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_ARG_STORE_H
11#define _LIBCPP___FORMAT_FORMAT_ARG_STORE_H
12
13#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
14#  pragma GCC system_header
15#endif
16
17#include <__concepts/arithmetic.h>
18#include <__concepts/same_as.h>
19#include <__config>
20#include <__format/concepts.h>
21#include <__format/format_arg.h>
22#include <__utility/forward.h>
23#include <cstring>
24#include <string>
25#include <string_view>
26#include <type_traits>
27
28_LIBCPP_BEGIN_NAMESPACE_STD
29
30#if _LIBCPP_STD_VER > 17
31
32namespace __format {
33
34/// \returns The @c __arg_t based on the type of the formatting argument.
35///
36/// \pre \c __formattable<_Tp, typename _Context::char_type>
37template <class _Context, class _Tp>
38consteval __arg_t __determine_arg_t();
39
40// Boolean
41template <class, same_as<bool> _Tp>
42consteval __arg_t __determine_arg_t() {
43  return __arg_t::__boolean;
44}
45
46// Char
47template <class _Context, same_as<typename _Context::char_type> _Tp>
48consteval __arg_t __determine_arg_t() {
49  return __arg_t::__char_type;
50}
51#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
52template <class _Context, class _CharT>
53  requires(same_as<typename _Context::char_type, wchar_t> && same_as<_CharT, char>)
54consteval __arg_t __determine_arg_t() {
55  return __arg_t::__char_type;
56}
57#  endif
58
59// Signed integers
60template <class, __libcpp_signed_integer _Tp>
61consteval __arg_t __determine_arg_t() {
62  if constexpr (sizeof(_Tp) <= sizeof(int))
63    return __arg_t::__int;
64  else if constexpr (sizeof(_Tp) <= sizeof(long long))
65    return __arg_t::__long_long;
66#  ifndef _LIBCPP_HAS_NO_INT128
67  else if constexpr (sizeof(_Tp) == sizeof(__int128_t))
68    return __arg_t::__i128;
69#  endif
70  else
71    static_assert(sizeof(_Tp) == 0, "an unsupported signed integer was used");
72}
73
74// Unsigned integers
75template <class, __libcpp_unsigned_integer _Tp>
76consteval __arg_t __determine_arg_t() {
77  if constexpr (sizeof(_Tp) <= sizeof(unsigned))
78    return __arg_t::__unsigned;
79  else if constexpr (sizeof(_Tp) <= sizeof(unsigned long long))
80    return __arg_t::__unsigned_long_long;
81#  ifndef _LIBCPP_HAS_NO_INT128
82  else if constexpr (sizeof(_Tp) == sizeof(__uint128_t))
83    return __arg_t::__u128;
84#  endif
85  else
86    static_assert(sizeof(_Tp) == 0, "an unsupported unsigned integer was used");
87}
88
89// Floating-point
90template <class, same_as<float> _Tp>
91consteval __arg_t __determine_arg_t() {
92  return __arg_t::__float;
93}
94template <class, same_as<double> _Tp>
95consteval __arg_t __determine_arg_t() {
96  return __arg_t::__double;
97}
98template <class, same_as<long double> _Tp>
99consteval __arg_t __determine_arg_t() {
100  return __arg_t::__long_double;
101}
102
103// Char pointer
104template <class _Context, class _Tp>
105  requires(same_as<typename _Context::char_type*, _Tp> || same_as<const typename _Context::char_type*, _Tp>)
106consteval __arg_t __determine_arg_t() {
107  return __arg_t::__const_char_type_ptr;
108}
109
110// Char array
111template <class _Context, class _Tp>
112  requires(is_array_v<_Tp> && same_as<_Tp, typename _Context::char_type[extent_v<_Tp>]>)
113consteval __arg_t __determine_arg_t() {
114  return __arg_t::__string_view;
115}
116
117// String view
118template <class _Context, class _Tp>
119  requires(same_as<typename _Context::char_type, typename _Tp::value_type> &&
120           same_as<_Tp, basic_string_view<typename _Tp::value_type, typename _Tp::traits_type>>)
121consteval __arg_t __determine_arg_t() {
122  return __arg_t::__string_view;
123}
124
125// String
126template <class _Context, class _Tp>
127  requires(
128      same_as<typename _Context::char_type, typename _Tp::value_type> &&
129      same_as<_Tp, basic_string<typename _Tp::value_type, typename _Tp::traits_type, typename _Tp::allocator_type>>)
130consteval __arg_t __determine_arg_t() {
131  return __arg_t::__string_view;
132}
133
134// Pointers
135template <class, class _Ptr>
136  requires(same_as<_Ptr, void*> || same_as<_Ptr, const void*> || same_as<_Ptr, nullptr_t>)
137consteval __arg_t __determine_arg_t() {
138  return __arg_t::__ptr;
139}
140
141// Handle
142//
143// Note this version can't be constrained avoiding ambiguous overloads.
144// That means it can be instantiated by disabled formatters. To solve this, a
145// constrained version for not formattable formatters is added. That overload
146// is marked as deleted to fail creating a storage type for disabled formatters.
