2 * Copyright 2014 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>
23 #ifndef FOLLY_SMALL_VECTOR_H_
24 #define FOLLY_SMALL_VECTOR_H_
26 #include "Portability.h"
30 #include <type_traits>
35 #include <boost/operators.hpp>
36 #include <boost/type_traits.hpp>
37 #include <boost/mpl/if.hpp>
38 #include <boost/mpl/eval_if.hpp>
39 #include <boost/mpl/vector.hpp>
40 #include <boost/mpl/front.hpp>
41 #include <boost/mpl/filter_view.hpp>
42 #include <boost/mpl/identity.hpp>
43 #include <boost/mpl/placeholders.hpp>
44 #include <boost/mpl/empty.hpp>
45 #include <boost/mpl/size.hpp>
46 #include <boost/mpl/count.hpp>
47 #include <boost/mpl/max.hpp>
49 #include <folly/Malloc.h>
51 #if defined(__GNUC__) && FOLLY_X64
52 # include "folly/SmallLocks.h"
53 # define FB_PACK_ATTR FOLLY_PACK_ATTR
54 # define FB_PACK_PUSH FOLLY_PACK_PUSH
55 # define FB_PACK_POP FOLLY_PACK_POP
62 #if FOLLY_HAVE_MALLOC_SIZE
63 extern "C" std::size_t malloc_size(const void*);
64 # if !FOLLY_HAVE_MALLOC_USABLE_SIZE
65 # define malloc_usable_size malloc_size
67 # ifndef malloc_usable_size
68 # define malloc_usable_size malloc_size
72 // Ignore shadowing warnings within this file, so includers can use -Wshadow.
73 #pragma GCC diagnostic push
74 #pragma GCC diagnostic ignored "-Wshadow"
78 //////////////////////////////////////////////////////////////////////
80 namespace small_vector_policy {
82 //////////////////////////////////////////////////////////////////////
85 * A flag which makes us refuse to use the heap at all. If we
86 * overflow the in situ capacity we throw an exception.
90 //////////////////////////////////////////////////////////////////////
92 } // small_vector_policy
94 //////////////////////////////////////////////////////////////////////
96 template<class T, std::size_t M, class A, class B, class C>
99 //////////////////////////////////////////////////////////////////////
104 * Move a range to a range of uninitialized memory. Assumes the
105 * ranges don't overlap.
108 typename std::enable_if<
109 !FOLLY_IS_TRIVIALLY_COPYABLE(T)
111 moveToUninitialized(T* first, T* last, T* out) {
112 auto const count = last - first;
115 for (; idx < count; ++first, ++idx) {
116 new (&out[idx]) T(std::move(*first));
119 // Even for callers trying to give the strong guarantee
120 // (e.g. push_back) it's ok to assume here that we don't have to
121 // move things back and that it was a copy constructor that
122 // threw: if someone throws from a move constructor the effects
124 for (std::size_t i = 0; i < idx; ++i) {
131 // Specialization for trivially copyable types.
133 typename std::enable_if<
134 FOLLY_IS_TRIVIALLY_COPYABLE(T)
136 moveToUninitialized(T* first, T* last, T* out) {
137 std::memmove(out, first, (last - first) * sizeof *first);
141 * Move objects in memory to the right into some uninitialized
142 * memory, where the region overlaps. This doesn't just use
143 * std::move_backward because move_backward only works if all the
144 * memory is initialized to type T already.
147 typename std::enable_if<
148 !FOLLY_IS_TRIVIALLY_COPYABLE(T)
150 moveObjectsRight(T* first, T* lastConstructed, T* realLast) {
151 if (lastConstructed == realLast) {
155 T* end = first - 1; // Past the end going backwards.
156 T* out = realLast - 1;
157 T* in = lastConstructed - 1;
159 for (; in != end && out >= lastConstructed; --in, --out) {
160 new (out) T(std::move(*in));
162 for (; in != end; --in, --out) {
163 *out = std::move(*in);
165 for (; out >= lastConstructed; --out) {
169 // We want to make sure the same stuff is uninitialized memory
170 // if we exit via an exception (this is to make sure we provide
171 // the basic exception safety guarantee for insert functions).
