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      1 // Deque implementation -*- C++ -*-
      2 
      3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
      4 // 2011 Free Software Foundation, Inc.
      5 //
      6 // This file is part of the GNU ISO C++ Library.  This library is free
      7 // software; you can redistribute it and/or modify it under the
      8 // terms of the GNU General Public License as published by the
      9 // Free Software Foundation; either version 3, or (at your option)
     10 // any later version.
     11 
     12 // This library is distributed in the hope that it will be useful,
     13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
     14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     15 // GNU General Public License for more details.
     16 
     17 // Under Section 7 of GPL version 3, you are granted additional
     18 // permissions described in the GCC Runtime Library Exception, version
     19 // 3.1, as published by the Free Software Foundation.
     20 
     21 // You should have received a copy of the GNU General Public License and
     22 // a copy of the GCC Runtime Library Exception along with this program;
     23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     24 // <http://www.gnu.org/licenses/>.
     25 
     26 /*
     27  *
     28  * Copyright (c) 1994
     29  * Hewlett-Packard Company
     30  *
     31  * Permission to use, copy, modify, distribute and sell this software
     32  * and its documentation for any purpose is hereby granted without fee,
     33  * provided that the above copyright notice appear in all copies and
     34  * that both that copyright notice and this permission notice appear
     35  * in supporting documentation.  Hewlett-Packard Company makes no
     36  * representations about the suitability of this software for any
     37  * purpose.  It is provided "as is" without express or implied warranty.
     38  *
     39  *
     40  * Copyright (c) 1997
     41  * Silicon Graphics Computer Systems, Inc.
     42  *
     43  * Permission to use, copy, modify, distribute and sell this software
     44  * and its documentation for any purpose is hereby granted without fee,
     45  * provided that the above copyright notice appear in all copies and
     46  * that both that copyright notice and this permission notice appear
     47  * in supporting documentation.  Silicon Graphics makes no
     48  * representations about the suitability of this software for any
     49  * purpose.  It is provided "as is" without express or implied warranty.
     50  */
     51 
     52 /** @file bits/stl_deque.h
     53  *  This is an internal header file, included by other library headers.
     54  *  Do not attempt to use it directly. @headername{deque}
     55  */
     56 
     57 #ifndef _STL_DEQUE_H
     58 #define _STL_DEQUE_H 1
     59 
     60 #include <bits/concept_check.h>
     61 #include <bits/stl_iterator_base_types.h>
     62 #include <bits/stl_iterator_base_funcs.h>
     63 #include <initializer_list>
     64 
     65 namespace std _GLIBCXX_VISIBILITY(default)
     66 {
     67 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
     68 
     69   /**
     70    *  @brief This function controls the size of memory nodes.
     71    *  @param  size  The size of an element.
     72    *  @return   The number (not byte size) of elements per node.
     73    *
     74    *  This function started off as a compiler kludge from SGI, but
     75    *  seems to be a useful wrapper around a repeated constant
     76    *  expression.  The @b 512 is tunable (and no other code needs to
     77    *  change), but no investigation has been done since inheriting the
     78    *  SGI code.  Touch _GLIBCXX_DEQUE_BUF_SIZE only if you know what
     79    *  you are doing, however: changing it breaks the binary
     80    *  compatibility!!
     81   */
     82 
     83 #ifndef _GLIBCXX_DEQUE_BUF_SIZE
     84 #define _GLIBCXX_DEQUE_BUF_SIZE 512
     85 #endif
     86 
     87   inline size_t
     88   __deque_buf_size(size_t __size)
     89   { return (__size < _GLIBCXX_DEQUE_BUF_SIZE
     90 	    ? size_t(_GLIBCXX_DEQUE_BUF_SIZE / __size) : size_t(1)); }
     91 
     92 
     93   /**
     94    *  @brief A deque::iterator.
     95    *
     96    *  Quite a bit of intelligence here.  Much of the functionality of
     97    *  deque is actually passed off to this class.  A deque holds two
     98    *  of these internally, marking its valid range.  Access to
     99    *  elements is done as offsets of either of those two, relying on
    100    *  operator overloading in this class.
    101    *
    102    *  All the functions are op overloads except for _M_set_node.
    103   */
    104   template<typename _Tp, typename _Ref, typename _Ptr>
    105     struct _Deque_iterator
    106     {
    107       typedef _Deque_iterator<_Tp, _Tp&, _Tp*>             iterator;
    108       typedef _Deque_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;
    109 
    110       static size_t _S_buffer_size()
    111       { return __deque_buf_size(sizeof(_Tp)); }
    112 
    113       typedef std::random_access_iterator_tag iterator_category;
    114       typedef _Tp                             value_type;
    115       typedef _Ptr                            pointer;
    116       typedef _Ref                            reference;
    117       typedef size_t                          size_type;
    118       typedef ptrdiff_t                       difference_type;
    119       typedef _Tp**                           _Map_pointer;
    120       typedef _Deque_iterator                 _Self;
    121 
    122       _Tp* _M_cur;
    123       _Tp* _M_first;
    124       _Tp* _M_last;
    125       _Map_pointer _M_node;
    126 
    127       _Deque_iterator(_Tp* __x, _Map_pointer __y)
    128       : _M_cur(__x), _M_first(*__y),
    129         _M_last(*__y + _S_buffer_size()), _M_node(__y) { }
    130 
    131       _Deque_iterator()
    132       : _M_cur(0), _M_first(0), _M_last(0), _M_node(0) { }
    133 
    134       _Deque_iterator(const iterator& __x)
    135       : _M_cur(__x._M_cur), _M_first(__x._M_first),
    136         _M_last(__x._M_last), _M_node(__x._M_node) { }
    137 
    138       reference
    139       operator*() const
    140       { return *_M_cur; }
    141 
    142       pointer
    143       operator->() const
    144       { return _M_cur; }
    145 
    146       _Self&
    147       operator++()
    148       {
    149 	++_M_cur;
    150 	if (_M_cur == _M_last)
    151 	  {
    152 	    _M_set_node(_M_node + 1);
    153 	    _M_cur = _M_first;
    154 	  }
    155 	return *this;
    156       }
    157 
    158       _Self
    159       operator++(int)
    160       {
    161 	_Self __tmp = *this;
    162 	++*this;
    163 	return __tmp;
    164       }
    165 
    166       _Self&
    167       operator--()
    168       {
    169 	if (_M_cur == _M_first)
    170 	  {
    171 	    _M_set_node(_M_node - 1);
    172 	    _M_cur = _M_last;
    173 	  }
    174 	--_M_cur;
    175 	return *this;
    176       }
    177 
    178       _Self
    179       operator--(int)
    180       {
    181 	_Self __tmp = *this;
    182 	--*this;
    183 	return __tmp;
    184       }
    185 
    186       _Self&
    187       operator+=(difference_type __n)
    188       {
    189 	const difference_type __offset = __n + (_M_cur - _M_first);
    190 	if (__offset >= 0 && __offset < difference_type(_S_buffer_size()))
    191 	  _M_cur += __n;
    192 	else
    193 	  {
    194 	    const difference_type __node_offset =
    195 	      __offset > 0 ? __offset / difference_type(_S_buffer_size())
    196 	                   : -difference_type((-__offset - 1)
    197 					      / _S_buffer_size()) - 1;
    198 	    _M_set_node(_M_node + __node_offset);
    199 	    _M_cur = _M_first + (__offset - __node_offset
    200 				 * difference_type(_S_buffer_size()));
    201 	  }
    202 	return *this;
    203       }
    204 
    205       _Self
    206       operator+(difference_type __n) const
    207       {
    208 	_Self __tmp = *this;
    209 	return __tmp += __n;
    210       }
    211 
    212       _Self&
    213       operator-=(difference_type __n)
    214       { return *this += -__n; }
    215 
    216       _Self
    217       operator-(difference_type __n) const
    218       {
    219 	_Self __tmp = *this;
    220 	return __tmp -= __n;
    221       }
    222 
    223       reference
    224       operator[](difference_type __n) const
    225       { return *(*this + __n); }
    226 
    227       /**
    228        *  Prepares to traverse new_node.  Sets everything except
    229        *  _M_cur, which should therefore be set by the caller
    230        *  immediately afterwards, based on _M_first and _M_last.
