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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/same_as.h>
18#include <__config>
19#include <__cstddef/size_t.h>
20#include <__format/concepts.h>
21#include <__format/format_arg.h>
22#include <__type_traits/conditional.h>
23#include <__type_traits/extent.h>
24#include <__type_traits/integer_traits.h>
25#include <__type_traits/remove_const.h>
26#include <cstdint>
27#include <string>
28#include <string_view>
29
30_LIBCPP_BEGIN_NAMESPACE_STD
31
32#if _LIBCPP_STD_VER >= 20
33
34namespace __format {
35
36template <class _Arr, class _Elem>
37inline constexpr bool __is_bounded_array_of = false;
38
39template <class _Elem, size_t _Len>
40inline constexpr bool __is_bounded_array_of<_Elem[_Len], _Elem> = true;
41
42/// \returns The @c __arg_t based on the type of the formatting argument.
43///
44/// \pre \c __formattable<_Tp, typename _Context::char_type>
45template <class _Context, class _Tp>
46consteval __arg_t __determine_arg_t();
47
48// Boolean
49template <class, same_as<bool> _Tp>
50consteval __arg_t __determine_arg_t() {
51 return __arg_t::__boolean;
52}
53
54// Char
55template <class _Context, same_as<typename _Context::char_type> _Tp>
56consteval __arg_t __determine_arg_t() {
57 return __arg_t::__char_type;
58}
59# if _LIBCPP_HAS_WIDE_CHARACTERS
60template <class _Context, class _CharT>
61 requires(same_as<typename _Context::char_type, wchar_t> && same_as<_CharT, char>)
62consteval __arg_t __determine_arg_t() {
63 return __arg_t::__char_type;
64}
65# endif
66
67// Signed integers
68template <class, __signed_integer _Tp>
69consteval __arg_t __determine_arg_t() {
70 if constexpr (sizeof(_Tp) <= sizeof(int))
71 return __arg_t::__int;
72 else if constexpr (sizeof(_Tp) <= sizeof(long long))
73 return __arg_t::__long_long;
74# if _LIBCPP_HAS_INT128
75 else if constexpr (sizeof(_Tp) == sizeof(__int128_t))
76 return __arg_t::__i128;
77# endif
78 else
79 static_assert(sizeof(_Tp) == 0, "an unsupported signed integer was used");
80}
81
82// Unsigned integers
83template <class, __unsigned_integer _Tp>
84consteval __arg_t __determine_arg_t() {
85 if constexpr (sizeof(_Tp) <= sizeof(unsigned))
86 return __arg_t::__unsigned;
87 else if constexpr (sizeof(_Tp) <= sizeof(unsigned long long))
88 return __arg_t::__unsigned_long_long;
89# if _LIBCPP_HAS_INT128
90 else if constexpr (sizeof(_Tp) == sizeof(__uint128_t))
91 return __arg_t::__u128;
92# endif
93 else
94 static_assert(sizeof(_Tp) == 0, "an unsupported unsigned integer was used");
95}
96
97// Floating-point
98template <class, same_as<float> _Tp>
99consteval __arg_t __determine_arg_t() {
100 return __arg_t::__float;
101}
102template <class, same_as<double> _Tp>
103consteval __arg_t __determine_arg_t() {
104 return __arg_t::__double;
105}
106template <class, same_as<long double> _Tp>
107consteval __arg_t __determine_arg_t() {
108 return __arg_t::__long_double;
109}
110
111// Char pointer
112template <class _Context, class _Tp>
113 requires(same_as<typename _Context::char_type*, _Tp> || same_as<const typename _Context::char_type*, _Tp>)
114consteval __arg_t __determine_arg_t() {
115 return __arg_t::__const_char_type_ptr;
116}
117
118// Char array
119template <class _Context, class _Tp>
120 requires __is_bounded_array_of<_Tp, typename _Context::char_type>
121consteval __arg_t __determine_arg_t() {
122 return __arg_t::__string_view;
123}
124
125// String view
126template <class _Context, class _Tp>
127 requires(same_as<typename _Context::char_type, typename _Tp::value_type> &&
128 same_as<_Tp, basic_string_view<typename _Tp::value_type, typename _Tp::traits_type>>)
129consteval __arg_t __determine_arg_t() {
130 return __arg_t::__string_view;
131}
132
133// String
134template <class _Context, class _Tp>
135 requires(
136 same_as<typename _Context::char_type, typename _Tp::value_type> &&
137 same_as<_Tp, basic_string<typename _Tp::value_type, typename _Tp::traits_type, typename _Tp::allocator_type>>)
138consteval __arg_t __determine_arg_t() {
139 return __arg_t::__string_view;
140}
141
142// Pointers
143template <class, class _Ptr>
144 requires(same_as<_Ptr, void*> || same_as<_Ptr, const void*> || same_as<_Ptr, nullptr_t>)
145consteval __arg_t __determine_arg_t() {
146 return __arg_t::__ptr;
147}
148
149// Handle
150//
151// Note this version can't be constrained avoiding ambiguous overloads.
152// That means it can be instantiated by disabled formatters. To solve this, a
153// constrained version for not formattable formatters is added.
154template <class _Context, class _Tp>
155consteval __arg_t __determine_arg_t() {
156 return __arg_t::__handle;
157}
158
159// The overload for not formattable types allows triggering the static
160// assertion below.
