The C and C++ Include Header Files

/usr/include/c++/11/bits/move.h


$ cat -n /usr/include/c++/11/bits/move.h

     1	// Move, forward and identity for C++11 + swap -*- C++ -*-
     2	
     3	// Copyright (C) 2007-2021 Free Software Foundation, Inc.
     4	//
     5	// This file is part of the GNU ISO C++ Library.  This library is free
     6	// software; you can redistribute it and/or modify it under the
     7	// terms of the GNU General Public License as published by the
     8	// Free Software Foundation; either version 3, or (at your option)
     9	// any later version.
    10	
    11	// This library is distributed in the hope that it will be useful,
    12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
    13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    14	// GNU General Public License for more details.
    15	
    16	// Under Section 7 of GPL version 3, you are granted additional
    17	// permissions described in the GCC Runtime Library Exception, version
    18	// 3.1, as published by the Free Software Foundation.
    19	
    20	// You should have received a copy of the GNU General Public License and
    21	// a copy of the GCC Runtime Library Exception along with this program;
    22	// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    23	// <http://www.gnu.org/licenses/>.
    24	
    25	/** @file bits/move.h
    26	 *  This is an internal header file, included by other library headers.
    27	 *  Do not attempt to use it directly. @headername{utility}
    28	 */
    29	
    30	#ifndef _MOVE_H
    31	#define _MOVE_H 1
    32	
    33	#include <bits/c++config.h>
    34	#if __cplusplus < 201103L
    35	# include <bits/concept_check.h>
    36	#endif
    37	
    38	namespace std _GLIBCXX_VISIBILITY(default)
    39	{
    40	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    41	
    42	  // Used, in C++03 mode too, by allocators, etc.
    43	  /**
    44	   *  @brief Same as C++11 std::addressof
    45	   *  @ingroup utilities
    46	   */
    47	  template<typename _Tp>
    48	    inline _GLIBCXX_CONSTEXPR _Tp*
    49	    __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT
    50	    { return __builtin_addressof(__r); }
    51	
    52	#if __cplusplus >= 201103L
    53	
    54	_GLIBCXX_END_NAMESPACE_VERSION
    55	} // namespace
    56	
    57	#include <type_traits> // Brings in std::declval too.
    58	
    59	namespace std _GLIBCXX_VISIBILITY(default)
    60	{
    61	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    62	
    63	  /**
    64	   *  @addtogroup utilities
    65	   *  @{
    66	   */
    67	
    68	  /**
    69	   *  @brief  Forward an lvalue.
    70	   *  @return The parameter cast to the specified type.
    71	   *
    72	   *  This function is used to implement "perfect forwarding".
    73	   */
    74	  template<typename _Tp>
    75	    _GLIBCXX_NODISCARD
    76	    constexpr _Tp&&
    77	    forward(typename std::remove_reference<_Tp>::type& __t) noexcept
    78	    { return static_cast<_Tp&&>(__t); }
    79	
    80	  /**
    81	   *  @brief  Forward an rvalue.
    82	   *  @return The parameter cast to the specified type.
    83	   *
    84	   *  This function is used to implement "perfect forwarding".
    85	   */
    86	  template<typename _Tp>
    87	    _GLIBCXX_NODISCARD
    88	    constexpr _Tp&&
    89	    forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
    90	    {
    91	      static_assert(!std::is_lvalue_reference<_Tp>::value,
    92		  "std::forward must not be used to convert an rvalue to an lvalue");
    93	      return static_cast<_Tp&&>(__t);
    94	    }
    95	
    96	  /**
    97	   *  @brief  Convert a value to an rvalue.
    98	   *  @param  __t  A thing of arbitrary type.
    99	   *  @return The parameter cast to an rvalue-reference to allow moving it.
   100	  */
   101	  template<typename _Tp>
   102	    _GLIBCXX_NODISCARD
   103	    constexpr typename std::remove_reference<_Tp>::type&&
   104	    move(_Tp&& __t) noexcept
   105	    { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
   106	
   107	
   108	  template<typename _Tp>
   109	    struct __move_if_noexcept_cond
   110	    : public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
   111	                    is_copy_constructible<_Tp>>::type { };