    231        */
    232       void
    233       _M_set_node(_Map_pointer __new_node)
    234       {
    235 	_M_node = __new_node;
    236 	_M_first = *__new_node;
    237 	_M_last = _M_first + difference_type(_S_buffer_size());
    238       }
    239     };
    240 
    241   // Note: we also provide overloads whose operands are of the same type in
    242   // order to avoid ambiguous overload resolution when std::rel_ops operators
    243   // are in scope (for additional details, see libstdc++/3628)
    244   template<typename _Tp, typename _Ref, typename _Ptr>
    245     inline bool
    246     operator==(const _Deque_iterator<_Tp, _Ref, _Ptr>& __x,
    247 	       const _Deque_iterator<_Tp, _Ref, _Ptr>& __y)
    248     { return __x._M_cur == __y._M_cur; }
    249 
    250   template<typename _Tp, typename _RefL, typename _PtrL,
    251 	   typename _RefR, typename _PtrR>
    252     inline bool
    253     operator==(const _Deque_iterator<_Tp, _RefL, _PtrL>& __x,
    254 	       const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
    255     { return __x._M_cur == __y._M_cur; }
    256 
    257   template<typename _Tp, typename _Ref, typename _Ptr>
    258     inline bool
    259     operator!=(const _Deque_iterator<_Tp, _Ref, _Ptr>& __x,
    260 	       const _Deque_iterator<_Tp, _Ref, _Ptr>& __y)
    261     { return !(__x == __y); }
    262 
    263   template<typename _Tp, typename _RefL, typename _PtrL,
    264 	   typename _RefR, typename _PtrR>
    265     inline bool
    266     operator!=(const _Deque_iterator<_Tp, _RefL, _PtrL>& __x,
    267 	       const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
    268     { return !(__x == __y); }
    269 
    270   template<typename _Tp, typename _Ref, typename _Ptr>
    271     inline bool
    272     operator<(const _Deque_iterator<_Tp, _Ref, _Ptr>& __x,
    273 	      const _Deque_iterator<_Tp, _Ref, _Ptr>& __y)
    274     { return (__x._M_node == __y._M_node) ? (__x._M_cur < __y._M_cur)
    275                                           : (__x._M_node < __y._M_node); }
    276 
    277   template<typename _Tp, typename _RefL, typename _PtrL,
    278 	   typename _RefR, typename _PtrR>
    279     inline bool
    280     operator<(const _Deque_iterator<_Tp, _RefL, _PtrL>& __x,
    281 	      const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
    282     { return (__x._M_node == __y._M_node) ? (__x._M_cur < __y._M_cur)
    283 	                                  : (__x._M_node < __y._M_node); }
    284 
    285   template<typename _Tp, typename _Ref, typename _Ptr>
    286     inline bool
    287     operator>(const _Deque_iterator<_Tp, _Ref, _Ptr>& __x,
    288 	      const _Deque_iterator<_Tp, _Ref, _Ptr>& __y)
    289     { return __y < __x; }
    290 
    291   template<typename _Tp, typename _RefL, typename _PtrL,
    292 	   typename _RefR, typename _PtrR>
    293     inline bool
    294     operator>(const _Deque_iterator<_Tp, _RefL, _PtrL>& __x,
    295 	      const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
    296     { return __y < __x; }
    297 
    298   template<typename _Tp, typename _Ref, typename _Ptr>
    299     inline bool
    300     operator<=(const _Deque_iterator<_Tp, _Ref, _Ptr>& __x,
    301 	       const _Deque_iterator<_Tp, _Ref, _Ptr>& __y)
    302     { return !(__y < __x); }
    303 
    304   template<typename _Tp, typename _RefL, typename _PtrL,
    305 	   typename _RefR, typename _PtrR>
    306     inline bool
    307     operator<=(const _Deque_iterator<_Tp, _RefL, _PtrL>& __x,
    308 	       const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
    309     { return !(__y < __x); }
    310 
    311   template<typename _Tp, typename _Ref, typename _Ptr>
    312     inline bool
    313     operator>=(const _Deque_iterator<_Tp, _Ref, _Ptr>& __x,
    314 	       const _Deque_iterator<_Tp, _Ref, _Ptr>& __y)
    315     { return !(__x < __y); }
    316 
    317   template<typename _Tp, typename _RefL, typename _PtrL,
    318 	   typename _RefR, typename _PtrR>
    319     inline bool
    320     operator>=(const _Deque_iterator<_Tp, _RefL, _PtrL>& __x,
    321 	       const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
    322     { return !(__x < __y); }
    323 
    324   // _GLIBCXX_RESOLVE_LIB_DEFECTS
    325   // According to the resolution of DR179 not only the various comparison
    326   // operators but also operator- must accept mixed iterator/const_iterator
    327   // parameters.
    328   template<typename _Tp, typename _Ref, typename _Ptr>
    329     inline typename _Deque_iterator<_Tp, _Ref, _Ptr>::difference_type
    330     operator-(const _Deque_iterator<_Tp, _Ref, _Ptr>& __x,
    331 	      const _Deque_iterator<_Tp, _Ref, _Ptr>& __y)
    332     {
    333       return typename _Deque_iterator<_Tp, _Ref, _Ptr>::difference_type
    334 	(_Deque_iterator<_Tp, _Ref, _Ptr>::_S_buffer_size())
    335 	* (__x._M_node - __y._M_node - 1) + (__x._M_cur - __x._M_first)
    336 	+ (__y._M_last - __y._M_cur);
    337     }
    338 
    339   template<typename _Tp, typename _RefL, typename _PtrL,
    340 	   typename _RefR, typename _PtrR>
    341     inline typename _Deque_iterator<_Tp, _RefL, _PtrL>::difference_type
    342     operator-(const _Deque_iterator<_Tp, _RefL, _PtrL>& __x,
    343 	      const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
    344     {
    345       return typename _Deque_iterator<_Tp, _RefL, _PtrL>::difference_type
    346 	(_Deque_iterator<_Tp, _RefL, _PtrL>::_S_buffer_size())
    347 	* (__x._M_node - __y._M_node - 1) + (__x._M_cur - __x._M_first)
    348 	+ (__y._M_last - __y._M_cur);
    349     }
    350 
    351   template<typename _Tp, typename _Ref, typename _Ptr>
    352     inline _Deque_iterator<_Tp, _Ref, _Ptr>
    353     operator+(ptrdiff_t __n, const _Deque_iterator<_Tp, _Ref, _Ptr>& __x)
    354     { return __x + __n; }
    355 
    356   template<typename _Tp>
    357     void
    358     fill(const _Deque_iterator<_Tp, _Tp&, _Tp*>&,
    359 	 const _Deque_iterator<_Tp, _Tp&, _Tp*>&, const _Tp&);
    360 
    361   template<typename _Tp>
    362     _Deque_iterator<_Tp, _Tp&, _Tp*>
    363     copy(_Deque_iterator<_Tp, const _Tp&, const _Tp*>,
    364 	 _Deque_iterator<_Tp, const _Tp&, const _Tp*>,
    365 	 _Deque_iterator<_Tp, _Tp&, _Tp*>);
    366 
    367   template<typename _Tp>
    368     inline _Deque_iterator<_Tp, _Tp&, _Tp*>
    369     copy(_Deque_iterator<_Tp, _Tp&, _Tp*> __first,
    370 	 _Deque_iterator<_Tp, _Tp&, _Tp*> __last,
    371 	 _Deque_iterator<_Tp, _Tp&, _Tp*> __result)
    372     { return std::copy(_Deque_iterator<_Tp, const _Tp&, const _Tp*>(__first),
    373 		       _Deque_iterator<_Tp, const _Tp&, const _Tp*>(__last),
    374 		       __result); }
    375 
    376   template<typename _Tp>
    377     _Deque_iterator<_Tp, _Tp&, _Tp*>
    378     copy_backward(_Deque_iterator<_Tp, const _Tp&, const _Tp*>,
    379 		  _Deque_iterator<_Tp, const _Tp&, const _Tp*>,
    380 		  _Deque_iterator<_Tp, _Tp&, _Tp*>);
    381 
    382   template<typename _Tp>
    383     inline _Deque_iterator<_Tp, _Tp&, _Tp*>
    384     copy_backward(_Deque_iterator<_Tp, _Tp&, _Tp*> __first,
    385 		  _Deque_iterator<_Tp, _Tp&, _Tp*> __last,
    386 		  _Deque_iterator<_Tp, _Tp&, _Tp*> __result)
    387     { return std::copy_backward(_Deque_iterator<_Tp,
    388 				const _Tp&, const _Tp*>(__first),
    389 				_Deque_iterator<_Tp,
    390 				const _Tp&, const _Tp*>(__last),
    391 				__result); }
    392 
    393 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    394   template<typename _Tp>
    395     _Deque_iterator<_Tp, _Tp&, _Tp*>
    396     move(_Deque_iterator<_Tp, const _Tp&, const _Tp*>,
    397 	 _Deque_iterator<_Tp, const _Tp&, const _Tp*>,
    398 	 _Deque_iterator<_Tp, _Tp&, _Tp*>);
    399 
    400   template<typename _Tp>
    401     inline _Deque_iterator<_Tp, _Tp&, _Tp*>
    402     move(_Deque_iterator<_Tp, _Tp&, _Tp*> __first,
    403 	 _Deque_iterator<_Tp, _Tp&, _Tp*> __last,
    404 	 _Deque_iterator<_Tp, _Tp&, _Tp*> __result)
    405     { return std::move(_Deque_iterator<_Tp, const _Tp&, const _Tp*>(__first),
    406 		       _Deque_iterator<_Tp, const _Tp&, const _Tp*>(__last),
    407 		       __result); }
    408 
    409   template<typename _Tp>
    410     _Deque_iterator<_Tp, _Tp&, _Tp*>
    411     move_backward(_Deque_iterator<_Tp, const _Tp&, const _Tp*>,
    412 		  _Deque_iterator<_Tp, const _Tp&, const _Tp*>,
    413 		  _Deque_iterator<_Tp, _Tp&, _Tp*>);
    414 
    415   template<typename _Tp>
    416     inline _Deque_iterator<_Tp, _Tp&, _Tp*>
    417     move_backward(_Deque_iterator<_Tp, _Tp&, _Tp*> __first,
    418 		  _Deque_iterator<_Tp, _Tp&, _Tp*> __last,
    419 		  _Deque_iterator<_Tp, _Tp&, _Tp*> __result)
    420     { return std::move_backward(_Deque_iterator<_Tp,
    421 				const _Tp&, const _Tp*>(__first),
    422 				_Deque_iterator<_Tp,
    423 				const _Tp&, const _Tp*>(__last),
    424 				__result); }
    425 #endif
    426 
    427   /**
    428    *  Deque base class.  This class provides the unified face for %deque's
    429    *  allocation.  This class's constructor and destructor allocate and
    430    *  deallocate (but do not initialize) storage.  This makes %exception
    431    *  safety easier.
    432    *
    433    *  Nothing in this class ever constructs or destroys an actual Tp element.
    434    *  (Deque handles that itself.)  Only/All memory management is performed
    435    *  here.
