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_fwd.h> 18 #include <__format/format_parse_context.h> 19 #include <__functional/invoke.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_BEGIN_NAMESPACE_STD 34 35 #if _LIBCPP_STD_VER >= 20 36 37 namespace __format { 38 /// The type stored in @ref basic_format_arg. 39 /// 40 /// @note The 128-bit types are unconditionally in the list to avoid the values 41 /// of the enums to depend on the availability of 128-bit integers. 42 /// 43 /// @note The value is stored as a 5-bit value in the __packed_arg_t_bits. This 44 /// limits the maximum number of elements to 32. 45 /// When modifying update the test 46 /// test/libcxx/utilities/format/format.arguments/format.arg/arg_t.compile.pass.cpp 47 /// It could be packed in 4-bits but that means a new type directly becomes an 48 /// ABI break. The packed type is 64-bit so this reduces the maximum number of 49 /// packed elements from 16 to 12. 50 /// 51 /// @note Some members of this enum are an extension. These extensions need 52 /// special behaviour in visit_format_arg. There they need to be wrapped in a 53 /// handle to satisfy the user observable behaviour. The internal function 54 /// __visit_format_arg doesn't do this wrapping. So in the format functions 55 /// this function is used to avoid unneeded overhead. 56 enum class _LIBCPP_ENUM_VIS __arg_t : uint8_t { 57 __none, 58 __boolean, 59 __char_type, 60 __int, 61 __long_long, 62 __i128, // extension 63 __unsigned, 64 __unsigned_long_long, 65 __u128, // extension 66 __float, 67 __double, 68 __long_double, 69 __const_char_type_ptr, 70 __string_view, 71 __ptr, 72 __handle 73 }; 74 75 inline constexpr unsigned __packed_arg_t_bits = 5; 76 inline constexpr uint8_t __packed_arg_t_mask = 0x1f; 77 78 inline constexpr unsigned __packed_types_storage_bits = 64; 79 inline constexpr unsigned __packed_types_max = __packed_types_storage_bits / __packed_arg_t_bits; 80 81 _LIBCPP_HIDE_FROM_ABI 82 constexpr bool __use_packed_format_arg_store(size_t __size) { return __size <= __packed_types_max; } 83 84 _LIBCPP_HIDE_FROM_ABI 85 constexpr __arg_t __get_packed_type(uint64_t __types, size_t __id) { 86 _LIBCPP_ASSERT_UNCATEGORIZED(__id <= __packed_types_max, ""); 87 88 if (__id > 0) 89 __types >>= __id * __packed_arg_t_bits; 90 91 return static_cast<__format::__arg_t>(__types & __packed_arg_t_mask); 92 } 93 94 } // namespace __format 95 96 // This function is not user obervable, so it can directly use the non-standard 97 // types of the "variant". See __arg_t for more details. 98 template <class _Visitor, class _Context> 99 _LIBCPP_HIDE_FROM_ABI decltype(auto) 100 __visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) { 101 switch (__arg.__type_) { 102 case __format::__arg_t::__none: 103 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__monostate_); 104 case __format::__arg_t::__boolean: 105 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__boolean_); 106 case __format::__arg_t::__char_type: 107 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__char_type_); 108 case __format::__arg_t::__int: 109 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__int_); 110 case __format::__arg_t::__long_long: 111 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__long_long_); 112 case __format::__arg_t::__i128: 113 # ifndef _LIBCPP_HAS_NO_INT128 114 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__i128_); 115 # else 116 __libcpp_unreachable(); 117 # endif 118 case __format::__arg_t::__unsigned: 119 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__unsigned_); 120 case __format::__arg_t::__unsigned_long_long: 121 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__unsigned_long_long_); 122 case __format::__arg_t::__u128: 123 # ifndef _LIBCPP_HAS_NO_INT128 124 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__u128_); 125 # else 126 __libcpp_unreachable(); 127 # endif 128 case __format::__arg_t::__float: 129 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__float_); 130 case __format::__arg_t::__double: 131 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__double_); 132 case __format::__arg_t::__long_double: 133 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__long_double_); 134 case __format::__arg_t::__const_char_type_ptr: 135 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__const_char_type_ptr_); 136 case __format::__arg_t::__string_view: 137 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__string_view_); 138 case __format::__arg_t::__ptr: 139 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__ptr_); 140 case __format::__arg_t::__handle: 141 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), 142 typename basic_format_arg<_Context>::handle{__arg.__value_.__handle_}); 143 } 144 145 __libcpp_unreachable(); 146 } 147 148 /// Contains the values used in basic_format_arg. 149 /// 150 /// This is a separate type so it's possible to store the values and types in 151 /// separate arrays. 152 template <class _Context> 153 class __basic_format_arg_value { 154 using _CharT = typename _Context::char_type; 155 156 public: 157 /// Contains the implementation for basic_format_arg::handle. 