172 if (out < lastConstructed) {
173 out = lastConstructed - 1;
175 for (auto it = out + 1; it != realLast; ++it) {
182 // Specialization for trivially copyable types. The call to
183 // std::move_backward here will just turn into a memmove. (TODO:
184 // change to std::is_trivially_copyable when that works.)
186 typename std::enable_if<
187 FOLLY_IS_TRIVIALLY_COPYABLE(T)
189 moveObjectsRight(T* first, T* lastConstructed, T* realLast) {
190 std::move_backward(first, lastConstructed, realLast);
194 * Populate a region of memory using `op' to construct elements. If
195 * anything throws, undo what we did.
197 template<class T, class Function>
198 void populateMemForward(T* mem, std::size_t n, Function const& op) {
201 for (size_t i = 0; i < n; ++i) {
206 for (std::size_t i = 0; i < idx; ++i) {
213 template<class SizeType, bool ShouldUseHeap>
214 struct IntegralSizePolicy {
215 typedef SizeType InternalSizeType;
217 IntegralSizePolicy() : size_(0) {}
220 static constexpr std::size_t policyMaxSize() {
221 return SizeType(~kExternMask);
224 std::size_t doSize() const {
225 return size_ & ~kExternMask;
228 std::size_t isExtern() const {
229 return kExternMask & size_;
232 void setExtern(bool b) {
234 size_ |= kExternMask;
236 size_ &= ~kExternMask;
240 void setSize(std::size_t sz) {
241 assert(sz <= policyMaxSize());
242 size_ = (kExternMask & size_) | SizeType(sz);
245 void swapSizePolicy(IntegralSizePolicy& o) {
246 std::swap(size_, o.size_);
250 static bool const kShouldUseHeap = ShouldUseHeap;
253 static SizeType const kExternMask =
254 kShouldUseHeap ? SizeType(1) << (sizeof(SizeType) * 8 - 1)
261 * If you're just trying to use this class, ignore everything about
262 * this next small_vector_base class thing.
264 * The purpose of this junk is to minimize sizeof(small_vector<>)
265 * and allow specifying the template parameters in whatever order is
266 * convenient for the user. There's a few extra steps here to try
267 * to keep the error messages at least semi-reasonable.
269 * Apologies for all the black magic.
271 namespace mpl = boost::mpl;
272 template<class Value,
273 std::size_t RequestedMaxInline,
277 struct small_vector_base {
278 typedef mpl::vector<InPolicyA,InPolicyB,InPolicyC> PolicyList;
281 * Determine the size type
283 typedef typename mpl::filter_view<
285 boost::is_integral<mpl::placeholders::_1>
287 typedef typename mpl::eval_if<
288 mpl::empty<Integrals>,
289 mpl::identity<std::size_t>,
290 mpl::front<Integrals>
293 static_assert(std::is_unsigned<SizeType>::value,
294 "Size type should be an unsigned integral type");
295 static_assert(mpl::size<Integrals>::value == 0 ||
296 mpl::size<Integrals>::value == 1,
297 "Multiple size types specified in small_vector<>");
300 * Determine whether we should allow spilling to the heap or not.
302 typedef typename mpl::count<
303 PolicyList,small_vector_policy::NoHeap
306 static_assert(HasNoHeap::value == 0 || HasNoHeap::value == 1,
307 "Multiple copies of small_vector_policy::NoHeap "
308 "supplied; this is probably a mistake");
311 * Make the real policy base classes.
313 typedef IntegralSizePolicy<SizeType,!HasNoHeap::value>
317 * Now inherit from them all. This is done in such a convoluted
318 * way to make sure we get the empty base optimizaton on all these
319 * types to keep sizeof(small_vector<>) minimal.
