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 <__availability>
14 #include <__config>
15 #include <__format/format_arg.h>
16 #include <__format/format_arg_store.h>
17 #include <__format/format_fwd.h>
18 #include <cstddef>
19 #include <cstdint>
20 
21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22 #  pragma GCC system_header
23 #endif
24 
25 _LIBCPP_BEGIN_NAMESPACE_STD
26 
27 #if _LIBCPP_STD_VER >= 20
28 
29 template <class _Context>
30 class _LIBCPP_TEMPLATE_VIS basic_format_args {
31 public:
32   basic_format_args() noexcept = default;
33 
34   template <class... _Args>
35   _LIBCPP_HIDE_FROM_ABI basic_format_args(const __format_arg_store<_Context, _Args...>& __store) noexcept
36       : __size_(sizeof...(_Args)) {
37     if constexpr (sizeof...(_Args) != 0) {
38       if constexpr (__format::__use_packed_format_arg_store(sizeof...(_Args))) {
39         __values_ = __store.__storage.__values_;
40         __types_  = __store.__storage.__types_;
41       } else
42         __args_ = __store.__storage.__args_;
43     }
44   }
45 
46   _LIBCPP_HIDE_FROM_ABI basic_format_arg<_Context> get(size_t __id) const noexcept {
47     if (__id >= __size_)
48       return basic_format_arg<_Context>{};
49 
50     if (__format::__use_packed_format_arg_store(__size_))
51       return basic_format_arg<_Context>{__format::__get_packed_type(__types_, __id), __values_[__id]};
52 
53     return __args_[__id];
54   }
55 
56   _LIBCPP_HIDE_FROM_ABI size_t __size() const noexcept { return __size_; }
57 
58 private:
59   size_t __size_{0};
60   // [format.args]/5
61   // [Note 1: Implementations are encouraged to optimize the representation of
62   // basic_format_args for small number of formatting arguments by storing
63   // indices of type alternatives separately from values and packing the
64   // former. - end note]
65   union {
66     struct {
67       const __basic_format_arg_value<_Context>* __values_;
68       uint64_t __types_;
69     };
70     const basic_format_arg<_Context>* __args_;
71   };
72 };
73 
74 template <class _Context, class... _Args>
75 basic_format_args(__format_arg_store<_Context, _Args...>) -> basic_format_args<_Context>;
76 
77 #endif //_LIBCPP_STD_VER >= 20
78 
79 _LIBCPP_END_NAMESPACE_STD
80 
81 #endif // _LIBCPP___FORMAT_FORMAT_ARGS_H
82