1// -*- C++ -*-
2#ifndef _LIBCPP_SPLIT_BUFFER
3#define _LIBCPP_SPLIT_BUFFER
4
5#include <__config>
6#include <type_traits>
7#include <algorithm>
8
9#include <__undef_min_max>
10
11#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
12#pragma GCC system_header
13#endif
14
15_LIBCPP_BEGIN_NAMESPACE_STD
16
17template <bool>
18class __split_buffer_common
19{
20protected:
21    void __throw_length_error() const;
22    void __throw_out_of_range() const;
23};
24
25template <class _Tp, class _Allocator = allocator<_Tp> >
26struct __split_buffer
27    : private __split_buffer_common<true>
28{
29private:
30    __split_buffer(const __split_buffer&);
31    __split_buffer& operator=(const __split_buffer&);
32public:
33    typedef _Tp                                             value_type;
34    typedef _Allocator                                      allocator_type;
35    typedef typename remove_reference<allocator_type>::type __alloc_rr;
36    typedef allocator_traits<__alloc_rr>                    __alloc_traits;
37    typedef value_type&                                     reference;
38    typedef const value_type&                               const_reference;
39    typedef typename __alloc_traits::size_type              size_type;
40    typedef typename __alloc_traits::difference_type        difference_type;
41    typedef typename __alloc_traits::pointer                pointer;
42    typedef typename __alloc_traits::const_pointer          const_pointer;
43    typedef pointer                                         iterator;
44    typedef const_pointer                                   const_iterator;
45
46    pointer                                         __first_;
47    pointer                                         __begin_;
48    pointer                                         __end_;
49    __compressed_pair<pointer, allocator_type> __end_cap_;
50
51    typedef typename add_lvalue_reference<allocator_type>::type __alloc_ref;
52    typedef typename add_lvalue_reference<allocator_type>::type __alloc_const_ref;
53
54    _LIBCPP_INLINE_VISIBILITY __alloc_rr&           __alloc() _NOEXCEPT         {return __end_cap_.second();}
55    _LIBCPP_INLINE_VISIBILITY const __alloc_rr&     __alloc() const _NOEXCEPT   {return __end_cap_.second();}
56    _LIBCPP_INLINE_VISIBILITY pointer&              __end_cap() _NOEXCEPT       {return __end_cap_.first();}
57    _LIBCPP_INLINE_VISIBILITY const pointer&        __end_cap() const _NOEXCEPT {return __end_cap_.first();}
58
59    __split_buffer()
60        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
61    explicit __split_buffer(__alloc_rr& __a);
62    explicit __split_buffer(const __alloc_rr& __a);
63    __split_buffer(size_type __cap, size_type __start, __alloc_rr& __a);
64    ~__split_buffer();
65
66#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
67    __split_buffer(__split_buffer&& __c)
68        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
69    __split_buffer(__split_buffer&& __c, const __alloc_rr& __a);
70    __split_buffer& operator=(__split_buffer&& __c)
71        _NOEXCEPT_((__alloc_traits::propagate_on_container_move_assignment::value &&
72                is_nothrow_move_assignable<allocator_type>::value) ||
73               !__alloc_traits::propagate_on_container_move_assignment::value);
74#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
75
76    _LIBCPP_INLINE_VISIBILITY       iterator begin() _NOEXCEPT       {return __begin_;}
77    _LIBCPP_INLINE_VISIBILITY const_iterator begin() const _NOEXCEPT {return __begin_;}
78    _LIBCPP_INLINE_VISIBILITY       iterator end() _NOEXCEPT         {return __end_;}
79    _LIBCPP_INLINE_VISIBILITY const_iterator end() const _NOEXCEPT   {return __end_;}
80
81    _LIBCPP_INLINE_VISIBILITY
82    void clear() _NOEXCEPT
83        {__destruct_at_end(__begin_);}
84    _LIBCPP_INLINE_VISIBILITY size_type size() const {return static_cast<size_type>(__end_ - __begin_);}
