1/*
2 * Copyright 2011-present Facebook, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17// @author: Andrei Alexandrescu
18
19#pragma once
20
21#include <functional>
22#include <limits>
23#include <memory>
24#include <type_traits>
25
26#include <folly/Portability.h>
27
28// libc++ doesn't provide this header, nor does msvc
29#if __has_include(<bits/c++config.h>)
30// This file appears in two locations: inside fbcode and in the
31// libstdc++ source code (when embedding fbstring as std::string).
32// To aid in this schizophrenic use, two macros are defined in
33// c++config.h:
34// _LIBSTDCXX_FBSTRING - Set inside libstdc++. This is useful to
35// gate use inside fbcode v. libstdc++
36#include <bits/c++config.h>
37#endif
38
39#define FOLLY_CREATE_HAS_MEMBER_TYPE_TRAITS(classname, type_name) \
40 template <typename TTheClass_> \
41 struct classname##__folly_traits_impl__ { \
42 template <typename UTheClass_> \
43 static constexpr bool test(typename UTheClass_::type_name*) { \
44 return true; \
45 } \
46 template <typename> \
47 static constexpr bool test(...) { \
48 return false; \
49 } \
50 }; \
51 template <typename TTheClass_> \
52 using classname = typename std::conditional< \
53 classname##__folly_traits_impl__<TTheClass_>::template test<TTheClass_>( \
54 nullptr), \
55 std::true_type, \
56 std::false_type>::type
57
58#define FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, cv_qual) \
59 template <typename TTheClass_, typename RTheReturn_, typename... TTheArgs_> \
60 struct classname##__folly_traits_impl__< \
61 TTheClass_, \
62 RTheReturn_(TTheArgs_...) cv_qual> { \
63 template < \
64 typename UTheClass_, \
65 RTheReturn_ (UTheClass_::*)(TTheArgs_...) cv_qual> \
66 struct sfinae {}; \
67 template <typename UTheClass_> \
68 static std::true_type test(sfinae<UTheClass_, &UTheClass_::func_name>*); \
69 template <typename> \
70 static std::false_type test(...); \
71 }
72
73/*
74 * The FOLLY_CREATE_HAS_MEMBER_FN_TRAITS is used to create traits
75 * classes that check for the existence of a member function with
76 * a given name and signature. It currently does not support
77 * checking for inherited members.
78 *
79 * Such classes receive two template parameters: the class to be checked
80 * and the signature of the member function. A static boolean field
81 * named `value` (which is also constexpr) tells whether such member
82 * function exists.
83 *
84 * Each traits class created is bound only to the member name, not to
85 * its signature nor to the type of the class containing it.
86 *
87 * Say you need to know if a given class has a member function named
88 * `test` with the following signature:
89 *
90 * int test() const;
91 *
92 * You'd need this macro to create a traits class to check for a member
93 * named `test`, and then use this traits class to check for the signature:
94 *
95 * namespace {
96 *
97 * FOLLY_CREATE_HAS_MEMBER_FN_TRAITS(has_test_traits, test);
98 *
99 * } // unnamed-namespace
100 *
101 * void some_func() {
102 * cout << "Does class Foo have a member int test() const? "
103 * << boolalpha << has_test_traits<Foo, int() const>::value;
104 * }
105 *
106 * You can use the same traits class to test for a completely different
107 * signature, on a completely different class, as long as the member name
108 * is the same:
109 *
110 * void some_func() {
111 * cout << "Does class Foo have a member int test()? "
112 * << boolalpha << has_test_traits<Foo, int()>::value;
113 * cout << "Does class Foo have a member int test() const? "
114 * << boolalpha << has_test_traits<Foo, int() const>::value;
115 * cout << "Does class Bar have a member double test(const string&, long)? "
116 * << boolalpha << has_test_traits<Bar, double(const string&, long)>::value;
117 * }
118 *
119 * @author: Marcelo Juchem <marcelo@fb.com>
120 */
121#define FOLLY_CREATE_HAS_MEMBER_FN_TRAITS(classname, func_name) \
122 template <typename, typename> \
123 struct classname##__folly_traits_impl__; \
124 FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, ); \
125 FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, const); \
126 FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL( \
127 classname, func_name, /* nolint */ volatile); \
128 FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL( \
129 classname, func_name, /* nolint */ volatile const); \
130 template <typename TTheClass_, typename TTheSignature_> \
131 using classname = \
132 decltype(classname##__folly_traits_impl__<TTheClass_, TTheSignature_>:: \
133 template test<TTheClass_>(nullptr))
134
135namespace folly {
136
137#if __cpp_lib_bool_constant || _MSC_VER
138
139using std::bool_constant;
140
141#else
142
143// mimic: std::bool_constant, C++17
144template <bool B>
145using bool_constant = std::integral_constant<bool, B>;
146
147#endif
148
149template <std::size_t I>
150using index_constant = std::integral_constant<std::size_t, I>;
151
152/***
153 * _t
154 *
155 * Instead of:
156 *
157 * using decayed = typename std::decay<T>::type;
158 *
159 * With the C++14 standard trait aliases, we could use:
160 *
161 * using decayed = std::decay_t<T>;
162 *
163 * Without them, we could use:
164 *
165 * using decayed = _t<std::decay<T>>;
166 *
167 * Also useful for any other library with template types having dependent
168 * member types named `type`, like the standard trait types.
