1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___FUNCTIONAL_HASH_H 10 #define _LIBCPP___FUNCTIONAL_HASH_H 11 12 #include <__config> 13 #include <__cstddef/nullptr_t.h> 14 #include <__functional/unary_function.h> 15 #include <__fwd/functional.h> 16 #include <__type_traits/conjunction.h> 17 #include <__type_traits/enable_if.h> 18 #include <__type_traits/invoke.h> 19 #include <__type_traits/is_constructible.h> 20 #include <__type_traits/is_enum.h> 21 #include <__type_traits/underlying_type.h> 22 #include <__utility/pair.h> 23 #include <__utility/swap.h> 24 #include <cstdint> 25 #include <cstring> 26 27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 28 # pragma GCC system_header 29 #endif 30 31 _LIBCPP_BEGIN_NAMESPACE_STD 32 33 template <class _Size> 34 inline _LIBCPP_HIDE_FROM_ABI _Size __loadword(const void* __p) { 35 _Size __r; 36 std::memcpy(&__r, __p, sizeof(__r)); 37 return __r; 38 } 39 40 // We use murmur2 when size_t is 32 bits, and cityhash64 when size_t 41 // is 64 bits. This is because cityhash64 uses 64bit x 64bit 42 // multiplication, which can be very slow on 32-bit systems. 43 template <class _Size, size_t = sizeof(_Size) * __CHAR_BIT__> 44 struct __murmur2_or_cityhash; 45 46 template <class _Size> 47 struct __murmur2_or_cityhash<_Size, 32> { 48 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK _Size 49 operator()(const void* __key, _Size __len) const { 50 // murmur2 51 const _Size __m = 0x5bd1e995; 52 const _Size __r = 24; 53 _Size __h = __len; 54 const unsigned char* __data = static_cast<const unsigned char*>(__key); 55 for (; __len >= 4; __data += 4, __len -= 4) { 56 _Size __k = std::__loadword<_Size>(__data); 57 __k *= __m; 58 __k ^= __k >> __r; 59 __k *= __m; 60 __h *= __m; 61 __h ^= __k; 62 } 63 switch (__len) { 64 case 3: 65 __h ^= static_cast<_Size>(__data[2] << 16); 66 _LIBCPP_FALLTHROUGH(); 67 case 2: 68 __h ^= static_cast<_Size>(__data[1] << 8); 69 _LIBCPP_FALLTHROUGH(); 70 case 1: 71 __h ^= __data[0]; 72 __h *= __m; 73 } 74 __h ^= __h >> 13; 75 __h *= __m; 76 __h ^= __h >> 15; 77 return __h; 78 } 79 }; 80 81 template <class _Size> 82 struct __murmur2_or_cityhash<_Size, 64> { 83 // cityhash64 84 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK _Size 85 operator()(const void* __key, _Size __len) const { 86 const char* __s = static_cast<const char*>(__key); 87 if (__len <= 32) { 88 if (__len <= 16) { 89 return __hash_len_0_to_16(__s, __len); 90 } else { 91 return __hash_len_17_to_32(__s, __len); 92 } 93 } else if (__len <= 64) { 94 return __hash_len_33_to_64(__s, __len); 95 } 96 97 // For strings over 64 bytes we hash the end first, and then as we 98 // loop we keep 56 bytes of state: v, w, x, y, and z. 99 _Size __x = std::__loadword<_Size>(__s + __len - 40); 100 _Size __y = std::__loadword<_Size>(__s + __len - 16) + std::__loadword<_Size>(__s + __len - 56); 101 _Size __z = 102 __hash_len_16(std::__loadword<_Size>(__s + __len - 48) + __len, std::__loadword<_Size>(__s + __len - 24)); 103 pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z); 104 pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x); 105 __x = __x * __k1 + std::__loadword<_Size>(__s); 106 107 // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks. 108 __len = (__len - 1) & ~static_cast<_Size>(63); 109 do { 110 __x = __rotate(__x + __y + __v.first + std::__loadword<_Size>(__s + 8), 37) * __k1; 111 __y = __rotate(__y + __v.second + std::__loadword<_Size>(__s + 48), 42) * __k1; 112 __x ^= __w.second; 113 __y += __v.first + std::__loadword<_Size>(__s + 40); 114 __z = __rotate(__z + __w.first, 33) * __k1; 115 __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first); 116 __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second, __y + std::__loadword<_Size>(__s + 16)); 117 std::swap(__z, __x); 118 __s += 64; 119 __len -= 64; 120 } while (__len != 0); 121 return __hash_len_16(__hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z, 122 __hash_len_16(__v.second, __w.second) + __x); 123 } 124 125 private: 126 // Some primes between 2^63 and 2^64. 