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_H
11 #define _LIBCPP___FORMAT_FORMAT_ARG_H
12
13 #include <__assert>
14 #include <__concepts/arithmetic.h>
15 #include <__config>
16 #include <__format/concepts.h>
17 #include <__format/format_parse_context.h>
18 #include <__functional/invoke.h>
19 #include <__fwd/format.h>
20 #include <__memory/addressof.h>
21 #include <__type_traits/conditional.h>
22 #include <__utility/forward.h>
23 #include <__utility/move.h>
24 #include <__utility/unreachable.h>
25 #include <__variant/monostate.h>
26 #include <cstdint>
27 #include <string_view>
28
29 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
30 # pragma GCC system_header
31 #endif
32
33 _LIBCPP_PUSH_MACROS
34 #include <__undef_macros>
35
36 _LIBCPP_BEGIN_NAMESPACE_STD
37
38 #if _LIBCPP_STD_VER >= 20
39
40 namespace __format {
41 /// The type stored in @ref basic_format_arg.
42 ///
43 /// @note The 128-bit types are unconditionally in the list to avoid the values
44 /// of the enums to depend on the availability of 128-bit integers.
45 ///
46 /// @note The value is stored as a 5-bit value in the __packed_arg_t_bits. This
47 /// limits the maximum number of elements to 32.
48 /// When modifying update the test
49 /// test/libcxx/utilities/format/format.arguments/format.arg/arg_t.compile.pass.cpp
50 /// It could be packed in 4-bits but that means a new type directly becomes an
51 /// ABI break. The packed type is 64-bit so this reduces the maximum number of
52 /// packed elements from 16 to 12.
53 ///
54 /// @note Some members of this enum are an extension. These extensions need
55 /// special behaviour in visit_format_arg. There they need to be wrapped in a
56 /// handle to satisfy the user observable behaviour. The internal function
57 /// __visit_format_arg doesn't do this wrapping. So in the format functions
58 /// this function is used to avoid unneeded overhead.
59 enum class __arg_t : uint8_t {
60 __none,
61 __boolean,
62 __char_type,
63 __int,
64 __long_long,
65 __i128, // extension
66 __unsigned,
67 __unsigned_long_long,
68 __u128, // extension
69 __float,
70 __double,
71 __long_double,
72 __const_char_type_ptr,
73 __string_view,
74 __ptr,
75 __handle
76 };
77
78 inline constexpr unsigned __packed_arg_t_bits = 5;
79 inline constexpr uint8_t __packed_arg_t_mask = 0x1f;
80
81 inline constexpr unsigned __packed_types_storage_bits = 64;
82 inline constexpr unsigned __packed_types_max = __packed_types_storage_bits / __packed_arg_t_bits;
83
__use_packed_format_arg_store(size_t __size)84 _LIBCPP_HIDE_FROM_ABI constexpr bool __use_packed_format_arg_store(size_t __size) {
85 return __size <= __packed_types_max;
86 }
87
__get_packed_type(uint64_t __types,size_t __id)88 _LIBCPP_HIDE_FROM_ABI constexpr __arg_t __get_packed_type(uint64_t __types, size_t __id) {
89 _LIBCPP_ASSERT_INTERNAL(__id <= __packed_types_max, "");
90
91 if (__id > 0)
92 __types >>= __id * __packed_arg_t_bits;
93
94 return static_cast<__format::__arg_t>(__types & __packed_arg_t_mask);
95 }
96
97 } // namespace __format
98
99 // This function is not user observable, so it can directly use the non-standard
100 // types of the "variant". See __arg_t for more details.
