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_cpp17_input_iterator<_InputIter>::value &&
120           !__is_cpp17_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_cpp17_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    struct _ConstructTransaction {
166      explicit _ConstructTransaction(pointer* __p, size_type __n) _NOEXCEPT
167      : __pos_(*__p), __end_(*__p + __n), __dest_(__p) {
168      }
169      ~_ConstructTransaction() {
170        *__dest_ = __pos_;
171      }
172      pointer __pos_;
173     const pointer __end_;
174    private:
175     pointer *__dest_;
176    };
177};
178
179template <class _Tp, class _Allocator>
180bool
181__split_buffer<_Tp, _Allocator>::__invariants() const
182{
183    if (__first_ == nullptr)
184    {
185        if (__begin_ != nullptr)
186            return false;
187        if (__end_ != nullptr)
188            return false;
189        if (__end_cap() != nullptr)
190            return false;
191    }
192    else
193    {
194        if (__begin_ < __first_)
195            return false;
196        if (__end_ < __begin_)
197            return false;
198        if (__end_cap() < __end_)
199            return false;
200    }
201    return true;
202}
203
204//  Default constructs __n objects starting at __end_
205//  throws if construction throws
206//  Precondition:  __n > 0
207//  Precondition:  size() + __n <= capacity()
208//  Postcondition:  size() == size() + __n
209template <class _Tp, class _Allocator>
210void
211__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n)
212{
213    _ConstructTransaction __tx(&this->__end_, __n);
214    for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
215        __alloc_traits::construct(this->__alloc(), _VSTD::__to_address(__tx.__pos_));
216    }
217}
218
219//  Copy constructs __n objects starting at __end_ from __x
220//  throws if construction throws
221//  Precondition:  __n > 0
222//  Precondition:  size() + __n <= capacity()
223//  Postcondition:  size() == old size() + __n
224//  Postcondition:  [i] == __x for all i in [size() - __n, __n)
225template <class _Tp, class _Allocator>
226void
227__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x)
228{
229    _ConstructTransaction __tx(&this->__end_, __n);
230    for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
231        __alloc_traits::construct(this->__alloc(),
232            _VSTD::__to_address(__tx.__pos_), __x);
233    }
234}
235
236template <class _Tp, class _Allocator>
237template <class _InputIter>
238typename enable_if
239<
240     __is_cpp17_input_iterator<_InputIter>::value &&
241    !__is_cpp17_forward_iterator<_InputIter>::value,
242    void
243>::type
244__split_buffer<_Tp, _Allocator>::__construct_at_end(_InputIter __first, _InputIter __last)
245{
246    __alloc_rr& __a = this->__alloc();
247    for (; __first != __last; ++__first)
248    {
249        if (__end_ == __end_cap())
250        {
251            size_type __old_cap = __end_cap() - __first_;
252            size_type __new_cap = _VSTD::max<size_type>(2 * __old_cap, 8);
253            __split_buffer __buf(__new_cap, 0, __a);
254            for (pointer __p = __begin_; __p != __end_; ++__p, ++__buf.__end_)
255                __alloc_traits::construct(__buf.__alloc(),
256                        _VSTD::__to_address(__buf.__end_), _VSTD::move(*__p));
257            swap(__buf);
258        }
259        __alloc_traits::construct(__a, _VSTD::__to_address(this->__end_), *__first);
260        ++this->__end_;
261    }
262}
263
264template <class _Tp, class _Allocator>
265template <class _ForwardIterator>
266typename enable_if
267<
268    __is_cpp17_forward_iterator<_ForwardIterator>::value,
269    void
270>::type
271__split_buffer<_Tp, _Allocator>::__construct_at_end(_ForwardIterator __first, _ForwardIterator __last)
272{
273    _ConstructTransaction __tx(&this->__end_, std::distance(__first, __last));
274    for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_, ++__first) {
275        __alloc_traits::construct(this->__alloc(),
276            _VSTD::__to_address(__tx.__pos_), *__first);
277    }
278}
279
280template <class _Tp, class _Allocator>
281inline
282void