321 typedef boost::totally_ordered1<
322 small_vector<Value,RequestedMaxInline,InPolicyA,InPolicyB,InPolicyC>,
328 T* pointerFlagSet(T* p) {
329 return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(p) | 1);
332 bool pointerFlagGet(T* p) {
333 return reinterpret_cast<uintptr_t>(p) & 1;
336 T* pointerFlagClear(T* p) {
337 return reinterpret_cast<T*>(
338 reinterpret_cast<uintptr_t>(p) & ~uintptr_t(1));
340 inline void* shiftPointer(void* p, size_t sizeBytes) {
341 return static_cast<char*>(p) + sizeBytes;
345 //////////////////////////////////////////////////////////////////////
347 template<class Value,
348 std::size_t RequestedMaxInline = 1,
349 class PolicyA = void,
350 class PolicyB = void,
351 class PolicyC = void>
353 : public detail::small_vector_base<
354 Value,RequestedMaxInline,PolicyA,PolicyB,PolicyC
357 typedef typename detail::small_vector_base<
358 Value,RequestedMaxInline,PolicyA,PolicyB,PolicyC
360 typedef typename BaseType::InternalSizeType InternalSizeType;
363 * Figure out the max number of elements we should inline. (If
364 * the user asks for less inlined elements than we can fit unioned
365 * into our value_type*, we will inline more than they asked.)
368 MaxInline = boost::mpl::max<
369 boost::mpl::int_<sizeof(Value*) / sizeof(Value)>,
370 boost::mpl::int_<RequestedMaxInline>
375 typedef std::size_t size_type;
376 typedef Value value_type;
377 typedef value_type& reference;
378 typedef value_type const& const_reference;
379 typedef value_type* iterator;
380 typedef value_type const* const_iterator;
381 typedef std::ptrdiff_t difference_type;
383 typedef std::reverse_iterator<iterator> reverse_iterator;
384 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
386 explicit small_vector() {}
388 small_vector(small_vector const& o) {
392 std::uninitialized_copy(o.begin(), o.end(), begin());
394 if (this->isExtern()) u.freeHeap();
400 small_vector(small_vector&& o) {
404 std::uninitialized_copy(std::make_move_iterator(o.begin()),
405 std::make_move_iterator(o.end()),
407 this->setSize(o.size());
411 small_vector(std::initializer_list<value_type> il) {
412 constructImpl(il.begin(), il.end(), std::false_type());
415 explicit small_vector(size_type n, value_type const& t = value_type()) {
420 explicit small_vector(Arg arg1, Arg arg2) {
421 // Forward using std::is_arithmetic to get to the proper
422 // implementation; this disambiguates between the iterators and
423 // (size_t, value_type) meaning for this constructor.
424 constructImpl(arg1, arg2, std::is_arithmetic<Arg>());
428 for (auto& t : *this) {
431 if (this->isExtern()) {
436 small_vector& operator=(small_vector const& o) {
437 assign(o.begin(), o.end());
441 small_vector& operator=(small_vector&& o) {
442 // TODO: optimization:
443 // if both are internal, use move assignment where possible
444 if (this == &o) return *this;
450 bool operator==(small_vector const& o) const {
451 return size() == o.size() && std::equal(begin(), end(), o.begin());
454 bool operator<(small_vector const& o) const {
455 return std::lexicographical_compare(begin(), end(), o.begin(), o.end());
458 static constexpr size_type max_size() {
459 return !BaseType::kShouldUseHeap ? MaxInline
460 : BaseType::policyMaxSize();
463 size_type size() const { return this->doSize(); }
464 bool empty() const { return !size(); }
466 iterator begin() { return data(); }
467 iterator end() { return data() + size(); }
468 const_iterator begin() const { return data(); }
469 const_iterator end() const { return data() + size(); }
470 const_iterator cbegin() const { return begin(); }
471 const_iterator cend() const { return end(); }
473 reverse_iterator rbegin() { return reverse_iterator(end()); }
474 reverse_iterator rend() { return reverse_iterator(begin()); }
476 const_reverse_iterator rbegin() const {
477 return const_reverse_iterator(end());
480 const_reverse_iterator rend() const {
481 return const_reverse_iterator(begin());
484 const_reverse_iterator crbegin() const { return rbegin(); }
485 const_reverse_iterator crend() const { return rend(); }
488 * Usually one of the simplest functions in a Container-like class
489 * but a bit more complex here. We have to handle all combinations
490 * of in-place vs. heap between this and o.