    436   */
    437   template<typename _Tp, typename _Alloc>
    438     class _Deque_base
    439     {
    440     public:
    441       typedef _Alloc                  allocator_type;
    442 
    443       allocator_type
    444       get_allocator() const
    445       { return allocator_type(_M_get_Tp_allocator()); }
    446 
    447       typedef _Deque_iterator<_Tp, _Tp&, _Tp*>             iterator;
    448       typedef _Deque_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;
    449 
    450       _Deque_base()
    451       : _M_impl()
    452       { _M_initialize_map(0); }
    453 
    454       _Deque_base(size_t __num_elements)
    455       : _M_impl()
    456       { _M_initialize_map(__num_elements); }
    457 
    458       _Deque_base(const allocator_type& __a, size_t __num_elements)
    459       : _M_impl(__a)
    460       { _M_initialize_map(__num_elements); }
    461 
    462       _Deque_base(const allocator_type& __a)
    463       : _M_impl(__a)
    464       { }
    465 
    466 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    467       _Deque_base(_Deque_base&& __x)
    468       : _M_impl(__x._M_get_Tp_allocator())
    469       {
    470 	_M_initialize_map(0);
    471 	if (__x._M_impl._M_map)
    472 	  {
    473 	    std::swap(this->_M_impl._M_start, __x._M_impl._M_start);
    474 	    std::swap(this->_M_impl._M_finish, __x._M_impl._M_finish);
    475 	    std::swap(this->_M_impl._M_map, __x._M_impl._M_map);
    476 	    std::swap(this->_M_impl._M_map_size, __x._M_impl._M_map_size);
    477 	  }
    478       }
    479 #endif
    480 
    481       ~_Deque_base();
    482 
    483     protected:
    484       //This struct encapsulates the implementation of the std::deque
    485       //standard container and at the same time makes use of the EBO
    486       //for empty allocators.
    487       typedef typename _Alloc::template rebind<_Tp*>::other _Map_alloc_type;
    488 
    489       typedef typename _Alloc::template rebind<_Tp>::other  _Tp_alloc_type;
    490 
    491       struct _Deque_impl
    492       : public _Tp_alloc_type
    493       {
    494 	_Tp** _M_map;
    495 	size_t _M_map_size;
    496 	iterator _M_start;
    497 	iterator _M_finish;
    498 
    499 	_Deque_impl()
    500 	: _Tp_alloc_type(), _M_map(0), _M_map_size(0),
    501 	  _M_start(), _M_finish()
    502 	{ }
    503 
    504 	_Deque_impl(const _Tp_alloc_type& __a)
    505 	: _Tp_alloc_type(__a), _M_map(0), _M_map_size(0),
    506 	  _M_start(), _M_finish()
    507 	{ }
    508       };
    509 
    510       _Tp_alloc_type&
    511       _M_get_Tp_allocator()
    512       { return *static_cast<_Tp_alloc_type*>(&this->_M_impl); }
    513 
    514       const _Tp_alloc_type&
    515       _M_get_Tp_allocator() const
    516       { return *static_cast<const _Tp_alloc_type*>(&this->_M_impl); }
    517 
    518       _Map_alloc_type
    519       _M_get_map_allocator() const
    520       { return _Map_alloc_type(_M_get_Tp_allocator()); }
    521 
    522       _Tp*
    523       _M_allocate_node()
    524       {
    525 	return _M_impl._Tp_alloc_type::allocate(__deque_buf_size(sizeof(_Tp)));
    526       }
    527 
    528       void
    529       _M_deallocate_node(_Tp* __p)
    530       {
    531 	_M_impl._Tp_alloc_type::deallocate(__p, __deque_buf_size(sizeof(_Tp)));
    532       }
    533 
    534       _Tp**
    535       _M_allocate_map(size_t __n)
    536       { return _M_get_map_allocator().allocate(__n); }
    537 
    538       void
    539       _M_deallocate_map(_Tp** __p, size_t __n)
    540       { _M_get_map_allocator().deallocate(__p, __n); }
    541 
    542     protected:
    543       void _M_initialize_map(size_t);
    544       void _M_create_nodes(_Tp** __nstart, _Tp** __nfinish);
    545       void _M_destroy_nodes(_Tp** __nstart, _Tp** __nfinish);
    546       enum { _S_initial_map_size = 8 };
    547 
    548       _Deque_impl _M_impl;
    549     };
    550 
    551   template<typename _Tp, typename _Alloc>
    552     _Deque_base<_Tp, _Alloc>::
    553     ~_Deque_base()
    554     {
    555       if (this->_M_impl._M_map)
    556 	{
    557 	  _M_destroy_nodes(this->_M_impl._M_start._M_node,
    558 			   this->_M_impl._M_finish._M_node + 1);
    559 	  _M_deallocate_map(this->_M_impl._M_map, this->_M_impl._M_map_size);
    560 	}
    561     }
    562 
    563   /**
    564    *  @brief Layout storage.
    565    *  @param  num_elements  The count of T's for which to allocate space
    566    *                        at first.
    567    *  @return   Nothing.
    568    *
    569    *  The initial underlying memory layout is a bit complicated...
    570   */
    571   template<typename _Tp, typename _Alloc>
    572     void
    573     _Deque_base<_Tp, _Alloc>::
    574     _M_initialize_map(size_t __num_elements)
    575     {
    576       const size_t __num_nodes = (__num_elements/ __deque_buf_size(sizeof(_Tp))
    577 				  + 1);
    578 
    579       this->_M_impl._M_map_size = std::max((size_t) _S_initial_map_size,
    580 					   size_t(__num_nodes + 2));
    581       this->_M_impl._M_map = _M_allocate_map(this->_M_impl._M_map_size);
    582 
    583       // For "small" maps (needing less than _M_map_size nodes), allocation
    584       // starts in the middle elements and grows outwards.  So nstart may be
    585       // the beginning of _M_map, but for small maps it may be as far in as
    586       // _M_map+3.
    587 
    588       _Tp** __nstart = (this->_M_impl._M_map
    589 			+ (this->_M_impl._M_map_size - __num_nodes) / 2);
    590       _Tp** __nfinish = __nstart + __num_nodes;
    591 
    592       __try
    593 	{ _M_create_nodes(__nstart, __nfinish); }
    594       __catch(...)
    595 	{
    596 	  _M_deallocate_map(this->_M_impl._M_map, this->_M_impl._M_map_size);
    597 	  this->_M_impl._M_map = 0;
    598 	  this->_M_impl._M_map_size = 0;
    599 	  __throw_exception_again;
    600 	}
    601 
    602       this->_M_impl._M_start._M_set_node(__nstart);
    603       this->_M_impl._M_finish._M_set_node(__nfinish - 1);
    604       this->_M_impl._M_start._M_cur = _M_impl._M_start._M_first;
    605       this->_M_impl._M_finish._M_cur = (this->_M_impl._M_finish._M_first
    606 					+ __num_elements
    607 					% __deque_buf_size(sizeof(_Tp)));
    608     }
    609 
    610   template<typename _Tp, typename _Alloc>
    611     void
    612     _Deque_base<_Tp, _Alloc>::
    613     _M_create_nodes(_Tp** __nstart, _Tp** __nfinish)
    614     {
    615       _Tp** __cur;
    616       __try
    617 	{
    618 	  for (__cur = __nstart; __cur < __nfinish; ++__cur)
    619 	    *__cur = this->_M_allocate_node();
    620 	}
    621       __catch(...)
    622 	{
    623 	  _M_destroy_nodes(__nstart, __cur);
    624 	  __throw_exception_again;
    625 	}
    626     }
    627 
    628   template<typename _Tp, typename _Alloc>
    629     void
    630     _Deque_base<_Tp, _Alloc>::
    631     _M_destroy_nodes(_Tp** __nstart, _Tp** __nfinish)
    632     {
    633       for (_Tp** __n = __nstart; __n < __nfinish; ++__n)
    634 	_M_deallocate_node(*__n);
    635     }
    636 
    637   /**
    638    *  @brief  A standard container using fixed-size memory allocation and
    639    *  constant-time manipulation of elements at either end.
    640    *
    641    *  @ingroup sequences
    642    *
    643    *  Meets the requirements of a <a href="tables.html#65">container</a>, a
    644    *  <a href="tables.html#66">reversible container</a>, and a
    645    *  <a href="tables.html#67">sequence</a>, including the
    646    *  <a href="tables.html#68">optional sequence requirements</a>.
    647    *
    648    *  In previous HP/SGI versions of deque, there was an extra template
    649    *  parameter so users could control the node size.  This extension turned
    650    *  out to violate the C++ standard (it can be detected using template
    651    *  template parameters), and it was removed.
    652    *
    653    *  Here's how a deque<Tp> manages memory.  Each deque has 4 members:
    654    *
    655    *  - Tp**        _M_map
    656    *  - size_t      _M_map_size
    657    *  - iterator    _M_start, _M_finish
    658    *
    659    *  map_size is at least 8.  %map is an array of map_size
    660    *  pointers-to-@anodes.  (The name %map has nothing to do with the
    661    *  std::map class, and @b nodes should not be confused with
    662    *  std::list's usage of @a node.)
    663    *
    664    *  A @a node has no specific type name as such, but it is referred
    665    *  to as @a node in this file.  It is a simple array-of-Tp.  If Tp
    666    *  is very large, there will be one Tp element per node (i.e., an
    667    *  @a array of one).  For non-huge Tp's, node size is inversely
    668    *  related to Tp size: the larger the Tp, the fewer Tp's will fit
    669    *  in a node.  The goal here is to keep the total size of a node
    670    *  relatively small and constant over different Tp's, to improve
    671    *  allocator efficiency.
    672    *
    673    *  Not every pointer in the %map array will point to a node.  If
    674    *  the initial number of elements in the deque is small, the
    675    *  /middle/ %map pointers will be valid, and the ones at the edges
    676    *  will be unused.  This same situation will arise as the %map
    677    *  grows: available %map pointers, if any, will be on the ends.  As
    678    *  new nodes are created, only a subset of the %map's pointers need
    679    *  to be copied @a outward.
    680    *
    681    *  Class invariants:
    682    * - For any nonsingular iterator i:
    683    *    - i.node points to a member of the %map array.  (Yes, you read that
    684    *      correctly:  i.node does not actually point to a node.)  The member of
    685    *      the %map array is what actually points to the node.
    686    *    - i.first == *(i.node)    (This points to the node (first Tp element).)
    687    *    - i.last  == i.first + node_size
    688    *    - i.cur is a pointer in the range [i.first, i.last).  NOTE:
    689    *      the implication of this is that i.cur is always a dereferenceable
    690    *      pointer, even if i is a past-the-end iterator.
