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The C and C++ Include Header Files

cat -n /usr/include/c++/15/tr2/type_traits

     1	// TR2 <type_traits> -*- C++ -*-
     2	
     3	// Copyright (C) 2011-2025 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 tr2/type_traits
    26	 *  This is a TR2 C++ Library header.
    27	 */
    28	
    29	#ifndef _GLIBCXX_TR2_TYPE_TRAITS
    30	#define _GLIBCXX_TR2_TYPE_TRAITS 1
    31	
    32	#ifdef _GLIBCXX_SYSHDR
    33	#pragma GCC system_header
    34	#endif
    35	#include <type_traits>
    36	#include <bits/c++config.h>
    37	
    38	namespace std _GLIBCXX_VISIBILITY(default)
    39	{
    40	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    41	
    42	namespace tr2
    43	{
    44	  /**
    45	   * @addtogroup metaprogramming
    46	   * @{
    47	   */
    48	
    49	  /**
    50	   *  See N2965: Type traits and base classes
    51	   *  by Michael Spertus
    52	   */
    53	
    54	  /**
    55	   *  Simple typelist. Compile-time list of types.
    56	   */
    57	  template<typename... _Elements>
    58	    struct __reflection_typelist;
    59	
    60	  /// Specialization for an empty typelist.
    61	  template<>
    62	    struct __reflection_typelist<>
    63	    {
    64	      typedef std::true_type					empty;
    65	    };
    66	
    67	  /// Partial specialization.
    68	  template<typename _First, typename... _Rest>
    69	    struct __reflection_typelist<_First, _Rest...>
    70	    {
    71	      typedef std::false_type					empty;
    72	
    73	      struct first
    74	      {
    75		typedef _First						type;
    76	      };
    77	
    78	      struct rest
    79	      {
    80		typedef __reflection_typelist<_Rest...>			type;
    81	      };
    82	    };
    83	
    84	  /// Sequence abstraction metafunctions for manipulating a typelist.
    85	
    86	
    87	#if __has_builtin(__bases)
    88	  /// Enumerate all the base classes of a class. Form of a typelist.
    89	  template<typename _Tp>
    90	    struct bases
    91	    {
    92	      typedef __reflection_typelist<__bases(_Tp)...>		type;
    93	    };
    94	#endif
    95	
    96	#if __has_builtin(__direct_bases)
    97	  /// Enumerate all the direct base classes of a class. Form of a typelist.
    98	  template<typename _Tp>
    99	    struct direct_bases
   100	    {
   101	      typedef __reflection_typelist<__direct_bases(_Tp)...>	type;
   102	    };
   103	#endif
   104	
   105	  /// @} group metaprogramming
   106	}
   107	
   108	_GLIBCXX_END_NAMESPACE_VERSION
   109	}
   110	
   111	#endif // _GLIBCXX_TR2_TYPE_TRAITS