492 * Basic guarantee only. Provides the nothrow guarantee iff our
493 * value_type has a nothrow move or copy constructor.
495 void swap(small_vector& o) {
496 using std::swap; // Allow ADL on swap for our value_type.
498 if (this->isExtern() && o.isExtern()) {
499 this->swapSizePolicy(o);
501 auto thisCapacity = this->capacity();
502 auto oCapacity = o.capacity();
504 std::swap(unpackHack(&u.pdata_.heap_), unpackHack(&o.u.pdata_.heap_));
506 this->setCapacity(oCapacity);
507 o.setCapacity(thisCapacity);
512 if (!this->isExtern() && !o.isExtern()) {
513 auto& oldSmall = size() < o.size() ? *this : o;
514 auto& oldLarge = size() < o.size() ? o : *this;
516 for (size_type i = 0; i < oldSmall.size(); ++i) {
517 swap(oldSmall[i], oldLarge[i]);
520 size_type i = oldSmall.size();
521 const size_type ci = i;
523 for (; i < oldLarge.size(); ++i) {
524 auto addr = oldSmall.begin() + i;
525 new (addr) value_type(std::move(oldLarge[i]));
526 oldLarge[i].~value_type();
530 for (; i < oldLarge.size(); ++i) {
531 oldLarge[i].~value_type();
533 oldLarge.setSize(ci);
537 oldLarge.setSize(ci);
541 // isExtern != o.isExtern()
542 auto& oldExtern = o.isExtern() ? o : *this;
543 auto& oldIntern = o.isExtern() ? *this : o;
545 auto oldExternCapacity = oldExtern.capacity();
546 auto oldExternHeap = oldExtern.u.pdata_.heap_;
548 auto buff = oldExtern.u.buffer();
551 for (; i < oldIntern.size(); ++i) {
552 new (&buff[i]) value_type(std::move(oldIntern[i]));
553 oldIntern[i].~value_type();
556 for (size_type kill = 0; kill < i; ++kill) {
557 buff[kill].~value_type();
559 for (; i < oldIntern.size(); ++i) {
560 oldIntern[i].~value_type();
562 oldIntern.setSize(0);
563 oldExtern.u.pdata_.heap_ = oldExternHeap;
564 oldExtern.setCapacity(oldExternCapacity);
567 oldIntern.u.pdata_.heap_ = oldExternHeap;
568 this->swapSizePolicy(o);
569 oldIntern.setCapacity(oldExternCapacity);
572 void resize(size_type sz) {
574 erase(begin() + sz, end());
578 detail::populateMemForward(begin() + size(), sz - size(),
579 [&] (void* p) { new (p) value_type(); }
584 void resize(size_type sz, value_type const& v) {
586 erase(begin() + sz, end());
590 detail::populateMemForward(begin() + size(), sz - size(),
591 [&] (void* p) { new (p) value_type(v); }
596 value_type* data() noexcept {
597 return this->isExtern() ? u.heap() : u.buffer();
600 value_type const* data() const noexcept {
601 return this->isExtern() ? u.heap() : u.buffer();
604 template<class ...Args>
605 iterator emplace(const_iterator p, Args&&... args) {
607 emplace_back(std::forward<Args>(args)...);
612 * We implement emplace at places other than at the back with a
613 * temporary for exception safety reasons. It is possible to
614 * avoid having to do this, but it becomes hard to maintain the
615 * basic exception safety guarantee (unless you respond to a copy
616 * constructor throwing by clearing the whole vector).
618 * The reason for this is that otherwise you have to destruct an
619 * element before constructing this one in its place---if the
620 * constructor throws, you either need a nothrow default
621 * constructor or a nothrow copy/move to get something back in the
622 * "gap", and the vector requirements don't guarantee we have any
623 * of these. Clearing the whole vector is a legal response in
624 * this situation, but it seems like this implementation is easy
625 * enough and probably better.
