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
__loadword(const void * __p)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 #ifdef _LIBCPP_ABI_FIX_CITYHASH_IMPLEMENTATION
144 return __hash_len_16(__len + (static_cast<_Size>(__a) << 3), __b);
145 #else
146 return __hash_len_16(__len + (__a << 3), __b);
147 #endif
148 }
149 if (__len > 0) {
150 const unsigned char __a = static_cast<unsigned char>(__s[0]);
151 const unsigned char __b = static_cast<unsigned char>(__s[__len >> 1]);
152 const unsigned char __c = static_cast<unsigned char>(__s[__len - 1]);
153 const uint32_t __y = static_cast<uint32_t>(__a) +
154 (static_cast<uint32_t>(__b) << 8);
155 const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2);
156 return __shift_mix(__y * __k2 ^ __z * __k3) * __k2;
157 }
158 return __k2;
159 }
160
161 static _Size __hash_len_17_to_32(const char *__s, _Size __len)
162 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
163 {
164 const _Size __a = std::__loadword<_Size>(__s) * __k1;
165 const _Size __b = std::__loadword<_Size>(__s + 8);
166 const _Size __c = std::__loadword<_Size>(__s + __len - 8) * __k2;
167 const _Size __d = std::__loadword<_Size>(__s + __len - 16) * __k0;
168 return __hash_len_16(__rotate(__a - __b, 43) + __rotate(__c, 30) + __d,
169 __a + __rotate(__b ^ __k3, 20) - __c + __len);
170 }
171
172 // Return a 16-byte hash for 48 bytes. Quick and dirty.
173 // Callers do best to use "random-looking" values for a and b.
174 static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
175 _Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b)
176 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
177 {
178 __a += __w;
179 __b = __rotate(__b + __a + __z, 21);
180 const _Size __c = __a;
181 __a += __x;
182 __a += __y;
183 __b += __rotate(__a, 44);
184 return pair<_Size, _Size>(__a + __z, __b + __c);
185 }
186
187 // Return a 16-byte hash for s[0] ... s[31], a, and b. Quick and dirty.
188 static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
189 const char* __s, _Size __a, _Size __b)
190 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
191 {
192 return __weak_hash_len_32_with_seeds(std::__loadword<_Size>(__s),
193 std::__loadword<_Size>(__s + 8),
194 std::__loadword<_Size>(__s + 16),
195 std::__loadword<_Size>(__s + 24),
196 __a,
197 __b);
198 }
199
200 // Return an 8-byte hash for 33 to 64 bytes.
201 static _Size __hash_len_33_to_64(const char *__s, size_t __len)
202 _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
203 {
204 _Size __z = std::__loadword<_Size>(__s + 24);
205 _Size __a = std::__loadword<_Size>(__s) +
206 (__len + std::__loadword<_Size>(__s + __len - 16)) * __k0;
207 _Size __b = __rotate(__a + __z, 52);
208 _Size __c = __rotate(__a, 37);
209 __a += std::__loadword<_Size>(__s + 8);
210 __c += __rotate(__a, 7);
211 __a += std::__loadword<_Size>(__s + 16);
212 _Size __vf = __a + __z;
213 _Size __vs = __b + __rotate(__a, 31) + __c;
214 __a = std::__loadword<_Size>(__s + 16) + std::__loadword<_Size>(__s + __len - 32);
215 __z += std::__loadword<_Size>(__s + __len - 8);
216 __b = __rotate(__a + __z, 52);
217 __c = __rotate(__a, 37);
218 __a += std::__loadword<_Size>(__s + __len - 24);
219 __c += __rotate(__a, 7);
220 __a += std::__loadword<_Size>(__s + __len - 16);
221 _Size __wf = __a + __z;
222 _Size __ws = __b + __rotate(__a, 31) + __c;
223 _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0);
224 return __shift_mix(__r * __k0 + __vs) * __k2;
225 }
226 };
227
228 // cityhash64
229 template <class _Size>
230 _Size
231 __murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len)
232 {
233 const char* __s = static_cast<const char*>(__key);
234 if (__len <= 32) {
235 if (__len <= 16) {
236 return __hash_len_0_to_16(__s, __len);
237 } else {
238 return __hash_len_17_to_32(__s, __len);
239 }
240 } else if (__len <= 64) {
241 return __hash_len_33_to_64(__s, __len);
242 }
243
244 // For strings over 64 bytes we hash the end first, and then as we
245 // loop we keep 56 bytes of state: v, w, x, y, and z.
246 _Size __x = std::__loadword<_Size>(__s + __len - 40);
247 _Size __y = std::__loadword<_Size>(__s + __len - 16) +
248 std::__loadword<_Size>(__s + __len - 56);
249 _Size __z = __hash_len_16(std::__loadword<_Size>(__s + __len - 48) + __len,
250 std::__loadword<_Size>(__s + __len - 24));
251 pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z);
252 pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x);
253 __x = __x * __k1 + std::__loadword<_Size>(__s);
254
255 // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.
