__split_buffer revision 360660 
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
10#pragma GCC system_header
11#endif
12
13_LIBCPP_PUSH_MACROS
14#include <__undef_macros>
15
16
17_LIBCPP_BEGIN_NAMESPACE_STD
18
19template <bool>
20class __split_buffer_common
21{
22protected:
23    void __throw_length_error() const;
24    void __throw_out_of_range() const;
25};
26
27template <class _Tp, class _Allocator = allocator<_Tp> >
28struct __split_buffer
29    : private __split_buffer_common<true>
30{
31private:
32    __split_buffer(const __split_buffer&);
33    __split_buffer& operator=(const __split_buffer&);
34public:
35    typedef _Tp                                             value_type;
36    typedef _Allocator                                      allocator_type;
37    typedef typename remove_reference<allocator_type>::type __alloc_rr;
38    typedef allocator_traits<__alloc_rr>                    __alloc_traits;
39    typedef value_type&                                     reference;
40    typedef const value_type&                               const_reference;
41    typedef typename __alloc_traits::size_type              size_type;
42    typedef typename __alloc_traits::difference_type        difference_type;
43    typedef typename __alloc_traits::pointer                pointer;
44    typedef typename __alloc_traits::const_pointer          const_pointer;
45    typedef pointer                                         iterator;
46    typedef const_pointer                                   const_iterator;
47
48    pointer                                         __first_;
49    pointer                                         __begin_;
50    pointer                                         __end_;
51    __compressed_pair<pointer, allocator_type> __end_cap_;
52
53    typedef typename add_lvalue_reference<allocator_type>::type __alloc_ref;
54    typedef typename add_lvalue_reference<allocator_type>::type __alloc_const_ref;
55
56    _LIBCPP_INLINE_VISIBILITY __alloc_rr&           __alloc() _NOEXCEPT         {return __end_cap_.second();}
57    _LIBCPP_INLINE_VISIBILITY const __alloc_rr&     __alloc() const _NOEXCEPT   {return __end_cap_.second();}
58    _LIBCPP_INLINE_VISIBILITY pointer&              __end_cap() _NOEXCEPT       {return __end_cap_.first();}
59    _LIBCPP_INLINE_VISIBILITY const pointer&        __end_cap() const _NOEXCEPT {return __end_cap_.first();}
60
61    _LIBCPP_INLINE_VISIBILITY
62    __split_buffer()
63        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
64    _LIBCPP_INLINE_VISIBILITY
65    explicit __split_buffer(__alloc_rr& __a);
66    _LIBCPP_INLINE_VISIBILITY
67    explicit __split_buffer(const __alloc_rr& __a);
68    __split_buffer(size_type __cap, size_type __start, __alloc_rr& __a);
69    ~__split_buffer();
70
71#ifndef _LIBCPP_CXX03_LANG
72    __split_buffer(__split_buffer&& __c)
73        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
74    __split_buffer(__split_buffer&& __c, const __alloc_rr& __a);
75    __split_buffer& operator=(__split_buffer&& __c)
76        _NOEXCEPT_((__alloc_traits::propagate_on_container_move_assignment::value &&
77                is_nothrow_move_assignable<allocator_type>::value) ||
78               !__alloc_traits::propagate_on_container_move_assignment::value);
79#endif  // _LIBCPP_CXX03_LANG
80
81    _LIBCPP_INLINE_VISIBILITY       iterator begin() _NOEXCEPT       {return __begin_;}
82    _LIBCPP_INLINE_VISIBILITY const_iterator begin() const _NOEXCEPT {return __begin_;}
83    _LIBCPP_INLINE_VISIBILITY       iterator end() _NOEXCEPT         {return __end_;}
84    _LIBCPP_INLINE_VISIBILITY const_iterator end() const _NOEXCEPT   {return __end_;}
85
86    _LIBCPP_INLINE_VISIBILITY
87    void clear() _NOEXCEPT
88        {__destruct_at_end(__begin_);}
89    _LIBCPP_INLINE_VISIBILITY size_type size() const {return static_cast<size_type>(__end_ - __begin_);}