283__split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, false_type)
284{
285    while (__begin_ != __new_begin)
286        __alloc_traits::destroy(__alloc(), __to_address(__begin_++));
287}
288
289template <class _Tp, class _Allocator>
290inline
291void
292__split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, true_type)
293{
294    __begin_ = __new_begin;
295}
296
297template <class _Tp, class _Allocator>
298inline _LIBCPP_INLINE_VISIBILITY
299void
300__split_buffer<_Tp, _Allocator>::__destruct_at_end(pointer __new_last, false_type) _NOEXCEPT
301{
302    while (__new_last != __end_)
303        __alloc_traits::destroy(__alloc(), __to_address(--__end_));
304}
305
306template <class _Tp, class _Allocator>
307inline _LIBCPP_INLINE_VISIBILITY
308void
309__split_buffer<_Tp, _Allocator>::__destruct_at_end(pointer __new_last, true_type) _NOEXCEPT
310{
311    __end_ = __new_last;
312}
313
314template <class _Tp, class _Allocator>
315__split_buffer<_Tp, _Allocator>::__split_buffer(size_type __cap, size_type __start, __alloc_rr& __a)
316    : __end_cap_(nullptr, __a)
317{
318    __first_ = __cap != 0 ? __alloc_traits::allocate(__alloc(), __cap) : nullptr;
319    __begin_ = __end_ = __first_ + __start;
320    __end_cap() = __first_ + __cap;
321}
322
323template <class _Tp, class _Allocator>
324inline
325__split_buffer<_Tp, _Allocator>::__split_buffer()
326    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
327    : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr, __default_init_tag())
328{
329}
330
331template <class _Tp, class _Allocator>
332inline
333__split_buffer<_Tp, _Allocator>::__split_buffer(__alloc_rr& __a)
334    : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr, __a)
335{
336}
337
338template <class _Tp, class _Allocator>
339inline
340__split_buffer<_Tp, _Allocator>::__split_buffer(const __alloc_rr& __a)
341    : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr, __a)
342{
343}
344
345template <class _Tp, class _Allocator>
346__split_buffer<_Tp, _Allocator>::~__split_buffer()
347{
348    clear();
349    if (__first_)
350        __alloc_traits::deallocate(__alloc(), __first_, capacity());
351}
352
353#ifndef _LIBCPP_CXX03_LANG
354
355template <class _Tp, class _Allocator>
356__split_buffer<_Tp, _Allocator>::__split_buffer(__split_buffer&& __c)
357    _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
358    : __first_(_VSTD::move(__c.__first_)),
359      __begin_(_VSTD::move(__c.__begin_)),
360      __end_(_VSTD::move(__c.__end_)),
361      __end_cap_(_VSTD::move(__c.__end_cap_))
362{
363    __c.__first_ = nullptr;
364    __c.__begin_ = nullptr;
365    __c.__end_ = nullptr;
366    __c.__end_cap() = nullptr;
367}
368
369template <class _Tp, class _Allocator>
370__split_buffer<_Tp, _Allocator>::__split_buffer(__split_buffer&& __c, const __alloc_rr& __a)
371    : __end_cap_(nullptr, __a)
372{
373    if (__a == __c.__alloc())
374    {
375        __first_ = __c.__first_;
376        __begin_ = __c.__begin_;
377        __end_ = __c.__end_;
378        __end_cap() = __c.__end_cap();
379        __c.__first_ = nullptr;
380        __c.__begin_ = nullptr;
381        __c.__end_ = nullptr;
382        __c.__end_cap() = nullptr;
383    }
384    else
385    {
386        size_type __cap = __c.size();
387        __first_ = __alloc_traits::allocate(__alloc(), __cap);
388        __begin_ = __end_ = __first_;
389        __end_cap() = __first_ + __cap;
390        typedef move_iterator<iterator> _Ip;
391        __construct_at_end(_Ip(__c.begin()), _Ip(__c.end()));
392    }
393}
394
395template <class _Tp, class _Allocator>
396__split_buffer<_Tp, _Allocator>&
397__split_buffer<_Tp, _Allocator>::operator=(__split_buffer&& __c)
398    _NOEXCEPT_((__alloc_traits::propagate_on_container_move_assignment::value &&
399                is_nothrow_move_assignable<allocator_type>::value) ||
400               !__alloc_traits::propagate_on_container_move_assignment::value)
401{
402    clear();
403    shrink_to_fit();
404    __first_ = __c.__first_;
405    __begin_ = __c.__begin_;
406    __end_ = __c.__end_;
407    __end_cap() = __c.__end_cap();
408    __move_assign_alloc(__c,
409        integral_constant<bool,
