blob dfd8ea25 (19990B) - Raw
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 <__functional/invoke.h> 14 #include <__functional/unary_function.h> 15 #include <__fwd/hash.h> 16 #include <__tuple_dir/sfinae_helpers.h> 17 #include <__type_traits/is_copy_constructible.h> 18 #include <__type_traits/is_default_constructible.h> 19 #include <__type_traits/is_enum.h> 20 #include <__type_traits/is_move_constructible.h> 21 #include <__type_traits/underlying_type.h> 22 #include <__utility/forward.h> 23 #include <__utility/move.h> 24 #include <__utility/pair.h> 25 #include <__utility/swap.h> 26 #include <cstddef> 27 #include <cstdint> 28 #include <cstring> 29 #include <limits> 30 31 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 32 # pragma GCC system_header 33 #endif 34 35 _LIBCPP_BEGIN_NAMESPACE_STD 36 37 template <class _Size> 38 inline _LIBCPP_INLINE_VISIBILITY 39 _Size 40 __loadword(const void* __p) 41 { 42 _Size __r; 43 _VSTD::memcpy(&__r, __p, sizeof(__r)); 44 return __r; 45 } 46 47 // We use murmur2 when size_t is 32 bits, and cityhash64 when size_t 48 // is 64 bits. This is because cityhash64 uses 64bit x 64bit 49 // multiplication, which can be very slow on 32-bit systems. 50 template <class _Size, size_t = sizeof(_Size)*__CHAR_BIT__> 51 struct __murmur2_or_cityhash; 52 53 template <class _Size> 54 struct __murmur2_or_cityhash<_Size, 32> 55 { 56 inline _Size operator()(const void* __key, _Size __len) 57 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK; 58 }; 59 60 // murmur2 61 template <class _Size> 62 _Size 63 __murmur2_or_cityhash<_Size, 32>::operator()(const void* __key, _Size __len) 64 { 65 const _Size __m = 0x5bd1e995; 66 const _Size __r = 24; 67 _Size __h = __len; 68 const unsigned char* __data = static_cast<const unsigned char*>(__key); 69 for (; __len >= 4; __data += 4, __len -= 4) 70 { 71 _Size __k = std::__loadword<_Size>(__data); 72 __k *= __m; 73 __k ^= __k >> __r; 74 __k *= __m; 75 __h *= __m; 76 __h ^= __k; 77 } 78 switch (__len) 79 { 80 case 3: 81 __h ^= static_cast<_Size>(__data[2] << 16); 82 _LIBCPP_FALLTHROUGH(); 83 case 2: 84 __h ^= static_cast<_Size>(__data[1] << 8); 85 _LIBCPP_FALLTHROUGH(); 86 case 1: 87 __h ^= __data[0]; 88 __h *= __m; 89 } 90 __h ^= __h >> 13; 91 __h *= __m; 92 __h ^= __h >> 15; 93 return __h; 94 } 95 96 template <class _Size> 97 struct __murmur2_or_cityhash<_Size, 64> 98 { 99 inline _Size operator()(const void* __key, _Size __len) _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK; 100 101 private: 102 // Some primes between 2^63 and 2^64. 103 static const _Size __k0 = 0xc3a5c85c97cb3127ULL; 104 static const _Size __k1 = 0xb492b66fbe98f273ULL; 105 static const _Size __k2 = 0x9ae16a3b2f90404fULL; 106 static const _Size __k3 = 0xc949d7c7509e6557ULL; 107 108 static _Size __rotate(_Size __val, int __shift) { 109 return __shift == 0 ? __val : ((__val >> __shift) | (__val << (64 - __shift))); 110 } 111 112 static _Size __rotate_by_at_least_1(_Size __val, int __shift) { 113 return (__val >> __shift) | (__val << (64 - __shift)); 114 } 115 116 static _Size __shift_mix(_Size __val) { 117 return __val ^ (__val >> 47); 118 } 119 120 static _Size __hash_len_16(_Size __u, _Size __v) 121 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK 122 { 123 