85    _LIBCPP_INLINE_VISIBILITY bool empty()     const {return __end_ == __begin_;}
86    _LIBCPP_INLINE_VISIBILITY size_type capacity() const {return static_cast<size_type>(__end_cap() - __first_);}
87    _LIBCPP_INLINE_VISIBILITY size_type __front_spare() const {return static_cast<size_type>(__begin_ - __first_);}
88    _LIBCPP_INLINE_VISIBILITY size_type __back_spare() const {return static_cast<size_type>(__end_cap() - __end_);}
89
90    _LIBCPP_INLINE_VISIBILITY       reference front()       {return *__begin_;}
91    _LIBCPP_INLINE_VISIBILITY const_reference front() const {return *__begin_;}
92    _LIBCPP_INLINE_VISIBILITY       reference back()        {return *(__end_ - 1);}
93    _LIBCPP_INLINE_VISIBILITY const_reference back() const  {return *(__end_ - 1);}
94
95    void reserve(size_type __n);
96    void shrink_to_fit() _NOEXCEPT;
97    void push_front(const_reference __x);
98    _LIBCPP_INLINE_VISIBILITY void push_back(const_reference __x);
99#if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
100    void push_front(value_type&& __x);
101    void push_back(value_type&& __x);
102#if !defined(_LIBCPP_HAS_NO_VARIADICS)
103    template <class... _Args>
104        void emplace_back(_Args&&... __args);
105#endif  // !defined(_LIBCPP_HAS_NO_VARIADICS)
106#endif  // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
107
108    _LIBCPP_INLINE_VISIBILITY void pop_front() {__destruct_at_begin(__begin_+1);}
109    _LIBCPP_INLINE_VISIBILITY void pop_back() {__destruct_at_end(__end_-1);}
110
111    void __construct_at_end(size_type __n);
112    void __construct_at_end(size_type __n, const_reference __x);
113    template <class _InputIter>
114        typename enable_if
115        <
116            __is_input_iterator<_InputIter>::value &&
117           !__is_forward_iterator<_InputIter>::value,
118            void
119        >::type
120        __construct_at_end(_InputIter __first, _InputIter __last);
121    template <class _ForwardIterator>
122        typename enable_if
123        <
124            __is_forward_iterator<_ForwardIterator>::value,
125            void
126        >::type
127        __construct_at_end(_ForwardIterator __first, _ForwardIterator __last);
128
129    _LIBCPP_INLINE_VISIBILITY void __destruct_at_begin(pointer __new_begin)
130        {__destruct_at_begin(__new_begin, is_trivially_destructible<value_type>());}
131        void __destruct_at_begin(pointer __new_begin, false_type);
132        void __destruct_at_begin(pointer __new_begin, true_type);
133
134    _LIBCPP_INLINE_VISIBILITY
135    void __destruct_at_end(pointer __new_last) _NOEXCEPT
136        {__destruct_at_end(__new_last, false_type());}
137    _LIBCPP_INLINE_VISIBILITY
138        void __destruct_at_end(pointer __new_last, false_type) _NOEXCEPT;
139    _LIBCPP_INLINE_VISIBILITY
140        void __destruct_at_end(pointer __new_last, true_type) _NOEXCEPT;
141
142    void swap(__split_buffer& __x)
143        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value||
144                   __is_nothrow_swappable<__alloc_rr>::value);
145
146    bool __invariants() const;
147
148private:
149    _LIBCPP_INLINE_VISIBILITY
150    void __move_assign_alloc(__split_buffer& __c, true_type)
151        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
152        {
153            __alloc() = _VSTD::move(__c.__alloc());
154        }
155
156    _LIBCPP_INLINE_VISIBILITY
157    void __move_assign_alloc(__split_buffer&, false_type) _NOEXCEPT
158        {}
159};
160
161template <class _Tp, class _Allocator>
162bool
163__split_buffer<_Tp, _Allocator>::__invariants() const
164{
165    if (__first_ == nullptr)
166    {
167        if (__begin_ != nullptr)
168            return false;
169        if (__end_ != nullptr)
170            return false;
171        if (__end_cap() != nullptr)
172            return false;
173    }
174    else
175    {
176        if (__begin_ < __first_)
177            return false;
178        if (__end_ < __begin_)