127 static const _Size __k0 = 0xc3a5c85c97cb3127ULL; 128 static const _Size __k1 = 0xb492b66fbe98f273ULL; 129 static const _Size __k2 = 0x9ae16a3b2f90404fULL; 130 static const _Size __k3 = 0xc949d7c7509e6557ULL; 131 132 _LIBCPP_HIDE_FROM_ABI static _Size __rotate(_Size __val, int __shift) { 133 return __shift == 0 ? __val : ((__val >> __shift) | (__val << (64 - __shift))); 134 } 135 136 _LIBCPP_HIDE_FROM_ABI static _Size __rotate_by_at_least_1(_Size __val, int __shift) { 137 return (__val >> __shift) | (__val << (64 - __shift)); 138 } 139 140 _LIBCPP_HIDE_FROM_ABI static _Size __shift_mix(_Size __val) { return __val ^ (__val >> 47); } 141 142 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static _Size __hash_len_16(_Size __u, _Size __v) { 143 const _Size __mul = 0x9ddfea08eb382d69ULL; 144 _Size __a = (__u ^ __v) * __mul; 145 __a ^= (__a >> 47); 146 _Size __b = (__v ^ __a) * __mul; 147 __b ^= (__b >> 47); 148 __b *= __mul; 149 return __b; 150 } 151 152 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static _Size 153 __hash_len_0_to_16(const char* __s, _Size __len) { 154 if (__len > 8) { 155 const _Size __a = std::__loadword<_Size>(__s); 156 const _Size __b = std::__loadword<_Size>(__s + __len - 8); 157 return __hash_len_16(__a, __rotate_by_at_least_1(__b + __len, __len)) ^ __b; 158 } 159 if (__len >= 4) { 160 const uint32_t __a = std::__loadword<uint32_t>(__s); 161 const uint32_t __b = std::__loadword<uint32_t>(__s + __len - 4); 162 #ifdef _LIBCPP_ABI_FIX_CITYHASH_IMPLEMENTATION 163 return __hash_len_16(__len + (static_cast<_Size>(__a) << 3), __b); 164 #else 165 return __hash_len_16(__len + (__a << 3), __b); 166 #endif 167 } 168 if (__len > 0) { 169 const unsigned char __a = static_cast<unsigned char>(__s[0]); 170 const unsigned char __b = static_cast<unsigned char>(__s[__len >> 1]); 171 const unsigned char __c = static_cast<unsigned char>(__s[__len - 1]); 172 const uint32_t __y = static_cast<uint32_t>(__a) + (static_cast<uint32_t>(__b) << 8); 173 const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2); 174 return __shift_mix(__y * __k2 ^ __z * __k3) * __k2; 175 } 176 return __k2; 177 } 178 179 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static _Size 180 __hash_len_17_to_32(const char* __s, _Size __len) { 181 const _Size __a = std::__loadword<_Size>(__s) * __k1; 182 const _Size __b = std::__loadword<_Size>(__s + 8); 183 const _Size __c = std::__loadword<_Size>(__s + __len - 8) * __k2; 184 const _Size __d = std::__loadword<_Size>(__s + __len - 16) * __k0; 185 return __hash_len_16( 186 __rotate(__a - __b, 43) + __rotate(__c, 30) + __d, __a + __rotate(__b ^ __k3, 20) - __c + __len); 187 } 188 189 // Return a 16-byte hash for 48 bytes. Quick and dirty. 190 // Callers do best to use "random-looking" values for a and b. 191 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static pair<_Size, _Size> 192 __weak_hash_len_32_with_seeds(_Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b) { 193 __a += __w; 194 __b = __rotate(__b + __a + __z, 21); 195 const _Size __c = __a; 196 __a += __x; 197 __a += __y; 198 __b += __rotate(__a, 44); 199 return pair<_Size, _Size>(__a + __z, __b + __c); 200 } 201 202 // Return a 16-byte hash for s[0] ... s[31], a, and b. Quick and dirty. 203 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static pair<_Size, _Size> 204 __weak_hash_len_32_with_seeds(const char* __s, _Size __a, _Size __b) { 205 return __weak_hash_len_32_with_seeds( 206 std::__loadword<_Size>(__s), 207 std::__loadword<_Size>(__s + 8), 208 std::__loadword<_Size>(__s + 16), 209 std::__loadword<_Size>(__s + 24), 210 __a, 211 __b); 212 } 213 214 // Return an 8-byte hash for 33 to 64 bytes. 