_impl<_Res(*)(_ArgTypes...) _GLIBCXX_NOEXCEPT_QUAL>
    { typedef _Res result_type; };

/// Retrieve the result type for a varargs function pointer.
  template<typename _Res, typename... _ArgTypes _GLIBCXX_NOEXCEPT_PARM>
    struct
    _Weak_result_type_impl<_Res(*)(_ArgTypes......) _GLIBCXX_NOEXCEPT_QUAL>
    { typedef _Res result_type; };

// Let _Weak_result_type_impl perform the real work.
  template<typename _Functor,
	   bool = is_member_function_pointer<_Functor>::value>
    struct _Weak_result_type_memfun
    : _Weak_result_type_impl<_Functor>
    { };

// A pointer to member function has a weak result type.
  template<typename _MemFunPtr>
    struct _Weak_result_type_memfun<_MemFunPtr, true>
    {
      using result_type = typename _Mem_fn_traits<_MemFunPtr>::__result_type;
    };

// A pointer to data member doesn't have a weak result type.
  template<typename _Func, typename _Class>
    struct _Weak_result_type_memfun<_Func _Class::*, false>
    { };

/**
   *  Strip top-level cv-qualifiers from the function object and let
   *  _Weak_result_type_memfun perform the real work.
  */
  template<typename _Functor>
    struct _Weak_result_type
    : _Weak_result_type_memfun<typename remove_cv<_Functor>::type>
    { };

#if __cplusplus <= 201703L
  // 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 _GLIBCXX_NOEXCEPT_PARM>
    struct _Reference_wrapper_base<_Res(_T1) _GLIBCXX_NOEXCEPT_QUAL>
    : 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 _GLIBCXX_NOEXCEPT_PARM>
    struct _Reference_wrapper_base<_Res(_T1, _T2) _GLIBCXX_NOEXCEPT_QUAL>
    : 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 _GLIBCXX_NOEXCEPT_PARM>
    struct _Reference_wrapper_base<_Res(*)(_T1) _GLIBCXX_NOEXCEPT_QUAL>
    : unary_function<_T1, _Res>
    { };

// - a function pointer type (binary)
  template<typename _Res, typename _T1, typename _T2 _GLIBCXX_NOEXCEPT_PARM>
    struct _Reference_wrapper_base<_Res(*)(_T1, _T2) _GLIBCXX_NOEXCEPT_QUAL>
    : binary_function<_T1, _T2, _Res>
    { };

template<typename _Tp, bool = is_member_function_pointer<_Tp>::value>
    struct _Reference_wrapper_base_memfun
    : _Reference_wrapper_base<_Tp>
    { };

template<typename _MemFunPtr>
    struct _Reference_wrapper_base_memfun<_MemFunPtr, true>
    : _Mem_fn_traits<_MemFunPtr>::__maybe_type
    {
      using result_type = typename _Mem_fn_traits<_MemFunPtr>::__result_type;
    };
#endif // ! C++20

/**
   *  @brief Primary class template for reference_wrapper.
   *  @ingroup functors
   *  @{
   */
  template<typename _Tp>
    class reference_wrapper
#if __cplusplus <= 201703L
    // In C++20 std::reference_wrapper<T> allows T to be incomplete,
    // so checking for nested types could result in ODR violations.
    : public _Reference_wrapper_base_memfun<typename remove_cv<_Tp>::type>
#endif
    {
      _Tp* _M_data;

static _Tp* _S_fun(_Tp& __r) noexcept { return std::__addressof(__r); }
      static void _S_fun(_Tp&&) = delete;

template<typename _Up, typename _Up2 = __remove_cvref_t<_Up>>
	using __not_same
	  = typename enable_if<!is_same<reference_wrapper, _Up2>::value>::type;

public:
      typedef _Tp type;

// _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 2993. reference_wrapper<T> conversion from T&&
      // 3041. Unnecessary decay in reference_wrapper
      template<typename _Up, typename = __not_same<_Up>, typename
		= decltype(reference_wrapper::_S_fun(std::declval<_Up>()))>
	reference_wrapper(_Up&& __uref)
	noexcept(noexcept(reference_wrapper::_S_fun(std::declval<_Up>())))
	: _M_data(reference_wrapper::_S_fun(std::forward<_Up>(__uref)))
	{ }

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
	{
#if __cplusplus > 201703L
	  if constexpr (is_object_v<type>)
	    static_assert(sizeof(type), "type must be complete");
#endif
	  return std::__invoke(get(), std::forward<_Args>(__args)...);
	}
    };

#if __cpp_deduction_guides
  template<typename _Tp>
    reference_wrapper(_Tp&) -> reference_wrapper<_Tp>;
#endif

/// 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;

/// std::ref overload to prevent wrapping a reference_wrapper
  template<typename _Tp>
    inline reference_wrapper<_Tp>
    ref(reference_wrapper<_Tp> __t) noexcept
    { return __t; }

/// std::cref overload to prevent wrapping a reference_wrapper
  template<typename _Tp>
    inline reference_wrapper<const _Tp>
    cref(reference_wrapper<_Tp> __t) noexcept
    { return { __t.get() }; }

/// @} group functors

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // C++11

#endif // _GLIBCXX_REFWRAP_H

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