2194bca2b7
While working on #105430 I ran into an issue implementing [[optional.syn]](https://eel.is/c++draft/optional.syn) because of a circular include that looked like the following: `optional -> __format/range_default_formatter.h -> __format/range_formatter.h -> __format/format_context.h -> optional`. Only `format_kind` and `range_format` are needed, and so they looked like candidates to be put into an internal header.
72 lines
2.5 KiB
C++
72 lines
2.5 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_RANGE_FORMAT_H
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#define _LIBCPP___FORMAT_RANGE_FORMAT_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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#include <__concepts/same_as.h>
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#include <__config>
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#include <__format/concepts.h>
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#include <__ranges/concepts.h>
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#include <__type_traits/remove_cvref.h>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 23
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_LIBCPP_DIAGNOSTIC_PUSH
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_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wshadow")
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_LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wshadow")
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// This shadows map, set, and string.
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enum class range_format { disabled, map, set, sequence, string, debug_string };
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_LIBCPP_DIAGNOSTIC_POP
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template <class _Rp>
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constexpr range_format format_kind = [] {
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// [format.range.fmtkind]/1
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// A program that instantiates the primary template of format_kind is ill-formed.
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static_assert(sizeof(_Rp) != sizeof(_Rp), "create a template specialization of format_kind for your type");
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return range_format::disabled;
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}();
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template <ranges::input_range _Rp>
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requires same_as<_Rp, remove_cvref_t<_Rp>>
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inline constexpr range_format format_kind<_Rp> = [] {
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// [format.range.fmtkind]/2
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// 2.1 If same_as<remove_cvref_t<ranges::range_reference_t<R>>, R> is true,
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// Otherwise format_kind<R> is range_format::disabled.
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if constexpr (same_as<remove_cvref_t<ranges::range_reference_t<_Rp>>, _Rp>)
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return range_format::disabled;
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// 2.2 Otherwise, if the qualified-id R::key_type is valid and denotes a type:
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else if constexpr (requires { typename _Rp::key_type; }) {
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// 2.2.1 If the qualified-id R::mapped_type is valid and denotes a type ...
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if constexpr (requires { typename _Rp::mapped_type; } &&
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// 2.2.1 ... If either U is a specialization of pair or U is a specialization
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// of tuple and tuple_size_v<U> == 2
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__fmt_pair_like<remove_cvref_t<ranges::range_reference_t<_Rp>>>)
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return range_format::map;
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else
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// 2.2.2 Otherwise format_kind<R> is range_format::set.
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return range_format::set;
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} else
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// 2.3 Otherwise, format_kind<R> is range_format::sequence.
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return range_format::sequence;
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}();
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#endif // _LIBCPP_STD_VER >= 23
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_LIBCPP_END_NAMESPACE_STD
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#endif
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