215 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static _Size 216 __hash_len_33_to_64(const char* __s, size_t __len) { 217 _Size __z = std::__loadword<_Size>(__s + 24); 218 _Size __a = std::__loadword<_Size>(__s) + (__len + std::__loadword<_Size>(__s + __len - 16)) * __k0; 219 _Size __b = __rotate(__a + __z, 52); 220 _Size __c = __rotate(__a, 37); 221 __a += std::__loadword<_Size>(__s + 8); 222 __c += __rotate(__a, 7); 223 __a += std::__loadword<_Size>(__s + 16); 224 _Size __vf = __a + __z; 225 _Size __vs = __b + __rotate(__a, 31) + __c; 226 __a = std::__loadword<_Size>(__s + 16) + std::__loadword<_Size>(__s + __len - 32); 227 __z += std::__loadword<_Size>(__s + __len - 8); 228 __b = __rotate(__a + __z, 52); 229 __c = __rotate(__a, 37); 230 __a += std::__loadword<_Size>(__s + __len - 24); 231 __c += __rotate(__a, 7); 232 __a += std::__loadword<_Size>(__s + __len - 16); 233 _Size __wf = __a + __z; 234 _Size __ws = __b + __rotate(__a, 31) + __c; 235 _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0); 236 return __shift_mix(__r * __k0 + __vs) * __k2; 237 } 238 }; 239 240 template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)> 241 struct __scalar_hash; 242 243 template <class _Tp> 244 struct __scalar_hash<_Tp, 0> : public __unary_function<_Tp, size_t> { 245 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 246 union { 247 _Tp __t; 248 size_t __a; 249 } __u; 250 __u.__a = 0; 251 __u.__t = __v; 252 return __u.__a; 253 } 254 }; 255 256 template <class _Tp> 257 struct __scalar_hash<_Tp, 1> : public __unary_function<_Tp, size_t> { 258 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 259 union { 260 _Tp __t; 261 size_t __a; 262 } __u; 263 __u.__t = __v; 264 return __u.__a; 265 } 266 }; 267 268 template <class _Tp> 269 struct __scalar_hash<_Tp, 2> : public __unary_function<_Tp, size_t> { 270 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 271 union { 272 _Tp __t; 273 struct { 274 size_t __a; 275 size_t __b; 276 } __s; 277 } __u; 278 __u.__t = __v; 279 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 280 } 281 }; 282 283 template <class _Tp> 284 struct __scalar_hash<_Tp, 3> : public __unary_function<_Tp, size_t> { 285 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 286 union { 287 _Tp __t; 288 struct { 289 size_t __a; 290 size_t __b; 291 size_t __c; 292 } __s; 293 } __u; 294 __u.__t = __v; 295 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 296 } 297 }; 298 299 template <class _Tp> 300 struct __scalar_hash<_Tp, 4> : public __unary_function<_Tp, size_t> { 301 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 302 union { 303 _Tp __t; 304 struct { 305 size_t __a; 306 size_t __b; 307 size_t __c; 308 size_t __d; 309 } __s; 310 } __u; 311 __u.__t = __v; 312 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 313 } 314 }; 315 316 struct _PairT { 317 size_t first; 318 size_t second; 319 }; 320 321 _LIBCPP_HIDE_FROM_ABI inline size_t __hash_combine(size_t __lhs, size_t __rhs) _NOEXCEPT { 322 typedef __scalar_hash<_PairT> _HashT; 323 const _PairT __p = {__lhs, __rhs}; 324 return _HashT()(__p); 325 } 326 327 template <class _Tp> 328 struct _LIBCPP_TEMPLATE_VIS hash<_Tp*> : public __unary_function<_Tp*, size_t> { 329 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp* __v) const _NOEXCEPT { 330 union { 331 _Tp* __t; 332 size_t __a; 333 } __u; 334 __u.