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/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 37template <class _Size> 38inline _LIBCPP_HIDE_FROM_ABI _Size __loadword(const void* __p) { 39 _Size __r; 40 std::memcpy(&__r, __p, sizeof(__r)); 41 return __r; 42} 43 44// We use murmur2 when size_t is 32 bits, and cityhash64 when size_t 45// is 64 bits. This is because cityhash64 uses 64bit x 64bit 46// multiplication, which can be very slow on 32-bit systems. 47template <class _Size, size_t = sizeof(_Size) * __CHAR_BIT__> 48struct __murmur2_or_cityhash; 49 50template <class _Size> 51struct __murmur2_or_cityhash<_Size, 32> { 52 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK _Size 53 operator()(const void* __key, _Size __len) const { 54 // murmur2 55 const _Size __m = 0x5bd1e995; 56 const _Size __r = 24; 57 _Size __h = __len; 58 const unsigned char* __data = static_cast<const unsigned char*>(__key); 59 for (; __len >= 4; __data += 4, __len -= 4) { 60 _Size __k = std::__loadword<_Size>(__data); 61 __k *= __m; 62 __k ^= __k >> __r; 63 __k *= __m; 64 __h *= __m; 65 __h ^= __k; 66 } 67 switch (__len) { 68 case 3: 69 __h ^= static_cast<_Size>(__data[2] << 16); 70 _LIBCPP_FALLTHROUGH(); 71 case 2: 72 __h ^= static_cast<_Size>(__data[1] << 8); 73 _LIBCPP_FALLTHROUGH(); 74 case 1: 75 __h ^= __data[0]; 76 __h *= __m; 77 } 78 __h ^= __h >> 13; 79 __h *= __m; 80 __h ^= __h >> 15; 81 return __h; 82 } 83}; 84 85template <class _Size> 86struct __murmur2_or_cityhash<_Size, 64> { 87 // cityhash64 88 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK _Size 89 operator()(const void* __key, _Size __len) const { 90 const char* __s = static_cast<const char*>(__key); 91 if (__len <= 32) { 92 if (__len <= 16) { 93 return __hash_len_0_to_16(__s, __len); 94 } else { 95 return __hash_len_17_to_32(__s, __len); 96 } 97 } else if (__len <= 64) { 98 return __hash_len_33_to_64(__s, __len); 99 } 100 101 // For strings over 64 bytes we hash the end first, and then as we 102 // loop we keep 56 bytes of state: v, w, x, y, and z. 103 _Size __x = std::__loadword<_Size>(__s + __len - 40); 104 _Size __y = std::__loadword<_Size>(__s + __len - 16) + std::__loadword<_Size>(__s + __len - 56); 105 _Size __z = 106 __hash_len_16(std::__loadword<_Size>(__s + __len - 48) + __len, std::__loadword<_Size>(__s + __len - 24)); 107 pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z); 108 pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x); 109 __x = __x * __k1 + std::__loadword<_Size>(__s); 110 111 // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks. 112 __len = (__len - 1) & ~static_cast<_Size>(63); 113 do { 114 __x = __rotate(__x + __y + __v.first + std::__loadword<_Size>(__s + 8), 37) * __k1; 115 __y = __rotate(__y + __v.second + std::__loadword<_Size>(__s + 48), 42) * __k1; 116 __x ^= __w.second; 117 __y += __v.first + std::__loadword<_Size>(__s + 40); 118 __z = __rotate(__z + __w.first, 33) * __k1; 119 __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first); 120 __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second, __y + std::__loadword<_Size>(__s + 16)); 121 std::swap(__z, __x); 122 __s += 64; 123 __len -= 64; 124 } while (__len != 0); 125 return __hash_len_16(__hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z, 126 __hash_len_16(__v.second, __w.second) + __x); 127 } 128 129private: 130 // Some primes between 2^63 and 2^64. 