2 * Copyright 2016 Facebook, Inc.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
18 * For high-level documentation and usage examples see
19 * folly/docs/small_vector.md
21 * @author Jordan DeLong <delong.j@fb.com>
28 #include <type_traits>
33 #include <boost/operators.hpp>
34 #include <boost/type_traits.hpp>
35 #include <boost/mpl/if.hpp>
36 #include <boost/mpl/eval_if.hpp>
37 #include <boost/mpl/vector.hpp>
38 #include <boost/mpl/front.hpp>
39 #include <boost/mpl/filter_view.hpp>
40 #include <boost/mpl/identity.hpp>
41 #include <boost/mpl/placeholders.hpp>
42 #include <boost/mpl/empty.hpp>
43 #include <boost/mpl/size.hpp>
44 #include <boost/mpl/count.hpp>
46 #include <folly/FormatTraits.h>
47 #include <folly/Malloc.h>
48 #include <folly/Portability.h>
49 #include <folly/SmallLocks.h>
50 #include <folly/portability/Constexpr.h>
51 #include <folly/portability/Malloc.h>
52 #include <folly/portability/TypeTraits.h>
54 // Ignore shadowing warnings within this file, so includers can use -Wshadow.
55 #pragma GCC diagnostic push
56 #pragma GCC diagnostic ignored "-Wshadow"
60 //////////////////////////////////////////////////////////////////////
62 namespace small_vector_policy {
64 //////////////////////////////////////////////////////////////////////
67 * A flag which makes us refuse to use the heap at all. If we
68 * overflow the in situ capacity we throw an exception.
72 //////////////////////////////////////////////////////////////////////
74 } // small_vector_policy
76 //////////////////////////////////////////////////////////////////////
78 template<class T, std::size_t M, class A, class B, class C>
81 //////////////////////////////////////////////////////////////////////
86 * Move a range to a range of uninitialized memory. Assumes the
87 * ranges don't overlap.
90 typename std::enable_if<
91 !FOLLY_IS_TRIVIALLY_COPYABLE(T)
93 moveToUninitialized(T* first, T* last, T* out) {
96 for (; first != last; ++first, ++idx) {
97 new (&out[idx]) T(std::move(*first));
100 // Even for callers trying to give the strong guarantee
101 // (e.g. push_back) it's ok to assume here that we don't have to
102 // move things back and that it was a copy constructor that
103 // threw: if someone throws from a move constructor the effects
105 for (std::size_t i = 0; i < idx; ++i) {
112 // Specialization for trivially copyable types.
114 typename std::enable_if<
115 FOLLY_IS_TRIVIALLY_COPYABLE(T)
117 moveToUninitialized(T* first, T* last, T* out) {
118 std::memmove(out, first, (last - first) * sizeof *first);
122 * Move objects in memory to the right into some uninitialized
123 * memory, where the region overlaps. This doesn't just use
124 * std::move_backward because move_backward only works if all the
125 * memory is initialized to type T already.
128 typename std::enable_if<
129 !FOLLY_IS_TRIVIALLY_COPYABLE(T)
131 moveObjectsRight(T* first, T* lastConstructed, T* realLast) {
132 if (lastConstructed == realLast) {
136 T* end = first - 1; // Past the end going backwards.
137 T* out = realLast - 1;
138 T* in = lastConstructed - 1;
140 for (; in != end && out >= lastConstructed; --in, --out) {
141 new (out) T(std::move(*in));
143 for (; in != end; --in, --out) {
144 *out = std::move(*in);
146 for (; out >= lastConstructed; --out) {
150 // We want to make sure the same stuff is uninitialized memory
151 // if we exit via an exception (this is to make sure we provide
152 // the basic exception safety guarantee for insert functions).
153 if (out < lastConstructed) {
154 out = lastConstructed - 1;
156 for (auto it = out + 1; it != realLast; ++it) {
163 // Specialization for trivially copyable types. The call to
164 // std::move_backward here will just turn into a memmove. (TODO:
165 // change to std::is_trivially_copyable when that works.)