__t = __v; 335 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 336 } 337 }; 338 339 template <> 340 struct _LIBCPP_TEMPLATE_VIS hash<bool> : public __unary_function<bool, size_t> { 341 _LIBCPP_HIDE_FROM_ABI size_t operator()(bool __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 342 }; 343 344 template <> 345 struct _LIBCPP_TEMPLATE_VIS hash<char> : public __unary_function<char, size_t> { 346 _LIBCPP_HIDE_FROM_ABI size_t operator()(char __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 347 }; 348 349 template <> 350 struct _LIBCPP_TEMPLATE_VIS hash<signed char> : public __unary_function<signed char, size_t> { 351 _LIBCPP_HIDE_FROM_ABI size_t operator()(signed char __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 352 }; 353 354 template <> 355 struct _LIBCPP_TEMPLATE_VIS hash<unsigned char> : public __unary_function<unsigned char, size_t> { 356 _LIBCPP_HIDE_FROM_ABI size_t operator()(unsigned char __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 357 }; 358 359 #if _LIBCPP_HAS_CHAR8_T 360 template <> 361 struct _LIBCPP_TEMPLATE_VIS hash<char8_t> : public __unary_function<char8_t, size_t> { 362 _LIBCPP_HIDE_FROM_ABI size_t operator()(char8_t __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 363 }; 364 #endif // _LIBCPP_HAS_CHAR8_T 365 366 template <> 367 struct _LIBCPP_TEMPLATE_VIS hash<char16_t> : public __unary_function<char16_t, size_t> { 368 _LIBCPP_HIDE_FROM_ABI size_t operator()(char16_t __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 369 }; 370 371 template <> 372 struct _LIBCPP_TEMPLATE_VIS hash<char32_t> : public __unary_function<char32_t, size_t> { 373 _LIBCPP_HIDE_FROM_ABI size_t operator()(char32_t __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 374 }; 375 376 #if _LIBCPP_HAS_WIDE_CHARACTERS 377 template <> 378 struct _LIBCPP_TEMPLATE_VIS hash<wchar_t> : public __unary_function<wchar_t, size_t> { 379 _LIBCPP_HIDE_FROM_ABI size_t operator()(wchar_t __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 380 }; 381 #endif // _LIBCPP_HAS_WIDE_CHARACTERS 382 383 template <> 384 struct _LIBCPP_TEMPLATE_VIS hash<short> : public __unary_function<short, size_t> { 385 _LIBCPP_HIDE_FROM_ABI size_t operator()(short __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 386 }; 387 388 template <> 389 struct _LIBCPP_TEMPLATE_VIS hash<unsigned short> : public __unary_function<unsigned short, size_t> { 390 _LIBCPP_HIDE_FROM_ABI size_t operator()(unsigned short __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 391 }; 392 393 template <> 394 struct _LIBCPP_TEMPLATE_VIS hash<int> : public __unary_function<int, size_t> { 395 _LIBCPP_HIDE_FROM_ABI size_t operator()(int __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 396 }; 397 398 template <> 399 struct _LIBCPP_TEMPLATE_VIS hash<unsigned int> : public __unary_function<unsigned int, size_t> { 400 _LIBCPP_HIDE_FROM_ABI size_t operator()(unsigned int __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 401 }; 402 403 template <> 404 struct _LIBCPP_TEMPLATE_VIS hash<long> : public __unary_function<long, size_t> { 405 _LIBCPP_HIDE_FROM_ABI size_t operator()(long __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 406 }; 407 408 template <> 409 struct _LIBCPP_TEMPLATE_VIS hash<unsigned long> : public __unary_function<unsigned long, size_t> { 410 _LIBCPP_HIDE_FROM_ABI size_t operator()(unsigned long __v) const _NOEXCEPT { 411 static_assert(sizeof(size_t) >= sizeof(unsigned long), 412 "This would be a terrible hash function on a platform where size_t is smaller than unsigned long"); 413 return static_cast<size_t>(__v); 414 } 415 }; 416 417 template <> 418 struct _LIBCPP_TEMPLATE_VIS hash<long long> : public __scalar_hash<long long> {}; 419 420 template <> 421 struct _LIBCPP_TEMPLATE_VIS hash<unsigned long long> : public __scalar_hash<unsigned long long> {}; 422 423 #if _LIBCPP_HAS_INT128 424 425 template <> 426 struct _LIBCPP_TEMPLATE_VIS hash<__int128_t> : public __scalar_hash<__int128_t> {}; 