1 /* Copyright (C) 2015-2023 Free Software Foundation, Inc. 2 3 This file is part of GDB. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17 18 #ifndef COMMON_ENUM_FLAGS_H 19 #define COMMON_ENUM_FLAGS_H 20 21 #include "traits.h" 22 23 /* Type-safe wrapper for enum flags. enum flags are enums where the 24 values are bits that are meant to be ORed together. 25 26 This allows writing code like the below, while with raw enums this 27 would fail to compile without casts to enum type at the assignments 28 to 'f': 29 30 enum some_flag 31 { 32 flag_val1 = 1 << 1, 33 flag_val2 = 1 << 2, 34 flag_val3 = 1 << 3, 35 flag_val4 = 1 << 4, 36 }; 37 DEF_ENUM_FLAGS_TYPE(enum some_flag, some_flags); 38 39 some_flags f = flag_val1 | flag_val2; 40 f |= flag_val3; 41 42 It's also possible to assign literal zero to an enum flags variable 43 (meaning, no flags), dispensing adding an awkward explicit "no 44 value" value to the enumeration. For example: 45 46 some_flags f = 0; 47 f |= flag_val3 | flag_val4; 48 49 Note that literal integers other than zero fail to compile: 50 51 some_flags f = 1; // error 52 */ 53 54 #ifdef __cplusplus 55 56 /* Use this to mark an enum as flags enum. It defines FLAGS_TYPE as 57 enum_flags wrapper class for ENUM, and enables the global operator 58 overloads for ENUM. */ 59 #define DEF_ENUM_FLAGS_TYPE(enum_type, flags_type) \ 60 typedef enum_flags<enum_type> flags_type; \ 61 void is_enum_flags_enum_type (enum_type *) 62 63 /* To enable the global enum_flags operators for enum, declare an 64 "is_enum_flags_enum_type" overload that has exactly one parameter, 65 of type a pointer to that enum class. E.g.,: 66 67 void is_enum_flags_enum_type (enum some_flag *); 68 69 The function does not need to be defined, only declared. 70 DEF_ENUM_FLAGS_TYPE declares this. 71 72 A function declaration is preferred over a traits type, because the 73 former allows calling the DEF_ENUM_FLAGS_TYPE macro inside a 74 namespace to define the corresponding enum flags type in that 75 namespace. The compiler finds the corresponding 76 is_enum_flags_enum_type function via ADL. */ 77 78 /* Note that std::underlying_type<enum_type> is not what we want here, 79 since that returns unsigned int even when the enum decays to signed 80 int. */ 81 template<int size, bool sign> class integer_for_size { typedef void type; }; 82 template<> struct integer_for_size<1, 0> { typedef uint8_t type; }; 83 template<> struct integer_for_size<2, 0> { typedef uint16_t type; }; 84 template<> struct integer_for_size<4, 0> { typedef uint32_t type; }; 85 template<> struct integer_for_size<8, 0> { typedef uint64_t type; }; 86 template<> struct integer_for_size<1, 1> { typedef int8_t type; }; 87 template<> struct integer_for_size<2, 1> { typedef int16_t type; }; 88 template<> struct integer_for_size<4, 1> { typedef int32_t type; }; 89 template<> struct integer_for_size<8, 1> { typedef int64_t type; }; 90 91 template<typename T> 92 struct enum_underlying_type 93 { 94 DIAGNOSTIC_PUSH 95 DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION 96 typedef typename 97 integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type 98 type; 99 DIAGNOSTIC_POP 100 }; 101 102 namespace enum_flags_detail 103 { 104 105 /* Private type used to support initializing flag types with zero: 106 107 foo_flags f = 0; 108 109 but not other integers: 110 111 foo_flags f = 1; 112 113 The way this works is that we define an implicit constructor that 114 takes a pointer to this private type. Since nothing can 115 instantiate an object of this type, the only possible pointer to 116 pass to the constructor is the NULL pointer, or, zero. */ 117 struct