70 lines · c
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-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___FORMAT_CONCEPTS_H11#define _LIBCPP___FORMAT_CONCEPTS_H12 13#include <__concepts/same_as.h>14#include <__concepts/semiregular.h>15#include <__config>16#include <__format/format_parse_context.h>17#include <__fwd/format.h>18#include <__type_traits/remove_const.h>19#include <__type_traits/remove_reference.h>20 21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)22# pragma GCC system_header23#endif24 25_LIBCPP_BEGIN_NAMESPACE_STD26 27#if _LIBCPP_STD_VER >= 2028 29/// The character type specializations of \ref formatter.30template <class _CharT>31concept __fmt_char_type =32 same_as<_CharT, char>33# if _LIBCPP_HAS_WIDE_CHARACTERS34 || same_as<_CharT, wchar_t>35# endif36 ;37 38// The output iterator isn't specified. A formatter should accept any39// output_iterator. This iterator is a minimal iterator to test the concept.40// (Note testing for (w)format_context would be a valid choice, but requires41// selecting the proper one depending on the type of _CharT.)42template <class _CharT>43using __fmt_iter_for _LIBCPP_NODEBUG = _CharT*;44 45template <class _Tp, class _Context, class _Formatter = typename _Context::template formatter_type<remove_const_t<_Tp>>>46concept __formattable_with =47 semiregular<_Formatter> &&48 requires(_Formatter& __f,49 const _Formatter& __cf,50 _Tp&& __t,51 _Context __fc,52 basic_format_parse_context<typename _Context::char_type> __pc) {53 { __f.parse(__pc) } -> same_as<typename decltype(__pc)::iterator>;54 { __cf.format(__t, __fc) } -> same_as<typename _Context::iterator>;55 };56 57template <class _Tp, class _CharT>58concept __formattable =59 __formattable_with<remove_reference_t<_Tp>, basic_format_context<__fmt_iter_for<_CharT>, _CharT>>;60 61# if _LIBCPP_STD_VER >= 2362template <class _Tp, class _CharT>63concept formattable = __formattable<_Tp, _CharT>;64# endif // _LIBCPP_STD_VER >= 2365#endif // _LIBCPP_STD_VER >= 2066 67_LIBCPP_END_NAMESPACE_STD68 69#endif // _LIBCPP___FORMAT_CONCEPTS_H70