256 __len = (__len - 1) & ~static_cast<_Size>(63);
257 do {
258 __x = __rotate(__x + __y + __v.first + std::__loadword<_Size>(__s + 8), 37) * __k1;
259 __y = __rotate(__y + __v.second + std::__loadword<_Size>(__s + 48), 42) * __k1;
260 __x ^= __w.second;
261 __y += __v.first + std::__loadword<_Size>(__s + 40);
262 __z = __rotate(__z + __w.first, 33) * __k1;
263 __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first);
264 __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second,
265 __y + std::__loadword<_Size>(__s + 16));
266 _VSTD::swap(__z, __x);
267 __s += 64;
268 __len -= 64;
269 } while (__len != 0);
270 return __hash_len_16(
271 __hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z,
272 __hash_len_16(__v.second, __w.second) + __x);
273 }
274
275 template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)>
276 struct __scalar_hash;
277
278 template <class _Tp>
279 struct __scalar_hash<_Tp, 0>
280 : public __unary_function<_Tp, size_t>
281 {
282 _LIBCPP_INLINE_VISIBILITY
283 size_t operator()(_Tp __v) const _NOEXCEPT
284 {
285 union
286 {
287 _Tp __t;
288 size_t __a;
289 } __u;
290 __u.__a = 0;
291 __u.__t = __v;
292 return __u.__a;
293 }
294 };
295
296 template <class _Tp>
297 struct __scalar_hash<_Tp, 1>
298 : public __unary_function<_Tp, size_t>
299 {
300 _LIBCPP_INLINE_VISIBILITY
301 size_t operator()(_Tp __v) const _NOEXCEPT
302 {
303 union
304 {
305 _Tp __t;
306 size_t __a;
307 } __u;
308 __u.__t = __v;
309 return __u.__a;
310 }
311 };
312
313 template <class _Tp>
314 struct __scalar_hash<_Tp, 2>
315 : public __unary_function<_Tp, size_t>
316 {
317 _LIBCPP_INLINE_VISIBILITY
318 size_t operator()(_Tp __v) const _NOEXCEPT
319 {
320 union
321 {
322 _Tp __t;
323 struct
324 {
325 size_t __a;
326 size_t __b;
327 } __s;
328 } __u;
329 __u.__t = __v;
330 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
331 }
332 };
333
334 template <class _Tp>
335 struct __scalar_hash<_Tp, 3>
336 : public __unary_function<_Tp, size_t>
337 {
338 _LIBCPP_INLINE_VISIBILITY
339 size_t operator()(_Tp __v) const _NOEXCEPT
340 {
341 union
342 {
343 _Tp __t;
344 struct
345 {
346 size_t __a;
347 size_t __b;
348 size_t __c;
349 } __s;
350 } __u;
351 __u.__t = __v;
352 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
353 }
354 };
355
356 template <class _Tp>
357 struct __scalar_hash<_Tp, 4>
358 : public __unary_function<_Tp, size_t>
359 {
360 _LIBCPP_INLINE_VISIBILITY
361 size_t operator()(_Tp __v) const _NOEXCEPT
362 {
363 union
364 {
365 _Tp __t;
366 struct
367 {
368 size_t __a;
369 size_t __b;
370 size_t __c;
371 size_t __d;
372 } __s;
373 } __u;
374 __u.__t = __v;
375 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
376 }
377 };
378
379 struct _PairT {
380 size_t first;
381 size_t second;
382 };
383
384 _LIBCPP_INLINE_VISIBILITY
385 inline size_t __hash_combine(size_t __lhs, size_t __rhs) _NOEXCEPT {
386 typedef __scalar_hash<_PairT> _HashT;
387 const _PairT __p = {__lhs, __rhs};
388 return _HashT()(__p);
389 }
390
391 template<class _Tp>
392 struct _LIBCPP_TEMPLATE_VIS hash<_Tp*>
393 : public __unary_function<_Tp*, size_t>
394 {
395 _LIBCPP_INLINE_VISIBILITY
396 size_t operator()(_Tp* __v) const _NOEXCEPT
397 {
398 union
399 {
400 _Tp* __t;
401 size_t __a;
402 } __u;
403 __u.__t = __v;
404 return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
405 }
406 };
407
408 template <>
409 struct _LIBCPP_TEMPLATE_VIS hash<bool>
410 : public __unary_function<bool, size_t>
411 {
412 _LIBCPP_INLINE_VISIBILITY
413 size_t operator()(bool __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
414 };
415
416 template <>
417 struct _LIBCPP_TEMPLATE_VIS hash<char>
418 : public __unary_function<char, size_t>
419 {
420 _LIBCPP_INLINE_VISIBILITY
421 size_t operator()(char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