131 static const _Size __k0 = 0xc3a5c85c97cb3127ULL; 132 static const _Size __k1 = 0xb492b66fbe98f273ULL; 133 static const _Size __k2 = 0x9ae16a3b2f90404fULL; 134 static const _Size __k3 = 0xc949d7c7509e6557ULL; 135 136 _LIBCPP_HIDE_FROM_ABI static _Size __rotate(_Size __val, int __shift) { 137 return __shift == 0 ? __val : ((__val >> __shift) | (__val << (64 - __shift))); 138 } 139 140 _LIBCPP_HIDE_FROM_ABI static _Size __rotate_by_at_least_1(_Size __val, int __shift) { 141 return (__val >> __shift) | (__val << (64 - __shift)); 142 } 143 144 _LIBCPP_HIDE_FROM_ABI static _Size __shift_mix(_Size __val) { return __val ^ (__val >> 47); } 145 146 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static _Size __hash_len_16(_Size __u, _Size __v) { 147 const _Size __mul = 0x9ddfea08eb382d69ULL; 148 _Size __a = (__u ^ __v) * __mul; 149 __a ^= (__a >> 47); 150 _Size __b = (__v ^ __a) * __mul; 151 __b ^= (__b >> 47); 152 __b *= __mul; 153 return __b; 154 } 155 156 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static _Size 157 __hash_len_0_to_16(const char* __s, _Size __len) { 158 if (__len > 8) { 159 const _Size __a = std::__loadword<_Size>(__s); 160 const _Size __b = std::__loadword<_Size>(__s + __len - 8); 161 return __hash_len_16(__a, __rotate_by_at_least_1(__b + __len, __len)) ^ __b; 162 } 163 if (__len >= 4) { 164 const uint32_t __a = std::__loadword<uint32_t>(__s); 165 const uint32_t __b = std::__loadword<uint32_t>(__s + __len - 4); 166#ifdef _LIBCPP_ABI_FIX_CITYHASH_IMPLEMENTATION 167 return __hash_len_16(__len + (static_cast<_Size>(__a) << 3), __b); 168#else 169 return __hash_len_16(__len + (__a << 3), __b); 170#endif 171 } 172 if (__len > 0) { 173 const unsigned char __a = static_cast<unsigned char>(__s[0]); 174 const unsigned char __b = static_cast<unsigned char>(__s[__len >> 1]); 175 const unsigned char __c = static_cast<unsigned char>(__s[__len - 1]); 176 const uint32_t __y = static_cast<uint32_t>(__a) + (static_cast<uint32_t>(__b) << 8); 177 const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2); 178 return __shift_mix(__y * __k2 ^ __z * __k3) * __k2; 179 } 180 return __k2; 181 } 182 183 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static _Size 184 __hash_len_17_to_32(const char* __s, _Size __len) { 185 const _Size __a = std::__loadword<_Size>(__s) * __k1; 186 const _Size __b = std::__loadword<_Size>(__s + 8); 187 const _Size __c = std::__loadword<_Size>(__s + __len - 8) * __k2; 188 const _Size __d = std::__loadword<_Size>(__s + __len - 16) * __k0; 189 return __hash_len_16( 190 __rotate(__a - __b, 43) + __rotate(__c, 30) + __d, __a + __rotate(__b ^ __k3, 20) - __c + __len); 191 } 192 193 // Return a 16-byte hash for 48 bytes. Quick and dirty. 194 // Callers do best to use "random-looking" values for a and b. 195 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static pair<_Size, _Size> 196 __weak_hash_len_32_with_seeds(_Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b) { 197 __a += __w; 198 __b = __rotate(__b + __a + __z, 21); 199 const _Size __c = __a; 200 __a += __x; 201 __a += __y; 202 __b += __rotate(__a, 44); 203 return pair<_Size, _Size>(__a + __z, __b + __c); 204 } 205 206 // Return a 16-byte hash for s[0] ... s[31], a, and b. Quick and dirty. 207 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static pair<_Size, _Size> 208 __weak_hash_len_32_with_seeds(const char* __s, _Size __a, _Size __b) { 209 return __weak_hash_len_32_with_seeds( 210 std::__loadword<_Size>(__s), 211 std::__loadword<_Size>(__s + 8), 212 std::__loadword<_Size>(__s + 16), 213 std::__loadword<_Size>(__s + 24), 214 __a, 215 __b); 216 } 217 218 // Return an 8-byte hash for 33 to 64 bytes. 219 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK static _Size 220 __hash_len_33_to_64(const char* __s, size_t __len) { 221 _Size __z = std::__loadword<_Size>(__s + 24); 222 _Size __a = std::__loadword<_Size>(__s) + (__len + std::__loadword<_Size>(__s + __len - 16)) * __k0; 223 _Size __b = __rotate(__a + __z, 52); 224 _Size __c = __rotate(__a, 37); 225 __a += std::__loadword<_Size>(__s + 8); 226 __c += __rotate(__a, 7); 227 __a += std::__loadword<_Size>(__s + 16); 228 _Size __vf = __a + __z; 229 _Size __vs = __b + __rotate(__a, 31) + __c; 230 __a = std::__loadword<_Size>(__s + 16) + std::__loadword<_Size>(__s + __len - 32); 231 __z += std::__loadword<_Size>(__s + __len - 8); 232 __b = __rotate(__a + __z, 52); 233 __c = __rotate(__a, 37); 234 __a += std::__loadword<_Size>(__s + __len - 24); 235 __c += __rotate(__a, 7); 236 __a += std::__loadword<_Size>(__s + __len - 16); 237 _Size __wf = __a + __z; 238 _Size __ws = __b + __rotate(__a, 31) + __c; 239 _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0); 240 return __shift_mix(__r * __k0 + __vs) * __k2; 241 } 242}; 243 244template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)> 245struct __scalar_hash; 246 247template <class _Tp> 248struct __scalar_hash<_Tp, 0> : public __unary_function<_Tp, size_t> { 249 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 250 union { 251 _Tp __t; 252 size_t __a; 253 } __u; 254 __u.