    691    * - Start and Finish are always nonsingular iterators.  NOTE: this
    692    * means that an empty deque must have one node, a deque with <N
    693    * elements (where N is the node buffer size) must have one node, a
    694    * deque with N through (2N-1) elements must have two nodes, etc.
    695    * - For every node other than start.node and finish.node, every
    696    * element in the node is an initialized object.  If start.node ==
    697    * finish.node, then [start.cur, finish.cur) are initialized
    698    * objects, and the elements outside that range are uninitialized
    699    * storage.  Otherwise, [start.cur, start.last) and [finish.first,
    700    * finish.cur) are initialized objects, and [start.first, start.cur)
    701    * and [finish.cur, finish.last) are uninitialized storage.
    702    * - [%map, %map + map_size) is a valid, non-empty range.
    703    * - [start.node, finish.node] is a valid range contained within
    704    *   [%map, %map + map_size).
    705    * - A pointer in the range [%map, %map + map_size) points to an allocated
    706    *   node if and only if the pointer is in the range
    707    *   [start.node, finish.node].
    708    *
    709    *  Here's the magic:  nothing in deque is @b aware of the discontiguous
    710    *  storage!
    711    *
    712    *  The memory setup and layout occurs in the parent, _Base, and the iterator
    713    *  class is entirely responsible for @a leaping from one node to the next.
    714    *  All the implementation routines for deque itself work only through the
    715    *  start and finish iterators.  This keeps the routines simple and sane,
    716    *  and we can use other standard algorithms as well.
    717   */
    718   template<typename _Tp, typename _Alloc = std::allocator<_Tp> >
    719     class deque : protected _Deque_base<_Tp, _Alloc>
    720     {
    721       // concept requirements
    722       typedef typename _Alloc::value_type        _Alloc_value_type;
    723       __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
    724       __glibcxx_class_requires2(_Tp, _Alloc_value_type, _SameTypeConcept)
    725 
    726       typedef _Deque_base<_Tp, _Alloc>           _Base;
    727       typedef typename _Base::_Tp_alloc_type	 _Tp_alloc_type;
    728 
    729     public:
    730       typedef _Tp                                        value_type;
    731       typedef typename _Tp_alloc_type::pointer           pointer;
    732       typedef typename _Tp_alloc_type::const_pointer     const_pointer;
    733       typedef typename _Tp_alloc_type::reference         reference;
    734       typedef typename _Tp_alloc_type::const_reference   const_reference;
    735       typedef typename _Base::iterator                   iterator;
    736       typedef typename _Base::const_iterator             const_iterator;
    737       typedef std::reverse_iterator<const_iterator>      const_reverse_iterator;
    738       typedef std::reverse_iterator<iterator>            reverse_iterator;
    739       typedef size_t                             size_type;
    740       typedef ptrdiff_t                          difference_type;
    741       typedef _Alloc                             allocator_type;
    742 
    743     protected:
    744       typedef pointer*                           _Map_pointer;
    745 
    746       static size_t _S_buffer_size()
    747       { return __deque_buf_size(sizeof(_Tp)); }
    748 
    749       // Functions controlling memory layout, and nothing else.
    750       using _Base::_M_initialize_map;
    751       using _Base::_M_create_nodes;
    752       using _Base::_M_destroy_nodes;
    753       using _Base::_M_allocate_node;
    754       using _Base::_M_deallocate_node;
    755       using _Base::_M_allocate_map;
    756       using _Base::_M_deallocate_map;
    757       using _Base::_M_get_Tp_allocator;
    758 
    759       /**
    760        *  A total of four data members accumulated down the hierarchy.
    761        *  May be accessed via _M_impl.*
    762        */
    763       using _Base::_M_impl;
    764 
    765     public:
    766       // [23.2.1.1] construct/copy/destroy
    767       // (assign() and get_allocator() are also listed in this section)
    768       /**
    769        *  @brief  Default constructor creates no elements.
    770        */
    771       deque()
    772       : _Base() { }
    773 
    774       /**
    775        *  @brief  Creates a %deque with no elements.
    776        *  @param  a  An allocator object.
    777        */
    778       explicit
    779       deque(const allocator_type& __a)
    780       : _Base(__a, 0) { }
    781 
    782 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    783       /**
    784        *  @brief  Creates a %deque with default constructed elements.
    785        *  @param  n  The number of elements to initially create.
    786        *
    787        *  This constructor fills the %deque with @a n default
    788        *  constructed elements.
    789        */
    790       explicit
    791       deque(size_type __n)
    792       : _Base(__n)
    793       { _M_default_initialize(); }
    794 
    795       /**
    796        *  @brief  Creates a %deque with copies of an exemplar element.
    797        *  @param  n  The number of elements to initially create.
    798        *  @param  value  An element to copy.
    799        *  @param  a  An allocator.
    800        *
    801        *  This constructor fills the %deque with @a n copies of @a value.
    802        */
    803       deque(size_type __n, const value_type& __value,
    804 	    const allocator_type& __a = allocator_type())
    805       : _Base(__a, __n)
    806       { _M_fill_initialize(__value); }
    807 #else
    808       /**
    809        *  @brief  Creates a %deque with copies of an exemplar element.
    810        *  @param  n  The number of elements to initially create.
    811        *  @param  value  An element to copy.
    812        *  @param  a  An allocator.
    813        *
    814        *  This constructor fills the %deque with @a n copies of @a value.
    815        */
    816       explicit
    817       deque(size_type __n, const value_type& __value = value_type(),
    818 	    const allocator_type& __a = allocator_type())
    819       : _Base(__a, __n)
    820       { _M_fill_initialize(__value); }
    821 #endif
    822 
    823       /**
    824        *  @brief  %Deque copy constructor.
    825        *  @param  x  A %deque of identical element and allocator types.
    826        *
    827        *  The newly-created %deque uses a copy of the allocation object used
    828        *  by @a x.
    829        */
    830       deque(const deque& __x)
    831       : _Base(__x._M_get_Tp_allocator(), __x.size())
    832       { std::__uninitialized_copy_a(__x.begin(), __x.end(),
    833 				    this->_M_impl._M_start,
    834 				    _M_get_Tp_allocator()); }
    835 
    836 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    837       /**
    838        *  @brief  %Deque move constructor.
    839        *  @param  x  A %deque of identical element and allocator types.
    840        *
    841        *  The newly-created %deque contains the exact contents of @a x.
    842        *  The contents of @a x are a valid, but unspecified %deque.
    843        */
    844       deque(deque&& __x)
    845       : _Base(std::move(__x)) { }
    846 
    847       /**
    848        *  @brief  Builds a %deque from an initializer list.
    849        *  @param  l  An initializer_list.
    850        *  @param  a  An allocator object.
    851        *
    852        *  Create a %deque consisting of copies of the elements in the
    853        *  initializer_list @a l.
    854        *
    855        *  This will call the element type's copy constructor N times
    856        *  (where N is l.size()) and do no memory reallocation.
    857        */
    858       deque(initializer_list<value_type> __l,
    859 	    const allocator_type& __a = allocator_type())
    860       : _Base(__a)
    861       {
    862 	_M_range_initialize(__l.begin(), __l.end(),
    863 			    random_access_iterator_tag());
    864       }
    865 #endif
    866 
    867       /**
    868        *  @brief  Builds a %deque from a range.
    869        *  @param  first  An input iterator.
    870        *  @param  last  An input iterator.
    871        *  @param  a  An allocator object.
    872        *
    873        *  Create a %deque consisting of copies of the elements from [first,
    874        *  last).
    875        *
    876        *  If the iterators are forward, bidirectional, or random-access, then
    877        *  this will call the elements' copy constructor N times (where N is
    878        *  distance(first,last)) and do no memory reallocation.  But if only
    879        *  input iterators are used, then this will do at most 2N calls to the
    880        *  copy constructor, and logN memory reallocations.
    881        */
    882       template<typename _InputIterator>
    883         deque(_InputIterator __first, _InputIterator __last,
    884 	      const allocator_type& __a = allocator_type())
    885 	: _Base(__a)
    886         {
    887 	  // Check whether it's an integral type.  If so, it's not an iterator.
    888 	  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
    889 	  _M_initialize_dispatch(__first, __last, _Integral());
    890 	}
    891 
    892       /**
    893        *  The dtor only erases the elements, and note that if the elements
    894        *  themselves are pointers, the pointed-to memory is not touched in any
    895        *  way.  Managing the pointer is the user's responsibility.
    896        */
    897       ~deque()
    898       { _M_destroy_data(begin(), end(), _M_get_Tp_allocator()); }
    899 
    900       /**
    901        *  @brief  %Deque assignment operator.
    902        *  @param  x  A %deque of identical element and allocator types.
    903        *
    904        *  All the elements of @a x are copied, but unlike the copy constructor,
    905        *  the allocator object is not copied.
    906        */
    907       deque&
    908       operator=(const deque& __x);
    909 
    910 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    911       /**
    912        *  @brief  %Deque move assignment operator.
    913        *  @param  x  A %deque of identical element and allocator types.
    914        *
    915        *  The contents of @a x are moved into this deque (without copying).
    916        *  @a x is a valid, but unspecified %deque.
    917        */
    918       deque&
    919       operator=(deque&& __x)
    920       {
    921 	// NB: DR 1204.
    922 	// NB: DR 675.
    923 	this->clear();
    924 	this->swap(__x);
    925 	return *this;
    926       }
    927 
    928       /**
    929        *  @brief  Assigns an initializer list to a %deque.
    930        *  @param  l  An initializer_list.
    931        *
    932        *  This function fills a %deque with copies of the elements in the
    933        *  initializer_list @a l.
    934        *
    935        *  Note that the assignment completely changes the %deque and that the
    936        *  resulting %deque's size is the same as the number of elements
    937        *  assigned.  Old data may be lost.
    938        */
    939       deque&
    940       operator=(initializer_list<value_type> __l)
    941       {
    942 	this->assign(__l.begin(), __l.end());
    943 	return *this;
    944       }
    945 #endif
    946 
    947       /**
    948        *  @brief  Assigns a given value to a %deque.
