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_FORMAT_ARGS_H
11#define _LIBCPP___FORMAT_FORMAT_ARGS_H
12
13#include <__config>
14#include <__cstddef/size_t.h>
15#include <__format/format_arg.h>
16#include <__format/format_arg_store.h>
17#include <__fwd/format.h>
18#include <cstdint>
19
20#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21#  pragma GCC system_header
22#endif
23
24_LIBCPP_BEGIN_NAMESPACE_STD
25
26#if _LIBCPP_STD_VER >= 20
27
28template <class _Context>
29class basic_format_args {
30public:
31  template <class... _Args>
32  _LIBCPP_HIDE_FROM_ABI basic_format_args(const __format_arg_store<_Context, _Args...>& __store) noexcept
33      : __size_(sizeof...(_Args)) {
34    if constexpr (sizeof...(_Args) != 0) {
35      if constexpr (__format::__use_packed_format_arg_store(sizeof...(_Args))) {
36        __values_ = __store.__storage.__values_;
37        __types_  = __store.__storage.__types_;
38      } else
39        __args_ = __store.__storage.__args_;
40    }
41  }
42
43  _LIBCPP_HIDE_FROM_ABI basic_format_arg<_Context> get(size_t __id) const noexcept {
44    if (__id >= __size_)
45      return basic_format_arg<_Context>{};
46
47    if (__format::__use_packed_format_arg_store(__size_))
48      return basic_format_arg<_Context>{__format::__get_packed_type(__types_, __id), __values_[__id]};
49
50    return __args_[__id];
51  }
52
53  _LIBCPP_HIDE_FROM_ABI size_t __size() const noexcept { return __size_; }
54
55private:
56  size_t __size_{0};
57  // [format.args]/5
58  // [Note 1: Implementations are encouraged to optimize the representation of
59  // basic_format_args for small number of formatting arguments by storing
60  // indices of type alternatives separately from values and packing the
61  // former. - end note]
62  union {
63    struct {
64      const __basic_format_arg_value<_Context>* __values_;
65      uint64_t __types_;
66    };
67    const basic_format_arg<_Context>* __args_;
68  };
69};
70
71template <class _Context, class... _Args>
72basic_format_args(__format_arg_store<_Context, _Args...>) -> basic_format_args<_Context>;
73
74#endif // _LIBCPP_STD_VER >= 20
75
76_LIBCPP_END_NAMESPACE_STD
77
78#endif // _LIBCPP___FORMAT_FORMAT_ARGS_H