__a = 0; 255 __u.__t = __v; 256 return __u.__a; 257 } 258}; 259 260template <class _Tp> 261struct __scalar_hash<_Tp, 1> : public __unary_function<_Tp, size_t> { 262 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 263 union { 264 _Tp __t; 265 size_t __a; 266 } __u; 267 __u.__t = __v; 268 return __u.__a; 269 } 270}; 271 272template <class _Tp> 273struct __scalar_hash<_Tp, 2> : public __unary_function<_Tp, size_t> { 274 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 275 union { 276 _Tp __t; 277 struct { 278 size_t __a; 279 size_t __b; 280 } __s; 281 } __u; 282 __u.__t = __v; 283 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 284 } 285}; 286 287template <class _Tp> 288struct __scalar_hash<_Tp, 3> : public __unary_function<_Tp, size_t> { 289 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 290 union { 291 _Tp __t; 292 struct { 293 size_t __a; 294 size_t __b; 295 size_t __c; 296 } __s; 297 } __u; 298 __u.__t = __v; 299 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 300 } 301}; 302 303template <class _Tp> 304struct __scalar_hash<_Tp, 4> : public __unary_function<_Tp, size_t> { 305 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp __v) const _NOEXCEPT { 306 union { 307 _Tp __t; 308 struct { 309 size_t __a; 310 size_t __b; 311 size_t __c; 312 size_t __d; 313 } __s; 314 } __u; 315 __u.__t = __v; 316 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 317 } 318}; 319 320struct _PairT { 321 size_t first; 322 size_t second; 323}; 324 325_LIBCPP_HIDE_FROM_ABI inline size_t __hash_combine(size_t __lhs, size_t __rhs) _NOEXCEPT { 326 typedef __scalar_hash<_PairT> _HashT; 327 const _PairT __p = {__lhs, __rhs}; 328 return _HashT()(__p); 329} 330 331template <class _Tp> 332struct _LIBCPP_TEMPLATE_VIS hash<_Tp*> : public __unary_function<_Tp*, size_t> { 333 _LIBCPP_HIDE_FROM_ABI size_t operator()(_Tp* __v) const _NOEXCEPT { 334 union { 335 _Tp* __t; 336 size_t __a; 337 } __u; 338 __u.__t = __v; 339 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u)); 340 } 341}; 342 343template <> 344struct _LIBCPP_TEMPLATE_VIS hash<bool> : public __unary_function<bool, size_t> { 345 _LIBCPP_HIDE_FROM_ABI size_t operator()(bool __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 346}; 347 348template <> 349struct _LIBCPP_TEMPLATE_VIS hash<char> : public __unary_function<char, size_t> { 350 _LIBCPP_HIDE_FROM_ABI size_t operator()(char __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 351}; 352 353template <> 354struct _LIBCPP_TEMPLATE_VIS hash<signed char> : public __unary_function<signed char, size_t> { 355 _LIBCPP_HIDE_FROM_ABI size_t operator()(signed char __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 356}; 357 358template <> 359struct _LIBCPP_TEMPLATE_VIS hash<unsigned char> : public __unary_function<unsigned char, size_t> { 360 _LIBCPP_HIDE_FROM_ABI size_t operator()(unsigned char __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 361}; 362 363#ifndef _LIBCPP_HAS_NO_CHAR8_T 364template <> 365struct _LIBCPP_TEMPLATE_VIS hash<char8_t> : public __unary_function<char8_t, size_t> { 366 _LIBCPP_HIDE_FROM_ABI size_t operator()(char8_t __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 367}; 368#endif // !