    949        *  @param  n  Number of elements to be assigned.
    950        *  @param  val  Value to be assigned.
    951        *
    952        *  This function fills a %deque with @a n copies of the given
    953        *  value.  Note that the assignment completely changes the
    954        *  %deque and that the resulting %deque's size is the same as
    955        *  the number of elements assigned.  Old data may be lost.
    956        */
    957       void
    958       assign(size_type __n, const value_type& __val)
    959       { _M_fill_assign(__n, __val); }
    960 
    961       /**
    962        *  @brief  Assigns a range to a %deque.
    963        *  @param  first  An input iterator.
    964        *  @param  last   An input iterator.
    965        *
    966        *  This function fills a %deque with copies of the elements in the
    967        *  range [first,last).
    968        *
    969        *  Note that the assignment completely changes the %deque and that the
    970        *  resulting %deque's size is the same as the number of elements
    971        *  assigned.  Old data may be lost.
    972        */
    973       template<typename _InputIterator>
    974         void
    975         assign(_InputIterator __first, _InputIterator __last)
    976         {
    977 	  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
    978 	  _M_assign_dispatch(__first, __last, _Integral());
    979 	}
    980 
    981 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    982       /**
    983        *  @brief  Assigns an initializer list to a %deque.
    984        *  @param  l  An initializer_list.
    985        *
    986        *  This function fills a %deque with copies of the elements in the
    987        *  initializer_list @a l.
    988        *
    989        *  Note that the assignment completely changes the %deque and that the
    990        *  resulting %deque's size is the same as the number of elements
    991        *  assigned.  Old data may be lost.
    992        */
    993       void
    994       assign(initializer_list<value_type> __l)
    995       { this->assign(__l.begin(), __l.end()); }
    996 #endif
    997 
    998       /// Get a copy of the memory allocation object.
    999       allocator_type
   1000       get_allocator() const
   1001       { return _Base::get_allocator(); }
   1002 
   1003       // iterators
   1004       /**
   1005        *  Returns a read/write iterator that points to the first element in the
   1006        *  %deque.  Iteration is done in ordinary element order.
   1007        */
   1008       iterator
   1009       begin()
   1010       { return this->_M_impl._M_start; }
   1011 
   1012       /**
   1013        *  Returns a read-only (constant) iterator that points to the first
   1014        *  element in the %deque.  Iteration is done in ordinary element order.
   1015        */
   1016       const_iterator
   1017       begin() const
   1018       { return this->_M_impl._M_start; }
   1019 
   1020       /**
   1021        *  Returns a read/write iterator that points one past the last
   1022        *  element in the %deque.  Iteration is done in ordinary
   1023        *  element order.
   1024        */
   1025       iterator
   1026       end()
   1027       { return this->_M_impl._M_finish; }
   1028 
   1029       /**
   1030        *  Returns a read-only (constant) iterator that points one past
   1031        *  the last element in the %deque.  Iteration is done in
   1032        *  ordinary element order.
   1033        */
   1034       const_iterator
   1035       end() const
   1036       { return this->_M_impl._M_finish; }
   1037 
   1038       /**
   1039        *  Returns a read/write reverse iterator that points to the
   1040        *  last element in the %deque.  Iteration is done in reverse
   1041        *  element order.
   1042        */
   1043       reverse_iterator
   1044       rbegin()
   1045       { return reverse_iterator(this->_M_impl._M_finish); }
   1046 
   1047       /**
   1048        *  Returns a read-only (constant) reverse iterator that points
   1049        *  to the last element in the %deque.  Iteration is done in
   1050        *  reverse element order.
   1051        */
   1052       const_reverse_iterator
   1053       rbegin() const
   1054       { return const_reverse_iterator(this->_M_impl._M_finish); }
   1055 
   1056       /**
   1057        *  Returns a read/write reverse iterator that points to one
   1058        *  before the first element in the %deque.  Iteration is done
   1059        *  in reverse element order.
   1060        */
   1061       reverse_iterator
   1062       rend()
   1063       { return reverse_iterator(this->_M_impl._M_start); }
   1064 
   1065       /**
   1066        *  Returns a read-only (constant) reverse iterator that points
   1067        *  to one before the first element in the %deque.  Iteration is
   1068        *  done in reverse element order.
   1069        */
   1070       const_reverse_iterator
   1071       rend() const
   1072       { return const_reverse_iterator(this->_M_impl._M_start); }
   1073 
   1074 #ifdef __GXX_EXPERIMENTAL_CXX0X__
   1075       /**
   1076        *  Returns a read-only (constant) iterator that points to the first
   1077        *  element in the %deque.  Iteration is done in ordinary element order.
   1078        */
   1079       const_iterator
   1080       cbegin() const
   1081       { return this->_M_impl._M_start; }
   1082 
   1083       /**
   1084        *  Returns a read-only (constant) iterator that points one past
   1085        *  the last element in the %deque.  Iteration is done in
   1086        *  ordinary element order.
   1087        */
   1088       const_iterator
   1089       cend() const
   1090       { return this->_M_impl._M_finish; }
   1091 
   1092       /**
   1093        *  Returns a read-only (constant) reverse iterator that points
   1094        *  to the last element in the %deque.  Iteration is done in
   1095        *  reverse element order.
   1096        */
   1097       const_reverse_iterator
   1098       crbegin() const
   1099       { return const_reverse_iterator(this->_M_impl._M_finish); }
   1100 
   1101       /**
   1102        *  Returns a read-only (constant) reverse iterator that points
   1103        *  to one before the first element in the %deque.  Iteration is
   1104        *  done in reverse element order.
   1105        */
   1106       const_reverse_iterator
   1107       crend() const
   1108       { return const_reverse_iterator(this->_M_impl._M_start); }
   1109 #endif
   1110 
   1111       // [23.2.1.2] capacity
   1112       /**  Returns the number of elements in the %deque.  */
   1113       size_type
   1114       size() const
   1115       { return this->_M_impl._M_finish - this->_M_impl._M_start; }
   1116 
   1117       /**  Returns the size() of the largest possible %deque.  */
   1118       size_type
   1119       max_size() const
   1120       { return _M_get_Tp_allocator().max_size(); }
   1121 
   1122 #ifdef __GXX_EXPERIMENTAL_CXX0X__
   1123       /**
   1124        *  @brief  Resizes the %deque to the specified number of elements.
   1125        *  @param  new_size  Number of elements the %deque should contain.
   1126        *
   1127        *  This function will %resize the %deque to the specified
   1128        *  number of elements.  If the number is smaller than the
   1129        *  %deque's current size the %deque is truncated, otherwise
   1130        *  default constructed elements are appended.
   1131        */
   1132       void
   1133       resize(size_type __new_size)
   1134       {
   1135 	const size_type __len = size();
   1136 	if (__new_size > __len)
   1137 	  _M_default_append(__new_size - __len);
   1138 	else if (__new_size < __len)
   1139 	  _M_erase_at_end(this->_M_impl._M_start
   1140 			  + difference_type(__new_size));
   1141       }
   1142 
   1143       /**
   1144        *  @brief  Resizes the %deque to the specified number of elements.
   1145        *  @param  new_size  Number of elements the %deque should contain.
   1146        *  @param  x  Data with which new elements should be populated.
   1147        *
   1148        *  This function will %resize the %deque to the specified
   1149        *  number of elements.  If the number is smaller than the
   1150        *  %deque's current size the %deque is truncated, otherwise the
   1151        *  %deque is extended and new elements are populated with given
   1152        *  data.
   1153        */
   1154       void
   1155       resize(size_type __new_size, const value_type& __x)
   1156       {
   1157 	const size_type __len = size();
   1158 	if (__new_size > __len)
   1159 	  insert(this->_M_impl._M_finish, __new_size - __len, __x);
   1160 	else if (__new_size < __len)
   1161 	  _M_erase_at_end(this->_M_impl._M_start
   1162 			  + difference_type(__new_size));
   1163       }
   1164 #else
   1165       /**
   1166        *  @brief  Resizes the %deque to the specified number of elements.
   1167        *  @param  new_size  Number of elements the %deque should contain.
   1168        *  @param  x  Data with which new elements should be populated.
   1169        *
   1170        *  This function will %resize the %deque to the specified
   1171        *  number of elements.  If the number is smaller than the
   1172        *  %deque's current size the %deque is truncated, otherwise the
   1173        *  %deque is extended and new elements are populated with given
   1174        *  data.
   1175        */
   1176       void
   1177       resize(size_type __new_size, value_type __x = value_type())
   1178       {
   1179 	const size_type __len = size();
   1180 	if (__new_size > __len)
   1181 	  insert(this->_M_impl._M_finish, __new_size - __len, __x);
   1182 	else if (__new_size < __len)
   1183 	  _M_erase_at_end(this->_M_impl._M_start
   1184 			  + difference_type(__new_size));
   1185       }
   1186 #endif
   1187 
   1188 #ifdef __GXX_EXPERIMENTAL_CXX0X__
   1189       /**  A non-binding request to reduce memory use.  */
   1190       void
   1191       shrink_to_fit()
   1192       { std::__shrink_to_fit<deque>::_S_do_it(*this); }
   1193 #endif
   1194 
   1195       /**
   1196        *  Returns true if the %deque is empty.  (Thus begin() would
   1197        *  equal end().)
   1198        */
   1199       bool
   1200       empty() const
   1201       { return this->_M_impl._M_finish == this->_M_impl._M_start; }
   1202 
   1203       // element access
   1204       /**
   1205        *  @brief Subscript access to the data contained in the %deque.
   1206        *  @param n The index of the element for which data should be
   1207        *  accessed.
   1208        *  @return  Read/write reference to data.
   1209        *
   1210        *  This operator allows for easy, array-style, data access.
   1211        *  Note that data access with this operator is unchecked and
   1212        *  out_of_range lookups are not defined. (For checked lookups
   1213        *  see at().)