   112	
   113	  /**
   114	   *  @brief  Conditionally convert a value to an rvalue.
   115	   *  @param  __x  A thing of arbitrary type.
   116	   *  @return The parameter, possibly cast to an rvalue-reference.
   117	   *
   118	   *  Same as std::move unless the type's move constructor could throw and the
   119	   *  type is copyable, in which case an lvalue-reference is returned instead.
   120	   */
   121	  template<typename _Tp>
   122	    _GLIBCXX_NODISCARD
   123	    constexpr typename
   124	    conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type
   125	    move_if_noexcept(_Tp& __x) noexcept
   126	    { return std::move(__x); }
   127	
   128	  // declval, from type_traits.
   129	
   130	#if __cplusplus > 201402L
   131	  // _GLIBCXX_RESOLVE_LIB_DEFECTS
   132	  // 2296. std::addressof should be constexpr
   133	# define __cpp_lib_addressof_constexpr 201603
   134	#endif
   135	  /**
   136	   *  @brief Returns the actual address of the object or function
   137	   *         referenced by r, even in the presence of an overloaded
   138	   *         operator&.
   139	   *  @param  __r  Reference to an object or function.
   140	   *  @return   The actual address.
   141	  */
   142	  template<typename _Tp>
   143	    _GLIBCXX_NODISCARD
   144	    inline _GLIBCXX17_CONSTEXPR _Tp*
   145	    addressof(_Tp& __r) noexcept
   146	    { return std::__addressof(__r); }
   147	
   148	  // _GLIBCXX_RESOLVE_LIB_DEFECTS
   149	  // 2598. addressof works on temporaries
   150	  template<typename _Tp>
   151	    const _Tp* addressof(const _Tp&&) = delete;
   152	
   153	  // C++11 version of std::exchange for internal use.
   154	  template <typename _Tp, typename _Up = _Tp>
   155	    _GLIBCXX20_CONSTEXPR
   156	    inline _Tp
   157	    __exchange(_Tp& __obj, _Up&& __new_val)
   158	    {
   159	      _Tp __old_val = std::move(__obj);
   160	      __obj = std::forward<_Up>(__new_val);
   161	      return __old_val;
   162	    }
   163	
   164	  /// @} group utilities
   165	
   166	#define _GLIBCXX_FWDREF(_Tp) _Tp&&
   167	#define _GLIBCXX_MOVE(__val) std::move(__val)
   168	#define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
   169	#else
   170	#define _GLIBCXX_FWDREF(_Tp) const _Tp&
   171	#define _GLIBCXX_MOVE(__val) (__val)
   172	#define _GLIBCXX_FORWARD(_Tp, __val) (__val)
   173	#endif
   174	
   175	  /**
   176	   *  @addtogroup utilities
   177	   *  @{
   178	   */
   179	
   180	  /**
   181	   *  @brief Swaps two values.
   182	   *  @param  __a  A thing of arbitrary type.
   183	   *  @param  __b  Another thing of arbitrary type.
   184	   *  @return   Nothing.
   185	  */
   186	  template<typename _Tp>
   187	    _GLIBCXX20_CONSTEXPR
   188	    inline
   189	#if __cplusplus >= 201103L
   190	    typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>,
   191				      is_move_constructible<_Tp>,
   192				      is_move_assignable<_Tp>>::value>::type
   193	#else
   194	    void
   195	#endif
   196	    swap(_Tp& __a, _Tp& __b)
   197	    _GLIBCXX_NOEXCEPT_IF(__and_<is_nothrow_move_constructible<_Tp>,
   198					is_nothrow_move_assignable<_Tp>>::value)
   199	    {
   200	#if __cplusplus < 201103L
   201	      // concept requirements
   202	      __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
   203	#endif
   204	      _Tp __tmp = _GLIBCXX_MOVE(__a);
   205	      __a = _GLIBCXX_MOVE(__b);
   206	      __b = _GLIBCXX_MOVE(__tmp);
   207	    }
   208	
   209	  // _GLIBCXX_RESOLVE_LIB_DEFECTS
   210	  // DR 809. std::swap should be overloaded for array types.
   211	  /// Swap the contents of two arrays.
   212	  template<typename _Tp, size_t _Nm>
   213	    _GLIBCXX20_CONSTEXPR
   214	    inline
   215	#if __cplusplus >= 201103L
   216	    typename enable_if<__is_swappable<_Tp>::value>::type
   217	#else
   218	    void
   219	#endif
   220	    swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
   221	    _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Tp>::value)
   222	    {
   223	      for (size_t __n = 0; __n < _Nm; ++__n)
   224		swap(__a[__n], __b[__n]);
   225	    }
   226	
   227	  /// @} group utilities
   228	_GLIBCXX_END_NAMESPACE_VERSION
   229	} // namespace
   230	
   231	#endif /* _MOVE_H */