410                          __alloc_traits::propagate_on_container_move_assignment::value>());
411    __c.__first_ = __c.__begin_ = __c.__end_ = __c.__end_cap() = nullptr;
412    return *this;
413}
414
415#endif  // _LIBCPP_CXX03_LANG
416
417template <class _Tp, class _Allocator>
418void
419__split_buffer<_Tp, _Allocator>::swap(__split_buffer& __x)
420        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value||
421                   __is_nothrow_swappable<__alloc_rr>::value)
422{
423    _VSTD::swap(__first_, __x.__first_);
424    _VSTD::swap(__begin_, __x.__begin_);
425    _VSTD::swap(__end_, __x.__end_);
426    _VSTD::swap(__end_cap(), __x.__end_cap());
427    __swap_allocator(__alloc(), __x.__alloc());
428}
429
430template <class _Tp, class _Allocator>
431void
432__split_buffer<_Tp, _Allocator>::reserve(size_type __n)
433{
434    if (__n < capacity())
435    {
436        __split_buffer<value_type, __alloc_rr&> __t(__n, 0, __alloc());
437        __t.__construct_at_end(move_iterator<pointer>(__begin_),
438                               move_iterator<pointer>(__end_));
439        _VSTD::swap(__first_, __t.__first_);
440        _VSTD::swap(__begin_, __t.__begin_);
441        _VSTD::swap(__end_, __t.__end_);
442        _VSTD::swap(__end_cap(), __t.__end_cap());
443    }
444}
445
446template <class _Tp, class _Allocator>
447void
448__split_buffer<_Tp, _Allocator>::shrink_to_fit() _NOEXCEPT
449{
450    if (capacity() > size())
451    {
452#ifndef _LIBCPP_NO_EXCEPTIONS
453        try
454        {
455#endif  // _LIBCPP_NO_EXCEPTIONS
456            __split_buffer<value_type, __alloc_rr&> __t(size(), 0, __alloc());
457            __t.__construct_at_end(move_iterator<pointer>(__begin_),
458                                   move_iterator<pointer>(__end_));
459            __t.__end_ = __t.__begin_ + (__end_ - __begin_);
460            _VSTD::swap(__first_, __t.__first_);
461            _VSTD::swap(__begin_, __t.__begin_);
462            _VSTD::swap(__end_, __t.__end_);
463            _VSTD::swap(__end_cap(), __t.__end_cap());
464#ifndef _LIBCPP_NO_EXCEPTIONS
465        }
466        catch (...)
467        {
468        }
469#endif  // _LIBCPP_NO_EXCEPTIONS
470    }
471}
472
473template <class _Tp, class _Allocator>
474void
475__split_buffer<_Tp, _Allocator>::push_front(const_reference __x)
476{
477    if (__begin_ == __first_)
478    {
479        if (__end_ < __end_cap())
480        {
481            difference_type __d = __end_cap() - __end_;
482            __d = (__d + 1) / 2;
483            __begin_ = _VSTD::move_backward(__begin_, __end_, __end_ + __d);
484            __end_ += __d;
485        }
486        else
487        {
488            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
489            __split_buffer<value_type, __alloc_rr&> __t(__c, (__c + 3) / 4, __alloc());
490            __t.__construct_at_end(move_iterator<pointer>(__begin_),
491                                   move_iterator<pointer>(__end_));
492            _VSTD::swap(__first_, __t.__first_);
493            _VSTD::swap(__begin_, __t.__begin_);
494            _VSTD::swap(__end_, __t.__end_);
495            _VSTD::swap(__end_cap(), __t.__end_cap());
496        }
497    }
498    __alloc_traits::construct(__alloc(), _VSTD::__to_address(__begin_-1), __x);
499    --__begin_;
500}
501
502#ifndef _LIBCPP_CXX03_LANG
503
504template <class _Tp, class _Allocator>
505void
506__split_buffer<_Tp, _Allocator>::push_front(value_type&& __x)
507{
508    if (__begin_ == __first_)
509    {
510        if (__end_ < __end_cap())
511        {
512            difference_type __d = __end_cap() - __end_;
513            __d = (__d + 1) / 2;
514            __begin_ = _VSTD::move_backward(__begin_, __end_, __end_ + __d);
515            __end_ += __d;
516        }
517        else
518        {
519            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
520            __split_buffer<value_type, __alloc_rr&> __t(__c, (__c + 3) / 4, __alloc());
521            __t.__construct_at_end(move_iterator<pointer>(__begin_),
522                                   move_iterator<pointer>(__end_));
523            _VSTD::swap(__first_, __t.__first_);
524            _VSTD::swap(__begin_, __t.__begin_);