90    _LIBCPP_INLINE_VISIBILITY bool empty()     const {return __end_ == __begin_;}
91    _LIBCPP_INLINE_VISIBILITY size_type capacity() const {return static_cast<size_type>(__end_cap() - __first_);}
92    _LIBCPP_INLINE_VISIBILITY size_type __front_spare() const {return static_cast<size_type>(__begin_ - __first_);}
93    _LIBCPP_INLINE_VISIBILITY size_type __back_spare() const {return static_cast<size_type>(__end_cap() - __end_);}
94
95    _LIBCPP_INLINE_VISIBILITY       reference front()       {return *__begin_;}
96    _LIBCPP_INLINE_VISIBILITY const_reference front() const {return *__begin_;}
97    _LIBCPP_INLINE_VISIBILITY       reference back()        {return *(__end_ - 1);}
98    _LIBCPP_INLINE_VISIBILITY const_reference back() const  {return *(__end_ - 1);}
99
100    void reserve(size_type __n);
101    void shrink_to_fit() _NOEXCEPT;
102    void push_front(const_reference __x);
103    _LIBCPP_INLINE_VISIBILITY void push_back(const_reference __x);
104#ifndef _LIBCPP_CXX03_LANG
105    void push_front(value_type&& __x);
106    void push_back(value_type&& __x);
107    template <class... _Args>
108        void emplace_back(_Args&&... __args);
109#endif  // !defined(_LIBCPP_CXX03_LANG)
110
111    _LIBCPP_INLINE_VISIBILITY void pop_front() {__destruct_at_begin(__begin_+1);}
112    _LIBCPP_INLINE_VISIBILITY void pop_back() {__destruct_at_end(__end_-1);}
113
114    void __construct_at_end(size_type __n);
115    void __construct_at_end(size_type __n, const_reference __x);
116    template <class _InputIter>
117        typename enable_if
118        <
119            __is_input_iterator<_InputIter>::value &&
120           !__is_forward_iterator<_InputIter>::value,
121            void
122        >::type
123        __construct_at_end(_InputIter __first, _InputIter __last);
124    template <class _ForwardIterator>
125        typename enable_if
126        <
127            __is_forward_iterator<_ForwardIterator>::value,
128            void
129        >::type
130        __construct_at_end(_ForwardIterator __first, _ForwardIterator __last);
131
132    _LIBCPP_INLINE_VISIBILITY void __destruct_at_begin(pointer __new_begin)
133        {__destruct_at_begin(__new_begin, is_trivially_destructible<value_type>());}
134        _LIBCPP_INLINE_VISIBILITY
135        void __destruct_at_begin(pointer __new_begin, false_type);
136        _LIBCPP_INLINE_VISIBILITY
137        void __destruct_at_begin(pointer __new_begin, true_type);
138
139    _LIBCPP_INLINE_VISIBILITY
140    void __destruct_at_end(pointer __new_last) _NOEXCEPT
141        {__destruct_at_end(__new_last, false_type());}
142    _LIBCPP_INLINE_VISIBILITY
143        void __destruct_at_end(pointer __new_last, false_type) _NOEXCEPT;
144    _LIBCPP_INLINE_VISIBILITY
145        void __destruct_at_end(pointer __new_last, true_type) _NOEXCEPT;
146
147    void swap(__split_buffer& __x)
148        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value||
149                   __is_nothrow_swappable<__alloc_rr>::value);
150
151    bool __invariants() const;
152
153private:
154    _LIBCPP_INLINE_VISIBILITY
155    void __move_assign_alloc(__split_buffer& __c, true_type)
156        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
157        {
158            __alloc() = _VSTD::move(__c.__alloc());
159        }
160
161    _LIBCPP_INLINE_VISIBILITY
162    void __move_assign_alloc(__split_buffer&, false_type) _NOEXCEPT
163        {}
164};
165
166template <class _Tp, class _Allocator>
167bool
168__split_buffer<_Tp, _Allocator>::__invariants() const
169{
170    if (__first_ == nullptr)
171    {
172        if (__begin_ != nullptr)
173            return false;
174        if (__end_ != nullptr)
175            return false;
176        if (__end_cap() != nullptr)
177            return false;
178    }
179    else
180    {
181        if (__begin_ < __first_)
182            return false;