169 */
170template <typename T>
171using _t = typename T::type;
172
173/**
174 * A type trait to remove all const volatile and reference qualifiers on a
175 * type T
176 */
177template <typename T>
178struct remove_cvref {
179 using type =
180 typename std::remove_cv<typename std::remove_reference<T>::type>::type;
181};
182template <typename T>
183using remove_cvref_t = typename remove_cvref<T>::type;
184
185namespace detail {
186template <typename Src>
187struct like_ {
188 template <typename Dst>
189 using apply = Dst;
190};
191template <typename Src>
192struct like_<Src const> {
193 template <typename Dst>
194 using apply = Dst const;
195};
196template <typename Src>
197struct like_<Src volatile> {
198 template <typename Dst>
199 using apply = Dst volatile;
200};
201template <typename Src>
202struct like_<Src const volatile> {
203 template <typename Dst>
204 using apply = Dst const volatile;
205};
206template <typename Src>
207struct like_<Src&> {
208 template <typename Dst>
209 using apply = typename like_<Src>::template apply<Dst>&;
210};
211template <typename Src>
212struct like_<Src&&> {
213 template <typename Dst>
214 using apply = typename like_<Src>::template apply<Dst>&&;
215};
216} // namespace detail
217
218// mimic: like_t, p0847r0
219template <typename Src, typename Dst>
220using like_t = typename detail::like_<Src>::template apply<remove_cvref_t<Dst>>;
221
222// mimic: like, p0847r0
223template <typename Src, typename Dst>
224struct like {
225 using type = like_t<Src, Dst>;
226};
227
228/**
229 * type_t
230 *
231 * A type alias for the first template type argument. `type_t` is useful for
232 * controlling class-template and function-template partial specialization.
233 *
234 * Example:
235 *
236 * template <typename Value>
237 * class Container {
238 * public:
239 * template <typename... Args>
240 * Container(
241 * type_t<in_place_t, decltype(Value(std::declval<Args>()...))>,
242 * Args&&...);
243 * };
244 *
245 * void_t
246 *
247 * A type alias for `void`. `void_t` is useful for controling class-template
248 * and function-template partial specialization.
249 *
250 * Example:
251 *
252 * // has_value_type<T>::value is true if T has a nested type `value_type`
253 * template <class T, class = void>
254 * struct has_value_type
255 * : std::false_type {};
256 *
257 * template <class T>
258 * struct has_value_type<T, folly::void_t<typename T::value_type>>
259 * : std::true_type {};
260 */
261
262/**
263 * There is a bug in libstdc++, libc++, and MSVC's STL that causes it to
264 * ignore unused template parameter arguments in template aliases and does not
265 * cause substitution failures. This defect has been recorded here:
266 * http://open-std.org/JTC1/SC22/WG21/docs/cwg_defects.html#1558.
267 *
268 * This causes the implementation of std::void_t to be buggy, as it is likely
269 * defined as something like the following:
270 *
271 * template <typename...>
272 * using void_t = void;
273 *
274 * This causes the compiler to ignore all the template arguments and does not
275 * help when one wants to cause substitution failures. Rather declarations
276 * which have void_t in orthogonal specializations are treated as the same.