161template <class _Context, class _Tp>
162 requires(!__formattable_with<_Tp, _Context>)
163consteval __arg_t __determine_arg_t() {
164 return __arg_t::__none;
165}
166
167// Pseudo constuctor for basic_format_arg
168//
169// Modeled after template<class T> explicit basic_format_arg(T& v) noexcept;
170// [format.arg]/4-6
171template <class _Context, class _Tp>
172_LIBCPP_HIDE_FROM_ABI basic_format_arg<_Context> __create_format_arg(_Tp& __value) noexcept {
173 using _Dp = remove_const_t<_Tp>;
174 constexpr __arg_t __arg = __format::__determine_arg_t<_Context, _Dp>();
175 static_assert(__arg != __arg_t::__none, "the supplied type is not formattable");
176 static_assert(__formattable_with<_Tp, _Context>);
177
178 using __context_char_type = _Context::char_type;
179 // Not all types can be used to directly initialize the
180 // __basic_format_arg_value. First handle all types needing adjustment, the
181 // final else requires no adjustment.
182 if constexpr (__arg == __arg_t::__char_type)
183
184# if _LIBCPP_HAS_WIDE_CHARACTERS
185 if constexpr (same_as<__context_char_type, wchar_t> && same_as<_Dp, char>)
186 return basic_format_arg<_Context>{__arg, static_cast<wchar_t>(static_cast<unsigned char>(__value))};
187 else
188# endif
189 return basic_format_arg<_Context>{__arg, __value};
190 else if constexpr (__arg == __arg_t::__int)
191 return basic_format_arg<_Context>{__arg, static_cast<int>(__value)};
192 else if constexpr (__arg == __arg_t::__long_long)
193 return basic_format_arg<_Context>{__arg, static_cast<long long>(__value)};
194 else if constexpr (__arg == __arg_t::__unsigned)
195 return basic_format_arg<_Context>{__arg, static_cast<unsigned>(__value)};
196 else if constexpr (__arg == __arg_t::__unsigned_long_long)
197 return basic_format_arg<_Context>{__arg, static_cast<unsigned long long>(__value)};
198 else if constexpr (__arg == __arg_t::__string_view)
199 // Using std::size on a character array will add the NUL-terminator to the size.
200 if constexpr (__is_bounded_array_of<_Dp, __context_char_type>) {
201 const __context_char_type* const __pbegin = std::begin(__value);
202 const __context_char_type* const __pzero =
203 char_traits<__context_char_type>::find(__pbegin, extent_v<_Dp>, __context_char_type{});
204 _LIBCPP_ASSERT_VALID_INPUT_RANGE(__pzero != nullptr, "formatting a non-null-terminated array");
205 return basic_format_arg<_Context>{
206 __arg, basic_string_view<__context_char_type>{__pbegin, static_cast<size_t>(__pzero - __pbegin)}};
207 } else
208 // When the _Traits or _Allocator are different an implicit conversion will fail.
209 return basic_format_arg<_Context>{__arg, basic_string_view<__context_char_type>{__value.data(), __value.size()}};
210 else if constexpr (__arg == __arg_t::__ptr)
211 return basic_format_arg<_Context>{__arg, static_cast<const void*>(__value)};
212 else if constexpr (__arg == __arg_t::__handle)
213 return basic_format_arg<_Context>{__arg, typename __basic_format_arg_value<_Context>::__handle{__value}};
214 else
215 return basic_format_arg<_Context>{__arg, __value};
216}
217
218template <class _Context, class... _Args>
219_LIBCPP_HIDE_FROM_ABI void
220__create_packed_storage(uint64_t& __types, __basic_format_arg_value<_Context>* __values, _Args&... __args) noexcept {
221 int __shift = 0;
222 (
223 [&] {
224 basic_format_arg<_Context> __arg = __format::__create_format_arg<_Context>(__args);
225 if (__shift != 0)
226 __types |= static_cast<uint64_t>(__arg.__type_) << __shift;
227 else
228 // Assigns the initial value.
229 __types = static_cast<uint64_t>(__arg.__type_);
230 __shift += __packed_arg_t_bits;
231 *__values++ = __arg.__value_;
232 }(),
233 ...);
234}
235
236template <class _Context, class... _Args>
237_LIBCPP_HIDE_FROM_ABI void __store_basic_format_arg(basic_format_arg<_Context>* __data, _Args&... __args) noexcept {
238 ([&] { *__data++ = __format::__create_format_arg<_Context>(__args); }(), ...);
239}
240
241template <class _Context, size_t _Np>
242struct __packed_format_arg_store {
243 __basic_format_arg_value<_Context> __values_[_Np];
244 uint64_t __types_ = 0;
245};
246
247template <class _Context>
248struct __packed_format_arg_store<_Context, 0> {
249 uint64_t __types_ = 0;
250};
251
252template <class _Context, size_t _Np>
253struct __unpacked_format_arg_store {
254 basic_format_arg<_Context> __args_[_Np];
255};
256
257} // namespace __format
258
259template <class _Context, class... _Args>
260struct __format_arg_store {
261 _LIBCPP_HIDE_FROM_ABI __format_arg_store(_Args&... __args) noexcept {
262 if constexpr (sizeof...(_Args) != 0) {
263 if constexpr (__format::__use_packed_format_arg_store(sizeof...(_Args)))
264 __format::__create_packed_storage(__storage.__types_, __storage.__values_, __args...);
265 else
266 __format::__store_basic_format_arg<_Context>(__storage.__args_, __args...);
267 }
268 }
269
270 using _Storage _LIBCPP_NODEBUG =
271 conditional_t<__format::__use_packed_format_arg_store(sizeof...(_Args)),
272 __format::__packed_format_arg_store<_Context, sizeof...(_Args)>,
273 __format::__unpacked_format_arg_store<_Context, sizeof...(_Args)>>;
274
275 _Storage __storage;
276};
277
278#endif // _LIBCPP_STD_VER >= 20
279
280_LIBCPP_END_NAMESPACE_STD
281
282#endif // _LIBCPP___FORMAT_FORMAT_ARG_STORE_H