179            return false;
180        if (__end_cap() < __end_)
181            return false;
182    }
183    return true;
184}
185
186//  Default constructs __n objects starting at __end_
187//  throws if construction throws
188//  Precondition:  __n > 0
189//  Precondition:  size() + __n <= capacity()
190//  Postcondition:  size() == size() + __n
191template <class _Tp, class _Allocator>
192void
193__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n)
194{
195    __alloc_rr& __a = this->__alloc();
196    do
197    {
198        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_));
199        ++this->__end_;
200        --__n;
201    } while (__n > 0);
202}
203
204//  Copy constructs __n objects starting at __end_ from __x
205//  throws if construction throws
206//  Precondition:  __n > 0
207//  Precondition:  size() + __n <= capacity()
208//  Postcondition:  size() == old size() + __n
209//  Postcondition:  [i] == __x for all i in [size() - __n, __n)
210template <class _Tp, class _Allocator>
211void
212__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x)
213{
214    __alloc_rr& __a = this->__alloc();
215    do
216    {
217        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_), __x);
218        ++this->__end_;
219        --__n;
220    } while (__n > 0);
221}
222
223template <class _Tp, class _Allocator>
224template <class _InputIter>
225typename enable_if
226<
227     __is_input_iterator<_InputIter>::value &&
228    !__is_forward_iterator<_InputIter>::value,
229    void
230>::type
231__split_buffer<_Tp, _Allocator>::__construct_at_end(_InputIter __first, _InputIter __last)
232{
233    __alloc_rr& __a = this->__alloc();
234    for (; __first != __last; ++__first)
235    {
236        if (__end_ == __end_cap())
237        {
238            size_type __old_cap = __end_cap() - __first_;
239            size_type __new_cap = _VSTD::max<size_type>(2 * __old_cap, 8);
240            __split_buffer __buf(__new_cap, 0, __a);
241            for (pointer __p = __begin_; __p != __end_; ++__p, ++__buf.__end_)
242                __alloc_traits::construct(__buf.__alloc(),
243                        _VSTD::__to_raw_pointer(__buf.__end_), _VSTD::move(*__p));
244            swap(__buf);
245        }
246        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_), *__first);
247        ++this->__end_;
248    }
249}
250
251template <class _Tp, class _Allocator>
252template <class _ForwardIterator>
253typename enable_if
254<
255    __is_forward_iterator<_ForwardIterator>::value,
256    void
257>::type
258__split_buffer<_Tp, _Allocator>::__construct_at_end(_ForwardIterator __first, _ForwardIterator __last)
259{
260    __alloc_rr& __a = this->__alloc();
261    for (; __first != __last; ++__first)
262    {
263        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_), *__first);
264        ++this->__end_;
265    }
266}
267
268template <class _Tp, class _Allocator>
269inline _LIBCPP_INLINE_VISIBILITY
270void
271__split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, false_type)
272{
273    while (__begin_ != __new_begin)
274        __alloc_traits::destroy(__alloc(), __to_raw_pointer(__begin_++));
275}
276
277template <class _Tp, class _Allocator>
278inline _LIBCPP_INLINE_VISIBILITY
279void
280__split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, true_type)
281{
282    __begin_ = __new_begin;
283}
284
285template <class _Tp, class _Allocator>
286inline _LIBCPP_INLINE_VISIBILITY
287void
288__split_buffer<_Tp, _Allocator>::__destruct_at_end(pointer __new_last, false_type) _NOEXCEPT
289{
290    while (__new_last != __end_)
291        __alloc_traits::destroy(__alloc(), __to_raw_pointer(--__end_));
292}
293
294template <class _Tp, class _Allocator>
295inline _LIBCPP_INLINE_VISIBILITY
296void
297__split_buffer<_Tp, _Allocator>::__destruct_at_end(pointer __new_last, true_type) _NOEXCEPT
298{
299    __end_ = __new_last;
300}
301
302template <class _Tp, class _Allocator>