277 * For example, assuming the possible `T` types are only allowed to have
278 * either the alias `one` or `two` and never both or none:
279 *
280 * template <typename T,
281 * typename std::void_t<std::decay_t<T>::one>* = nullptr>
282 * void foo(T&&) {}
283 * template <typename T,
284 * typename std::void_t<std::decay_t<T>::two>* = nullptr>
285 * void foo(T&&) {}
286 *
287 * The second foo() will be a redefinition because it conflicts with the first
288 * one; void_t does not cause substitution failures - the template types are
289 * just ignored.
290 */
291
292namespace traits_detail {
293template <class T, class...>
294struct type_t_ {
295 using type = T;
296};
297} // namespace traits_detail
298
299template <class T, class... Ts>
300using type_t = typename traits_detail::type_t_<T, Ts...>::type;
301template <class... Ts>
302using void_t = type_t<void, Ts...>;
303
304template <typename T>
305using aligned_storage_for_t =
306 typename std::aligned_storage<sizeof(T), alignof(T)>::type;
307
308// Older versions of libstdc++ do not provide std::is_trivially_copyable
309#if defined(__clang__) && !defined(_LIBCPP_VERSION)
310template <class T>
311struct is_trivially_copyable : bool_constant<__is_trivially_copyable(T)> {};
312#elif defined(__GNUC__) && !defined(__clang__) && __GNUC__ < 5
313template <class T>
314struct is_trivially_copyable : std::is_trivial<T> {};
315#else
316template <class T>
317using is_trivially_copyable = std::is_trivially_copyable<T>;
318#endif
319
320/**
321 * IsRelocatable<T>::value describes the ability of moving around
322 * memory a value of type T by using memcpy (as opposed to the
323 * conservative approach of calling the copy constructor and then
324 * destroying the old temporary. Essentially for a relocatable type,
325 * the following two sequences of code should be semantically
326 * equivalent:
327 *
328 * void move1(T * from, T * to) {
329 * new(to) T(from);
330 * (*from).~T();
331 * }
332 *
333 * void move2(T * from, T * to) {
334 * memcpy(to, from, sizeof(T));
335 * }
336 *
337 * Most C++ types are relocatable; the ones that aren't would include
338 * internal pointers or (very rarely) would need to update remote
339 * pointers to pointers tracking them. All C++ primitive types and
340 * type constructors are relocatable.
341 *
342 * This property can be used in a variety of optimizations. Currently
343 * fbvector uses this property intensively.
344 *
345 * The default conservatively assumes the type is not
346 * relocatable. Several specializations are defined for known
347 * types. You may want to add your own specializations. Do so in
348 * namespace folly and make sure you keep the specialization of
349 * IsRelocatable<SomeStruct> in the same header as SomeStruct.
350 *
351 * You may also declare a type to be relocatable by including
352 * `typedef std::true_type IsRelocatable;`
353 * in the class header.
354 *
355 * It may be unset in a base class by overriding the typedef to false_type.
356 */
357/*
358 * IsZeroInitializable describes the property that default construction is the
359 * same as memset(dst, 0, sizeof(T)).
360 */
361
362namespace traits_detail {
363
364#define FOLLY_HAS_TRUE_XXX(name) \
365 FOLLY_CREATE_HAS_MEMBER_TYPE_TRAITS(has_##name, name); \
366 template <class T> \
367 struct name##_is_true : std::is_same<typename T::name, std::true_type> {}; \
368 template <class T> \
369 struct has_true_##name : std::conditional< \
370 has_##name<T>::value, \
371 name##_is_true<T>, \
372 std::false_type>::type {}
373
374FOLLY_HAS_TRUE_XXX(IsRelocatable);
375FOLLY_HAS_TRUE_XXX(IsZeroInitializable);
376
377#undef FOLLY_HAS_TRUE_XXX
378
379} // namespace traits_detail
380
381struct Ignore {
382 Ignore() = default;
383 template <class T>
384 constexpr /* implicit */ Ignore(const T&) {}
385 template <class T>
386 const Ignore& operator=(T const&) const {
387 return *this;
388 }
389};
390
391template <class...>
392using Ignored = Ignore;
393
394namespace traits_detail_IsEqualityComparable {
395Ignore operator==(Ignore, Ignore);
396
397template <class T, class U = T>
398struct IsEqualityComparable
399 : std::is_convertible<
400 decltype(std::declval<T>() == std::declval<U>()),
401 bool> {};
402} // namespace traits_detail_IsEqualityComparable
403
404/* using override */ using traits_detail_IsEqualityComparable::
405 IsEqualityComparable;
406
407namespace traits_detail_IsLessThanComparable {
408Ignore operator<(Ignore, Ignore);
409
410template <class T, class U = T>
411struct IsLessThanComparable
412 : std::is_convertible<
413 decltype(std::declval<T>() < std::declval<U>()),
414 bool> {};
415} // namespace traits_detail_IsLessThanComparable
416
417/* using override */ using traits_detail_IsLessThanComparable::
418 IsLessThanComparable;
419
420namespace traits_detail_IsNothrowSwappable {
421#if defined(__cpp_lib_is_swappable) || (_CPPLIB_VER && _HAS_CXX17)
422// MSVC 2015+ already implements the C++17 P0185R1 proposal which
423// adds std::is_nothrow_swappable, so use it instead if C++17 mode
424// is enabled.
