chromium/third_party/libc++/src/include/__format/format_arg.h

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___FORMAT_FORMAT_ARG_H
#define _LIBCPP___FORMAT_FORMAT_ARG_H

#include <__assert>
#include <__concepts/arithmetic.h>
#include <__config>
#include <__format/concepts.h>
#include <__format/format_parse_context.h>
#include <__functional/invoke.h>
#include <__fwd/format.h>
#include <__memory/addressof.h>
#include <__type_traits/conditional.h>
#include <__type_traits/remove_const.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <__utility/unreachable.h>
#include <__variant/monostate.h>
#include <cstdint>
#include <string_view>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER >= 20

namespace __format {
/// The type stored in @ref basic_format_arg.
///
/// @note The 128-bit types are unconditionally in the list to avoid the values
/// of the enums to depend on the availability of 128-bit integers.
///
/// @note The value is stored as a 5-bit value in the __packed_arg_t_bits. This
/// limits the maximum number of elements to 32.
/// When modifying update the test
/// test/libcxx/utilities/format/format.arguments/format.arg/arg_t.compile.pass.cpp
/// It could be packed in 4-bits but that means a new type directly becomes an
/// ABI break. The packed type is 64-bit so this reduces the maximum number of
/// packed elements from 16 to 12.
///
/// @note Some members of this enum are an extension. These extensions need
/// special behaviour in visit_format_arg. There they need to be wrapped in a
/// handle to satisfy the user observable behaviour. The internal function
/// __visit_format_arg doesn't do this wrapping. So in the format functions
/// this function is used to avoid unneeded overhead.
enum class __arg_t : uint8_t { … };

inline constexpr unsigned __packed_arg_t_bits = …;
inline constexpr uint8_t __packed_arg_t_mask  = …;

inline constexpr unsigned __packed_types_storage_bits = …;
inline constexpr unsigned __packed_types_max          = …;

_LIBCPP_HIDE_FROM_ABI constexpr bool __use_packed_format_arg_store(size_t __size) { … }

_LIBCPP_HIDE_FROM_ABI constexpr __arg_t __get_packed_type(uint64_t __types, size_t __id) { … }

} // namespace __format

// This function is not user observable, so it can directly use the non-standard
// types of the "variant". See __arg_t for more details.
template <class _Visitor, class _Context>
_LIBCPP_HIDE_FROM_ABI decltype(auto) __visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) { … }

#  if _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)

template <class _Rp, class _Visitor, class _Context>
_LIBCPP_HIDE_FROM_ABI _Rp __visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
  switch (__arg.__type_) {
  case __format::__arg_t::__none:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__monostate_);
  case __format::__arg_t::__boolean:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__boolean_);
  case __format::__arg_t::__char_type:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__char_type_);
  case __format::__arg_t::__int:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__int_);
  case __format::__arg_t::__long_long:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__long_long_);
  case __format::__arg_t::__i128:
#    ifndef _LIBCPP_HAS_NO_INT128
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__i128_);
#    else
    __libcpp_unreachable();
#    endif
  case __format::__arg_t::__unsigned:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__unsigned_);
  case __format::__arg_t::__unsigned_long_long:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__unsigned_long_long_);
  case __format::__arg_t::__u128:
#    ifndef _LIBCPP_HAS_NO_INT128
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__u128_);
#    else
    __libcpp_unreachable();
#    endif
  case __format::__arg_t::__float:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__float_);
  case __format::__arg_t::__double:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__double_);
  case __format::__arg_t::__long_double:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__long_double_);
  case __format::__arg_t::__const_char_type_ptr:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__const_char_type_ptr_);
  case __format::__arg_t::__string_view:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__string_view_);
  case __format::__arg_t::__ptr:
    return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__ptr_);
  case __format::__arg_t::__handle:
    return std::invoke_r<_Rp>(
        std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__arg.__value_.__handle_});
  }

  __libcpp_unreachable();
}

#  endif // _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)

/// Contains the values used in basic_format_arg.
///
/// This is a separate type so it's possible to store the values and types in
/// separate arrays.
template <class _Context>
class __basic_format_arg_value { … };

template <class _Context>
class _LIBCPP_TEMPLATE_VIS basic_format_arg { … };

template <class _Context>
class _LIBCPP_TEMPLATE_VIS basic_format_arg<_Context>::handle { … };

// This function is user facing, so it must wrap the non-standard types of
// the "variant" in a handle to stay conforming. See __arg_t for more details.
template <class _Visitor, class _Context>
#  if _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
_LIBCPP_DEPRECATED_IN_CXX26
#  endif
    _LIBCPP_HIDE_FROM_ABI decltype(auto)
    visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) { … }

#endif // _LIBCPP_STD_VER >= 20

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP___FORMAT_FORMAT_ARG_H