xref: /freebsd-src/contrib/llvm-project/libcxx/include/__format/concepts.h (revision bdd1243df58e60e85101c09001d9812a789b6bc4)
181ad6265SDimitry Andric // -*- C++ -*-
281ad6265SDimitry Andric //===----------------------------------------------------------------------===//
381ad6265SDimitry Andric //
481ad6265SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
581ad6265SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
681ad6265SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
781ad6265SDimitry Andric //
881ad6265SDimitry Andric //===----------------------------------------------------------------------===//
981ad6265SDimitry Andric 
1081ad6265SDimitry Andric #ifndef _LIBCPP___FORMAT_CONCEPTS_H
1181ad6265SDimitry Andric #define _LIBCPP___FORMAT_CONCEPTS_H
1281ad6265SDimitry Andric 
1381ad6265SDimitry Andric #include <__concepts/same_as.h>
1481ad6265SDimitry Andric #include <__concepts/semiregular.h>
1581ad6265SDimitry Andric #include <__config>
1681ad6265SDimitry Andric #include <__format/format_fwd.h>
1781ad6265SDimitry Andric #include <__format/format_parse_context.h>
18*bdd1243dSDimitry Andric #include <__type_traits/is_specialization.h>
19*bdd1243dSDimitry Andric #include <__utility/pair.h>
20*bdd1243dSDimitry Andric #include <tuple>
2181ad6265SDimitry Andric #include <type_traits>
2281ad6265SDimitry Andric 
2381ad6265SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
2481ad6265SDimitry Andric #  pragma GCC system_header
2581ad6265SDimitry Andric #endif
2681ad6265SDimitry Andric 
2781ad6265SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD
2881ad6265SDimitry Andric 
2981ad6265SDimitry Andric #if _LIBCPP_STD_VER > 17
3081ad6265SDimitry Andric 
31*bdd1243dSDimitry Andric /// The character type specializations of \ref formatter.
32*bdd1243dSDimitry Andric template <class _CharT>
33*bdd1243dSDimitry Andric concept __fmt_char_type =
34*bdd1243dSDimitry Andric     same_as<_CharT, char>
35*bdd1243dSDimitry Andric #  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
36*bdd1243dSDimitry Andric     || same_as<_CharT, wchar_t>
37*bdd1243dSDimitry Andric #  endif
38*bdd1243dSDimitry Andric     ;
39*bdd1243dSDimitry Andric 
4081ad6265SDimitry Andric // The output iterator isn't specified. A formatter should accept any
4181ad6265SDimitry Andric // output_iterator. This iterator is a minimal iterator to test the concept.
4281ad6265SDimitry Andric // (Note testing for (w)format_context would be a valid choice, but requires
4381ad6265SDimitry Andric // selecting the proper one depending on the type of _CharT.)
4481ad6265SDimitry Andric template <class _CharT>
4581ad6265SDimitry Andric using __fmt_iter_for = _CharT*;
4681ad6265SDimitry Andric 
4781ad6265SDimitry Andric template <class _Tp, class _CharT>
48*bdd1243dSDimitry Andric concept __formattable =
49*bdd1243dSDimitry Andric     (semiregular<formatter<remove_cvref_t<_Tp>, _CharT>>) &&
5081ad6265SDimitry Andric     requires(formatter<remove_cvref_t<_Tp>, _CharT> __f,
51*bdd1243dSDimitry Andric              const formatter<remove_cvref_t<_Tp>, _CharT> __cf,
52*bdd1243dSDimitry Andric              _Tp __t,
5381ad6265SDimitry Andric              basic_format_context<__fmt_iter_for<_CharT>, _CharT> __fc,
5481ad6265SDimitry Andric              basic_format_parse_context<_CharT> __pc) {
5581ad6265SDimitry Andric       { __f.parse(__pc) } -> same_as<typename basic_format_parse_context<_CharT>::iterator>;
5681ad6265SDimitry Andric       { __cf.format(__t, __fc) } -> same_as<__fmt_iter_for<_CharT>>;
5781ad6265SDimitry Andric     };
5881ad6265SDimitry Andric 
59*bdd1243dSDimitry Andric #  if _LIBCPP_STD_VER > 20
60*bdd1243dSDimitry Andric template <class _Tp, class _CharT>
61*bdd1243dSDimitry Andric concept formattable = __formattable<_Tp, _CharT>;
62*bdd1243dSDimitry Andric 
63*bdd1243dSDimitry Andric // [tuple.like] defines a tuple-like exposition only concept. This concept is
64*bdd1243dSDimitry Andric // not related to that. Therefore it uses a different name for the concept.
65*bdd1243dSDimitry Andric //
66*bdd1243dSDimitry Andric // TODO FMT Add a test to validate we fail when using that concept after P2165
67*bdd1243dSDimitry Andric // has been implemented.
68*bdd1243dSDimitry Andric template <class _Tp>
69*bdd1243dSDimitry Andric concept __fmt_pair_like = __is_specialization_v<_Tp, pair> ||
70*bdd1243dSDimitry Andric                           // Use a requires since tuple_size_v may fail to instantiate,
71*bdd1243dSDimitry Andric                           (__is_specialization_v<_Tp, tuple> && requires { tuple_size_v<_Tp> == 2; });
72*bdd1243dSDimitry Andric 
73*bdd1243dSDimitry Andric #  endif //_LIBCPP_STD_VER > 20
7481ad6265SDimitry Andric #endif //_LIBCPP_STD_VER > 17
7581ad6265SDimitry Andric 
7681ad6265SDimitry Andric _LIBCPP_END_NAMESPACE_STD
7781ad6265SDimitry Andric 
7881ad6265SDimitry Andric #endif // _LIBCPP___FORMAT_CONCEPTS_H
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