zero_type; 118 119 /* gdb::Requires trait helpers. */ 120 template <typename enum_type> 121 using EnumIsUnsigned 122 = std::is_unsigned<typename enum_underlying_type<enum_type>::type>; 123 template <typename enum_type> 124 using EnumIsSigned 125 = std::is_signed<typename enum_underlying_type<enum_type>::type>; 126 127 } 128 129 template <typename E> 130 class enum_flags 131 { 132 public: 133 typedef E enum_type; 134 typedef typename enum_underlying_type<enum_type>::type underlying_type; 135 136 public: 137 /* Allow default construction. */ 138 constexpr enum_flags () 139 : m_enum_value ((enum_type) 0) 140 {} 141 142 /* The default move/copy ctor/assignment do the right thing. */ 143 144 /* If you get an error saying these two overloads are ambiguous, 145 then you tried to mix values of different enum types. */ 146 constexpr enum_flags (enum_type e) 147 : m_enum_value (e) 148 {} 149 constexpr enum_flags (enum_flags_detail::zero_type *zero) 150 : m_enum_value ((enum_type) 0) 151 {} 152 153 enum_flags &operator&= (enum_flags e) & 154 { 155 m_enum_value = (enum_type) (m_enum_value & e.m_enum_value); 156 return *this; 157 } 158 enum_flags &operator|= (enum_flags e) & 159 { 160 m_enum_value = (enum_type) (m_enum_value | e.m_enum_value); 161 return *this; 162 } 163 enum_flags &operator^= (enum_flags e) & 164 { 165 m_enum_value = (enum_type) (m_enum_value ^ e.m_enum_value); 166 return *this; 167 } 168 169 /* Delete rval versions. */ 170 void operator&= (enum_flags e) && = delete; 171 void operator|= (enum_flags e) && = delete; 172 void operator^= (enum_flags e) && = delete; 173 174 /* Like raw enums, allow conversion to the underlying type. */ 175 constexpr operator underlying_type () const 176 { 177 return m_enum_value; 178 } 179 180 /* Get the underlying value as a raw enum. */ 181 constexpr enum_type raw () const 182 { 183 return m_enum_value; 184 } 185 186 /* Binary operations involving some unrelated type (which would be a 187 bug) are implemented as non-members, and deleted. */ 188 189 private: 190 /* Stored as enum_type because GDB knows to print the bit flags 191 neatly if the enum values look like bit flags. */ 192 enum_type m_enum_value; 193 }; 194 195 template <typename E> 196 using is_enum_flags_enum_type_t 197 = decltype (is_enum_flags_enum_type (std::declval<E *> ())); 198 199 /* Global operator overloads. */ 200 201 /* Generate binary operators. */ 202 203 #define ENUM_FLAGS_GEN_BINOP(OPERATOR_OP, OP) \ 204 \ 205 /* Raw enum on both LHS/RHS. Returns raw enum type. */ \ 206 template <typename enum_type, \ 207 typename = is_enum_flags_enum_type_t<enum_type>> \ 208 constexpr enum_type \ 209 OPERATOR_OP (enum_type e1, enum_type e2) \ 210 { \ 211 using underlying = typename enum_flags<enum_type>::underlying_type; \ 212 return (enum_type) (underlying (e1) OP underlying (e2)); \ 213 } \ 214 \ 215 /* enum_flags on the LHS. */ \ 216 template <typename enum_type, \ 217 typename = is_enum_flags_enum_type_t<enum_type>> \ 218 constexpr enum_flags<enum_type> \ 219 OPERATOR_OP (enum_flags<enum_type> e1, enum_type e2) \ 220 { return e1.raw () OP e2; } \ 221 \ 222 /* enum_flags on the RHS. */ \ 223 template <typename enum_type, \ 224 typename = is_enum_flags_enum_type_t<enum_type>> \ 225 constexpr enum_flags<enum_type> \ 226 OPERATOR_OP (enum_type e1, enum_flags<enum_type> e2) \ 227 { return e1 OP e2.raw (); } \ 228 \ 229 /* enum_flags on both LHS/RHS. */ \ 230 template <typename enum_type, \ 231 typename = is_enum_flags_enum_type_t<enum_type>> \ 232 constexpr enum_flags<enum_type> \ 233 OPERATOR_OP (enum_flags<enum_type> e1, enum_flags<enum_type> e2) \ 234 { return e1.raw () OP e2.raw (); } \ 235 \ 236 /* Delete cases involving unrelated types. */ \ 237 \ 238 template <typename enum_type, typename unrelated_type, \ 239 typename = is_enum_flags_enum_type_t<enum_type>> \ 240 constexpr enum_flags<enum_type> \ 241 OPERATOR_OP (enum_type e1, unrelated_type e2) = delete; \ 242 \ 243 template <typename enum_type, typename unrelated_type, \ 244 typename = is_enum_flags_enum_type_t<enum_type>> \ 245 constexpr enum_flags<enum_type> \ 246 OPERATOR_OP (unrelated_type e1, enum_type e2) = delete; \ 247 \ 248 template <typename enum_type, typename unrelated_type, \ 249 typename = is_enum_flags_enum_type_t<enum_type>> \ 250 constexpr enum_flags<enum_type> \ 251 OPERATOR_OP (enum_flags<enum_type> e1, unrelated_type e2) = delete; \ 252 \ 253 template <typename enum_type, typename unrelated_type, \ 254 typename = is_enum_flags_enum_type_t<enum_type>> \ 255 constexpr enum_flags<enum_type> \ 256 OPERATOR_OP (unrelated_type e1, enum_flags<enum_type> e2) = delete; 257 258 /* Generate non-member compound assignment operators. Only the raw 259 enum versions are defined here. The enum_flags versions are 260 defined as member functions, simply because it's less code that 261 way. 262 263 Note we delete operators that would allow e.g., 264 265 "enum_type | 1" or "enum_type1 | enum_type2" 266 267 because that would allow a mistake like : 268 enum flags1 { F1_FLAGS1 = 1 }; 269 enum flags2 { F2_FLAGS2 = 2 }; 270 enum flags1 val; 271 switch (val) { 272 case F1_FLAGS1 | F2_FLAGS2: 273 ... 274 275 If you really need to 'or' enumerators of different flag types, 276 cast to integer first. 277 */ 278 #define ENUM_FLAGS_GEN_COMPOUND_ASSIGN(OPERATOR_OP, OP) \ 279 /* lval reference version. */ \ 280 template <typename enum_type, \ 281 typename = is_enum_flags_enum_type_t<enum_type>> \ 282 constexpr enum_type & \ 283 OPERATOR_OP (enum_type &e1, enum_type e2) \ 284 { return e1 = e1 OP e2; } \ 285 \ 286 /* rval reference version. */ \ 287 template <typename enum_type, \ 288 typename = is_enum_flags_enum_type_t<enum_type>> \ 289 void \ 290 OPERATOR_OP (enum_type &&e1, enum_type e2) = delete; \ 291 \ 292 /* Delete compound assignment from unrelated types. */ \ 293 \ 294 template <typename enum_type, typename other_enum_type, \ 295 typename = is_enum_flags_enum_type_t<enum_type>> \ 296 constexpr enum_type & \ 297 OPERATOR_OP (enum_type &e1, other_enum_type e2) = delete; \ 298 \ 299 template <typename enum_type, typename other_enum_type, \ 300 typename = is_enum_flags_enum_type_t<enum_type>> \ 301 void \ 302 OPERATOR_OP (enum_type &&e1, other_enum_type e2) = delete; 303 304 ENUM_FLAGS_GEN_BINOP (operator|, |) 305 ENUM_FLAGS_GEN_BINOP (operator&, &) 306 ENUM_FLAGS_GEN_BINOP (operator^, ^) 307 308 ENUM_FLAGS_GEN_COMPOUND_ASSIGN (operator|=, |) 309 ENUM_FLAGS_GEN_COMPOUND_ASSIGN (operator&=, &) 310 ENUM_FLAGS_GEN_COMPOUND_ASSIGN (operator^=, ^) 311 312 /* Allow comparison with enum_flags, raw enum, and integers, only. 313 The latter case allows "== 0". As side effect, it allows comparing 314 with integer variables too, but that's not a common mistake to 315 make. It's important to disable comparison with unrelated types to 316 prevent accidentally comparing with unrelated enum values, which 317 are convertible to integer, and thus coupled with enum_flags 318 convertion to underlying type too, would trigger the built-in 'bool 319 operator==(unsigned, int)' operator. */ 320 321 #define ENUM_FLAGS_GEN_COMP(OPERATOR_OP, OP) \ 322 \ 323 /* enum_flags OP enum_flags */ \ 324 \ 325 template <typename enum_type> \ 326 constexpr bool \ 327 OPERATOR_OP (enum_flags<enum_type> lhs, enum_flags<enum_type> rhs) \ 328 { return