422 };
423
424 template <>
425 struct _LIBCPP_TEMPLATE_VIS hash<signed char>
426 : public __unary_function<signed char, size_t>
427 {
428 _LIBCPP_INLINE_VISIBILITY
429 size_t operator()(signed char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
430 };
431
432 template <>
433 struct _LIBCPP_TEMPLATE_VIS hash<unsigned char>
434 : public __unary_function<unsigned char, size_t>
435 {
436 _LIBCPP_INLINE_VISIBILITY
437 size_t operator()(unsigned char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
438 };
439
440 #ifndef _LIBCPP_HAS_NO_CHAR8_T
441 template <>
442 struct _LIBCPP_TEMPLATE_VIS hash<char8_t>
443 : public __unary_function<char8_t, size_t>
444 {
445 _LIBCPP_INLINE_VISIBILITY
446 size_t operator()(char8_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
447 };
448 #endif // !_LIBCPP_HAS_NO_CHAR8_T
449
450 template <>
451 struct _LIBCPP_TEMPLATE_VIS hash<char16_t>
452 : public __unary_function<char16_t, size_t>
453 {
454 _LIBCPP_INLINE_VISIBILITY
455 size_t operator()(char16_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
456 };
457
458 template <>
459 struct _LIBCPP_TEMPLATE_VIS hash<char32_t>
460 : public __unary_function<char32_t, size_t>
461 {
462 _LIBCPP_INLINE_VISIBILITY
463 size_t operator()(char32_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
464 };
465
466 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
467 template <>
468 struct _LIBCPP_TEMPLATE_VIS hash<wchar_t>
469 : public __unary_function<wchar_t, size_t>
470 {
471 _LIBCPP_INLINE_VISIBILITY
472 size_t operator()(wchar_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
473 };
474 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
475
476 template <>
477 struct _LIBCPP_TEMPLATE_VIS hash<short>
478 : public __unary_function<short, size_t>
479 {
480 _LIBCPP_INLINE_VISIBILITY
481 size_t operator()(short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
482 };
483
484 template <>
485 struct _LIBCPP_TEMPLATE_VIS hash<unsigned short>
486 : public __unary_function<unsigned short, size_t>
487 {
488 _LIBCPP_INLINE_VISIBILITY
489 size_t operator()(unsigned short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
490 };
491
492 template <>
493 struct _LIBCPP_TEMPLATE_VIS hash<int>
494 : public __unary_function<int, size_t>
495 {
496 _LIBCPP_INLINE_VISIBILITY
497 size_t operator()(int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
498 };
499
500 template <>
501 struct _LIBCPP_TEMPLATE_VIS hash<unsigned int>
502 : public __unary_function<unsigned int, size_t>
503 {
504 _LIBCPP_INLINE_VISIBILITY
505 size_t operator()(unsigned int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
506 };
507
508 template <>
509 struct _LIBCPP_TEMPLATE_VIS hash<long>
510 : public __unary_function<long, size_t>
511 {
512 _LIBCPP_INLINE_VISIBILITY
513 size_t operator()(long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
514 };
515
516 template <>
517 struct _LIBCPP_TEMPLATE_VIS hash<unsigned long>
518 : public __unary_function<unsigned long, size_t>
519 {
520 _LIBCPP_INLINE_VISIBILITY
521 size_t operator()(unsigned long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
522 };
523
524 template <>
525 struct _LIBCPP_TEMPLATE_VIS hash<long long>
526 : public __scalar_hash<long long>
527 {
528 };
529
530 template <>
531 struct _LIBCPP_TEMPLATE_VIS hash<unsigned long long>
532 : public __scalar_hash<unsigned long long>
533 {
534 };
535
536 #ifndef _LIBCPP_HAS_NO_INT128
537
538 template <>
539 struct _LIBCPP_TEMPLATE_VIS hash<__int128_t>
540 : public __scalar_hash<__int128_t>
541 {
542 };
543
544 template <>
545 struct _LIBCPP_TEMPLATE_VIS hash<__uint128_t>
546 : public __scalar_hash<__uint128_t>
547 {
548 };
549
550 #endif
551
552 template <>