183        if (__end_ < __begin_)
184            return false;
185        if (__end_cap() < __end_)
186            return false;
187    }
188    return true;
189}
190
191//  Default constructs __n objects starting at __end_
192//  throws if construction throws
193//  Precondition:  __n > 0
194//  Precondition:  size() + __n <= capacity()
195//  Postcondition:  size() == size() + __n
196template <class _Tp, class _Allocator>
197void
198__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n)
199{
200    __alloc_rr& __a = this->__alloc();
201    do
202    {
203        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_));
204        ++this->__end_;
205        --__n;
206    } while (__n > 0);
207}
208
209//  Copy constructs __n objects starting at __end_ from __x
210//  throws if construction throws
211//  Precondition:  __n > 0
212//  Precondition:  size() + __n <= capacity()
213//  Postcondition:  size() == old size() + __n
214//  Postcondition:  [i] == __x for all i in [size() - __n, __n)
215template <class _Tp, class _Allocator>
216void
217__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x)
218{
219    __alloc_rr& __a = this->__alloc();
220    do
221    {
222        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_), __x);
223        ++this->__end_;
224        --__n;
225    } while (__n > 0);
226}
227
228template <class _Tp, class _Allocator>
229template <class _InputIter>
230typename enable_if
231<
232     __is_input_iterator<_InputIter>::value &&
233    !__is_forward_iterator<_InputIter>::value,
234    void
235>::type
236__split_buffer<_Tp, _Allocator>::__construct_at_end(_InputIter __first, _InputIter __last)
237{
238    __alloc_rr& __a = this->__alloc();
239    for (; __first != __last; ++__first)
240    {
241        if (__end_ == __end_cap())
242        {
243            size_type __old_cap = __end_cap() - __first_;
244            size_type __new_cap = _VSTD::max<size_type>(2 * __old_cap, 8);
245            __split_buffer __buf(__new_cap, 0, __a);
246            for (pointer __p = __begin_; __p != __end_; ++__p, ++__buf.__end_)
247                __alloc_traits::construct(__buf.__alloc(),
248                        _VSTD::__to_raw_pointer(__buf.__end_), _VSTD::move(*__p));
249            swap(__buf);
250        }
251        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_), *__first);
252        ++this->__end_;
253    }
254}
255
256template <class _Tp, class _Allocator>
257template <class _ForwardIterator>
258typename enable_if
259<
260    __is_forward_iterator<_ForwardIterator>::value,
261    void
262>::type
263__split_buffer<_Tp, _Allocator>::__construct_at_end(_ForwardIterator __first, _ForwardIterator __last)
264{
265    __alloc_rr& __a = this->__alloc();
266    for (; __first != __last; ++__first)
267    {
268        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_), *__first);
269        ++this->__end_;
270    }
271}
272
273template <class _Tp, class _Allocator>
274inline
275void
276__split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, false_type)
277{
278    while (__begin_ != __new_begin)
279        __alloc_traits::destroy(__alloc(), __to_raw_pointer(__begin_++));
280}
281
282template <class _Tp, class _Allocator>
283inline
284void
285__split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, true_type)
286{
287    __begin_ = __new_begin;
288}
289
290template <class _Tp, class _Allocator>
291inline _LIBCPP_INLINE_VISIBILITY
292void
293__split_buffer<_Tp, _Allocator>::__destruct_at_end(pointer __new_last, false_type) _NOEXCEPT
294{
295    while (__new_last != __end_)
296        __alloc_traits::destroy(__alloc(), __to_raw_pointer(--__end_));
297}
298
299template <class _Tp, class _Allocator>
300inline _LIBCPP_INLINE_VISIBILITY
301void
302__split_buffer<_Tp, _Allocator>::__destruct_at_end(pointer __new_last, true_type) _NOEXCEPT
303{