167 typename std::enable_if<
168 FOLLY_IS_TRIVIALLY_COPYABLE(T)
170 moveObjectsRight(T* first, T* lastConstructed, T* realLast) {
171 std::move_backward(first, lastConstructed, realLast);
175 * Populate a region of memory using `op' to construct elements. If
176 * anything throws, undo what we did.
178 template<class T, class Function>
179 void populateMemForward(T* mem, std::size_t n, Function const& op) {
182 for (size_t i = 0; i < n; ++i) {
187 for (std::size_t i = 0; i < idx; ++i) {
194 template<class SizeType, bool ShouldUseHeap>
195 struct IntegralSizePolicy {
196 typedef SizeType InternalSizeType;
198 IntegralSizePolicy() : size_(0) {}
201 static constexpr std::size_t policyMaxSize() {
202 return SizeType(~kExternMask);
205 std::size_t doSize() const {
206 return size_ & ~kExternMask;
209 std::size_t isExtern() const {
210 return kExternMask & size_;
213 void setExtern(bool b) {
215 size_ |= kExternMask;
217 size_ &= ~kExternMask;
221 void setSize(std::size_t sz) {
222 assert(sz <= policyMaxSize());
223 size_ = (kExternMask & size_) | SizeType(sz);
226 void swapSizePolicy(IntegralSizePolicy& o) {
227 std::swap(size_, o.size_);
231 static bool const kShouldUseHeap = ShouldUseHeap;
234 static SizeType const kExternMask =
235 kShouldUseHeap ? SizeType(1) << (sizeof(SizeType) * 8 - 1)
242 * If you're just trying to use this class, ignore everything about
243 * this next small_vector_base class thing.
245 * The purpose of this junk is to minimize sizeof(small_vector<>)
246 * and allow specifying the template parameters in whatever order is
247 * convenient for the user. There's a few extra steps here to try
248 * to keep the error messages at least semi-reasonable.
250 * Apologies for all the black magic.
252 namespace mpl = boost::mpl;
253 template<class Value,
254 std::size_t RequestedMaxInline,
258 struct small_vector_base {
259 typedef mpl::vector<InPolicyA,InPolicyB,InPolicyC> PolicyList;
262 * Determine the size type
264 typedef typename mpl::filter_view<
266 boost::is_integral<mpl::placeholders::_1>
268 typedef typename mpl::eval_if<
269 mpl::empty<Integrals>,
270 mpl::identity<std::size_t>,
271 mpl::front<Integrals>
274 static_assert(std::is_unsigned<SizeType>::value,
275 "Size type should be an unsigned integral type");
276 static_assert(mpl::size<Integrals>::value == 0 ||
277 mpl::size<Integrals>::value == 1,
278 "Multiple size types specified in small_vector<>");
281 * Determine whether we should allow spilling to the heap or not.
283 typedef typename mpl::count<
284 PolicyList,small_vector_policy::NoHeap
287 static_assert(HasNoHeap::value == 0 || HasNoHeap::value == 1,
288 "Multiple copies of small_vector_policy::NoHeap "
289 "supplied; this is probably a mistake");
292 * Make the real policy base classes.
294 typedef IntegralSizePolicy<SizeType,!HasNoHeap::value>
298 * Now inherit from them all. This is done in such a convoluted
299 * way to make sure we get the empty base optimizaton on all these
300 * types to keep sizeof(small_vector<>) minimal.
302 typedef boost::totally_ordered1<
303 small_vector<Value,RequestedMaxInline,InPolicyA,InPolicyB,InPolicyC>,
309 T* pointerFlagSet(T* p) {
310 return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(p) | 1);
313 bool pointerFlagGet(T* p) {
314 return reinterpret_cast<uintptr_t>(p) & 1;
317 T* pointerFlagClear(T* p) {
318 return reinterpret_cast<T*>(
319 reinterpret_cast<uintptr_t>(p) & ~uintptr_t(1));
321 inline void* shiftPointer(void* p, size_t sizeBytes) {
322 return static_cast<char*>(p) + sizeBytes;
326 //////////////////////////////////////////////////////////////////////
328 template<class Value,
329 std::size_t RequestedMaxInline = 1,
330 class PolicyA = void,
331 class PolicyB = void,
332 class PolicyC = void>
334 : public detail::small_vector_base<
335 Value,RequestedMaxInline,PolicyA,PolicyB,PolicyC
338 typedef typename detail::small_vector_base<
339 Value,RequestedMaxInline,PolicyA,PolicyB,PolicyC
341 typedef typename BaseType::InternalSizeType InternalSizeType;
344 * Figure out the max number of elements we should inline. (If
345 * the user asks for less inlined elements than we can fit unioned
346 * into our value_type*, we will inline more than they asked.)