427 428 template <> 429 struct _LIBCPP_TEMPLATE_VIS hash<__uint128_t> : public __scalar_hash<__uint128_t> {}; 430 431 #endif 432 433 template <> 434 struct _LIBCPP_TEMPLATE_VIS hash<float> : public __scalar_hash<float> { 435 _LIBCPP_HIDE_FROM_ABI size_t operator()(float __v) const _NOEXCEPT { 436 // -0.0 and 0.0 should return same hash 437 if (__v == 0.0f) 438 return 0; 439 return __scalar_hash<float>::operator()(__v); 440 } 441 }; 442 443 template <> 444 struct _LIBCPP_TEMPLATE_VIS hash<double> : public __scalar_hash<double> { 445 _LIBCPP_HIDE_FROM_ABI size_t operator()(double __v) const _NOEXCEPT { 446 // -0.0 and 0.0 should return same hash 447 if (__v == 0.0) 448 return 0; 449 return __scalar_hash<double>::operator()(__v); 450 } 451 }; 452 453 template <> 454 struct _LIBCPP_TEMPLATE_VIS hash<long double> : public __scalar_hash<long double> { 455 _LIBCPP_HIDE_FROM_ABI size_t operator()(long double __v) const _NOEXCEPT { 456 // -0.0 and 0.0 should return same hash 457 if (__v == 0.0L) 458 return 0; 459 #if defined(__i386__) || (defined(__x86_64__) && defined(__ILP32__)) 460 // Zero out padding bits 461 union { 462 long double __t; 463 struct { 464 size_t __a; 465 size_t __b; 466 size_t __c; 467 size_t __d; 468 } __s; 469 } __u; 470 __u.__s.__a = 0; 471 __u.__s.__b = 0; 472 __u.__s.__c = 0; 473 __u.__s.__d = 0; 474 __u.__t = __v; 475 return __u.__s.__a ^ __u.__s.__b ^ __u.__s.__c ^ __u.__s.__d; 476 #elif defined(__x86_64__) 477 // Zero out padding bits 478 union { 479 long double __t; 480 struct { 481 size_t __a; 482 size_t __b; 483 } __s; 484 } __u; 485 __u.__s.__a = 0; 486 __u.__s.__b = 0; 487 __u.__t = __v; 488 return __u.__s.__a ^ __u.__s.__b; 489 #else 490 return __scalar_hash<long double>::operator()(__v); 491 #endif 492 } 493 }; 494 495 template <class _Tp, bool = is_enum<_Tp>::value> 496 struct _LIBCPP_TEMPLATE_VIS __enum_hash : public __unary_function<_Tp, size_t> { 497 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 498 typedef typename underlying_type<_Tp>::type type; 499 return hash<type>()(static_cast<type>(__v)); 500 } 501 }; 502 template <class _Tp> 503 struct _LIBCPP_TEMPLATE_VIS __enum_hash<_Tp, false> { 504 __enum_hash() = delete; 505 __enum_hash(__enum_hash const&) = delete; 506 __enum_hash& operator=(__enum_hash const&) = delete; 507 }; 508 509 template <class _Tp> 510 struct _LIBCPP_TEMPLATE_VIS hash : public __enum_hash<_Tp> {}; 511 512 #if _LIBCPP_STD_VER >= 17 513 514 template <> 515 struct _LIBCPP_TEMPLATE_VIS hash<nullptr_t> : public __unary_function<nullptr_t, size_t> { 516 _LIBCPP_HIDE_FROM_ABI size_t operator()(nullptr_t) const _NOEXCEPT { return 662607004ull; } 517 }; 518 #endif 519 520 #ifndef _LIBCPP_CXX03_LANG 521 template <class _Key, class _Hash> 522 using __check_hash_requirements _LIBCPP_NODEBUG = 523 integral_constant<bool, 524 is_copy_constructible<_Hash>::value && is_move_constructible<_Hash>::value && 525 __is_invocable_r_v<size_t, _Hash, _Key const&> >; 526 527 template <class _Key, class _Hash = hash<_Key> > 528 using __has_enabled_hash _LIBCPP_NODEBUG = 529 integral_constant<bool, __check_hash_requirements<_Key, _Hash>::value && is_default_constructible<_Hash>::value >; 530 531 # if _LIBCPP_STD_VER >= 17 532 template <class _Type, class> 533 using __enable_hash_helper_imp _LIBCPP_NODEBUG = _Type; 534 535 template <class _Type, class... _Keys> 536 using __enable_hash_helper _LIBCPP_NODEBUG = 537 __enable_hash_helper_imp<_Type, __enable_if_t<__all<__has_enabled_hash<_Keys>::value...>::value> >; 538 # else 539 template <class _Type, class...> 540 using __enable_hash_helper _LIBCPP_NODEBUG = _Type; 541 # endif 542 543 #endif // !_LIBCPP_CXX03_LANG 544 545 _LIBCPP_END_NAMESPACE_STD 546 547 #endif // _LIBCPP___FUNCTIONAL_HASH_H 548