304    __end_ = __new_last;
305}
306
307template <class _Tp, class _Allocator>
308__split_buffer<_Tp, _Allocator>::__split_buffer(size_type __cap, size_type __start, __alloc_rr& __a)
309    : __end_cap_(nullptr, __a)
310{
311    __first_ = __cap != 0 ? __alloc_traits::allocate(__alloc(), __cap) : nullptr;
312    __begin_ = __end_ = __first_ + __start;
313    __end_cap() = __first_ + __cap;
314}
315
316template <class _Tp, class _Allocator>
317inline
318__split_buffer<_Tp, _Allocator>::__split_buffer()
319    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
320    : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr)
321{
322}
323
324template <class _Tp, class _Allocator>
325inline
326__split_buffer<_Tp, _Allocator>::__split_buffer(__alloc_rr& __a)
327    : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr, __a)
328{
329}
330
331template <class _Tp, class _Allocator>
332inline
333__split_buffer<_Tp, _Allocator>::__split_buffer(const __alloc_rr& __a)
334    : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr, __a)
335{
336}
337
338template <class _Tp, class _Allocator>
339__split_buffer<_Tp, _Allocator>::~__split_buffer()
340{
341    clear();
342    if (__first_)
343        __alloc_traits::deallocate(__alloc(), __first_, capacity());
344}
345
346#ifndef _LIBCPP_CXX03_LANG
347
348template <class _Tp, class _Allocator>
349__split_buffer<_Tp, _Allocator>::__split_buffer(__split_buffer&& __c)
350    _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
351    : __first_(_VSTD::move(__c.__first_)),
352      __begin_(_VSTD::move(__c.__begin_)),
353      __end_(_VSTD::move(__c.__end_)),
354      __end_cap_(_VSTD::move(__c.__end_cap_))
355{
356    __c.__first_ = nullptr;
357    __c.__begin_ = nullptr;
358    __c.__end_ = nullptr;
359    __c.__end_cap() = nullptr;
360}
361
362template <class _Tp, class _Allocator>
363__split_buffer<_Tp, _Allocator>::__split_buffer(__split_buffer&& __c, const __alloc_rr& __a)
364    : __end_cap_(__second_tag(), __a)
365{
366    if (__a == __c.__alloc())
367    {
368        __first_ = __c.__first_;
369        __begin_ = __c.__begin_;
370        __end_ = __c.__end_;
371        __end_cap() = __c.__end_cap();
372        __c.__first_ = nullptr;
373        __c.__begin_ = nullptr;
374        __c.__end_ = nullptr;
375        __c.__end_cap() = nullptr;
376    }
377    else
378    {
379        size_type __cap = __c.size();
380        __first_ = __alloc_traits::allocate(__alloc(), __cap);
381        __begin_ = __end_ = __first_;
382        __end_cap() = __first_ + __cap;
383        typedef move_iterator<iterator> _Ip;
384        __construct_at_end(_Ip(__c.begin()), _Ip(__c.end()));
385    }
386}
387
388template <class _Tp, class _Allocator>
389__split_buffer<_Tp, _Allocator>&
390__split_buffer<_Tp, _Allocator>::operator=(__split_buffer&& __c)
391    _NOEXCEPT_((__alloc_traits::propagate_on_container_move_assignment::value &&
392                is_nothrow_move_assignable<allocator_type>::value) ||
393               !__alloc_traits::propagate_on_container_move_assignment::value)
394{
395    clear();
396    shrink_to_fit();
397    __first_ = __c.__first_;
398    __begin_ = __c.__begin_;
399    __end_ = __c.__end_;
400    __end_cap() = __c.__end_cap();
401    __move_assign_alloc(__c,
402        integral_constant<bool,
403                          __alloc_traits::propagate_on_container_move_assignment::value>());
404    __c.__first_ = __c.__begin_ = __c.__end_ = __c.__end_cap() = nullptr;
405    return *this;
406}
407
408#endif  // _LIBCPP_CXX03_LANG
409
410template <class _Tp, class _Allocator>
411void
412__split_buffer<_Tp, _Allocator>::swap(__split_buffer& __x)
413        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value||
414                   __is_nothrow_swappable<__alloc_rr>::value)
415{
416    _VSTD::swap(__first_, __x.__first_);
417    _VSTD::swap(__begin_, __x.__begin_);