348 static constexpr std::size_t MaxInline{
349 constexpr_max(sizeof(Value*) / sizeof(Value), RequestedMaxInline)};
352 typedef std::size_t size_type;
353 typedef Value value_type;
354 typedef value_type& reference;
355 typedef value_type const& const_reference;
356 typedef value_type* iterator;
357 typedef value_type const* const_iterator;
358 typedef std::ptrdiff_t difference_type;
360 typedef std::reverse_iterator<iterator> reverse_iterator;
361 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
363 explicit small_vector() = default;
365 small_vector(small_vector const& o) {
369 std::uninitialized_copy(o.begin(), o.end(), begin());
371 if (this->isExtern()) {
379 small_vector(small_vector&& o)
380 noexcept(std::is_nothrow_move_constructible<Value>::value) {
384 std::uninitialized_copy(std::make_move_iterator(o.begin()),
385 std::make_move_iterator(o.end()),
387 this->setSize(o.size());
391 small_vector(std::initializer_list<value_type> il) {
392 constructImpl(il.begin(), il.end(), std::false_type());
395 explicit small_vector(size_type n, value_type const& t = value_type()) {
400 explicit small_vector(Arg arg1, Arg arg2) {
401 // Forward using std::is_arithmetic to get to the proper
402 // implementation; this disambiguates between the iterators and
403 // (size_t, value_type) meaning for this constructor.
404 constructImpl(arg1, arg2, std::is_arithmetic<Arg>());
408 for (auto& t : *this) {
411 if (this->isExtern()) {
416 small_vector& operator=(small_vector const& o) {
417 assign(o.begin(), o.end());
421 small_vector& operator=(small_vector&& o) {
422 // TODO: optimization:
423 // if both are internal, use move assignment where possible
424 if (this == &o) return *this;
430 bool operator==(small_vector const& o) const {
431 return size() == o.size() && std::equal(begin(), end(), o.begin());
434 bool operator<(small_vector const& o) const {
435 return std::lexicographical_compare(begin(), end(), o.begin(), o.end());
438 static constexpr size_type max_size() {
439 return !BaseType::kShouldUseHeap ? static_cast<size_type>(MaxInline)
440 : BaseType::policyMaxSize();
443 size_type size() const { return this->doSize(); }
444 bool empty() const { return !size(); }
446 iterator begin() { return data(); }
447 iterator end() { return data() + size(); }
448 const_iterator begin() const { return data(); }
449 const_iterator end() const { return data() + size(); }
450 const_iterator cbegin() const { return begin(); }
451 const_iterator cend() const { return end(); }
453 reverse_iterator rbegin() { return reverse_iterator(end()); }
454 reverse_iterator rend() { return reverse_iterator(begin()); }
456 const_reverse_iterator rbegin() const {
457 return const_reverse_iterator(end());
460 const_reverse_iterator rend() const {
461 return const_reverse_iterator(begin());
464 const_reverse_iterator crbegin() const { return rbegin(); }
465 const_reverse_iterator crend() const { return rend(); }
468 * Usually one of the simplest functions in a Container-like class
469 * but a bit more complex here. We have to handle all combinations
470 * of in-place vs. heap between this and o.
472 * Basic guarantee only. Provides the nothrow guarantee iff our
473 * value_type has a nothrow move or copy constructor.
475 void swap(small_vector& o) {
476 using std::swap; // Allow ADL on swap for our value_type.