101 template <class _Visitor, class _Context>
decltype(auto)102 _LIBCPP_HIDE_FROM_ABI decltype(auto) __visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
103 switch (__arg.__type_) {
104 case __format::__arg_t::__none:
105 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__monostate_);
106 case __format::__arg_t::__boolean:
107 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__boolean_);
108 case __format::__arg_t::__char_type:
109 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__char_type_);
110 case __format::__arg_t::__int:
111 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__int_);
112 case __format::__arg_t::__long_long:
113 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__long_long_);
114 case __format::__arg_t::__i128:
115 # ifndef _LIBCPP_HAS_NO_INT128
116 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__i128_);
117 # else
118 __libcpp_unreachable();
119 # endif
120 case __format::__arg_t::__unsigned:
121 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__unsigned_);
122 case __format::__arg_t::__unsigned_long_long:
123 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__unsigned_long_long_);
124 case __format::__arg_t::__u128:
125 # ifndef _LIBCPP_HAS_NO_INT128
126 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__u128_);
127 # else
128 __libcpp_unreachable();
129 # endif
130 case __format::__arg_t::__float:
131 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__float_);
132 case __format::__arg_t::__double:
133 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__double_);
134 case __format::__arg_t::__long_double:
135 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__long_double_);
136 case __format::__arg_t::__const_char_type_ptr:
137 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__const_char_type_ptr_);
138 case __format::__arg_t::__string_view:
139 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__string_view_);
140 case __format::__arg_t::__ptr:
141 return std::invoke(std::forward<_Visitor>(__vis), __arg.__value_.__ptr_);
142 case __format::__arg_t::__handle:
143 return std::invoke(
144 std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__arg.__value_.__handle_});
145 }
146
147 __libcpp_unreachable();
148 }
149
150 # if _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
151
152 template <class _Rp, class _Visitor, class _Context>
__visit_format_arg(_Visitor && __vis,basic_format_arg<_Context> __arg)153 _LIBCPP_HIDE_FROM_ABI _Rp __visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
154 switch (__arg.__type_) {
155 case __format::__arg_t::__none:
156 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__monostate_);
157 case __format::__arg_t::__boolean:
158 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__boolean_);
159 case __format::__arg_t::__char_type:
160 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__char_type_);
161 case __format::__arg_t::__int:
162 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__int_);
163 case __format::__arg_t::__long_long:
164 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__long_long_);
165 case __format::__arg_t::__i128:
166 # ifndef _LIBCPP_HAS_NO_INT128
167 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__i128_);
168 # else
169 __libcpp_unreachable();
170 # endif
171 case __format::__arg_t::__unsigned:
172 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__unsigned_);
173 case __format::__arg_t::__unsigned_long_long:
174 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__unsigned_long_long_);
175 case __format::__arg_t::__u128:
176 # ifndef _LIBCPP_HAS_NO_INT128
177 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__u128_);
178 # else
179 __libcpp_unreachable();
180 # endif
181 case __format::__arg_t::__float:
182 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__float_);
183 case __format::__arg_t::__double:
184 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__double_);
185 case __format::__arg_t::__long_double:
186 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__long_double_);
187 case __format::__arg_t::__const_char_type_ptr:
188 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__const_char_type_ptr_);
189 case __format::__arg_t::__string_view:
190 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__string_view_);
191 case __format::__arg_t::__ptr:
192 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__ptr_);
193 case __format::__arg_t::__handle:
194 return std::invoke_r<_Rp>(
195 std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__arg.__value_.__handle_});
196 }
197
198 __libcpp_unreachable();
199 }
200
201 # endif // _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
202
203 /// Contains the values used in basic_format_arg.
204 ///
205 /// This is a separate type so it's possible to store the values and types in
206 /// separate arrays.
207 template <class _Context>
208 class __basic_format_arg_value {
209 using _CharT = typename _Context::char_type;
210
211 public:
212 /// Contains the implementation for basic_format_arg::handle.
213 struct __handle {
214 template <class _Tp>
__handle__handle215 _LIBCPP_HIDE_FROM_ABI explicit __handle(_Tp& __v) noexcept
216 : __ptr_(std::addressof(__v)),
217 __format_([](basic_format_parse_context<_CharT>& __parse_ctx, _Context& __ctx, const void* __ptr) {
218 using _Dp = remove_const_t<_Tp>;
219 using _Qp = conditional_t<__formattable_with<const _Dp, _Context>, const _Dp, _Dp>;
220 static_assert(__formattable_with<_Qp, _Context>, "Mandated by [format.arg]/10");
221
222 typename _Context::template formatter_type<_Dp> __f;
223 __parse_ctx.advance_to(__f.parse(__parse_ctx));
224 __ctx.advance_to(__f.format(*const_cast<_Qp*>(static_cast<const _Dp*>(__ptr)), __ctx));
225 }) {}
226
227 const void* __ptr_;
228 void (*__format_)(basic_format_parse_context<_CharT>&, _Context&, const void*);
229 };
230
231 union {
232 monostate __monostate_;
233 bool __boolean_;
234 _CharT __char_type_;
235 int __int_;
236 unsigned __unsigned_;
237 long long __long_long_;
238 unsigned long long __unsigned_long_long_;
239 # ifndef _LIBCPP_HAS_NO_INT128
240 __int128_t __i128_;
241 __uint128_t __u128_;
242 # endif
243 float __float_;
244 double __double_;
245 long double __long_double_;
246 const _CharT* __const_char_type_ptr_;
247 basic_string_view<_CharT> __string_view_;
248 const void* __ptr_;
249 __handle __handle_;
250 };
251
252 // These constructors contain the exact storage type used. If adjustments are
253 // required, these will be done in __create_format_arg.
