a749e68ac4
`<optional>` needs `format_kind` and `range_format` since C++26, but it shouldn't drag in too many other stuffs necessary for `<__format/concepts.h>`.
70 lines
2.3 KiB
C++
70 lines
2.3 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___FORMAT_CONCEPTS_H
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#define _LIBCPP___FORMAT_CONCEPTS_H
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#include <__concepts/same_as.h>
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#include <__concepts/semiregular.h>
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#include <__config>
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#include <__format/format_parse_context.h>
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#include <__fwd/format.h>
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#include <__type_traits/remove_const.h>
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#include <__type_traits/remove_reference.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 20
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/// The character type specializations of \ref formatter.
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template <class _CharT>
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concept __fmt_char_type =
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same_as<_CharT, char>
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# if _LIBCPP_HAS_WIDE_CHARACTERS
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|| same_as<_CharT, wchar_t>
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# endif
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;
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// The output iterator isn't specified. A formatter should accept any
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// output_iterator. This iterator is a minimal iterator to test the concept.
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// (Note testing for (w)format_context would be a valid choice, but requires
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// selecting the proper one depending on the type of _CharT.)
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template <class _CharT>
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using __fmt_iter_for _LIBCPP_NODEBUG = _CharT*;
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template <class _Tp, class _Context, class _Formatter = typename _Context::template formatter_type<remove_const_t<_Tp>>>
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concept __formattable_with =
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semiregular<_Formatter> &&
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requires(_Formatter& __f,
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const _Formatter& __cf,
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_Tp&& __t,
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_Context __fc,
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basic_format_parse_context<typename _Context::char_type> __pc) {
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{ __f.parse(__pc) } -> same_as<typename decltype(__pc)::iterator>;
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{ __cf.format(__t, __fc) } -> same_as<typename _Context::iterator>;
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};
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template <class _Tp, class _CharT>
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concept __formattable =
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__formattable_with<remove_reference_t<_Tp>, basic_format_context<__fmt_iter_for<_CharT>, _CharT>>;
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# if _LIBCPP_STD_VER >= 23
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template <class _Tp, class _CharT>
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concept formattable = __formattable<_Tp, _CharT>;
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# endif // _LIBCPP_STD_VER >= 23
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___FORMAT_CONCEPTS_H
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