const _Size __mul = 0x9ddfea08eb382d69ULL; 124 _Size __a = (__u ^ __v) * __mul; 125 __a ^= (__a >> 47); 126 _Size __b = (__v ^ __a) * __mul; 127 __b ^= (__b >> 47); 128 __b *= __mul; 129 return __b; 130 } 131 132 static _Size __hash_len_0_to_16(const char* __s, _Size __len) 133 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK 134 { 135 if (__len > 8) { 136 const _Size __a = std::__loadword<_Size>(__s); 137 const _Size __b = std::__loadword<_Size>(__s + __len - 8); 138 return __hash_len_16(__a, __rotate_by_at_least_1(__b + __len, __len)) ^ __b; 139 } 140 if (__len >= 4) { 141 const uint32_t __a = std::__loadword<uint32_t>(__s); 142 const uint32_t __b = std::__loadword<uint32_t>(__s + __len - 4); 143 return __hash_len_16(__len + (static_cast<_Size>(__a) << 3), __b); 144 } 145 if (__len > 0) { 146 const unsigned char __a = static_cast<unsigned char>(__s[0]); 147 const unsigned char __b = static_cast<unsigned char>(__s[__len >> 1]); 148 const unsigned char __c = static_cast<unsigned char>(__s[__len - 1]); 149 const uint32_t __y = static_cast<uint32_t>(__a) + 150 (static_cast<uint32_t>(__b) << 8); 151 const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2); 152 return __shift_mix(__y * __k2 ^ __z * __k3) * __k2; 153 } 154 return __k2; 155 } 156 157 static _Size __hash_len_17_to_32(const char *__s, _Size __len) 158 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK 159 { 160 const _Size __a = std::__loadword<_Size>(__s) * __k1; 161 const _Size __b = std::__loadword<_Size>(__s + 8); 162 const _Size __c = std::__loadword<_Size>(__s + __len - 8) * __k2; 163 const _Size __d = std::__loadword<_Size>(__s + __len - 16) * __k0; 164 return __hash_len_16(__rotate(__a - __b, 43) + __rotate(__c, 30) + __d, 165 __a + __rotate(__b ^ __k3, 20) - __c + __len); 166 } 167 168 // Return a 16-byte hash for 48 bytes. Quick and dirty. 169 // Callers do best to use "random-looking" values for a and b. 170 static pair<_Size, _Size> __weak_hash_len_32_with_seeds( 171 _Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b) 172 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK 173 { 174 __a += __w; 175 __b = __rotate(__b + __a + __z, 21); 176 const _Size __c = __a; 177 __a += __x; 178 __a += __y; 179 __b += __rotate(__a, 44); 180 return pair<_Size, _Size>(__a + __z, __b + __c); 181 } 182 183 // Return a 16-byte hash for s[0] ... s[31], a, and b. Quick and dirty. 184 static pair<_Size, _Size> __weak_hash_len_32_with_seeds( 185 const char* __s, _Size __a, _Size __b) 186 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK 187 { 188 return __weak_hash_len_32_with_seeds(std::__loadword<_Size>(__s), 189 std::__loadword<_Size>(__s + 8), 190 std::__loadword<_Size>(__s + 16), 191 std::__loadword<_Size>(__s + 24), 192 __a, 193 __b); 194 } 195 196 // Return an 8-byte hash for 33 to 64 bytes. 