147template <class _Context, class _Tp>
148consteval __arg_t __determine_arg_t() {
149  return __arg_t::__handle;
150}
151
152template <class _Context, class _Tp>
153  requires(!__formattable<_Tp, typename _Context::char_type>)
154consteval __arg_t __determine_arg_t() = delete;
155
156template <class _Context, class _Tp>
157_LIBCPP_HIDE_FROM_ABI basic_format_arg<_Context> __create_format_arg(_Tp&& __value) noexcept {
158  constexpr __arg_t __arg = __determine_arg_t<_Context, remove_cvref_t<_Tp>>();
159  static_assert(__arg != __arg_t::__none);
160
161  // Not all types can be used to directly initialize the
162  // __basic_format_arg_value.  First handle all types needing adjustment, the
163  // final else requires no adjustment.
164  if constexpr (__arg == __arg_t::__char_type)
165    // On some platforms initializing a wchar_t from a char is a narrowing
166    // conversion.
167    return basic_format_arg<_Context>{__arg, static_cast<typename _Context::char_type>(__value)};
168  else if constexpr (__arg == __arg_t::__int)
169    return basic_format_arg<_Context>{__arg, static_cast<int>(__value)};
170  else if constexpr (__arg == __arg_t::__long_long)
171    return basic_format_arg<_Context>{__arg, static_cast<long long>(__value)};
172  else if constexpr (__arg == __arg_t::__unsigned)
173    return basic_format_arg<_Context>{__arg, static_cast<unsigned>(__value)};
174  else if constexpr (__arg == __arg_t::__unsigned_long_long)
175    return basic_format_arg<_Context>{__arg, static_cast<unsigned long long>(__value)};
176  else if constexpr (__arg == __arg_t::__string_view)
177    // Using std::size on a character array will add the NUL-terminator to the size.
178    if constexpr (is_array_v<remove_cvref_t<_Tp>>)
179      return basic_format_arg<_Context>{
180          __arg, basic_string_view<typename _Context::char_type>{__value, extent_v<remove_cvref_t<_Tp>> - 1}};
181    else
182      // When the _Traits or _Allocator are different an implicit conversion will
183      // fail.
184      return basic_format_arg<_Context>{
185          __arg, basic_string_view<typename _Context::char_type>{__value.data(), __value.size()}};
186  else if constexpr (__arg == __arg_t::__ptr)
187    return basic_format_arg<_Context>{__arg, static_cast<const void*>(__value)};
188  else if constexpr (__arg == __arg_t::__handle)
189    return basic_format_arg<_Context>{
190        __arg, typename __basic_format_arg_value<_Context>::__handle{_VSTD::forward<_Tp>(__value)}};
191  else
192    return basic_format_arg<_Context>{__arg, __value};
193}
194
195template <class _Context, class... _Args>
196_LIBCPP_HIDE_FROM_ABI void __create_packed_storage(uint64_t& __types, __basic_format_arg_value<_Context>* __values,
197                                                   _Args&&... __args) noexcept {
198  int __shift = 0;
199  (
200      [&] {
201        basic_format_arg<_Context> __arg = __format::__create_format_arg<_Context>(__args);
202        if (__shift != 0)
203          __types |= static_cast<uint64_t>(__arg.__type_) << __shift;
204        else
205          // Assigns the initial value.
206          __types = static_cast<uint64_t>(__arg.__type_);
207        __shift += __packed_arg_t_bits;
208        *__values++ = __arg.__value_;
209      }(),
210      ...);
211}
212
213template <class _Context, class... _Args>
214_LIBCPP_HIDE_FROM_ABI void __store_basic_format_arg(basic_format_arg<_Context>* __data, _Args&&... __args) noexcept {
215  ([&] { *__data++ = __format::__create_format_arg<_Context>(__args); }(), ...);
216}
217
218template <class _Context, size_t N>
219struct __packed_format_arg_store {
220  __basic_format_arg_value<_Context> __values_[N];
221  uint64_t __types_;
222};
223
224template <class _Context, size_t N>
225struct __unpacked_format_arg_store {
226  basic_format_arg<_Context> __args_[N];
227};
228
229} // namespace __format
230
231template <class _Context, class... _Args>
232struct _LIBCPP_TEMPLATE_VIS __format_arg_store {
233  _LIBCPP_HIDE_FROM_ABI
234  __format_arg_store(_Args&... __args) noexcept {
235    if constexpr (sizeof...(_Args) != 0) {
236      if constexpr (__format::__use_packed_format_arg_store(sizeof...(_Args)))
237        __format::__create_packed_storage(__storage.__types_, __storage.__values_, __args...);
238      else
239        __format::__store_basic_format_arg<_Context>(__storage.__args_, __args...);
240    }
241  }
242
243  using _Storage = conditional_t<__format::__use_packed_format_arg_store(sizeof...(_Args)),
244                                 __format::__packed_format_arg_store<_Context, sizeof...(_Args)>,
245                                 __format::__unpacked_format_arg_store<_Context, sizeof...(_Args)>>;
246
247  _Storage __storage;
248};
249
250#endif //_LIBCPP_STD_VER > 17
251
252_LIBCPP_END_NAMESPACE_STD
253
254#endif // _LIBCPP___FORMAT_FORMAT_ARG_STORE_H
255