303__split_buffer<_Tp, _Allocator>::__split_buffer(size_type __cap, size_type __start, __alloc_rr& __a)
304    : __end_cap_(nullptr, __a)
305{
306    __first_ = __cap != 0 ? __alloc_traits::allocate(__alloc(), __cap) : nullptr;
307    __begin_ = __end_ = __first_ + __start;
308    __end_cap() = __first_ + __cap;
309}
310
311template <class _Tp, class _Allocator>
312inline _LIBCPP_INLINE_VISIBILITY
313__split_buffer<_Tp, _Allocator>::__split_buffer()
314    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
315    : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr)
316{
317}
318
319template <class _Tp, class _Allocator>
320inline _LIBCPP_INLINE_VISIBILITY
321__split_buffer<_Tp, _Allocator>::__split_buffer(__alloc_rr& __a)
322    : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr, __a)
323{
324}
325
326template <class _Tp, class _Allocator>
327inline _LIBCPP_INLINE_VISIBILITY
328__split_buffer<_Tp, _Allocator>::__split_buffer(const __alloc_rr& __a)
329    : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr, __a)
330{
331}
332
333template <class _Tp, class _Allocator>
334__split_buffer<_Tp, _Allocator>::~__split_buffer()
335{
336    clear();
337    if (__first_)
338        __alloc_traits::deallocate(__alloc(), __first_, capacity());
339}
340
341#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
342
343template <class _Tp, class _Allocator>
344__split_buffer<_Tp, _Allocator>::__split_buffer(__split_buffer&& __c)
345    _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
346    : __first_(_VSTD::move(__c.__first_)),
347      __begin_(_VSTD::move(__c.__begin_)),
348      __end_(_VSTD::move(__c.__end_)),
349      __end_cap_(_VSTD::move(__c.__end_cap_))
350{
351    __c.__first_ = nullptr;
352    __c.__begin_ = nullptr;
353    __c.__end_ = nullptr;
354    __c.__end_cap() = nullptr;
355}
356
357template <class _Tp, class _Allocator>
358__split_buffer<_Tp, _Allocator>::__split_buffer(__split_buffer&& __c, const __alloc_rr& __a)
359    : __end_cap_(__a)
360{
361    if (__a == __c.__alloc())
362    {
363        __first_ = __c.__first_;
364        __begin_ = __c.__begin_;
365        __end_ = __c.__end_;
366        __end_cap() = __c.__end_cap();
367        __c.__first_ = nullptr;
368        __c.__begin_ = nullptr;
369        __c.__end_ = nullptr;
370        __c.__end_cap() = nullptr;
371    }
372    else
373    {
374        size_type __cap = __c.size();
375        __first_ = __alloc_traits::allocate(__alloc(), __cap);
376        __begin_ = __end_ = __first_;
377        __end_cap() = __first_ + __cap;
378        typedef move_iterator<iterator> _Ip;
379        __construct_at_end(_Ip(__c.begin()), _Ip(__c.end()));
380    }
381}
382
383template <class _Tp, class _Allocator>
384__split_buffer<_Tp, _Allocator>&
385__split_buffer<_Tp, _Allocator>::operator=(__split_buffer&& __c)
386    _NOEXCEPT_((__alloc_traits::propagate_on_container_move_assignment::value &&
387                is_nothrow_move_assignable<allocator_type>::value) ||
388               !__alloc_traits::propagate_on_container_move_assignment::value)
389{
390    clear();
391    shrink_to_fit();
392    __first_ = __c.__first_;
393    __begin_ = __c.__begin_;
394    __end_ = __c.__end_;
395    __end_cap() = __c.__end_cap();
396    __move_assign_alloc(__c,
397        integral_constant<bool,
398                          __alloc_traits::propagate_on_container_move_assignment::value>());
399    __c.__first_ = __c.__begin_ = __c.__end_ = __c.__end_cap() = nullptr;
400    return *this;
401}
402
403#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
404
405template <class _Tp, class _Allocator>
406void
407__split_buffer<_Tp, _Allocator>::swap(__split_buffer& __x)
408        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value||
409                   __is_nothrow_swappable<__alloc_rr>::value)
410{
411    _VSTD::swap(__first_, __x.__first_);
412    _VSTD::swap(__begin_, __x.__begin_);