197 static _Size __hash_len_33_to_64(const char *__s, size_t __len) 198 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK 199 { 200 _Size __z = std::__loadword<_Size>(__s + 24); 201 _Size __a = std::__loadword<_Size>(__s) + 202 (__len + std::__loadword<_Size>(__s + __len - 16)) * __k0; 203 _Size __b = __rotate(__a + __z, 52); 204 _Size __c = __rotate(__a, 37); 205 __a += std::__loadword<_Size>(__s + 8); 206 __c += __rotate(__a, 7); 207 __a += std::__loadword<_Size>(__s + 16); 208 _Size __vf = __a + __z; 209 _Size __vs = __b + __rotate(__a, 31) + __c; 210 __a = std::__loadword<_Size>(__s + 16) + std::__loadword<_Size>(__s + __len - 32); 211 __z += std::__loadword<_Size>(__s + __len - 8); 212 __b = __rotate(__a + __z, 52); 213 __c = __rotate(__a, 37); 214 __a += std::__loadword<_Size>(__s + __len - 24); 215 __c += __rotate(__a, 7); 216 __a += std::__loadword<_Size>(__s + __len - 16); 217 _Size __wf = __a + __z; 218 _Size __ws = __b + __rotate(__a, 31) + __c; 219 _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0); 220 return __shift_mix(__r * __k0 + __vs) * __k2; 221 } 222 }; 223 224 // cityhash64 225 template <class _Size> 226 _Size 227 __murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len) 228 { 229 const char* __s = static_cast<const char*>(__key); 230 if (__len <= 32) { 231 if (__len <= 16) { 232 return __hash_len_0_to_16(__s, __len); 233 } else { 234 return __hash_len_17_to_32(__s, __len); 235 } 236 } else if (__len <= 64) { 237 return __hash_len_33_to_64(__s, __len); 238 } 239 240 // For strings over 64 bytes we hash the end first, and then as we 241 // loop we keep 56 bytes of state: v, w, x, y, and z. 242 _Size __x = std::__loadword<_Size>(__s + __len - 40); 243 _Size __y = std::__loadword<_Size>(__s + __len - 16) + 244 std::__loadword<_Size>(__s + __len - 56); 245 _Size __z = __hash_len_16(std::__loadword<_Size>(__s + __len - 48) + __len, 246 std::__loadword<_Size>(__s + __len - 24)); 247 pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z); 248 pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x); 249 __x = __x * __k1 + std::__loadword<_Size>(__s); 250 251 // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks. 252 __len = (__len - 1) & ~static_cast<_Size>(63); 253 do { 254 __x = __rotate(__x + __y + __v.first + std::__loadword<_Size>(__s + 8), 37) * __k1; 255 __y = __rotate(__y + __v.second + std::__loadword<_Size>(__s + 48), 42) * __k1; 256 __x ^= __w.second; 257 __y += __v.first + std::__loadword<_Size>(__s + 40); 258 __z = __rotate(__z + __w.first, 33) * __k1; 259 __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first); 260 __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second, 261 __y + std::__loadword<_Size>(__s + 16)); 262 _VSTD::swap(__z, __x); 263 __s += 64; 264 __len -= 64; 265 } while (__len != 0); 266 return __hash_len_16( 267 __hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z, 268 __hash_len_16(__v.second, __w.second) + __x); 269 } 270 271 template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)> 272 struct __scalar_hash; 273 274 template <class _Tp> 275 struct __scalar_hash<_Tp, 0> 276 : public __unary_function<_Tp, size_t> 277 { 278 _LIBCPP_INLINE_VISIBILITY 279 size_t operator()(_Tp __v) const _NOEXCEPT 280 { 281 union 282 { 283 _Tp __t; 284 size_t __a; 285 } __u; 286 __u.__a = 0; 287 __u.__t = __v; 288 return __u.__a; 289 } 290 }; 291 292 template <class _Tp> 293 struct __scalar_hash<_Tp, 1> 294 : public __unary_function<_Tp, size_t> 295 { 296 _LIBCPP_INLINE_VISIBILITY 297 size_t operator()(_Tp __v) const _NOEXCEPT 298 { 299 union 300 { 301 _Tp __t; 302 size_t __a; 303 } __u; 304 __u.__t = __v; 305 return __u.