   1214        */
   1215       reference
   1216       operator[](size_type __n)
   1217       { return this->_M_impl._M_start[difference_type(__n)]; }
   1218 
   1219       /**
   1220        *  @brief Subscript access to the data contained in the %deque.
   1221        *  @param n The index of the element for which data should be
   1222        *  accessed.
   1223        *  @return  Read-only (constant) reference to data.
   1224        *
   1225        *  This operator allows for easy, array-style, data access.
   1226        *  Note that data access with this operator is unchecked and
   1227        *  out_of_range lookups are not defined. (For checked lookups
   1228        *  see at().)
   1229        */
   1230       const_reference
   1231       operator[](size_type __n) const
   1232       { return this->_M_impl._M_start[difference_type(__n)]; }
   1233 
   1234     protected:
   1235       /// Safety check used only from at().
   1236       void
   1237       _M_range_check(size_type __n) const
   1238       {
   1239 	if (__n >= this->size())
   1240 	  __throw_out_of_range(__N("deque::_M_range_check"));
   1241       }
   1242 
   1243     public:
   1244       /**
   1245        *  @brief  Provides access to the data contained in the %deque.
   1246        *  @param n The index of the element for which data should be
   1247        *  accessed.
   1248        *  @return  Read/write reference to data.
   1249        *  @throw  std::out_of_range  If @a n is an invalid index.
   1250        *
   1251        *  This function provides for safer data access.  The parameter
   1252        *  is first checked that it is in the range of the deque.  The
   1253        *  function throws out_of_range if the check fails.
   1254        */
   1255       reference
   1256       at(size_type __n)
   1257       {
   1258 	_M_range_check(__n);
   1259 	return (*this)[__n];
   1260       }
   1261 
   1262       /**
   1263        *  @brief  Provides access to the data contained in the %deque.
   1264        *  @param n The index of the element for which data should be
   1265        *  accessed.
   1266        *  @return  Read-only (constant) reference to data.
   1267        *  @throw  std::out_of_range  If @a n is an invalid index.
   1268        *
   1269        *  This function provides for safer data access.  The parameter is first
   1270        *  checked that it is in the range of the deque.  The function throws
   1271        *  out_of_range if the check fails.
   1272        */
   1273       const_reference
   1274       at(size_type __n) const
   1275       {
   1276 	_M_range_check(__n);
   1277 	return (*this)[__n];
   1278       }
   1279 
   1280       /**
   1281        *  Returns a read/write reference to the data at the first
   1282        *  element of the %deque.
   1283        */
   1284       reference
   1285       front()
   1286       { return *begin(); }
   1287 
   1288       /**
   1289        *  Returns a read-only (constant) reference to the data at the first
   1290        *  element of the %deque.
   1291        */
   1292       const_reference
   1293       front() const
   1294       { return *begin(); }
   1295 
   1296       /**
   1297        *  Returns a read/write reference to the data at the last element of the
   1298        *  %deque.
   1299        */
   1300       reference
   1301       back()
   1302       {
   1303 	iterator __tmp = end();
   1304 	--__tmp;
   1305 	return *__tmp;
   1306       }
   1307 
   1308       /**
   1309        *  Returns a read-only (constant) reference to the data at the last
   1310        *  element of the %deque.
   1311        */
   1312       const_reference
   1313       back() const
   1314       {
   1315 	const_iterator __tmp = end();
   1316 	--__tmp;
   1317 	return *__tmp;
   1318       }
   1319 
   1320       // [23.2.1.2] modifiers
   1321       /**
   1322        *  @brief  Add data to the front of the %deque.
   1323        *  @param  x  Data to be added.
   1324        *
   1325        *  This is a typical stack operation.  The function creates an
   1326        *  element at the front of the %deque and assigns the given
   1327        *  data to it.  Due to the nature of a %deque this operation
   1328        *  can be done in constant time.
   1329        */
   1330       void
   1331       push_front(const value_type& __x)
   1332       {
   1333 	if (this->_M_impl._M_start._M_cur != this->_M_impl._M_start._M_first)
   1334 	  {
   1335 	    this->_M_impl.construct(this->_M_impl._M_start._M_cur - 1, __x);
   1336 	    --this->_M_impl._M_start._M_cur;
   1337 	  }
   1338 	else
   1339 	  _M_push_front_aux(__x);
   1340       }
   1341 
   1342 #ifdef __GXX_EXPERIMENTAL_CXX0X__
   1343       void
   1344       push_front(value_type&& __x)
   1345       { emplace_front(std::move(__x)); }
   1346 
   1347       template<typename... _Args>
   1348         void
   1349         emplace_front(_Args&&... __args);
   1350 #endif
   1351 
   1352       /**
   1353        *  @brief  Add data to the end of the %deque.
   1354        *  @param  x  Data to be added.
   1355        *
   1356        *  This is a typical stack operation.  The function creates an
   1357        *  element at the end of the %deque and assigns the given data
   1358        *  to it.  Due to the nature of a %deque this operation can be
   1359        *  done in constant time.
   1360        */
   1361       void
   1362       push_back(const value_type& __x)
   1363       {
   1364 	if (this->_M_impl._M_finish._M_cur
   1365 	    != this->_M_impl._M_finish._M_last - 1)
   1366 	  {
   1367 	    this->_M_impl.construct(this->_M_impl._M_finish._M_cur, __x);
   1368 	    ++this->_M_impl._M_finish._M_cur;
   1369 	  }
   1370 	else
   1371 	  _M_push_back_aux(__x);
   1372       }
   1373 
   1374 #ifdef __GXX_EXPERIMENTAL_CXX0X__
   1375       void
   1376       push_back(value_type&& __x)
   1377       { emplace_back(std::move(__x)); }
   1378 
   1379       template<typename... _Args>
   1380         void
   1381         emplace_back(_Args&&... __args);
   1382 #endif
   1383 
   1384       /**
   1385        *  @brief  Removes first element.
   1386        *
   1387        *  This is a typical stack operation.  It shrinks the %deque by one.
   1388        *
   1389        *  Note that no data is returned, and if the first element's data is
   1390        *  needed, it should be retrieved before pop_front() is called.
   1391        */
   1392       void
   1393       pop_front()
   1394       {
   1395 	if (this->_M_impl._M_start._M_cur
   1396 	    != this->_M_impl._M_start._M_last - 1)
   1397 	  {
   1398 	    this->_M_impl.destroy(this->_M_impl._M_start._M_cur);
   1399 	    ++this->_M_impl._M_start._M_cur;
   1400 	  }
   1401 	else
   1402 	  _M_pop_front_aux();
   1403       }
   1404 
   1405       /**
   1406        *  @brief  Removes last element.
   1407        *
   1408        *  This is a typical stack operation.  It shrinks the %deque by one.
   1409        *
   1410        *  Note that no data is returned, and if the last element's data is
   1411        *  needed, it should be retrieved before pop_back() is called.
   1412        */
   1413       void
   1414       pop_back()
   1415       {
   1416 	if (this->_M_impl._M_finish._M_cur
   1417 	    != this->_M_impl._M_finish._M_first)
   1418 	  {
   1419 	    --this->_M_impl._M_finish._M_cur;
   1420 	    this->_M_impl.destroy(this->_M_impl._M_finish._M_cur);
   1421 	  }
   1422 	else
   1423 	  _M_pop_back_aux();
   1424       }
   1425 
   1426 #ifdef __GXX_EXPERIMENTAL_CXX0X__
   1427       /**
   1428        *  @brief  Inserts an object in %deque before specified iterator.
   1429        *  @param  position  An iterator into the %deque.
   1430        *  @param  args  Arguments.
   1431        *  @return  An iterator that points to the inserted data.
   1432        *
   1433        *  This function will insert an object of type T constructed
   1434        *  with T(std::forward<Args>(args)...) before the specified location.
   1435        */
   1436       template<typename... _Args>
   1437         iterator
   1438         emplace(iterator __position, _Args&&... __args);
   1439 #endif
   1440 
   1441       /**
   1442        *  @brief  Inserts given value into %deque before specified iterator.
   1443        *  @param  position  An iterator into the %deque.
   1444        *  @param  x  Data to be inserted.
   1445        *  @return  An iterator that points to the inserted data.
   1446        *
   1447        *  This function will insert a copy of the given value before the
   1448        *  specified location.
   1449        */
   1450       iterator
   1451       insert(iterator __position, const value_type& __x);
   1452 
   1453 #ifdef __GXX_EXPERIMENTAL_CXX0X__
   1454       /**
   1455        *  @brief  Inserts given rvalue into %deque before specified iterator.
   1456        *  @param  position  An iterator into the %deque.
   1457        *  @param  x  Data to be inserted.
   1458        *  @return  An iterator that points to the inserted data.
   1459        *
   1460        *  This function will insert a copy of the given rvalue before the
   1461        *  specified location.
   1462        */
   1463       iterator
   1464       insert(iterator __position, value_type&& __x)
   1465       { return emplace(__position, std::move(__x)); }
   1466 
   1467       /**
   1468        *  @brief  Inserts an initializer list into the %deque.
   1469        *  @param  p  An iterator into the %deque.
   1470        *  @param  l  An initializer_list.
   1471        *
   1472        *  This function will insert copies of the data in the
   1473        *  initializer_list @a l into the %deque before the location
   1474        *  specified by @a p.  This is known as <em>list insert</em>.
   1475        */
   1476       void
   1477       insert(iterator __p, initializer_list<value_type> __l)
   1478       { this->insert(__p, __l.begin(), __l.end()); }
   1479 #endif
   1480 
   1481       /**
   1482        *  @brief  Inserts a number of copies of given data into the %deque.
   1483        *  @param  position  An iterator into the %deque.
   1484        *  @param  n  Number of elements to be inserted.
   1485        *  @param  x  Data to be inserted.
   1486        *
   1487        *  This function will insert a specified number of copies of the given
   1488        *  data before the location specified by @a position.
   1489        */
   1490       void
   1491       insert(iterator __position, size_type __n, const value_type& __x)
   1492       { _M_fill_insert(__position, __n, __x); }
   1493 
   1494       /**
   1495        *  @brief  Inserts a range into the %deque.