413    _VSTD::swap(__end_, __x.__end_);
414    _VSTD::swap(__end_cap(), __x.__end_cap());
415    __swap_allocator(__alloc(), __x.__alloc());
416}
417
418template <class _Tp, class _Allocator>
419void
420__split_buffer<_Tp, _Allocator>::reserve(size_type __n)
421{
422    if (__n < capacity())
423    {
424        __split_buffer<value_type, __alloc_rr&> __t(__n, 0, __alloc());
425        __t.__construct_at_end(move_iterator<pointer>(__begin_),
426                               move_iterator<pointer>(__end_));
427        _VSTD::swap(__first_, __t.__first_);
428        _VSTD::swap(__begin_, __t.__begin_);
429        _VSTD::swap(__end_, __t.__end_);
430        _VSTD::swap(__end_cap(), __t.__end_cap());
431    }
432}
433
434template <class _Tp, class _Allocator>
435void
436__split_buffer<_Tp, _Allocator>::shrink_to_fit() _NOEXCEPT
437{
438    if (capacity() > size())
439    {
440#ifndef _LIBCPP_NO_EXCEPTIONS
441        try
442        {
443#endif  // _LIBCPP_NO_EXCEPTIONS
444            __split_buffer<value_type, __alloc_rr&> __t(size(), 0, __alloc());
445            __t.__construct_at_end(move_iterator<pointer>(__begin_),
446                                   move_iterator<pointer>(__end_));
447            __t.__end_ = __t.__begin_ + (__end_ - __begin_);
448            _VSTD::swap(__first_, __t.__first_);
449            _VSTD::swap(__begin_, __t.__begin_);
450            _VSTD::swap(__end_, __t.__end_);
451            _VSTD::swap(__end_cap(), __t.__end_cap());
452#ifndef _LIBCPP_NO_EXCEPTIONS
453        }
454        catch (...)
455        {
456        }
457#endif  // _LIBCPP_NO_EXCEPTIONS
458    }
459}
460
461template <class _Tp, class _Allocator>
462void
463__split_buffer<_Tp, _Allocator>::push_front(const_reference __x)
464{
465    if (__begin_ == __first_)
466    {
467        if (__end_ < __end_cap())
468        {
469            difference_type __d = __end_cap() - __end_;
470            __d = (__d + 1) / 2;
471            __begin_ = _VSTD::move_backward(__begin_, __end_, __end_ + __d);
472            __end_ += __d;
473        }
474        else
475        {
476            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
477            __split_buffer<value_type, __alloc_rr&> __t(__c, (__c + 3) / 4, __alloc());
478            __t.__construct_at_end(move_iterator<pointer>(__begin_),
479                                   move_iterator<pointer>(__end_));
480            _VSTD::swap(__first_, __t.__first_);
481            _VSTD::swap(__begin_, __t.__begin_);
482            _VSTD::swap(__end_, __t.__end_);
483            _VSTD::swap(__end_cap(), __t.__end_cap());
484        }
485    }
486    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__begin_-1), __x);
487    --__begin_;
488}
489
490#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
491
492template <class _Tp, class _Allocator>
493void
494__split_buffer<_Tp, _Allocator>::push_front(value_type&& __x)
495{
496    if (__begin_ == __first_)
497    {
498        if (__end_ < __end_cap())
499        {
500            difference_type __d = __end_cap() - __end_;
501            __d = (__d + 1) / 2;
502            __begin_ = _VSTD::move_backward(__begin_, __end_, __end_ + __d);
503            __end_ += __d;
504        }
505        else
506        {
507            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
508            __split_buffer<value_type, __alloc_rr&> __t(__c, (__c + 3) / 4, __alloc());
509            __t.__construct_at_end(move_iterator<pointer>(__begin_),
510                                   move_iterator<pointer>(__end_));
511            _VSTD::swap(__first_, __t.__first_);
512            _VSTD::swap(__begin_, __t.__begin_);
513            _VSTD::swap(__end_, __t.__end_);
514            _VSTD::swap(__end_cap(), __t.__end_cap());
515        }
516    }
517    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__begin_-1),
518            _VSTD::move(__x));
519    --__begin_;
520}
521
522#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
