libstdc++: formatfwd.h Source File

libstdc++

formatfwd.h
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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
46namespace 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
60namespace __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 enum class _Align : unsigned char {
71 _Align_default,
72 _Align_left,
73 _Align_right,
74 _Align_centre,
75 };
76 using enum _Align;
77
78 template<typename _CharT> struct _Spec;
79
80 template<__char _CharT> struct __formatter_str;
81 template<__char _CharT> struct __formatter_int;
82 template<__char _CharT> struct __formatter_ptr;
83
84 template<typename _Tp, typename _Context,
85 typename _Formatter
86 = typename _Context::template formatter_type<remove_const_t<_Tp>>,
87 typename _ParseContext
88 = basic_format_parse_context<typename _Context::char_type>>
89 concept __parsable_with
90 = semiregular<_Formatter>
91 && requires (_Formatter __f, _ParseContext __pc)
92 {
93 { __f.parse(__pc) } -> same_as<typename _ParseContext::iterator>;
94 };
95
96 template<typename _Tp, typename _Context,
97 typename _Formatter
98 = typename _Context::template formatter_type<remove_const_t<_Tp>>,
99 typename _ParseContext
100 = basic_format_parse_context<typename _Context::char_type>>
101 concept __formattable_with
102 = semiregular<_Formatter>
103 && requires (const _Formatter __cf, _Tp&& __t, _Context __fc)
104 {
105 { __cf.format(__t, __fc) } -> same_as<typename _Context::iterator>;
106 };
107
108 // An unspecified output iterator type used in the `formattable` concept.
109 template<typename _CharT>
110 struct _Iter_for;
111 template<typename _CharT>
112 using _Iter_for_t = typename _Iter_for<_CharT>::type;
113
114 template<typename _Tp, typename _CharT,
115 typename _Context = basic_format_context<_Iter_for_t<_CharT>, _CharT>>
116 concept __formattable_impl
117 = __parsable_with<_Tp, _Context> && __formattable_with<_Tp, _Context>;
118
119 template<typename _Formatter>
120 concept __has_debug_format = requires(_Formatter __f)
121 {
122 __f.set_debug_format();
123 };
124} // namespace __format
125/// @endcond
126
127#if __glibcxx_format_ranges // C++ >= 23 && HOSTED
128 // [format.formattable], concept formattable
129 template<typename _Tp, typename _CharT>
130 concept formattable
131 = __format::__formattable_impl<remove_reference_t<_Tp>, _CharT>;
132
133 template<typename _Tp, __format::__char _CharT = char>
134 requires same_as<remove_cvref_t<_Tp>, _Tp> && formattable<_Tp, _CharT>
135 class range_formatter;
136
137/// @cond undocumented
138namespace __format
139{
140 template<typename _Rg, typename _CharT>
141 concept __const_formattable_range
142 = ranges::input_range<const _Rg>
143 && formattable<ranges::range_reference_t<const _Rg>, _CharT>;
144
145 // _Rg& and const _Rg& are both formattable and use same formatter
146 // specialization for their references.
147 template<typename _Rg, typename _CharT>
148 concept __simply_formattable_range
149 = __const_formattable_range<_Rg, _CharT>
150 && same_as<remove_cvref_t<ranges::range_reference_t<_Rg>>,
151 remove_cvref_t<ranges::range_reference_t<const _Rg>>>;
152
153 template<typename _Rg, typename _CharT>
154 using __maybe_const_range
155 = __conditional_t<__const_formattable_range<_Rg, _CharT>, const _Rg, _Rg>;
156
157 template<typename _Tp, typename _CharT>
158 using __maybe_const
159 = __conditional_t<formattable<const _Tp, _CharT>, const _Tp, _Tp>;
160}
161
162 // [format.range], formatting of ranges
163 // [format.range.fmtkind], variable template format_kind
164 enum class range_format {
165 disabled,
166 map,
167 set,
168 sequence,
169 string,
170 debug_string
171 };
172
173 /** @brief A constant determining how a range should be formatted.
174 *
175 * The primary template of `std::format_kind` cannot be instantiated.
176 * There is a partial specialization for input ranges and you can
177 * specialize the variable template for your own cv-unqualified types
178 * that satisfy the `ranges::input_range` concept.
179 *
180 * @since C++23
181 */
182 template<typename _Rg>
183 constexpr auto format_kind = []{
184 static_assert(false, "cannot use primary template of 'std::format_kind'");
185 return type_identity<_Rg>{};
186 }();
187#endif // format_ranges
188
189#if __glibcxx_print >= 202403L
190 template<typename>
191 constexpr bool enable_nonlocking_formatter_optimization = false;
192#endif
193
194_GLIBCXX_END_NAMESPACE_VERSION
195} // namespace std
196#endif // __glibcxx_format
197#endif // _GLIBCXX_FORMAT_FWD_H
concepts
type_traits
ranges_base.h
std::string
basic_string< char > string
A string of char.
Definition stringfwd.h:79
std
ISO C++ entities toplevel namespace is std.
std::map
A standard container made up of (key,value) pairs, which can be retrieved based on a key,...
Definition stl_map.h:107
std::set
A standard container made up of unique keys, which can be retrieved in logarithmic time.
Definition stl_set.h:101
std::same_as
[concept.same], concept same_as
Definition concepts:65