553 struct _LIBCPP_TEMPLATE_VIS hash<float>
554 : public __scalar_hash<float>
555 {
556 _LIBCPP_INLINE_VISIBILITY
557 size_t operator()(float __v) const _NOEXCEPT
558 {
559 // -0.0 and 0.0 should return same hash
560 if (__v == 0.0f)
561 return 0;
562 return __scalar_hash<float>::operator()(__v);
563 }
564 };
565
566 template <>
567 struct _LIBCPP_TEMPLATE_VIS hash<double>
568 : public __scalar_hash<double>
569 {
570 _LIBCPP_INLINE_VISIBILITY
571 size_t operator()(double __v) const _NOEXCEPT
572 {
573 // -0.0 and 0.0 should return same hash
574 if (__v == 0.0)
575 return 0;
576 return __scalar_hash<double>::operator()(__v);
577 }
578 };
579
580 template <>
581 struct _LIBCPP_TEMPLATE_VIS hash<long double>
582 : public __scalar_hash<long double>
583 {
584 _LIBCPP_INLINE_VISIBILITY
585 size_t operator()(long double __v) const _NOEXCEPT
586 {
587 // -0.0 and 0.0 should return same hash
588 if (__v == 0.0L)
589 return 0;
590 #if defined(__i386__) || (defined(__x86_64__) && defined(__ILP32__))
591 // Zero out padding bits
592 union
593 {
594 long double __t;
595 struct
596 {
597 size_t __a;
598 size_t __b;
599 size_t __c;
600 size_t __d;
601 } __s;
602 } __u;
603 __u.__s.__a = 0;
604 __u.__s.__b = 0;
605 __u.__s.__c = 0;
606 __u.__s.__d = 0;
607 __u.__t = __v;
608 return __u.__s.__a ^ __u.__s.__b ^ __u.__s.__c ^ __u.__s.__d;
609 #elif defined(__x86_64__)
610 // Zero out padding bits
611 union
612 {
613 long double __t;
614 struct
615 {
616 size_t __a;
617 size_t __b;
618 } __s;
619 } __u;
620 __u.__s.__a = 0;
621 __u.__s.__b = 0;
622 __u.__t = __v;
623 return __u.__s.__a ^ __u.__s.__b;
624 #else
625 return __scalar_hash<long double>::operator()(__v);
626 #endif
627 }
628 };
629
630 template <class _Tp, bool = is_enum<_Tp>::value>
631 struct _LIBCPP_TEMPLATE_VIS __enum_hash
632 : public __unary_function<_Tp, size_t>
633 {
634 _LIBCPP_INLINE_VISIBILITY
635 size_t operator()(_Tp __v) const _NOEXCEPT
636 {
637 typedef typename underlying_type<_Tp>::type type;
638 return hash<type>()(static_cast<type>(__v));
639 }
640 };
641 template <class _Tp>
642 struct _LIBCPP_TEMPLATE_VIS __enum_hash<_Tp, false> {
643 __enum_hash() = delete;
644 __enum_hash(__enum_hash const&) = delete;
645 __enum_hash& operator=(__enum_hash const&) = delete;
646 };
647
648 template <class _Tp>
649 struct _LIBCPP_TEMPLATE_VIS hash : public __enum_hash<_Tp>
650 {
651 };
652
653 #if _LIBCPP_STD_VER > 14
654
655 template <>
656 struct _LIBCPP_TEMPLATE_VIS hash<nullptr_t>
657 : public __unary_function<nullptr_t, size_t>
658 {
659 _LIBCPP_INLINE_VISIBILITY
660 size_t operator()(nullptr_t) const _NOEXCEPT {
661 return 662607004ull;
662 }
663 };
664 #endif
665
666 #ifndef _LIBCPP_CXX03_LANG
667 template <class _Key, class _Hash>
668 using __check_hash_requirements _LIBCPP_NODEBUG = integral_constant<bool,
669 is_copy_constructible<_Hash>::value &&
670 is_move_constructible<_Hash>::value &&
671 __invokable_r<size_t, _Hash, _Key const&>::value
672 >;
673
674 template <class _Key, class _Hash = hash<_Key> >
675 using __has_enabled_hash _LIBCPP_NODEBUG = integral_constant<bool,
676 __check_hash_requirements<_Key, _Hash>::value &&
677 is_default_constructible<_Hash>::value
678 >;
679
680 #if _LIBCPP_STD_VER > 14
681 template <class _Type, class>
682 using __enable_hash_helper_imp _LIBCPP_NODEBUG = _Type;
683
684 template <class _Type, class ..._Keys>
685 using __enable_hash_helper _LIBCPP_NODEBUG = __enable_hash_helper_imp<_Type,
686 typename enable_if<__all<__has_enabled_hash<_Keys>::value...>::value>::type
687 >;
688 #else
689 template <class _Type, class ...>
690 using __enable_hash_helper _LIBCPP_NODEBUG = _Type;
691 #endif
692
693 #endif // !_LIBCPP_CXX03_LANG
694
695 _LIBCPP_END_NAMESPACE_STD
696
697 #endif // _LIBCPP___FUNCTIONAL_HASH_H
698