__a; 306 } 307 }; 308 309 template <class _Tp> 310 struct __scalar_hash<_Tp, 2> 311 : public __unary_function<_Tp, size_t> 312 { 313 _LIBCPP_INLINE_VISIBILITY 314 size_t operator()(_Tp __v) const _NOEXCEPT 315 { 316 union 317 { 318 _Tp __t; 319 struct 320 { 321 size_t __a; 322 size_t __b; 323 } __s; 324 } __u; 325 __u.__t = __v; 326 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 327 } 328 }; 329 330 template <class _Tp> 331 struct __scalar_hash<_Tp, 3> 332 : public __unary_function<_Tp, size_t> 333 { 334 _LIBCPP_INLINE_VISIBILITY 335 size_t operator()(_Tp __v) const _NOEXCEPT 336 { 337 union 338 { 339 _Tp __t; 340 struct 341 { 342 size_t __a; 343 size_t __b; 344 size_t __c; 345 } __s; 346 } __u; 347 __u.__t = __v; 348 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 349 } 350 }; 351 352 template <class _Tp> 353 struct __scalar_hash<_Tp, 4> 354 : public __unary_function<_Tp, size_t> 355 { 356 _LIBCPP_INLINE_VISIBILITY 357 size_t operator()(_Tp __v) const _NOEXCEPT 358 { 359 union 360 { 361 _Tp __t; 362 struct 363 { 364 size_t __a; 365 size_t __b; 366 size_t __c; 367 size_t __d; 368 } __s; 369 } __u; 370 __u.__t = __v; 371 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 372 } 373 }; 374 375 struct _PairT { 376 size_t first; 377 size_t second; 378 }; 379 380 _LIBCPP_INLINE_VISIBILITY 381 inline size_t __hash_combine(size_t __lhs, size_t __rhs) _NOEXCEPT { 382 typedef __scalar_hash<_PairT> _HashT; 383 const _PairT __p = {__lhs, __rhs}; 384 return _HashT()(__p); 385 } 386 387 template<class _Tp> 388 struct _LIBCPP_TEMPLATE_VIS hash<_Tp*> 389 : public __unary_function<_Tp*, size_t> 390 { 391 _LIBCPP_INLINE_VISIBILITY 392 size_t operator()(_Tp* __v) const _NOEXCEPT 393 { 394 union 395 { 396 _Tp* __t; 397 size_t __a; 398 } __u; 399 __u.__t = __v; 400 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 401 } 402 }; 403 404 template <> 405 struct _LIBCPP_TEMPLATE_VIS hash<bool> 406 : public __unary_function<bool, size_t> 407 { 408 _LIBCPP_INLINE_VISIBILITY 409 size_t operator()(bool __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 410 }; 411 412 template <> 413 struct _LIBCPP_TEMPLATE_VIS hash<char> 414 : public __unary_function<char, size_t> 415 { 416 _LIBCPP_INLINE_VISIBILITY 417 size_t operator()(char __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 418 }; 419 420 template <> 421 struct _LIBCPP_TEMPLATE_VIS hash<signed char> 422 : public __unary_function<signed char, size_t> 423 { 424 _LIBCPP_INLINE_VISIBILITY 425 size_t operator()(signed char __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 426 }; 427 428 template <> 429 struct _LIBCPP_TEMPLATE_VIS hash<unsigned char> 430 : public __unary_function<unsigned char, size_t> 431 { 432 _LIBCPP_INLINE_VISIBILITY 433 size_t operator()(unsigned char __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 434 }; 435 436 #ifndef _LIBCPP_HAS_NO_CHAR8_T 437 template <> 438 struct _LIBCPP_TEMPLATE_VIS hash<char8_t> 439 : public __unary_function<char8_t, size_t> 440 { 441 _LIBCPP_INLINE_VISIBILITY 442 size_t operator()(char8_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 443 }; 444 #endif // !