254
__basic_format_arg_value()255 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value() noexcept : __monostate_() {}
__basic_format_arg_value(bool __value)256 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(bool __value) noexcept : __boolean_(__value) {}
__basic_format_arg_value(_CharT __value)257 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(_CharT __value) noexcept : __char_type_(__value) {}
__basic_format_arg_value(int __value)258 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(int __value) noexcept : __int_(__value) {}
__basic_format_arg_value(unsigned __value)259 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(unsigned __value) noexcept : __unsigned_(__value) {}
__basic_format_arg_value(long long __value)260 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(long long __value) noexcept : __long_long_(__value) {}
__basic_format_arg_value(unsigned long long __value)261 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(unsigned long long __value) noexcept
262 : __unsigned_long_long_(__value) {}
263 # ifndef _LIBCPP_HAS_NO_INT128
__basic_format_arg_value(__int128_t __value)264 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(__int128_t __value) noexcept : __i128_(__value) {}
__basic_format_arg_value(__uint128_t __value)265 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(__uint128_t __value) noexcept : __u128_(__value) {}
266 # endif
__basic_format_arg_value(float __value)267 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(float __value) noexcept : __float_(__value) {}
__basic_format_arg_value(double __value)268 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(double __value) noexcept : __double_(__value) {}
__basic_format_arg_value(long double __value)269 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(long double __value) noexcept : __long_double_(__value) {}
__basic_format_arg_value(const _CharT * __value)270 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(const _CharT* __value) noexcept : __const_char_type_ptr_(__value) {}
__basic_format_arg_value(basic_string_view<_CharT> __value)271 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(basic_string_view<_CharT> __value) noexcept
272 : __string_view_(__value) {}
__basic_format_arg_value(const void * __value)273 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(const void* __value) noexcept : __ptr_(__value) {}
__basic_format_arg_value(__handle && __value)274 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(__handle&& __value) noexcept : __handle_(std::move(__value)) {}
275 };
276
277 template <class _Context>
278 class _LIBCPP_TEMPLATE_VIS basic_format_arg {
279 public:
280 class _LIBCPP_TEMPLATE_VIS handle;
281
basic_format_arg()282 _LIBCPP_HIDE_FROM_ABI basic_format_arg() noexcept : __type_{__format::__arg_t::__none} {}
283
284 _LIBCPP_HIDE_FROM_ABI explicit operator bool() const noexcept { return __type_ != __format::__arg_t::__none; }
285
286 # if _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
287
288 // This function is user facing, so it must wrap the non-standard types of
289 // the "variant" in a handle to stay conforming. See __arg_t for more details.
290 template <class _Visitor>
decltype(auto)291 _LIBCPP_HIDE_FROM_ABI decltype(auto) visit(this basic_format_arg __arg, _Visitor&& __vis) {
292 switch (__arg.__type_) {
293 # ifndef _LIBCPP_HAS_NO_INT128
294 case __format::__arg_t::__i128: {
295 typename __basic_format_arg_value<_Context>::__handle __h{__arg.__value_.__i128_};
296 return std::invoke(std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__h});
297 }
298
299 case __format::__arg_t::__u128: {
300 typename __basic_format_arg_value<_Context>::__handle __h{__arg.__value_.__u128_};
301 return std::invoke(std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__h});
302 }
303 # endif
304 default:
305 return std::__visit_format_arg(std::forward<_Visitor>(__vis), __arg);
306 }
307 }
308
309 // This function is user facing, so it must wrap the non-standard types of
310 // the "variant" in a handle to stay conforming. See __arg_t for more details.