478 if (this->isExtern() && o.isExtern()) {
479 this->swapSizePolicy(o);
481 auto thisCapacity = this->capacity();
482 auto oCapacity = o.capacity();
484 std::swap(unpackHack(&u.pdata_.heap_), unpackHack(&o.u.pdata_.heap_));
486 this->setCapacity(oCapacity);
487 o.setCapacity(thisCapacity);
492 if (!this->isExtern() && !o.isExtern()) {
493 auto& oldSmall = size() < o.size() ? *this : o;
494 auto& oldLarge = size() < o.size() ? o : *this;
496 for (size_type i = 0; i < oldSmall.size(); ++i) {
497 swap(oldSmall[i], oldLarge[i]);
500 size_type i = oldSmall.size();
501 const size_type ci = i;
503 for (; i < oldLarge.size(); ++i) {
504 auto addr = oldSmall.begin() + i;
505 new (addr) value_type(std::move(oldLarge[i]));
506 oldLarge[i].~value_type();
510 for (; i < oldLarge.size(); ++i) {
511 oldLarge[i].~value_type();
513 oldLarge.setSize(ci);
517 oldLarge.setSize(ci);
521 // isExtern != o.isExtern()
522 auto& oldExtern = o.isExtern() ? o : *this;
523 auto& oldIntern = o.isExtern() ? *this : o;
525 auto oldExternCapacity = oldExtern.capacity();
526 auto oldExternHeap = oldExtern.u.pdata_.heap_;
528 auto buff = oldExtern.u.buffer();
531 for (; i < oldIntern.size(); ++i) {
532 new (&buff[i]) value_type(std::move(oldIntern[i]));
533 oldIntern[i].~value_type();
536 for (size_type kill = 0; kill < i; ++kill) {
537 buff[kill].~value_type();
539 for (; i < oldIntern.size(); ++i) {
540 oldIntern[i].~value_type();
542 oldIntern.setSize(0);
543 oldExtern.u.pdata_.heap_ = oldExternHeap;
544 oldExtern.setCapacity(oldExternCapacity);
547 oldIntern.u.pdata_.heap_ = oldExternHeap;
548 this->swapSizePolicy(o);
549 oldIntern.setCapacity(oldExternCapacity);
552 void resize(size_type sz) {
554 erase(begin() + sz, end());
558 detail::populateMemForward(begin() + size(), sz - size(),
559 [&] (void* p) { new (p) value_type(); }
564 void resize(size_type sz, value_type const& v) {
566 erase(begin() + sz, end());
570 detail::populateMemForward(begin() + size(), sz - size(),
571 [&] (void* p) { new (p) value_type(v); }
576 value_type* data() noexcept {
577 return this->isExtern() ? u.heap() : u.buffer();
580 value_type const* data() const noexcept {
581 return this->isExtern() ? u.heap() : u.buffer();
584 template<class ...Args>
585 iterator emplace(const_iterator p, Args&&... args) {
587 emplace_back(std::forward<Args>(args)...);
592 * We implement emplace at places other than at the back with a
593 * temporary for exception safety reasons. It is possible to
594 * avoid having to do this, but it becomes hard to maintain the
595 * basic exception safety guarantee (unless you respond to a copy
596 * constructor throwing by clearing the whole vector).
598 * The reason for this is that otherwise you have to destruct an
599 * element before constructing this one in its place---if the
600 * constructor throws, you either need a nothrow default
601 * constructor or a nothrow copy/move to get something back in the
602 * "gap", and the vector requirements don't guarantee we have any
603 * of these. Clearing the whole vector is a legal response in
604 * this situation, but it seems like this implementation is easy
605 * enough and probably better.