418    _VSTD::swap(__end_, __x.__end_);
419    _VSTD::swap(__end_cap(), __x.__end_cap());
420    __swap_allocator(__alloc(), __x.__alloc());
421}
422
423template <class _Tp, class _Allocator>
424void
425__split_buffer<_Tp, _Allocator>::reserve(size_type __n)
426{
427    if (__n < capacity())
428    {
429        __split_buffer<value_type, __alloc_rr&> __t(__n, 0, __alloc());
430        __t.__construct_at_end(move_iterator<pointer>(__begin_),
431                               move_iterator<pointer>(__end_));
432        _VSTD::swap(__first_, __t.__first_);
433        _VSTD::swap(__begin_, __t.__begin_);
434        _VSTD::swap(__end_, __t.__end_);
435        _VSTD::swap(__end_cap(), __t.__end_cap());
436    }
437}
438
439template <class _Tp, class _Allocator>
440void
441__split_buffer<_Tp, _Allocator>::shrink_to_fit() _NOEXCEPT
442{
443    if (capacity() > size())
444    {
445#ifndef _LIBCPP_NO_EXCEPTIONS
446        try
447        {
448#endif  // _LIBCPP_NO_EXCEPTIONS
449            __split_buffer<value_type, __alloc_rr&> __t(size(), 0, __alloc());
450            __t.__construct_at_end(move_iterator<pointer>(__begin_),
451                                   move_iterator<pointer>(__end_));
452            __t.__end_ = __t.__begin_ + (__end_ - __begin_);
453            _VSTD::swap(__first_, __t.__first_);
454            _VSTD::swap(__begin_, __t.__begin_);
455            _VSTD::swap(__end_, __t.__end_);
456            _VSTD::swap(__end_cap(), __t.__end_cap());
457#ifndef _LIBCPP_NO_EXCEPTIONS
458        }
459        catch (...)
460        {
461        }
462#endif  // _LIBCPP_NO_EXCEPTIONS
463    }
464}
465
466template <class _Tp, class _Allocator>
467void
468__split_buffer<_Tp, _Allocator>::push_front(const_reference __x)
469{
470    if (__begin_ == __first_)
471    {
472        if (__end_ < __end_cap())
473        {
474            difference_type __d = __end_cap() - __end_;
475            __d = (__d + 1) / 2;
476            __begin_ = _VSTD::move_backward(__begin_, __end_, __end_ + __d);
477            __end_ += __d;
478        }
479        else
480        {
481            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
482            __split_buffer<value_type, __alloc_rr&> __t(__c, (__c + 3) / 4, __alloc());
483            __t.__construct_at_end(move_iterator<pointer>(__begin_),
484                                   move_iterator<pointer>(__end_));
485            _VSTD::swap(__first_, __t.__first_);
486            _VSTD::swap(__begin_, __t.__begin_);
487            _VSTD::swap(__end_, __t.__end_);
488            _VSTD::swap(__end_cap(), __t.__end_cap());
489        }
490    }
491    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__begin_-1), __x);
492    --__begin_;
493}
494
495#ifndef _LIBCPP_CXX03_LANG
496
497template <class _Tp, class _Allocator>
498void
499__split_buffer<_Tp, _Allocator>::push_front(value_type&& __x)
500{
501    if (__begin_ == __first_)
502    {
503        if (__end_ < __end_cap())
504        {
505            difference_type __d = __end_cap() - __end_;
506            __d = (__d + 1) / 2;
507            __begin_ = _VSTD::move_backward(__begin_, __end_, __end_ + __d);
508            __end_ += __d;
509        }
510        else
511        {
512            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
513            __split_buffer<value_type, __alloc_rr&> __t(__c, (__c + 3) / 4, __alloc());
514            __t.__construct_at_end(move_iterator<pointer>(__begin_),
515                                   move_iterator<pointer>(__end_));
516            _VSTD::swap(__first_, __t.__first_);
517            _VSTD::swap(__begin_, __t.__begin_);
518            _VSTD::swap(__end_, __t.__end_);
519            _VSTD::swap(__end_cap(), __t.__end_cap());
520        }
521    }
522    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__begin_-1),
523            _VSTD::move(__x));
524    --__begin_;