_LIBCPP_HAS_NO_CHAR8_T 369 370template <> 371struct _LIBCPP_TEMPLATE_VIS hash<char16_t> : public __unary_function<char16_t, size_t> { 372 _LIBCPP_HIDE_FROM_ABI size_t operator()(char16_t __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 373}; 374 375template <> 376struct _LIBCPP_TEMPLATE_VIS hash<char32_t> : public __unary_function<char32_t, size_t> { 377 _LIBCPP_HIDE_FROM_ABI size_t operator()(char32_t __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 378}; 379 380#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS 381template <> 382struct _LIBCPP_TEMPLATE_VIS hash<wchar_t> : public __unary_function<wchar_t, size_t> { 383 _LIBCPP_HIDE_FROM_ABI size_t operator()(wchar_t __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 384}; 385#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS 386 387template <> 388struct _LIBCPP_TEMPLATE_VIS hash<short> : public __unary_function<short, size_t> { 389 _LIBCPP_HIDE_FROM_ABI size_t operator()(short __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 390}; 391 392template <> 393struct _LIBCPP_TEMPLATE_VIS hash<unsigned short> : public __unary_function<unsigned short, size_t> { 394 _LIBCPP_HIDE_FROM_ABI size_t operator()(unsigned short __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 395}; 396 397template <> 398struct _LIBCPP_TEMPLATE_VIS hash<int> : public __unary_function<int, size_t> { 399 _LIBCPP_HIDE_FROM_ABI size_t operator()(int __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 400}; 401 402template <> 403struct _LIBCPP_TEMPLATE_VIS hash<unsigned int> : public __unary_function<unsigned int, size_t> { 404 _LIBCPP_HIDE_FROM_ABI size_t operator()(unsigned int __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 405}; 406 407template <> 408struct _LIBCPP_TEMPLATE_VIS hash<long> : public __unary_function<long, size_t> { 409 _LIBCPP_HIDE_FROM_ABI size_t operator()(long __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 410}; 411 412template <> 413struct _LIBCPP_TEMPLATE_VIS hash<unsigned long> : public __unary_function<unsigned long, size_t> { 414 _LIBCPP_HIDE_FROM_ABI size_t operator()(unsigned long __v) const _NOEXCEPT { return static_cast<size_t>(__v); } 415}; 416 417template <> 418struct _LIBCPP_TEMPLATE_VIS hash<long long> : public __scalar_hash<long long> {}; 419 420template <> 421struct _LIBCPP_TEMPLATE_VIS hash<unsigned long long> : public __scalar_hash<unsigned long long> {}; 422 423#ifndef _LIBCPP_HAS_NO_INT128 424 425template <> 426struct _LIBCPP_TEMPLATE_VIS hash<__int128_t> : public __scalar_hash<__int128_t> {}; 427 428template <> 429struct _LIBCPP_TEMPLATE_VIS hash<__uint128_t> : public __scalar_hash<__uint128_t> {}; 430 431#endif 432 433template <> 434struct _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 443template <> 444struct _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 453template <> 454struct _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 495template <class _Tp, bool = is_enum<_Tp>::value> 496struct _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}; 502template <class _Tp> 503struct _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 509template <class _Tp> 510struct _LIBCPP_TEMPLATE_VIS hash : public __enum_hash<_Tp> {}; 511 512#if _LIBCPP_STD_VER >= 17 513 514template <> 515struct _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 521template <class _Key, class _Hash> 522using __check_hash_requirements _LIBCPP_NODEBUG = 523 integral_constant<bool, 524 is_copy_constructible<_Hash>::value && is_move_constructible<_Hash>::value && 525 __invokable_r<size_t, _Hash, _Key const&>::value >; 526 527template <class _Key, class _Hash = hash<_Key> > 528using __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 532template <class _Type, class> 533using __enable_hash_helper_imp _LIBCPP_NODEBUG = _Type; 534 535template <class _Type, class... _Keys> 536using __enable_hash_helper _LIBCPP_NODEBUG = 537 __enable_hash_helper_imp<_Type, __enable_if_t<__all<__has_enabled_hash<_Keys>::value...>::value> >; 538# else 539template <class _Type, class...> 540using __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