523
524template <class _Tp, class _Allocator>
525inline _LIBCPP_INLINE_VISIBILITY
526void
527__split_buffer<_Tp, _Allocator>::push_back(const_reference __x)
528{
529    if (__end_ == __end_cap())
530    {
531        if (__begin_ > __first_)
532        {
533            difference_type __d = __begin_ - __first_;
534            __d = (__d + 1) / 2;
535            __end_ = _VSTD::move(__begin_, __end_, __begin_ - __d);
536            __begin_ -= __d;
537        }
538        else
539        {
540            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
541            __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc());
542            __t.__construct_at_end(move_iterator<pointer>(__begin_),
543                                   move_iterator<pointer>(__end_));
544            _VSTD::swap(__first_, __t.__first_);
545            _VSTD::swap(__begin_, __t.__begin_);
546            _VSTD::swap(__end_, __t.__end_);
547            _VSTD::swap(__end_cap(), __t.__end_cap());
548        }
549    }
550    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__end_), __x);
551    ++__end_;
552}
553
554#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
555
556template <class _Tp, class _Allocator>
557void
558__split_buffer<_Tp, _Allocator>::push_back(value_type&& __x)
559{
560    if (__end_ == __end_cap())
561    {
562        if (__begin_ > __first_)
563        {
564            difference_type __d = __begin_ - __first_;
565            __d = (__d + 1) / 2;
566            __end_ = _VSTD::move(__begin_, __end_, __begin_ - __d);
567            __begin_ -= __d;
568        }
569        else
570        {
571            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
572            __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc());
573            __t.__construct_at_end(move_iterator<pointer>(__begin_),
574                                   move_iterator<pointer>(__end_));
575            _VSTD::swap(__first_, __t.__first_);
576            _VSTD::swap(__begin_, __t.__begin_);
577            _VSTD::swap(__end_, __t.__end_);
578            _VSTD::swap(__end_cap(), __t.__end_cap());
579        }
580    }
581    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__end_),
582            _VSTD::move(__x));
583    ++__end_;
584}
585
586#ifndef _LIBCPP_HAS_NO_VARIADICS
587
588template <class _Tp, class _Allocator>
589template <class... _Args>
590void
591__split_buffer<_Tp, _Allocator>::emplace_back(_Args&&... __args)
592{
593    if (__end_ == __end_cap())
594    {
595        if (__begin_ > __first_)
596        {
597            difference_type __d = __begin_ - __first_;
598            __d = (__d + 1) / 2;
599            __end_ = _VSTD::move(__begin_, __end_, __begin_ - __d);
600            __begin_ -= __d;
601        }
602        else
603        {
604            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
605            __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc());
606            __t.__construct_at_end(move_iterator<pointer>(__begin_),
607                                   move_iterator<pointer>(__end_));
608            _VSTD::swap(__first_, __t.__first_);
609            _VSTD::swap(__begin_, __t.__begin_);
610            _VSTD::swap(__end_, __t.__end_);
611            _VSTD::swap(__end_cap(), __t.__end_cap());
612        }
613    }
614    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__end_),
615                              _VSTD::forward<_Args>(__args)...);
616    ++__end_;
617}
618
619#endif  // _LIBCPP_HAS_NO_VARIADICS
620
621#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
622
623template <class _Tp, class _Allocator>
624inline _LIBCPP_INLINE_VISIBILITY
625void
626swap(__split_buffer<_Tp, _Allocator>& __x, __split_buffer<_Tp, _Allocator>& __y)
627        _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
628{
629    __x.swap(__y);
630}
631
632
633_LIBCPP_END_NAMESPACE_STD
634
635#endif  // _LIBCPP_SPLIT_BUFFER
636