425template <typename T>
426using IsNothrowSwappable = std::is_nothrow_swappable<T>;
427#elif _CPPLIB_VER
428// MSVC 2015+ defines the base even if C++17 is disabled, and
429// MSVC 2015 has issues with our fallback implementation due to
430// over-eager evaluation of noexcept.
431template <typename T>
432using IsNothrowSwappable = std::_Is_nothrow_swappable<T>;
433#else
434/* using override */ using std::swap;
435
436template <class T>
437struct IsNothrowSwappable
438 : bool_constant<std::is_nothrow_move_constructible<T>::value&& noexcept(
439 swap(std::declval<T&>(), std::declval<T&>()))> {};
440#endif
441} // namespace traits_detail_IsNothrowSwappable
442
443/* using override */ using traits_detail_IsNothrowSwappable::IsNothrowSwappable;
444
445template <class T>
446struct IsRelocatable : std::conditional<
447 traits_detail::has_IsRelocatable<T>::value,
448 traits_detail::has_true_IsRelocatable<T>,
449 // TODO add this line (and some tests for it) when we
450 // upgrade to gcc 4.7
451 // std::is_trivially_move_constructible<T>::value ||
452 is_trivially_copyable<T>>::type {};
453
454template <class T>
455struct IsZeroInitializable
456 : std::conditional<
457 traits_detail::has_IsZeroInitializable<T>::value,
458 traits_detail::has_true_IsZeroInitializable<T>,
459 bool_constant<!std::is_class<T>::value>>::type {};
460
461template <typename...>
462struct Conjunction : std::true_type {};
463template <typename T>
464struct Conjunction<T> : T {};
465template <typename T, typename... TList>
466struct Conjunction<T, TList...>
467 : std::conditional<T::value, Conjunction<TList...>, T>::type {};
468
469template <typename...>
470struct Disjunction : std::false_type {};
471template <typename T>
472struct Disjunction<T> : T {};
473template <typename T, typename... TList>
474struct Disjunction<T, TList...>
475 : std::conditional<T::value, T, Disjunction<TList...>>::type {};
476
477template <typename T>
478struct Negation : bool_constant<!T::value> {};
479
480template <bool... Bs>
481struct Bools {
482 using valid_type = bool;
483 static constexpr std::size_t size() {
484 return sizeof...(Bs);
485 }
486};
487
488// Lighter-weight than Conjunction, but evaluates all sub-conditions eagerly.
489template <class... Ts>
490struct StrictConjunction
491 : std::is_same<Bools<Ts::value...>, Bools<(Ts::value || true)...>> {};
492
493template <class... Ts>
494struct StrictDisjunction
495 : Negation<
496 std::is_same<Bools<Ts::value...>, Bools<(Ts::value && false)...>>> {};
497
498} // namespace folly
499
500/**
501 * Use this macro ONLY inside namespace folly. When using it with a
502 * regular type, use it like this:
503 *
504 * // Make sure you're at namespace ::folly scope
505 * template <> FOLLY_ASSUME_RELOCATABLE(MyType)
506 *
507 * When using it with a template type, use it like this:
508 *
509 * // Make sure you're at namespace ::folly scope
510 * template <class T1, class T2>
511 * FOLLY_ASSUME_RELOCATABLE(MyType<T1, T2>)
512 */
513#define FOLLY_ASSUME_RELOCATABLE(...) \
514 struct IsRelocatable<__VA_ARGS__> : std::true_type {}
515
516/**
517 * The FOLLY_ASSUME_FBVECTOR_COMPATIBLE* macros below encode the
518 * assumption that the type is relocatable per IsRelocatable
519 * above. Many types can be assumed to satisfy this condition, but
520 * it is the responsibility of the user to state that assumption.