158 struct __handle { 159 template <class _Tp> 160 _LIBCPP_HIDE_FROM_ABI explicit __handle(_Tp& __v) noexcept 161 : __ptr_(_VSTD::addressof(__v)), 162 __format_([](basic_format_parse_context<_CharT>& __parse_ctx, _Context& __ctx, const void* __ptr) { 163 using _Dp = remove_const_t<_Tp>; 164 using _Qp = conditional_t<__formattable_with<const _Dp, _Context>, const _Dp, _Dp>; 165 static_assert(__formattable_with<_Qp, _Context>, "Mandated by [format.arg]/10"); 166 167 typename _Context::template formatter_type<_Dp> __f; 168 __parse_ctx.advance_to(__f.parse(__parse_ctx)); 169 __ctx.advance_to(__f.format(*const_cast<_Qp*>(static_cast<const _Dp*>(__ptr)), __ctx)); 170 }) {} 171 172 const void* __ptr_; 173 void (*__format_)(basic_format_parse_context<_CharT>&, _Context&, const void*); 174 }; 175 176 union { 177 monostate __monostate_; 178 bool __boolean_; 179 _CharT __char_type_; 180 int __int_; 181 unsigned __unsigned_; 182 long long __long_long_; 183 unsigned long long __unsigned_long_long_; 184 # ifndef _LIBCPP_HAS_NO_INT128 185 __int128_t __i128_; 186 __uint128_t __u128_; 187 # endif 188 float __float_; 189 double __double_; 190 long double __long_double_; 191 const _CharT* __const_char_type_ptr_; 192 basic_string_view<_CharT> __string_view_; 193 const void* __ptr_; 194 __handle __handle_; 195 }; 196 197 // These constructors contain the exact storage type used. If adjustments are 198 // required, these will be done in __create_format_arg. 199 200 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value() noexcept : __monostate_() {} 201 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(bool __value) noexcept : __boolean_(__value) {} 202 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(_CharT __value) noexcept : __char_type_(__value) {} 203 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(int __value) noexcept : __int_(__value) {} 204 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(unsigned __value) noexcept : __unsigned_(__value) {} 205 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(long long __value) noexcept : __long_long_(__value) {} 206 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(unsigned long long __value) noexcept 207 : __unsigned_long_long_(__value) {} 208 # ifndef _LIBCPP_HAS_NO_INT128 209 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(__int128_t __value) noexcept : __i128_(__value) {} 210 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(__uint128_t __value) noexcept : __u128_(__value) {} 211 # endif 212 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(float __value) noexcept : __float_(__value) {} 213 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(double __value) noexcept : __double_(__value) {} 214 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(long double __value) noexcept : __long_double_(__value) {} 215 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(const _CharT* __value) noexcept : __const_char_type_ptr_(__value) {} 216 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(basic_string_view<_CharT> __value) noexcept 217 : __string_view_(__value) {} 218 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(const void* __value) noexcept : __ptr_(__value) {} 219 _LIBCPP_HIDE_FROM_ABI __basic_format_arg_value(__handle&& __value) noexcept : __handle_(std::move(__value)) {} 220 }; 221 222 template <class _Context> 223 class _LIBCPP_TEMPLATE_VIS basic_format_arg { 224 public: 225 class _LIBCPP_TEMPLATE_VIS handle; 226 227 _LIBCPP_HIDE_FROM_ABI basic_format_arg() noexcept 228 : __type_{__format::__arg_t::__none} {} 229 230 _LIBCPP_HIDE_FROM_ABI explicit operator bool() const noexcept { 231 return __type_ != __format::__arg_t::__none; 232 } 233 234 private: 235 using char_type = typename _Context::char_type; 236 237 // TODO FMT Implement constrain [format.arg]/4 238 // Constraints: The template specialization 239 // typename Context::template formatter_type<T> 240 // meets the Formatter requirements ([formatter.requirements]). The extent 241 // to which an implementation determines that the specialization meets the 242 // Formatter requirements is unspecified, except that as a minimum the 243 // expression 244 // typename Context::template formatter_type<T>() 245 // .format(declval<const T&>(), declval<Context&>()) 246 // shall be well-formed when treated as an unevaluated operand. 247 248 public: 249 __basic_format_arg_value<_Context> __value_; 250 __format::__arg_t __type_; 251 252 _LIBCPP_HIDE_FROM_ABI explicit basic_format_arg(__format::__arg_t __type, 253 __basic_format_arg_value<_Context> __value) noexcept 254 : __value_(__value), __type_(__type) {} 255 }; 256 257 template <class _Context> 258 class _LIBCPP_TEMPLATE_VIS basic_format_arg<_Context>::handle { 259 public: 260 _LIBCPP_HIDE_FROM_ABI 261 void format(basic_format_parse_context<char_type>& __parse_ctx, _Context& __ctx) const { 262 __handle_.__format_(__parse_ctx, __ctx, __handle_.__ptr_); 263 } 264 265 _LIBCPP_HIDE_FROM_ABI explicit handle(typename __basic_format_arg_value<_Context>::__handle& __handle) noexcept 266 : __handle_(__handle) {} 267 268 private: 269 typename __basic_format_arg_value<_Context>::__handle& __handle_; 270 }; 271 272 // This function is user facing, so it must wrap the non-standard types of 273 // the "variant" in a handle to stay conforming. See __arg_t for more details. 274 template <class _Visitor, class _Context> 275 _LIBCPP_HIDE_FROM_ABI decltype(auto) 276 visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) { 277 switch (__arg.__type_) { 278 # ifndef _LIBCPP_HAS_NO_INT128 279 case __format::__arg_t::__i128: { 280 typename __basic_format_arg_value<_Context>::__handle __h{__arg.__value_.__i128_}; 281 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__h}); 282 } 283 284 case __format::__arg_t::__u128: { 285 typename __basic_format_arg_value<_Context>::__handle __h{__arg.__value_.__u128_}; 286 return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__h}); 287 } 288 # endif 289 default: 290 return _VSTD::__visit_format_arg(_VSTD::forward<_Visitor>(__vis), __arg); 291 } 292 } 293 294 #endif //_LIBCPP_STD_VER >= 20 295 296 _LIBCPP_END_NAMESPACE_STD 297 298 #endif // _LIBCPP___FORMAT_FORMAT_ARG_H 299