   1496        *  @param  position  An iterator into the %deque.
   1497        *  @param  first  An input iterator.
   1498        *  @param  last   An input iterator.
   1499        *
   1500        *  This function will insert copies of the data in the range
   1501        *  [first,last) into the %deque before the location specified
   1502        *  by @a pos.  This is known as <em>range insert</em>.
   1503        */
   1504       template<typename _InputIterator>
   1505         void
   1506         insert(iterator __position, _InputIterator __first,
   1507 	       _InputIterator __last)
   1508         {
   1509 	  // Check whether it's an integral type.  If so, it's not an iterator.
   1510 	  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
   1511 	  _M_insert_dispatch(__position, __first, __last, _Integral());
   1512 	}
   1513 
   1514       /**
   1515        *  @brief  Remove element at given position.
   1516        *  @param  position  Iterator pointing to element to be erased.
   1517        *  @return  An iterator pointing to the next element (or end()).
   1518        *
   1519        *  This function will erase the element at the given position and thus
   1520        *  shorten the %deque by one.
   1521        *
   1522        *  The user is cautioned that
   1523        *  this function only erases the element, and that if the element is
   1524        *  itself a pointer, the pointed-to memory is not touched in any way.
   1525        *  Managing the pointer is the user's responsibility.
   1526        */
   1527       iterator
   1528       erase(iterator __position);
   1529 
   1530       /**
   1531        *  @brief  Remove a range of elements.
   1532        *  @param  first  Iterator pointing to the first element to be erased.
   1533        *  @param  last  Iterator pointing to one past the last element to be
   1534        *                erased.
   1535        *  @return  An iterator pointing to the element pointed to by @a last
   1536        *           prior to erasing (or end()).
   1537        *
   1538        *  This function will erase the elements in the range [first,last) and
   1539        *  shorten the %deque accordingly.
   1540        *
   1541        *  The user is cautioned that
   1542        *  this function only erases the elements, and that if the elements
   1543        *  themselves are pointers, the pointed-to memory is not touched in any
   1544        *  way.  Managing the pointer is the user's responsibility.
   1545        */
   1546       iterator
   1547       erase(iterator __first, iterator __last);
   1548 
   1549       /**
   1550        *  @brief  Swaps data with another %deque.
   1551        *  @param  x  A %deque of the same element and allocator types.
   1552        *
   1553        *  This exchanges the elements between two deques in constant time.
   1554        *  (Four pointers, so it should be quite fast.)
   1555        *  Note that the global std::swap() function is specialized such that
   1556        *  std::swap(d1,d2) will feed to this function.
   1557        */
   1558       void
   1559       swap(deque& __x)
   1560       {
   1561 	std::swap(this->_M_impl._M_start, __x._M_impl._M_start);
   1562 	std::swap(this->_M_impl._M_finish, __x._M_impl._M_finish);
   1563 	std::swap(this->_M_impl._M_map, __x._M_impl._M_map);
   1564 	std::swap(this->_M_impl._M_map_size, __x._M_impl._M_map_size);
   1565 
   1566 	// _GLIBCXX_RESOLVE_LIB_DEFECTS
   1567 	// 431. Swapping containers with unequal allocators.
   1568 	std::__alloc_swap<_Tp_alloc_type>::_S_do_it(_M_get_Tp_allocator(),
   1569 						    __x._M_get_Tp_allocator());
   1570       }
   1571 
   1572       /**
   1573        *  Erases all the elements.  Note that this function only erases the
   1574        *  elements, and that if the elements themselves are pointers, the
   1575        *  pointed-to memory is not touched in any way.  Managing the pointer is
   1576        *  the user's responsibility.
   1577        */
   1578       void
   1579       clear()
   1580       { _M_erase_at_end(begin()); }
   1581 
   1582     protected:
   1583       // Internal constructor functions follow.
   1584 
   1585       // called by the range constructor to implement [23.1.1]/9
   1586 
   1587       // _GLIBCXX_RESOLVE_LIB_DEFECTS
   1588       // 438. Ambiguity in the "do the right thing" clause
   1589       template<typename _Integer>
   1590         void
   1591         _M_initialize_dispatch(_Integer __n, _Integer __x, __true_type)
   1592         {
   1593 	  _M_initialize_map(static_cast<size_type>(__n));
   1594 	  _M_fill_initialize(__x);
   1595 	}
   1596 
   1597       // called by the range constructor to implement [23.1.1]/9
   1598       template<typename _InputIterator>
   1599         void
   1600         _M_initialize_dispatch(_InputIterator __first, _InputIterator __last,
   1601 			       __false_type)
   1602         {
   1603 	  typedef typename std::iterator_traits<_InputIterator>::
   1604 	    iterator_category _IterCategory;
   1605 	  _M_range_initialize(__first, __last, _IterCategory());
   1606 	}
   1607 
   1608       // called by the second initialize_dispatch above
   1609       //@{
   1610       /**
   1611        *  @brief Fills the deque with whatever is in [first,last).
   1612        *  @param  first  An input iterator.
   1613        *  @param  last  An input iterator.
   1614        *  @return   Nothing.
   1615        *
   1616        *  If the iterators are actually forward iterators (or better), then the
   1617        *  memory layout can be done all at once.  Else we move forward using
   1618        *  push_back on each value from the iterator.
   1619        */
   1620       template<typename _InputIterator>
   1621         void
   1622         _M_range_initialize(_InputIterator __first, _InputIterator __last,
   1623 			    std::input_iterator_tag);
   1624 
   1625       // called by the second initialize_dispatch above
   1626       template<typename _ForwardIterator>
   1627         void
   1628         _M_range_initialize(_ForwardIterator __first, _ForwardIterator __last,
   1629 			    std::forward_iterator_tag);
   1630       //@}
   1631 
   1632       /**
   1633        *  @brief Fills the %deque with copies of value.
   1634        *  @param  value  Initial value.
   1635        *  @return   Nothing.
   1636        *  @pre _M_start and _M_finish have already been initialized,
   1637        *  but none of the %deque's elements have yet been constructed.
   1638        *
   1639        *  This function is called only when the user provides an explicit size
   1640        *  (with or without an explicit exemplar value).
   1641        */
   1642       void
   1643       _M_fill_initialize(const value_type& __value);
   1644 
   1645 #ifdef __GXX_EXPERIMENTAL_CXX0X__
   1646       // called by deque(n).
   1647       void
   1648       _M_default_initialize();
   1649 #endif
   1650 
   1651       // Internal assign functions follow.  The *_aux functions do the actual
   1652       // assignment work for the range versions.
   1653 
   1654       // called by the range assign to implement [23.1.1]/9
   1655 
   1656       // _GLIBCXX_RESOLVE_LIB_DEFECTS
   1657       // 438. Ambiguity in the "do the right thing" clause
   1658       template<typename _Integer>
   1659         void
   1660         _M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
   1661         { _M_fill_assign(__n, __val); }
   1662 
   1663       // called by the range assign to implement [23.1.1]/9
   1664       template<typename _InputIterator>
   1665         void
   1666         _M_assign_dispatch(_InputIterator __first, _InputIterator __last,
   1667 			   __false_type)
   1668         {
   1669 	  typedef typename std::iterator_traits<_InputIterator>::
   1670 	    iterator_category _IterCategory;
   1671 	  _M_assign_aux(__first, __last, _IterCategory());
   1672 	}
   1673 
   1674       // called by the second assign_dispatch above
   1675       template<typename _InputIterator>
   1676         void
   1677         _M_assign_aux(_InputIterator __first, _InputIterator __last,
   1678 		      std::input_iterator_tag);
   1679 
   1680       // called by the second assign_dispatch above
   1681       template<typename _ForwardIterator>
   1682         void
   1683         _M_assign_aux(_ForwardIterator __first, _ForwardIterator __last,
   1684 		      std::forward_iterator_tag)
   1685         {
   1686 	  const size_type __len = std::distance(__first, __last);
   1687 	  if (__len > size())
   1688 	    {
   1689 	      _ForwardIterator __mid = __first;
   1690 	      std::advance(__mid, size());
   1691 	      std::copy(__first, __mid, begin());
   1692 	      insert(end(), __mid, __last);
   1693 	    }
   1694 	  else
   1695 	    _M_erase_at_end(std::copy(__first, __last, begin()));
   1696 	}
   1697 
   1698       // Called by assign(n,t), and the range assign when it turns out
   1699       // to be the same thing.
   1700       void
   1701       _M_fill_assign(size_type __n, const value_type& __val)
   1702       {
   1703 	if (__n > size())
   1704 	  {
   1705 	    std::fill(begin(), end(), __val);
   1706 	    insert(end(), __n - size(), __val);
   1707 	  }
   1708 	else
   1709 	  {
   1710 	    _M_erase_at_end(begin() + difference_type(__n));
   1711 	    std::fill(begin(), end(), __val);
   1712 	  }
   1713       }
   1714 
   1715       //@{
   1716       /// Helper functions for push_* and pop_*.
   1717 #ifndef __GXX_EXPERIMENTAL_CXX0X__
   1718       void _M_push_back_aux(const value_type&);
   1719 
   1720       void _M_push_front_aux(const value_type&);
   1721 #else
   1722       template<typename... _Args>
   1723         void _M_push_back_aux(_Args&&... __args);
   1724 
   1725       template<typename... _Args>
   1726         void _M_push_front_aux(_Args&&... __args);
   1727 #endif
   1728 
   1729       void _M_pop_back_aux();
   1730 
   1731       void _M_pop_front_aux();
   1732       //@}
   1733 
   1734       // Internal insert functions follow.  The *_aux functions do the actual
   1735       // insertion work when all shortcuts fail.