607 return insert(p, value_type(std::forward<Args>(args)...));
610 void reserve(size_type sz) {
614 size_type capacity() const {
615 if (this->isExtern()) {
616 if (u.hasCapacity()) {
617 return *u.getCapacity();
619 return malloc_usable_size(u.pdata_.heap_) / sizeof(value_type);
624 void shrink_to_fit() {
625 if (!this->isExtern()) {
629 small_vector tmp(begin(), end());
633 template<class ...Args>
634 void emplace_back(Args&&... args) {
635 // call helper function for static dispatch of special cases
636 emplaceBack(std::forward<Args>(args)...);
639 void emplace_back(const value_type& t) {
642 void emplace_back(value_type& t) {
646 void emplace_back(value_type&& t) {
647 push_back(std::move(t));
650 void push_back(value_type&& t) {
651 if (capacity() == size()) {
652 makeSize(std::max(size_type(2), 3 * size() / 2), &t, size());
654 new (end()) value_type(std::move(t));
656 this->setSize(size() + 1);
659 void push_back(value_type const& t) {
660 // TODO: we'd like to make use of makeSize (it can be optimized better,
661 // because it manipulates the internals)
662 // unfortunately the current implementation only supports moving from
663 // a supplied rvalue, and doing an extra move just to reuse it is a perf
665 if (size() == capacity()) {// && isInside(&t)) {
667 emplaceBack(std::move(tmp));
677 iterator insert(const_iterator constp, value_type&& t) {
678 iterator p = unconst(constp);
681 push_back(std::move(t));
685 auto offset = p - begin();
687 if (capacity() == size()) {
688 makeSize(size() + 1, &t, offset);
689 this->setSize(this->size() + 1);
691 makeSize(size() + 1);
692 detail::moveObjectsRight(data() + offset,
694 data() + size() + 1);
695 this->setSize(size() + 1);
696 data()[offset] = std::move(t);
698 return begin() + offset;
702 iterator insert(const_iterator p, value_type const& t) {
703 // Make a copy and forward to the rvalue value_type&& overload
705 return insert(p, value_type(t));
708 iterator insert(const_iterator pos, size_type n, value_type const& val) {
709 auto offset = pos - begin();
710 makeSize(size() + n);
711 detail::moveObjectsRight(data() + offset,
713 data() + size() + n);
714 this->setSize(size() + n);
715 std::generate_n(begin() + offset, n, [&] { return val; });
716 return begin() + offset;
720 iterator insert(const_iterator p, Arg arg1, Arg arg2) {
721 // Forward using std::is_arithmetic to get to the proper
722 // implementation; this disambiguates between the iterators and
723 // (size_t, value_type) meaning for this function.
724 return insertImpl(unconst(p), arg1, arg2, std::is_arithmetic<Arg>());
727 iterator insert(const_iterator p, std::initializer_list<value_type> il) {
728 return insert(p, il.begin(), il.end());
731 iterator erase(const_iterator q) {
732 std::move(unconst(q) + 1, end(), unconst(q));
733 (data() + size() - 1)->~value_type();
734 this->setSize(size() - 1);
738 iterator erase(const_iterator q1, const_iterator q2) {
739 if (q1 == q2) return unconst(q1);
740 std::move(unconst(q2), end(), unconst(q1));
741 for (auto it = (end() - std::distance(q1, q2)); it != end(); ++it) {
744 this->setSize(size() - (q2 - q1));
749 erase(begin(), end());
753 void assign(Arg first, Arg last) {
755 insert(end(), first, last);
758 void assign(std::initializer_list<value_type> il) {
759 assign(il.begin(), il.end());
762 void assign(size_type n, const value_type& t) {
767 reference front() { assert(!empty()); return *begin(); }
768 reference back() { assert(!empty()); return *(end() - 1); }
769 const_reference front() const { assert(!empty()); return *begin(); }
770 const_reference back() const { assert(!empty()); return *(end() - 1); }
772 reference operator[](size_type i) {
774 return *(begin() + i);
777 const_reference operator[](size_type i) const {
779 return *(begin() + i);
782 reference at(size_type i) {
784 throw std::out_of_range("index out of range");
789 const_reference at(size_type i) const {
791 throw std::out_of_range("index out of range");
799 * This is doing the same like emplace_back, but we need this helper
800 * to catch the special case - see the next overload function..
802 template<class ...Args>
803 void emplaceBack(Args&&... args) {
804 makeSize(size() + 1);
805 new (end()) value_type(std::forward<Args>(args)...);
806 this->setSize(size() + 1);
809 static iterator unconst(const_iterator it) {
810 return const_cast<iterator>(it);
814 * g++ doesn't allow you to bind a non-const reference to a member
815 * of a packed structure, presumably because it would make it too
816 * easy to accidentally make an unaligned memory access?
818 template<class T> static T& unpackHack(T* p) {
822 // The std::false_type argument is part of disambiguating the
823 // iterator insert functions from integral types (see insert().)