525            _VSTD::swap(__end_, __t.__end_);
526            _VSTD::swap(__end_cap(), __t.__end_cap());
527        }
528    }
529    __alloc_traits::construct(__alloc(), _VSTD::__to_address(__begin_-1),
530            _VSTD::move(__x));
531    --__begin_;
532}
533
534#endif  // _LIBCPP_CXX03_LANG
535
536template <class _Tp, class _Allocator>
537inline _LIBCPP_INLINE_VISIBILITY
538void
539__split_buffer<_Tp, _Allocator>::push_back(const_reference __x)
540{
541    if (__end_ == __end_cap())
542    {
543        if (__begin_ > __first_)
544        {
545            difference_type __d = __begin_ - __first_;
546            __d = (__d + 1) / 2;
547            __end_ = _VSTD::move(__begin_, __end_, __begin_ - __d);
548            __begin_ -= __d;
549        }
550        else
551        {
552            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
553            __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc());
554            __t.__construct_at_end(move_iterator<pointer>(__begin_),
555                                   move_iterator<pointer>(__end_));
556            _VSTD::swap(__first_, __t.__first_);
557            _VSTD::swap(__begin_, __t.__begin_);
558            _VSTD::swap(__end_, __t.__end_);
559            _VSTD::swap(__end_cap(), __t.__end_cap());
560        }
561    }
562    __alloc_traits::construct(__alloc(), _VSTD::__to_address(__end_), __x);
563    ++__end_;
564}
565
566#ifndef _LIBCPP_CXX03_LANG
567
568template <class _Tp, class _Allocator>
569void
570__split_buffer<_Tp, _Allocator>::push_back(value_type&& __x)
571{
572    if (__end_ == __end_cap())
573    {
574        if (__begin_ > __first_)
575        {
576            difference_type __d = __begin_ - __first_;
577            __d = (__d + 1) / 2;
578            __end_ = _VSTD::move(__begin_, __end_, __begin_ - __d);
579            __begin_ -= __d;
580        }
581        else
582        {
583            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
584            __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc());
585            __t.__construct_at_end(move_iterator<pointer>(__begin_),
586                                   move_iterator<pointer>(__end_));
587            _VSTD::swap(__first_, __t.__first_);
588            _VSTD::swap(__begin_, __t.__begin_);
589            _VSTD::swap(__end_, __t.__end_);
590            _VSTD::swap(__end_cap(), __t.__end_cap());
591        }
592    }
593    __alloc_traits::construct(__alloc(), _VSTD::__to_address(__end_),
594            _VSTD::move(__x));
595    ++__end_;
596}
597
598template <class _Tp, class _Allocator>
599template <class... _Args>
600void
601__split_buffer<_Tp, _Allocator>::emplace_back(_Args&&... __args)
602{
603    if (__end_ == __end_cap())
604    {
605        if (__begin_ > __first_)
606        {
607            difference_type __d = __begin_ - __first_;
608            __d = (__d + 1) / 2;
609            __end_ = _VSTD::move(__begin_, __end_, __begin_ - __d);
610            __begin_ -= __d;
611        }
612        else
613        {
614            size_type __c = max<size_type>(2 * static_cast<size_t>(__end_cap() - __first_), 1);
615            __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc());
616            __t.__construct_at_end(move_iterator<pointer>(__begin_),
617                                   move_iterator<pointer>(__end_));
618            _VSTD::swap(__first_, __t.__first_);
619            _VSTD::swap(__begin_, __t.__begin_);
620            _VSTD::swap(__end_, __t.__end_);
621            _VSTD::swap(__end_cap(), __t.__end_cap());
622        }
623    }
624    __alloc_traits::construct(__alloc(), _VSTD::__to_address(__end_),
625                              _VSTD::forward<_Args>(__args)...);
626    ++__end_;
627}
628
629#endif  // _LIBCPP_CXX03_LANG
630
631template <class _Tp, class _Allocator>
632inline _LIBCPP_INLINE_VISIBILITY
633void
634swap(__split_buffer<_Tp, _Allocator>& __x, __split_buffer<_Tp, _Allocator>& __y)
635        _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
636{
637    __x.swap(__y);
638}
639
640_LIBCPP_END_NAMESPACE_STD
641
642_LIBCPP_POP_MACROS
643
644#endif  // _LIBCPP_SPLIT_BUFFER
645