   1736 
   1737       // called by the range insert to implement [23.1.1]/9
   1738 
   1739       // _GLIBCXX_RESOLVE_LIB_DEFECTS
   1740       // 438. Ambiguity in the "do the right thing" clause
   1741       template<typename _Integer>
   1742         void
   1743         _M_insert_dispatch(iterator __pos,
   1744 			   _Integer __n, _Integer __x, __true_type)
   1745         { _M_fill_insert(__pos, __n, __x); }
   1746 
   1747       // called by the range insert to implement [23.1.1]/9
   1748       template<typename _InputIterator>
   1749         void
   1750         _M_insert_dispatch(iterator __pos,
   1751 			   _InputIterator __first, _InputIterator __last,
   1752 			   __false_type)
   1753         {
   1754 	  typedef typename std::iterator_traits<_InputIterator>::
   1755 	    iterator_category _IterCategory;
   1756           _M_range_insert_aux(__pos, __first, __last, _IterCategory());
   1757 	}
   1758 
   1759       // called by the second insert_dispatch above
   1760       template<typename _InputIterator>
   1761         void
   1762         _M_range_insert_aux(iterator __pos, _InputIterator __first,
   1763 			    _InputIterator __last, std::input_iterator_tag);
   1764 
   1765       // called by the second insert_dispatch above
   1766       template<typename _ForwardIterator>
   1767         void
   1768         _M_range_insert_aux(iterator __pos, _ForwardIterator __first,
   1769 			    _ForwardIterator __last, std::forward_iterator_tag);
   1770 
   1771       // Called by insert(p,n,x), and the range insert when it turns out to be
   1772       // the same thing.  Can use fill functions in optimal situations,
   1773       // otherwise passes off to insert_aux(p,n,x).
   1774       void
   1775       _M_fill_insert(iterator __pos, size_type __n, const value_type& __x);
   1776 
   1777       // called by insert(p,x)
   1778 #ifndef __GXX_EXPERIMENTAL_CXX0X__
   1779       iterator
   1780       _M_insert_aux(iterator __pos, const value_type& __x);
   1781 #else
   1782       template<typename... _Args>
   1783         iterator
   1784         _M_insert_aux(iterator __pos, _Args&&... __args);
   1785 #endif
   1786 
   1787       // called by insert(p,n,x) via fill_insert
   1788       void
   1789       _M_insert_aux(iterator __pos, size_type __n, const value_type& __x);
   1790 
   1791       // called by range_insert_aux for forward iterators
   1792       template<typename _ForwardIterator>
   1793         void
   1794         _M_insert_aux(iterator __pos,
   1795 		      _ForwardIterator __first, _ForwardIterator __last,
   1796 		      size_type __n);
   1797 
   1798 
   1799       // Internal erase functions follow.
   1800 
   1801       void
   1802       _M_destroy_data_aux(iterator __first, iterator __last);
   1803 
   1804       // Called by ~deque().
   1805       // NB: Doesn't deallocate the nodes.
   1806       template<typename _Alloc1>
   1807         void
   1808         _M_destroy_data(iterator __first, iterator __last, const _Alloc1&)
   1809         { _M_destroy_data_aux(__first, __last); }
   1810 
   1811       void
   1812       _M_destroy_data(iterator __first, iterator __last,
   1813 		      const std::allocator<_Tp>&)
   1814       {
   1815 	if (!__has_trivial_destructor(value_type))
   1816 	  _M_destroy_data_aux(__first, __last);
   1817       }
   1818 
   1819       // Called by erase(q1, q2).
   1820       void
   1821       _M_erase_at_begin(iterator __pos)
   1822       {
   1823 	_M_destroy_data(begin(), __pos, _M_get_Tp_allocator());
   1824 	_M_destroy_nodes(this->_M_impl._M_start._M_node, __pos._M_node);
   1825 	this->_M_impl._M_start = __pos;
   1826       }
   1827 
   1828       // Called by erase(q1, q2), resize(), clear(), _M_assign_aux,
   1829       // _M_fill_assign, operator=.
   1830       void
   1831       _M_erase_at_end(iterator __pos)
   1832       {
   1833 	_M_destroy_data(__pos, end(), _M_get_Tp_allocator());
   1834 	_M_destroy_nodes(__pos._M_node + 1,
   1835 			 this->_M_impl._M_finish._M_node + 1);
   1836 	this->_M_impl._M_finish = __pos;
   1837       }
   1838 
   1839 #ifdef __GXX_EXPERIMENTAL_CXX0X__
   1840       // Called by resize(sz).
   1841       void
   1842       _M_default_append(size_type __n);
   1843 #endif
   1844 
   1845       //@{
   1846       /// Memory-handling helpers for the previous internal insert functions.
   1847       iterator
   1848       _M_reserve_elements_at_front(size_type __n)
   1849       {
   1850 	const size_type __vacancies = this->_M_impl._M_start._M_cur
   1851 	                              - this->_M_impl._M_start._M_first;
   1852 	if (__n > __vacancies)
   1853 	  _M_new_elements_at_front(__n - __vacancies);
   1854 	return this->_M_impl._M_start - difference_type(__n);
   1855       }
   1856 
   1857       iterator
   1858       _M_reserve_elements_at_back(size_type __n)
   1859       {
   1860 	const size_type __vacancies = (this->_M_impl._M_finish._M_last
   1861 				       - this->_M_impl._M_finish._M_cur) - 1;
   1862 	if (__n > __vacancies)
   1863 	  _M_new_elements_at_back(__n - __vacancies);
   1864 	return this->_M_impl._M_finish + difference_type(__n);
   1865       }
   1866 
   1867       void
   1868       _M_new_elements_at_front(size_type __new_elements);
   1869 
   1870       void
   1871       _M_new_elements_at_back(size_type __new_elements);
   1872       //@}
   1873 
   1874 
   1875       //@{
   1876       /**
   1877        *  @brief Memory-handling helpers for the major %map.
   1878        *
   1879        *  Makes sure the _M_map has space for new nodes.  Does not
   1880        *  actually add the nodes.  Can invalidate _M_map pointers.
   1881        *  (And consequently, %deque iterators.)
   1882        */
   1883       void
   1884       _M_reserve_map_at_back(size_type __nodes_to_add = 1)
   1885       {
   1886 	if (__nodes_to_add + 1 > this->_M_impl._M_map_size
   1887 	    - (this->_M_impl._M_finish._M_node - this->_M_impl._M_map))
   1888 	  _M_reallocate_map(__nodes_to_add, false);
   1889       }
   1890 
   1891       void
   1892       _M_reserve_map_at_front(size_type __nodes_to_add = 1)
   1893       {
   1894 	if (__nodes_to_add > size_type(this->_M_impl._M_start._M_node
   1895 				       - this->_M_impl._M_map))
   1896 	  _M_reallocate_map(__nodes_to_add, true);
   1897       }
   1898 
   1899       void
   1900       _M_reallocate_map(size_type __nodes_to_add, bool __add_at_front);
   1901       //@}
   1902     };
   1903 
   1904 
   1905   /**
   1906    *  @brief  Deque equality comparison.
   1907    *  @param  x  A %deque.
   1908    *  @param  y  A %deque of the same type as @a x.
   1909    *  @return  True iff the size and elements of the deques are equal.
   1910    *
   1911    *  This is an equivalence relation.  It is linear in the size of the
   1912    *  deques.  Deques are considered equivalent if their sizes are equal,
   1913    *  and if corresponding elements compare equal.
   1914   */
   1915   template<typename _Tp, typename _Alloc>
   1916     inline bool
   1917     operator==(const deque<_Tp, _Alloc>& __x,
   1918                          const deque<_Tp, _Alloc>& __y)
   1919     { return __x.size() == __y.size()
   1920              && std::equal(__x.begin(), __x.end(), __y.begin()); }
   1921 
   1922   /**
   1923    *  @brief  Deque ordering relation.
   1924    *  @param  x  A %deque.
   1925    *  @param  y  A %deque of the same type as @a x.
   1926    *  @return  True iff @a x is lexicographically less than @a y.
   1927    *
   1928    *  This is a total ordering relation.  It is linear in the size of the
   1929    *  deques.  The elements must be comparable with @c <.
   1930    *
   1931    *  See std::lexicographical_compare() for how the determination is made.
   1932   */
   1933   template<typename _Tp, typename _Alloc>
   1934     inline bool
   1935     operator<(const deque<_Tp, _Alloc>& __x,
   1936 	      const deque<_Tp, _Alloc>& __y)
   1937     { return std::lexicographical_compare(__x.begin(), __x.end(),
   1938 					  __y.begin(), __y.end()); }
   1939 
   1940   /// Based on operator==
   1941   template<typename _Tp, typename _Alloc>
   1942     inline bool
   1943     operator!=(const deque<_Tp, _Alloc>& __x,
   1944 	       const deque<_Tp, _Alloc>& __y)
   1945     { return !(__x == __y); }
   1946 
   1947   /// Based on operator<
   1948   template<typename _Tp, typename _Alloc>
   1949     inline bool
   1950     operator>(const deque<_Tp, _Alloc>& __x,
   1951 	      const deque<_Tp, _Alloc>& __y)
   1952     { return __y < __x; }
   1953 
   1954   /// Based on operator<
   1955   template<typename _Tp, typename _Alloc>
   1956     inline bool
   1957     operator<=(const deque<_Tp, _Alloc>& __x,
   1958 	       const deque<_Tp, _Alloc>& __y)
   1959     { return !(__y < __x); }
   1960 
   1961   /// Based on operator<
   1962   template<typename _Tp, typename _Alloc>
   1963     inline bool
   1964     operator>=(const deque<_Tp, _Alloc>& __x,
   1965 	       const deque<_Tp, _Alloc>& __y)
   1966     { return !(__x < __y); }
   1967 
   1968   /// See std::deque::swap().
   1969   template<typename _Tp, typename _Alloc>
   1970     inline void
   1971     swap(deque<_Tp,_Alloc>& __x, deque<_Tp,_Alloc>& __y)
   1972     { __x.swap(__y); }
   1973 
   1974 #undef _GLIBCXX_DEQUE_BUF_SIZE
   1975 
   1976 _GLIBCXX_END_NAMESPACE_CONTAINER
   1977 } // namespace std
   1978 
   1979 #endif /* _STL_DEQUE_H */
   1980