825 iterator insertImpl(iterator pos, It first, It last, std::false_type) {
826 typedef typename std::iterator_traits<It>::iterator_category categ;
827 if (std::is_same<categ,std::input_iterator_tag>::value) {
828 auto offset = pos - begin();
829 while (first != last) {
830 pos = insert(pos, *first++);
833 return begin() + offset;
836 auto distance = std::distance(first, last);
837 auto offset = pos - begin();
838 makeSize(size() + distance);
839 detail::moveObjectsRight(data() + offset,
841 data() + size() + distance);
842 this->setSize(size() + distance);
843 std::copy_n(first, distance, begin() + offset);
844 return begin() + offset;
847 iterator insertImpl(iterator pos, size_type n, const value_type& val,
849 // The true_type means this should call the size_t,value_type
850 // overload. (See insert().)
851 return insert(pos, n, val);
854 // The std::false_type argument came from std::is_arithmetic as part
855 // of disambiguating an overload (see the comment in the
858 void constructImpl(It first, It last, std::false_type) {
859 typedef typename std::iterator_traits<It>::iterator_category categ;
860 if (std::is_same<categ,std::input_iterator_tag>::value) {
861 // With iterators that only allow a single pass, we can't really
862 // do anything sane here.
863 while (first != last) {
864 emplace_back(*first++);
869 auto distance = std::distance(first, last);
871 this->setSize(distance);
873 detail::populateMemForward(data(), distance,
874 [&] (void* p) { new (p) value_type(*first++); }
877 if (this->isExtern()) {
884 void doConstruct(size_type n, value_type const& val) {
888 detail::populateMemForward(data(), n,
889 [&] (void* p) { new (p) value_type(val); }
892 if (this->isExtern()) {
899 // The true_type means we should forward to the size_t,value_type
901 void constructImpl(size_type n, value_type const& val, std::true_type) {
905 void makeSize(size_type size, value_type* v = nullptr) {
906 makeSize(size, v, size - 1);
910 * Ensure we have a large enough memory region to be size `size'.
911 * Will move/copy elements if we are spilling to heap_ or needed to
912 * allocate a new region, but if resized in place doesn't initialize
913 * anything in the new region. In any case doesn't change size().
914 * Supports insertion of new element during reallocation by given
915 * pointer to new element and position of new element.
916 * NOTE: If reallocation is not needed, and new element should be
917 * inserted in the middle of vector (not at the end), do the move
918 * objects and insertion outside the function, otherwise exception is thrown.
920 void makeSize(size_type size, value_type* v, size_type pos) {
921 if (size > this->max_size()) {
922 throw std::length_error("max_size exceeded in small_vector");
924 if (size <= this->capacity()) {
928 auto needBytes = size * sizeof(value_type);
929 // If the capacity isn't explicitly stored inline, but the heap
930 // allocation is grown to over some threshold, we should store
931 // a capacity at the front of the heap allocation.
932 bool heapifyCapacity =
933 !kHasInlineCapacity && needBytes > kHeapifyCapacityThreshold;
934 if (heapifyCapacity) {
935 needBytes += kHeapifyCapacitySize;
937 auto const sizeBytes = goodMallocSize(needBytes);
938 void* newh = checkedMalloc(sizeBytes);
939 // We expect newh to be at least 2-aligned, because we want to
940 // use its least significant bit as a flag.
941 assert(!detail::pointerFlagGet(newh));
943 value_type* newp = static_cast<value_type*>(
945 detail::shiftPointer(newh, kHeapifyCapacitySize) :
951 new (&newp[pos]) value_type(std::move(*v));
957 // move old elements to the left of the new one
959 detail::moveToUninitialized(begin(), begin() + pos, newp);
961 newp[pos].~value_type();
966 // move old elements to the right of the new one
969 detail::moveToUninitialized(begin() + pos, end(), newp + pos + 1);
972 for (size_type i = 0; i <= pos; ++i) {
973 newp[i].~value_type();
979 // move without inserting new element
981 detail::moveToUninitialized(begin(), end(), newp);
987 for (auto& val : *this) {
991 if (this->isExtern()) {
994 auto availableSizeBytes = sizeBytes;
995 if (heapifyCapacity) {
996 u.pdata_.heap_ = detail::pointerFlagSet(newh);
997 availableSizeBytes -= kHeapifyCapacitySize;
999 u.pdata_.heap_ = newh;
1001 this->setExtern(true);
1002 this->setCapacity(availableSizeBytes / sizeof(value_type));
1006 * This will set the capacity field, stored inline in the storage_ field
1007 * if there is sufficient room to store it.
