1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___FORMAT_CONCEPTS_H 11 #define _LIBCPP___FORMAT_CONCEPTS_H 12 13 #include <__concepts/same_as.h> 14 #include <__concepts/semiregular.h> 15 #include <__config> 16 #include <__format/format_fwd.h> 17 #include <__format/format_parse_context.h> 18 #include <__type_traits/is_specialization.h> 19 #include <__type_traits/remove_const.h> 20 #include <__utility/pair.h> 21 #include <tuple> 22 23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 24 # pragma GCC system_header 25 #endif 26 27 _LIBCPP_BEGIN_NAMESPACE_STD 28 29 #if _LIBCPP_STD_VER >= 20 30 31 /// The character type specializations of \ref formatter. 32 template <class _CharT> 33 concept __fmt_char_type = 34 same_as<_CharT, char> 35 # ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS 36 || same_as<_CharT, wchar_t> 37 # endif 38 ; 39 40 // The output iterator isn't specified. A formatter should accept any 41 // output_iterator. This iterator is a minimal iterator to test the concept. 42 // (Note testing for (w)format_context would be a valid choice, but requires 43 // selecting the proper one depending on the type of _CharT.) 44 template <class _CharT> 45 using __fmt_iter_for = _CharT*; 46 47 template <class _Tp, class _Context, class _Formatter = typename _Context::template formatter_type<remove_const_t<_Tp>>> 48 concept __formattable_with = 49 semiregular<_Formatter> && 50 requires(_Formatter& __f, 51 const _Formatter& __cf, 52 _Tp&& __t, 53 _Context __fc, 54 basic_format_parse_context<typename _Context::char_type> __pc) { 55 { __f.parse(__pc) } -> same_as<typename decltype(__pc)::iterator>; 56 { __cf.format(__t, __fc) } -> same_as<typename _Context::iterator>; 57 }; 58 59 template <class _Tp, class _CharT> 60 concept __formattable = 61 __formattable_with<remove_reference_t<_Tp>, basic_format_context<__fmt_iter_for<_CharT>, _CharT>>; 62 63 # if _LIBCPP_STD_VER >= 23 64 template <class _Tp, class _CharT> 65 concept formattable = __formattable<_Tp, _CharT>; 66 67 // [tuple.like] defines a tuple-like exposition only concept. This concept is 68 // not related to that. Therefore it uses a different name for the concept. 69 // 70 // TODO FMT Add a test to validate we fail when using that concept after P2165 71 // has been implemented. 72 template <class _Tp> 73 concept __fmt_pair_like = 74 __is_specialization_v<_Tp, pair> || (__is_specialization_v<_Tp, tuple> && tuple_size_v<_Tp> == 2); 75 76 # endif //_LIBCPP_STD_VER >= 23 77 #endif //_LIBCPP_STD_VER >= 20 78 79 _LIBCPP_END_NAMESPACE_STD 80 81 #endif // _LIBCPP___FORMAT_CONCEPTS_H 82