521 * User-defined classes will not be optimized for use with
522 * fbvector (see FBVector.h) unless they state that assumption.
523 *
524 * Use FOLLY_ASSUME_FBVECTOR_COMPATIBLE with regular types like this:
525 *
526 * FOLLY_ASSUME_FBVECTOR_COMPATIBLE(MyType)
527 *
528 * The versions FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1, _2, _3, and _4
529 * allow using the macro for describing templatized classes with 1, 2,
530 * 3, and 4 template parameters respectively. For template classes
531 * just use the macro with the appropriate number and pass the name of
532 * the template to it. Example:
533 *
534 * template <class T1, class T2> class MyType { ... };
535 * ...
536 * // Make sure you're at global scope
537 * FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(MyType)
538 */
539
540// Use this macro ONLY at global level (no namespace)
541#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE(...) \
542 namespace folly { \
543 template <> \
544 FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__); \
545 }
546// Use this macro ONLY at global level (no namespace)
547#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(...) \
548 namespace folly { \
549 template <class T1> \
550 FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1>); \
551 }
552// Use this macro ONLY at global level (no namespace)
553#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(...) \
554 namespace folly { \
555 template <class T1, class T2> \
556 FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2>); \
557 }
558// Use this macro ONLY at global level (no namespace)
559#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_3(...) \
560 namespace folly { \
561 template <class T1, class T2, class T3> \
562 FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2, T3>); \
563 }
564// Use this macro ONLY at global level (no namespace)
565#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_4(...) \
566 namespace folly { \
567 template <class T1, class T2, class T3, class T4> \
568 FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2, T3, T4>); \
569 }
570
571/**
572 * Instantiate FOLLY_ASSUME_FBVECTOR_COMPATIBLE for a few types. It is
573 * safe to assume that pair is compatible if both of its components
574 * are. Furthermore, all STL containers can be assumed to comply,
575 * although that is not guaranteed by the standard.
576 */
577
578FOLLY_NAMESPACE_STD_BEGIN
579
580template <class T, class U>
581struct pair;
582#ifndef _GLIBCXX_USE_FB
583FOLLY_GLIBCXX_NAMESPACE_CXX11_BEGIN
584template <class T, class R, class A>
585class basic_string;
586FOLLY_GLIBCXX_NAMESPACE_CXX11_END
587#else
588template <class T, class R, class A, class S>
589class basic_string;
590#endif
591template <class T, class A>
592class vector;
593template <class T, class A>
594class deque;
595template <class T, class C, class A>
596class set;
597template <class K, class V, class C, class A>
598class map;
599template <class T>
600class shared_ptr;
601
602FOLLY_NAMESPACE_STD_END
603
604namespace folly {
605
606// STL commonly-used types
607template <class T, class U>
608struct IsRelocatable<std::pair<T, U>>
609 : bool_constant<IsRelocatable<T>::value && IsRelocatable<U>::value> {};
610
611// Is T one of T1, T2, ..., Tn?
612template <typename T, typename... Ts>
613using IsOneOf = StrictDisjunction<std::is_same<T, Ts>...>;
614
615/*
616 * Complementary type traits for integral comparisons.
617 *
618 * For instance, `if(x < 0)` yields an error in clang for unsigned types
619 * when -Werror is used due to -Wtautological-compare
620 *
621 *
622 * @author: Marcelo Juchem <marcelo@fb.com>
623 */
624
625namespace detail {
626
627template <typename T, bool>
628struct is_negative_impl {
629 constexpr static bool check(T x) {
630 return x < 0;
631 }
632};
633
634template <typename T>
635struct is_negative_impl<T, false> {
636 constexpr static bool check(T) {
637 return false;
638 }
639};
640
641// folly::to integral specializations can end up generating code
642// inside what are really static ifs (not executed because of the templated
643// types) that violate -Wsign-compare and/or -Wbool-compare so suppress them
644// in order to not prevent all calling code from using it.