1009 void setCapacity(size_type newCapacity) {
1010 assert(this->isExtern());
1011 if (u.hasCapacity()) {
1012 assert(newCapacity < std::numeric_limits<InternalSizeType>::max());
1013 *u.getCapacity() = InternalSizeType(newCapacity);
1018 struct HeapPtrWithCapacity {
1020 InternalSizeType capacity_;
1022 InternalSizeType* getCapacity() {
1028 // Lower order bit of heap_ is used as flag to indicate whether capacity is
1029 // stored at the front of the heap allocation.
1032 InternalSizeType* getCapacity() {
1033 assert(detail::pointerFlagGet(heap_));
1034 return static_cast<InternalSizeType*>(
1035 detail::pointerFlagClear(heap_));
1039 #if (FOLLY_X64 || FOLLY_PPC64)
1040 typedef unsigned char InlineStorageDataType[sizeof(value_type) * MaxInline];
1042 typedef typename std::aligned_storage<
1043 sizeof(value_type) * MaxInline,
1045 >::type InlineStorageDataType;
1048 typedef typename std::conditional<
1049 sizeof(value_type) * MaxInline != 0,
1050 InlineStorageDataType,
1052 >::type InlineStorageType;
1054 static bool const kHasInlineCapacity =
1055 sizeof(HeapPtrWithCapacity) < sizeof(InlineStorageType);
1057 // This value should we multiple of word size.
1058 static size_t const kHeapifyCapacitySize = sizeof(
1059 typename std::aligned_storage<
1060 sizeof(InternalSizeType),
1063 // Threshold to control capacity heapifying.
1064 static size_t const kHeapifyCapacityThreshold =
1065 100 * kHeapifyCapacitySize;
1067 typedef typename std::conditional<
1069 HeapPtrWithCapacity,
1071 >::type PointerType;
1074 explicit Data() { pdata_.heap_ = 0; }
1077 InlineStorageType storage_;
1079 value_type* buffer() noexcept {
1080 void* vp = &storage_;
1081 return static_cast<value_type*>(vp);
1083 value_type const* buffer() const noexcept {
1084 return const_cast<Data*>(this)->buffer();
1086 value_type* heap() noexcept {
1087 if (kHasInlineCapacity || !detail::pointerFlagGet(pdata_.heap_)) {
1088 return static_cast<value_type*>(pdata_.heap_);
1090 return static_cast<value_type*>(
1091 detail::shiftPointer(
1092 detail::pointerFlagClear(pdata_.heap_), kHeapifyCapacitySize));
1094 value_type const* heap() const noexcept {
1095 return const_cast<Data*>(this)->heap();
1098 bool hasCapacity() const {
1099 return kHasInlineCapacity || detail::pointerFlagGet(pdata_.heap_);
1101 InternalSizeType* getCapacity() {
1102 return pdata_.getCapacity();
1104 InternalSizeType* getCapacity() const {
1105 return const_cast<Data*>(this)->getCapacity();
1109 auto vp = detail::pointerFlagClear(pdata_.heap_);
1112 } FOLLY_PACK_ATTR u;
1116 //////////////////////////////////////////////////////////////////////
1118 // Basic guarantee only, or provides the nothrow guarantee iff T has a
1119 // nothrow move or copy constructor.
1120 template<class T, std::size_t MaxInline, class A, class B, class C>
1121 void swap(small_vector<T,MaxInline,A,B,C>& a,
1122 small_vector<T,MaxInline,A,B,C>& b) {
1126 //////////////////////////////////////////////////////////////////////
1131 template <class T, size_t M, class A, class B, class C>
1132 struct IndexableTraits<small_vector<T, M, A, B, C>>
1133 : public IndexableTraitsSeq<small_vector<T, M, A, B, C>> {
1136 } // namespace detail
1138 } // namespace folly
1140 #pragma GCC diagnostic pop