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The C and C++ Include Header Files

cat -n /usr/include/c++/15/bits/formatfwd.h

     1	// <format> Formatting -*- C++ -*-
     2	
     3	// Copyright The GNU Toolchain Authors.
     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/formatfwd.h
    26	 *  This is an internal header file, included by other library headers.
    27	 *  Do not attempt to use it directly. @headername{format}
    28	 */
    29	
    30	#ifndef _GLIBCXX_FORMAT_FWD_H
    31	#define _GLIBCXX_FORMAT_FWD_H 1
    32	
    33	#ifdef _GLIBCXX_SYSHDR
    34	#pragma GCC system_header
    35	#endif
    36	
    37	// <bits/version.h> must have been included before this header:
    38	#ifdef __glibcxx_format // C++ >= 20 && HOSTED
    39	
    40	#include <concepts>
    41	#include <type_traits>
    42	#if __glibcxx_format_ranges // C++ >= 23 && HOSTED
    43	#  include <bits/ranges_base.h>  // input_range, range_reference_t
    44	#endif
    45	
    46	namespace std _GLIBCXX_VISIBILITY(default)
    47	{
    48	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    49	
    50	  // [format.context], class template basic_format_context
    51	  template<typename _Out, typename _CharT> class basic_format_context;
    52	
    53	  // [format.parse.ctx], class template basic_format_parse_context
    54	  template<typename _CharT> class basic_format_parse_context;
    55	
    56	  // [format.formatter], formatter
    57	  template<typename _Tp, typename _CharT = char> struct formatter;
    58	
    59	/// @cond undocumented
    60	namespace __format
    61	{
    62	#ifdef _GLIBCXX_USE_WCHAR_T
    63	  template<typename _CharT>
    64	    concept __char = same_as<_CharT, char> || same_as<_CharT, wchar_t>;
    65	#else
    66	  template<typename _CharT>
    67	    concept __char = same_as<_CharT, char>;
    68	#endif
    69	
    70	  template<typename _Tp, typename _Context,
    71		   typename _Formatter
    72		     = typename _Context::template formatter_type<remove_const_t<_Tp>>,
    73		   typename _ParseContext
    74		     = basic_format_parse_context<typename _Context::char_type>>
    75	    concept __parsable_with
    76	      = semiregular<_Formatter>
    77		  && requires (_Formatter __f, _ParseContext __pc)
    78	    {
    79	      { __f.parse(__pc) } -> same_as<typename _ParseContext::iterator>;
    80	    };
    81	
    82	  template<typename _Tp, typename _Context,
    83		   typename _Formatter
    84		     = typename _Context::template formatter_type<remove_const_t<_Tp>>,
    85		   typename _ParseContext
    86		     = basic_format_parse_context<typename _Context::char_type>>
    87	    concept __formattable_with
    88	      = semiregular<_Formatter>
    89		  && requires (const _Formatter __cf, _Tp&& __t, _Context __fc)
    90	    {
    91	      { __cf.format(__t, __fc) } -> same_as<typename _Context::iterator>;
    92	    };
    93	
    94	  // An unspecified output iterator type used in the `formattable` concept.
    95	  template<typename _CharT>
    96	    struct _Iter_for;
    97	  template<typename _CharT>
    98	    using _Iter_for_t = typename _Iter_for<_CharT>::type;
    99	
   100	  template<typename _Tp, typename _CharT,
   101		   typename _Context = basic_format_context<_Iter_for_t<_CharT>, _CharT>>
   102	    concept __formattable_impl
   103	      = __parsable_with<_Tp, _Context> && __formattable_with<_Tp, _Context>;
   104	
   105	  template<typename _Formatter>
   106	    concept __has_debug_format = requires(_Formatter __f)
   107	    {
   108	      __f.set_debug_format();
   109	    };
   110	
   111	  template<__char _CharT>
   112	    struct __formatter_int;
   113	} // namespace __format
   114	/// @endcond
   115	
   116	#if __glibcxx_format_ranges // C++ >= 23 && HOSTED
   117	  // [format.formattable], concept formattable
   118	  template<typename _Tp, typename _CharT>
   119	    concept formattable
   120	      = __format::__formattable_impl<remove_reference_t<_Tp>, _CharT>;
   121	
   122	   template<typename _Tp, __format::__char _CharT = char>
   123	     requires same_as<remove_cvref_t<_Tp>, _Tp> && formattable<_Tp, _CharT>
   124	     class range_formatter;
   125	
   126	/// @cond undocumented
   127	namespace __format
   128	{
   129	  template<typename _Rg, typename _CharT>
   130	    concept __const_formattable_range
   131	      = ranges::input_range<const _Rg>
   132		  && formattable<ranges::range_reference_t<const _Rg>, _CharT>;
   133	
   134	  template<typename _Rg, typename _CharT>
   135	    using __maybe_const_range
   136	      = __conditional_t<__const_formattable_range<_Rg, _CharT>, const _Rg, _Rg>;
   137	
   138	  template<typename _Tp, typename _CharT>
   139	    using __maybe_const
   140	      = __conditional_t<formattable<const _Tp, _CharT>, const _Tp, _Tp>;
   141	}
   142	#endif // format_ranges
   143	
   144	
   145	_GLIBCXX_END_NAMESPACE_VERSION
   146	} // namespace std
   147	#endif // __glibcxx_format
   148	#endif // _GLIBCXX_FORMAT_FWD_H