645FOLLY_PUSH_WARNING
646FOLLY_GNU_DISABLE_WARNING("-Wsign-compare")
647#if __GNUC_PREREQ(5, 0)
648FOLLY_GNU_DISABLE_WARNING("-Wbool-compare")
649#endif
650FOLLY_MSVC_DISABLE_WARNING(4388) // sign-compare
651FOLLY_MSVC_DISABLE_WARNING(4804) // bool-compare
652
653template <typename RHS, RHS rhs, typename LHS>
654bool less_than_impl(LHS const lhs) {
655 // clang-format off
656 return
657 rhs > std::numeric_limits<LHS>::max() ? true :
658 rhs <= std::numeric_limits<LHS>::min() ? false :
659 lhs < rhs;
660 // clang-format on
661}
662
663template <typename RHS, RHS rhs, typename LHS>
664bool greater_than_impl(LHS const lhs) {
665 // clang-format off
666 return
667 rhs > std::numeric_limits<LHS>::max() ? false :
668 rhs < std::numeric_limits<LHS>::min() ? true :
669 lhs > rhs;
670 // clang-format on
671}
672
673FOLLY_POP_WARNING
674
675} // namespace detail
676
677// same as `x < 0`
678template <typename T>
679constexpr bool is_negative(T x) {
680 return folly::detail::is_negative_impl<T, std::is_signed<T>::value>::check(x);
681}
682
683// same as `x <= 0`
684template <typename T>
685constexpr bool is_non_positive(T x) {
686 return !x || folly::is_negative(x);
687}
688
689// same as `x > 0`
690template <typename T>
691constexpr bool is_positive(T x) {
692 return !is_non_positive(x);
693}
694
695// same as `x >= 0`
696template <typename T>
697constexpr bool is_non_negative(T x) {
698 return !x || is_positive(x);
699}
700
701template <typename RHS, RHS rhs, typename LHS>
702bool less_than(LHS const lhs) {
703 return detail::
704 less_than_impl<RHS, rhs, typename std::remove_reference<LHS>::type>(lhs);
705}
706
707template <typename RHS, RHS rhs, typename LHS>
708bool greater_than(LHS const lhs) {
709 return detail::
710 greater_than_impl<RHS, rhs, typename std::remove_reference<LHS>::type>(
711 lhs);
712}
713} // namespace folly
714
715// Assume nothing when compiling with MSVC.
716#ifndef _MSC_VER
717// gcc-5.0 changed string's implementation in libstdc++ to be non-relocatable
718#if !_GLIBCXX_USE_CXX11_ABI
719FOLLY_ASSUME_FBVECTOR_COMPATIBLE_3(std::basic_string)
720#endif
721FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::vector)
722FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::deque)
723FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::unique_ptr)
724FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::shared_ptr)
725FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::function)
726#endif
727
728/* Some combinations of compilers and C++ libraries make __int128 and
729 * unsigned __int128 available but do not correctly define their standard type
730 * traits.
731 *
732 * If FOLLY_SUPPLY_MISSING_INT128_TRAITS is defined, we define these traits
733 * here.
734 *
735 * @author: Phil Willoughby <philwill@fb.com>
736 */
737#if FOLLY_SUPPLY_MISSING_INT128_TRAITS
738FOLLY_NAMESPACE_STD_BEGIN
739template <>
740struct is_arithmetic<__int128> : ::std::true_type {};
741template <>
742struct is_arithmetic<unsigned __int128> : ::std::true_type {};
743template <>
744struct is_integral<__int128> : ::std::true_type {};
745template <>
746struct is_integral<unsigned __int128> : ::std::true_type {};
747template <>
748struct make_unsigned<__int128> {
749 typedef unsigned __int128 type;
750};
751template <>
752struct make_signed<__int128> {
753 typedef __int128 type;
754};
755template <>
756struct make_unsigned<unsigned __int128> {
757 typedef unsigned __int128 type;
758};
759template <>
760struct make_signed<unsigned __int128> {
761 typedef __int128 type;
762};
763template <>
764struct is_signed<__int128> : ::std::true_type {};
765template <>
766struct is_unsigned<unsigned __int128> : ::std::true_type {};
767FOLLY_NAMESPACE_STD_END
768#endif // FOLLY_SUPPLY_MISSING_INT128_TRAITS
769