525}
526
527#endif  // _LIBCPP_CXX03_LANG
528
529template <class _Tp, class _Allocator>
530inline _LIBCPP_INLINE_VISIBILITY
531void
532__split_buffer<_Tp, _Allocator>::push_back(const_reference __x)
533{
534    if (__end_ == __end_cap())
535    {
536        if (__begin_ > __first_)
537        {
538            difference_type __d = __begin_ - __first_;
539            __d = (__d + 1) / 2;
540            __end_ = _VSTD::move(__begin_, __end_, __begin_ - __d);
541            __begin_ -= __d;
542        }
543        else
544        {
545            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
546            __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc());
547            __t.__construct_at_end(move_iterator<pointer>(__begin_),
548                                   move_iterator<pointer>(__end_));
549            _VSTD::swap(__first_, __t.__first_);
550            _VSTD::swap(__begin_, __t.__begin_);
551            _VSTD::swap(__end_, __t.__end_);
552            _VSTD::swap(__end_cap(), __t.__end_cap());
553        }
554    }
555    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__end_), __x);
556    ++__end_;
557}
558
559#ifndef _LIBCPP_CXX03_LANG
560
561template <class _Tp, class _Allocator>
562void
563__split_buffer<_Tp, _Allocator>::push_back(value_type&& __x)
564{
565    if (__end_ == __end_cap())
566    {
567        if (__begin_ > __first_)
568        {
569            difference_type __d = __begin_ - __first_;
570            __d = (__d + 1) / 2;
571            __end_ = _VSTD::move(__begin_, __end_, __begin_ - __d);
572            __begin_ -= __d;
573        }
574        else
575        {
576            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
577            __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc());
578            __t.__construct_at_end(move_iterator<pointer>(__begin_),
579                                   move_iterator<pointer>(__end_));
580            _VSTD::swap(__first_, __t.__first_);
581            _VSTD::swap(__begin_, __t.__begin_);
582            _VSTD::swap(__end_, __t.__end_);
583            _VSTD::swap(__end_cap(), __t.__end_cap());
584        }
585    }
586    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__end_),
587            _VSTD::move(__x));
588    ++__end_;
589}
590
591template <class _Tp, class _Allocator>
592template <class... _Args>
593void
594__split_buffer<_Tp, _Allocator>::emplace_back(_Args&&... __args)
595{
596    if (__end_ == __end_cap())
597    {
598        if (__begin_ > __first_)
599        {
600            difference_type __d = __begin_ - __first_;
601            __d = (__d + 1) / 2;
602            __end_ = _VSTD::move(__begin_, __end_, __begin_ - __d);
603            __begin_ -= __d;
604        }
605        else
606        {
607            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
608            __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc());
609            __t.__construct_at_end(move_iterator<pointer>(__begin_),
610                                   move_iterator<pointer>(__end_));
611            _VSTD::swap(__first_, __t.__first_);
612            _VSTD::swap(__begin_, __t.__begin_);
613            _VSTD::swap(__end_, __t.__end_);
614            _VSTD::swap(__end_cap(), __t.__end_cap());
615        }
616    }
617    __alloc_traits::construct(__alloc(), _VSTD::__to_raw_pointer(__end_),
618                              _VSTD::forward<_Args>(__args)...);
619    ++__end_;
620}
621
622#endif  // _LIBCPP_CXX03_LANG
623
624template <class _Tp, class _Allocator>
625inline _LIBCPP_INLINE_VISIBILITY
626void
627swap(__split_buffer<_Tp, _Allocator>& __x, __split_buffer<_Tp, _Allocator>& __y)
628        _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
629{
630    __x.swap(__y);
631}
632
633_LIBCPP_END_NAMESPACE_STD
634
635_LIBCPP_POP_MACROS
636
637#endif  // _LIBCPP_SPLIT_BUFFER
638