_LIBCPP_HAS_NO_CHAR8_T 445 446 template <> 447 struct _LIBCPP_TEMPLATE_VIS hash<char16_t> 448 : public __unary_function<char16_t, size_t> 449 { 450 _LIBCPP_INLINE_VISIBILITY 451 size_t operator()(char16_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 452 }; 453 454 template <> 455 struct _LIBCPP_TEMPLATE_VIS hash<char32_t> 456 : public __unary_function<char32_t, size_t> 457 { 458 _LIBCPP_INLINE_VISIBILITY 459 size_t operator()(char32_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 460 }; 461 462 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS 463 template <> 464 struct _LIBCPP_TEMPLATE_VIS hash<wchar_t> 465 : public __unary_function<wchar_t, size_t> 466 { 467 _LIBCPP_INLINE_VISIBILITY 468 size_t operator()(wchar_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 469 }; 470 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS 471 472 template <> 473 struct _LIBCPP_TEMPLATE_VIS hash<short> 474 : public __unary_function<short, size_t> 475 { 476 _LIBCPP_INLINE_VISIBILITY 477 size_t operator()(short __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 478 }; 479 480 template <> 481 struct _LIBCPP_TEMPLATE_VIS hash<unsigned short> 482 : public __unary_function<unsigned short, size_t> 483 { 484 _LIBCPP_INLINE_VISIBILITY 485 size_t operator()(unsigned short __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 486 }; 487 488 template <> 489 struct _LIBCPP_TEMPLATE_VIS hash<int> 490 : public __unary_function<int, size_t> 491 { 492 _LIBCPP_INLINE_VISIBILITY 493 size_t operator()(int __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 494 }; 495 496 template <> 497 struct _LIBCPP_TEMPLATE_VIS hash<unsigned int> 498 : public __unary_function<unsigned int, size_t> 499 { 500 _LIBCPP_INLINE_VISIBILITY 501 size_t operator()(unsigned int __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 502 }; 503 504 template <> 505 struct _LIBCPP_TEMPLATE_VIS hash<long> 506 : public __unary_function<long, size_t> 507 { 508 _LIBCPP_INLINE_VISIBILITY 509 size_t operator()(long __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 510 }; 511 512 template <> 513 struct _LIBCPP_TEMPLATE_VIS hash<unsigned long> 514 : public __unary_function<unsigned long, size_t> 515 { 516 _LIBCPP_INLINE_VISIBILITY 517 size_t operator()(unsigned long __v) const _NOEXCEPT {return static_cast<size_t>(__v);} 518 }; 519 520 template <> 521 struct _LIBCPP_TEMPLATE_VIS hash<long long> 522 : public __scalar_hash<long long> 523 { 524 }; 525 526 template <> 527 struct _LIBCPP_TEMPLATE_VIS hash<unsigned long long> 528 : public __scalar_hash<unsigned long long> 529 { 530 }; 531 532 #ifndef _LIBCPP_HAS_NO_INT128 533 534 template <> 535 struct _LIBCPP_TEMPLATE_VIS hash<__int128_t> 536 : public __scalar_hash<__int128_t> 537 { 538 }; 539 540 template <> 541 struct _LIBCPP_TEMPLATE_VIS hash<__uint128_t> 542 : public __scalar_hash<__uint128_t> 543 { 544 }; 545 546 #endif 547 548 template <> 549 struct _LIBCPP_TEMPLATE_VIS hash<float> 550 : public __scalar_hash<float> 551 { 552 _LIBCPP_INLINE_VISIBILITY 553 size_t operator()(float __v) const _NOEXCEPT 554 { 555 // -0.0 and 0.0 should return same hash 556 if (__v == 0.0f) 557 return 0; 558 return __scalar_hash<float>::operator()(__v); 559 } 560 }; 561 562 template <> 563 struct _LIBCPP_TEMPLATE_VIS hash<double> 564 : public __scalar_hash<double> 565 { 566 _LIBCPP_INLINE_VISIBILITY 567 size_t operator()(double __v) const _NOEXCEPT 568 { 569 // -0.0 and 0.0 should return same hash 570 if (__v == 0.0) 571 return 0; 572 return __scalar_hash<double>::operator()(__v); 573 } 574 }; 575 576 template <> 577 struct _LIBCPP_TEMPLATE_VIS hash<long double> 578 : public __scalar_hash<long double> 579 { 580 _LIBCPP_INLINE_VISIBILITY 581 size_t operator()(long double __v) const _NOEXCEPT 582 { 583 // -0.0 and 0.0 should return same hash 584 if (__v == 0.0L) 585 return 0; 586 #if defined(__i386__) || (defined(__x86_64__) && defined(__ILP32__)) 587 // Zero out padding bits 588 union 589 { 590 long double __t; 591 struct 592 { 593 size_t __a; 594 size_t __b; 595 size_t __c; 596 size_t __d; 597 } __s; 598 } __u; 599 __u.__s.__a = 0; 600 __u.__s.__b = 0; 601 __u.__s.__c = 0; 602 __u.__s.__d = 0; 603 __u.__t = __v; 604 return __u.__s.__a ^ __u.__s.__b ^ __u.__s.__c ^ __u.__s.__d; 605 #elif defined(__x86_64__) 606 // Zero out padding bits 607 union 608 { 609 long double __t; 610 struct 611 { 612 size_t __a; 613 size_t __b; 614 } __s; 615 } __u; 616 __u.__s.__a = 0; 617 __u.__s.__b = 0; 618 __u.__t = __v; 619 return __u.__s.__a ^ __u.__s.__b; 620 #else 621 return __scalar_hash<long double>::operator()(__v); 622 #endif 623 } 624 }; 625 626 template <class _Tp, bool = is_enum<_Tp>::value> 627 struct _LIBCPP_TEMPLATE_VIS __enum_hash 628 : public __unary_function<_Tp, size_t> 629 { 630 _LIBCPP_INLINE_VISIBILITY 631 size_t operator()(_Tp __v) const _NOEXCEPT 632 { 633 typedef typename underlying_type<_Tp>::type type; 634 return hash<type>()(static_cast<type>(__v)); 635 } 636 }; 637 template <class _Tp> 638 struct _LIBCPP_TEMPLATE_VIS __enum_hash<_Tp, false> { 639 __enum_hash() = delete; 640 __enum_hash(__enum_hash const&) = delete; 641 __enum_hash& operator=(__enum_hash const&) = delete; 642 }; 643 644 template <class _Tp> 645 struct _LIBCPP_TEMPLATE_VIS hash : public __enum_hash<_Tp> 646 { 647 }; 648 649 #if _LIBCPP_STD_VER > 14 650 651 template <> 652 struct _LIBCPP_TEMPLATE_VIS hash<nullptr_t> 653 : public __unary_function<nullptr_t, size_t> 654 { 655 _LIBCPP_INLINE_VISIBILITY 656 size_t operator()(nullptr_t) const _NOEXCEPT { 657 return 662607004ull; 658 } 659 }; 660 #endif 661 662 #ifndef _LIBCPP_CXX03_LANG 663 template <class _Key, class _Hash> 664 using __check_hash_requirements _LIBCPP_NODEBUG = integral_constant<bool, 665 is_copy_constructible<_Hash>::value && 666 is_move_constructible<_Hash>::value && 667 __invokable_r<size_t, _Hash, _Key const&>::value 668 >; 669 670 template <class _Key, class _Hash = hash<_Key> > 671 using __has_enabled_hash _LIBCPP_NODEBUG = integral_constant<bool, 672 __check_hash_requirements<_Key, _Hash>::value && 673 is_default_constructible<_Hash>::value 674 >; 675 676 #if _LIBCPP_STD_VER > 14 677 template <class _Type, class> 678 using __enable_hash_helper_imp _LIBCPP_NODEBUG = _Type; 679 680 template <class _Type, class ..._Keys> 681 using __enable_hash_helper _LIBCPP_NODEBUG = __enable_hash_helper_imp<_Type, 682 typename enable_if<__all<__has_enabled_hash<_Keys>::value...>::value>::type 683 >; 684 #else 685 template <class _Type, class ...> 686 using __enable_hash_helper _LIBCPP_NODEBUG = _Type; 687 #endif 688 689 #endif // !_LIBCPP_CXX03_LANG 690 691 _LIBCPP_END_NAMESPACE_STD 692 693 #endif // _LIBCPP___FUNCTIONAL_HASH_H