627 return insert(p, value_type(std::forward<Args>(args)...));
630 void reserve(size_type sz) {
634 size_type capacity() const {
635 if (this->isExtern()) {
636 if (u.hasCapacity()) {
637 return *u.getCapacity();
639 return malloc_usable_size(u.pdata_.heap_) / sizeof(value_type);
644 void shrink_to_fit() {
645 if (!this->isExtern()) {
649 small_vector tmp(begin(), end());
653 template<class ...Args>
654 void emplace_back(Args&&... args) {
655 // call helper function for static dispatch of special cases
656 emplaceBack(std::forward<Args>(args)...);
659 void push_back(value_type&& t) {
660 if (capacity() == size()) {
661 makeSize(std::max(size_type(2), 3 * size() / 2), &t, size());
663 new (end()) value_type(std::move(t));
665 this->setSize(size() + 1);
668 void push_back(value_type const& t) {
669 // Make a copy and forward to the rvalue value_type&& overload
671 push_back(value_type(t));
678 iterator insert(const_iterator constp, value_type&& t) {
679 iterator p = unconst(constp);
682 push_back(std::move(t));
686 auto offset = p - begin();
688 if (capacity() == size()) {
689 makeSize(size() + 1, &t, offset);
690 this->setSize(this->size() + 1);
692 makeSize(size() + 1);
693 detail::moveObjectsRight(data() + offset,
695 data() + size() + 1);
696 this->setSize(size() + 1);
697 data()[offset] = std::move(t);
699 return begin() + offset;
703 iterator insert(const_iterator p, value_type const& t) {
704 // Make a copy and forward to the rvalue value_type&& overload
706 return insert(p, value_type(t));
709 iterator insert(const_iterator pos, size_type n, value_type const& val) {
710 auto offset = pos - begin();
711 makeSize(size() + n);
712 detail::moveObjectsRight(data() + offset,
714 data() + size() + n);
715 this->setSize(size() + n);
716 std::generate_n(begin() + offset, n, [&] { return val; });
717 return begin() + offset;
721 iterator insert(const_iterator p, Arg arg1, Arg arg2) {
722 // Forward using std::is_arithmetic to get to the proper
723 // implementation; this disambiguates between the iterators and
724 // (size_t, value_type) meaning for this function.
725 return insertImpl(unconst(p), arg1, arg2, std::is_arithmetic<Arg>());
728 iterator insert(const_iterator p, std::initializer_list<value_type> il) {
729 return insert(p, il.begin(), il.end());
732 iterator erase(const_iterator q) {
733 std::move(unconst(q) + 1, end(), unconst(q));
734 (data() + size() - 1)->~value_type();
735 this->setSize(size() - 1);
739 iterator erase(const_iterator q1, const_iterator q2) {
740 if (q1 == q2) return unconst(q1);
741 std::move(unconst(q2), end(), unconst(q1));
742 for (auto it = (end() - std::distance(q1, q2)); it != end(); ++it) {
745 this->setSize(size() - (q2 - q1));
750 erase(begin(), end());
754 void assign(Arg first, Arg last) {
756 insert(end(), first, last);
759 void assign(std::initializer_list<value_type> il) {
760 assign(il.begin(), il.end());
763 void assign(size_type n, const value_type& t) {
768 reference front() { assert(!empty()); return *begin(); }
769 reference back() { assert(!empty()); return *(end() - 1); }
770 const_reference front() const { assert(!empty()); return *begin(); }
771 const_reference back() const { assert(!empty()); return *(end() - 1); }
773 reference operator[](size_type i) {
775 return *(begin() + i);
778 const_reference operator[](size_type i) const {
780 return *(begin() + i);
783 reference at(size_type i) {
785 throw std::out_of_range("index out of range");
790 const_reference at(size_type i) const {
792 throw std::out_of_range("index out of range");
800 * This is doing the same like emplace_back, but we need this helper
801 * to catch the special case - see the next overload function..
803 template<class ...Args>
804 void emplaceBack(Args&&... args) {
805 makeSize(size() + 1);
806 new (end()) value_type(std::forward<Args>(args)...);
807 this->setSize(size() + 1);
811 * Special case of emplaceBack for rvalue
813 void emplaceBack(value_type&& t) {
814 push_back(std::move(t));
817 static iterator unconst(const_iterator it) {
818 return const_cast<iterator>(it);
822 * g++ doesn't allow you to bind a non-const reference to a member
823 * of a packed structure, presumably because it would make it too
824 * easy to accidentally make an unaligned memory access?