311 template <class _Rp, class _Visitor>
visit(this basic_format_arg __arg,_Visitor && __vis)312 _LIBCPP_HIDE_FROM_ABI _Rp visit(this basic_format_arg __arg, _Visitor&& __vis) {
313 switch (__arg.__type_) {
314 # ifndef _LIBCPP_HAS_NO_INT128
315 case __format::__arg_t::__i128: {
316 typename __basic_format_arg_value<_Context>::__handle __h{__arg.__value_.__i128_};
317 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__h});
318 }
319
320 case __format::__arg_t::__u128: {
321 typename __basic_format_arg_value<_Context>::__handle __h{__arg.__value_.__u128_};
322 return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__h});
323 }
324 # endif
325 default:
326 return std::__visit_format_arg<_Rp>(std::forward<_Visitor>(__vis), __arg);
327 }
328 }
329
330 # endif // _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
331
332 private:
333 using char_type = typename _Context::char_type;
334
335 // TODO FMT Implement constrain [format.arg]/4
336 // Constraints: The template specialization
337 // typename Context::template formatter_type<T>
338 // meets the Formatter requirements ([formatter.requirements]). The extent
339 // to which an implementation determines that the specialization meets the
340 // Formatter requirements is unspecified, except that as a minimum the
341 // expression
342 // typename Context::template formatter_type<T>()
343 // .format(declval<const T&>(), declval<Context&>())
344 // shall be well-formed when treated as an unevaluated operand.
345
346 public:
347 __basic_format_arg_value<_Context> __value_;
348 __format::__arg_t __type_;
349
basic_format_arg(__format::__arg_t __type,__basic_format_arg_value<_Context> __value)350 _LIBCPP_HIDE_FROM_ABI explicit basic_format_arg(__format::__arg_t __type,
351 __basic_format_arg_value<_Context> __value) noexcept
352 : __value_(__value), __type_(__type) {}
353 };
354
355 template <class _Context>
356 class _LIBCPP_TEMPLATE_VIS basic_format_arg<_Context>::handle {
357 public:
format(basic_format_parse_context<char_type> & __parse_ctx,_Context & __ctx)358 _LIBCPP_HIDE_FROM_ABI void format(basic_format_parse_context<char_type>& __parse_ctx, _Context& __ctx) const {
359 __handle_.__format_(__parse_ctx, __ctx, __handle_.__ptr_);
360 }
361
handle(typename __basic_format_arg_value<_Context>::__handle & __handle)362 _LIBCPP_HIDE_FROM_ABI explicit handle(typename __basic_format_arg_value<_Context>::__handle& __handle) noexcept
363 : __handle_(__handle) {}
364
365 private:
366 typename __basic_format_arg_value<_Context>::__handle& __handle_;
367 };
368
369 // This function is user facing, so it must wrap the non-standard types of
370 // the "variant" in a handle to stay conforming. See __arg_t for more details.
371 template <class _Visitor, class _Context>
372 # if _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
373 _LIBCPP_DEPRECATED_IN_CXX26
374 # endif
decltype(auto)375 _LIBCPP_HIDE_FROM_ABI decltype(auto)
376 visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
377 switch (__arg.__type_) {
378 # ifndef _LIBCPP_HAS_NO_INT128
379 case __format::__arg_t::__i128: {
380 typename __basic_format_arg_value<_Context>::__handle __h{__arg.__value_.__i128_};
381 return std::invoke(std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__h});
382 }
383
384 case __format::__arg_t::__u128: {
385 typename __basic_format_arg_value<_Context>::__handle __h{__arg.__value_.__u128_};
386 return std::invoke(std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__h});
387 }
388 # endif // _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
389 default:
390 return std::__visit_format_arg(std::forward<_Visitor>(__vis), __arg);
391 }
392 }
393
394 #endif //_LIBCPP_STD_VER >= 20
395
396 _LIBCPP_END_NAMESPACE_STD
397
398 _LIBCPP_POP_MACROS
399
400 #endif // _LIBCPP___FORMAT_FORMAT_ARG_H
401