lhs.raw () OP rhs.raw (); } \ 329 \ 330 /* enum_flags OP other */ \ 331 \ 332 template <typename enum_type> \ 333 constexpr bool \ 334 OPERATOR_OP (enum_flags<enum_type> lhs, enum_type rhs) \ 335 { return lhs.raw () OP rhs; } \ 336 \ 337 template <typename enum_type> \ 338 constexpr bool \ 339 OPERATOR_OP (enum_flags<enum_type> lhs, int rhs) \ 340 { return lhs.raw () OP rhs; } \ 341 \ 342 template <typename enum_type, typename U> \ 343 constexpr bool \ 344 OPERATOR_OP (enum_flags<enum_type> lhs, U rhs) = delete; \ 345 \ 346 /* other OP enum_flags */ \ 347 \ 348 template <typename enum_type> \ 349 constexpr bool \ 350 OPERATOR_OP (enum_type lhs, enum_flags<enum_type> rhs) \ 351 { return lhs OP rhs.raw (); } \ 352 \ 353 template <typename enum_type> \ 354 constexpr bool \ 355 OPERATOR_OP (int lhs, enum_flags<enum_type> rhs) \ 356 { return lhs OP rhs.raw (); } \ 357 \ 358 template <typename enum_type, typename U> \ 359 constexpr bool \ 360 OPERATOR_OP (U lhs, enum_flags<enum_type> rhs) = delete; 361 362 ENUM_FLAGS_GEN_COMP (operator==, ==) 363 ENUM_FLAGS_GEN_COMP (operator!=, !=) 364 365 /* Unary operators for the raw flags enum. */ 366 367 /* We require underlying type to be unsigned when using operator~ -- 368 if it were not unsigned, undefined behavior could result. However, 369 asserting this in the class itself would require too many 370 unnecessary changes to usages of otherwise OK enum types. */ 371 template <typename enum_type, 372 typename = is_enum_flags_enum_type_t<enum_type>, 373 typename 374 = gdb::Requires<enum_flags_detail::EnumIsUnsigned<enum_type>>> 375 constexpr enum_type 376 operator~ (enum_type e) 377 { 378 using underlying = typename enum_flags<enum_type>::underlying_type; 379 return (enum_type) ~underlying (e); 380 } 381 382 template <typename enum_type, 383 typename = is_enum_flags_enum_type_t<enum_type>, 384 typename = gdb::Requires<enum_flags_detail::EnumIsSigned<enum_type>>> 385 constexpr void operator~ (enum_type e) = delete; 386 387 template <typename enum_type, 388 typename = is_enum_flags_enum_type_t<enum_type>, 389 typename 390 = gdb::Requires<enum_flags_detail::EnumIsUnsigned<enum_type>>> 391 constexpr enum_flags<enum_type> 392 operator~ (enum_flags<enum_type> e) 393 { 394 using underlying = typename enum_flags<enum_type>::underlying_type; 395 return (enum_type) ~underlying (e); 396 } 397 398 template <typename enum_type, 399 typename = is_enum_flags_enum_type_t<enum_type>, 400 typename = gdb::Requires<enum_flags_detail::EnumIsSigned<enum_type>>> 401 constexpr void operator~ (enum_flags<enum_type> e) = delete; 402 403 /* Delete operator<< and operator>>. */ 404 405 template <typename enum_type, typename any_type, 406 typename = is_enum_flags_enum_type_t<enum_type>> 407 void operator<< (const enum_type &, const any_type &) = delete; 408 409 template <typename enum_type, typename any_type, 410 typename = is_enum_flags_enum_type_t<enum_type>> 411 void operator<< (const enum_flags<enum_type> &, const any_type &) = delete; 412 413 template <typename enum_type, typename any_type, 414 typename = is_enum_flags_enum_type_t<enum_type>> 415 void operator>> (const enum_type &, const any_type &) = delete; 416 417 template <typename enum_type, typename any_type, 418 typename = is_enum_flags_enum_type_t<enum_type>> 419 void operator>> (const enum_flags<enum_type> &, const any_type &) = delete; 420 421 #else /* __cplusplus */ 422 423 /* In C, the flags type is just a typedef for the enum type. */ 424 425 #define DEF_ENUM_FLAGS_TYPE(enum_type, flags_type) \ 426 typedef enum_type flags_type 427 428 #endif /* __cplusplus */ 429 430 #endif /* COMMON_ENUM_FLAGS_H */ 431