826 template<class T> static T& unpackHack(T* p) {
830 // The std::false_type argument is part of disambiguating the
831 // iterator insert functions from integral types (see insert().)
833 iterator insertImpl(iterator pos, It first, It last, std::false_type) {
834 typedef typename std::iterator_traits<It>::iterator_category categ;
835 if (std::is_same<categ,std::input_iterator_tag>::value) {
836 auto offset = pos - begin();
837 while (first != last) {
838 pos = insert(pos, *first++);
841 return begin() + offset;
844 auto distance = std::distance(first, last);
845 auto offset = pos - begin();
846 makeSize(size() + distance);
847 detail::moveObjectsRight(data() + offset,
849 data() + size() + distance);
850 this->setSize(size() + distance);
851 std::copy_n(first, distance, begin() + offset);
852 return begin() + offset;
855 iterator insertImpl(iterator pos, size_type n, const value_type& val,
857 // The true_type means this should call the size_t,value_type
858 // overload. (See insert().)
859 return insert(pos, n, val);
862 // The std::false_type argument came from std::is_arithmetic as part
863 // of disambiguating an overload (see the comment in the
866 void constructImpl(It first, It last, std::false_type) {
867 typedef typename std::iterator_traits<It>::iterator_category categ;
868 if (std::is_same<categ,std::input_iterator_tag>::value) {
869 // With iterators that only allow a single pass, we can't really
870 // do anything sane here.
871 while (first != last) {
877 auto distance = std::distance(first, last);
879 this->setSize(distance);
881 detail::populateMemForward(data(), distance,
882 [&] (void* p) { new (p) value_type(*first++); }
886 void doConstruct(size_type n, value_type const& val) {
889 detail::populateMemForward(data(), n,
890 [&] (void* p) { new (p) value_type(val); }
894 // The true_type means we should forward to the size_t,value_type
896 void constructImpl(size_type n, value_type const& val, std::true_type) {
900 void makeSize(size_type size, value_type* v = nullptr) {
901 makeSize(size, v, size - 1);
905 * Ensure we have a large enough memory region to be size `size'.
906 * Will move/copy elements if we are spilling to heap_ or needed to
907 * allocate a new region, but if resized in place doesn't initialize
908 * anything in the new region. In any case doesn't change size().
909 * Supports insertion of new element during reallocation by given
910 * pointer to new element and position of new element.
911 * NOTE: If reallocation is not needed, and new element should be
912 * inserted in the middle of vector (not at the end), do the move
913 * objects and insertion outside the function, otherwise exception is thrown.
915 void makeSize(size_type size, value_type* v, size_type pos) {
916 if (size > this->max_size()) {
917 throw std::length_error("max_size exceeded in small_vector");
919 if (size <= this->capacity()) {
923 auto needBytes = size * sizeof(value_type);
924 // If the capacity isn't explicitly stored inline, but the heap
925 // allocation is grown to over some threshold, we should store
926 // a capacity at the front of the heap allocation.
927 bool heapifyCapacity =
928 !kHasInlineCapacity && needBytes > kHeapifyCapacityThreshold;
929 if (heapifyCapacity) {
930 needBytes += kHeapifyCapacitySize;
932 auto const sizeBytes = goodMallocSize(needBytes);
933 void* newh = checkedMalloc(sizeBytes);
934 // We expect newh to be at least 2-aligned, because we want to
935 // use its least significant bit as a flag.
936 assert(!detail::pointerFlagGet(newh));
938 value_type* newp = static_cast<value_type*>(
940 detail::shiftPointer(newh, kHeapifyCapacitySize) :
946 new (&newp[pos]) value_type(std::move(*v));
952 // move old elements to the left of the new one
954 detail::moveToUninitialized(begin(), begin() + pos, newp);
956 newp[pos].~value_type();
961 // move old elements to the right of the new one
964 detail::moveToUninitialized(begin() + pos, end(), newp + pos + 1);
967 for (size_type i = 0; i <= pos; ++i) {
968 newp[i].~value_type();
974 // move without inserting new element
976 detail::moveToUninitialized(begin(), end(), newp);
982 for (auto& val : *this) {
986 if (this->isExtern()) {
989 auto availableSizeBytes = sizeBytes;
990 if (heapifyCapacity) {
991 u.pdata_.heap_ = detail::pointerFlagSet(newh);
992 availableSizeBytes -= kHeapifyCapacitySize;
994 u.pdata_.heap_ = newh;
996 this->setExtern(true);
997 this->setCapacity(availableSizeBytes / sizeof(value_type));
1001 * This will set the capacity field, stored inline in the storage_ field
1002 * if there is sufficient room to store it.
1004 void setCapacity(size_type newCapacity) {
1005 assert(this->isExtern());
1006 if (u.hasCapacity()) {
1007 assert(newCapacity < std::numeric_limits<InternalSizeType>::max());
1008 *u.getCapacity() = InternalSizeType(newCapacity);
1013 struct HeapPtrWithCapacity {
1015 InternalSizeType capacity_;
1017 InternalSizeType* getCapacity() {
1023 // Lower order bit of heap_ is used as flag to indicate whether capacity is
1024 // stored at the front of the heap allocation.
1027 InternalSizeType* getCapacity() {
1028 assert(detail::pointerFlagGet(heap_));
1029 return static_cast<InternalSizeType*>(
1030 detail::pointerFlagClear(heap_));
1035 typedef unsigned char InlineStorageType[sizeof(value_type) * MaxInline];
1037 typedef typename std::aligned_storage<
1038 sizeof(value_type) * MaxInline,
1040 >::type InlineStorageType;
1043 static bool const kHasInlineCapacity =
1044 sizeof(HeapPtrWithCapacity) < sizeof(InlineStorageType);
1046 // This value should we multiple of word size.
1047 static size_t const kHeapifyCapacitySize = sizeof(
1048 typename std::aligned_storage<
1049 sizeof(InternalSizeType),
1052 // Threshold to control capacity heapifying.
1053 static size_t const kHeapifyCapacityThreshold =
1054 100 * kHeapifyCapacitySize;
1056 typedef typename std::conditional<
1058 HeapPtrWithCapacity,
1060 >::type PointerType;
1063 explicit Data() { pdata_.heap_ = 0; }
1066 InlineStorageType storage_;
1068 value_type* buffer() noexcept {
1069 void* vp = &storage_;
1070 return static_cast<value_type*>(vp);
1072 value_type const* buffer() const noexcept {
1073 return const_cast<Data*>(this)->buffer();
1075 value_type* heap() noexcept {
1076 if (kHasInlineCapacity || !detail::pointerFlagGet(pdata_.heap_)) {
1077 return static_cast<value_type*>(pdata_.heap_);
1079 return static_cast<value_type*>(
1080 detail::shiftPointer(
1081 detail::pointerFlagClear(pdata_.heap_), kHeapifyCapacitySize));
1083 value_type const* heap() const noexcept {
1084 return const_cast<Data*>(this)->heap();
1087 bool hasCapacity() const {
1088 return kHasInlineCapacity || detail::pointerFlagGet(pdata_.heap_);
1090 InternalSizeType* getCapacity() {
1091 return pdata_.getCapacity();
1093 InternalSizeType* getCapacity() const {
1094 return const_cast<Data*>(this)->getCapacity();
1098 auto vp = detail::pointerFlagClear(pdata_.heap_);
1105 //////////////////////////////////////////////////////////////////////
1107 // Basic guarantee only, or provides the nothrow guarantee iff T has a
1108 // nothrow move or copy constructor.
1109 template<class T, std::size_t MaxInline, class A, class B, class C>
1110 void swap(small_vector<T,MaxInline,A,B,C>& a,
1111 small_vector<T,MaxInline,A,B,C>& b) {
1115 //////////////////////////////////////////////////////////////////////
1119 #pragma GCC diagnostic pop
1122 # undef FB_PACK_ATTR
1123 # undef FB_PACK_PUSH