libstdc++
forward_list.h
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00001 // <forward_list.h> -*- C++ -*-
00002 
00003 // Copyright (C) 2008-2018 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file bits/forward_list.h
00026  *  This is an internal header file, included by other library headers.
00027  *  Do not attempt to use it directly. @headername{forward_list}
00028  */
00029 
00030 #ifndef _FORWARD_LIST_H
00031 #define _FORWARD_LIST_H 1
00032 
00033 #pragma GCC system_header
00034 
00035 #include <initializer_list>
00036 #include <bits/stl_iterator_base_types.h>
00037 #include <bits/stl_iterator.h>
00038 #include <bits/stl_algobase.h>
00039 #include <bits/stl_function.h>
00040 #include <bits/allocator.h>
00041 #include <ext/alloc_traits.h>
00042 #include <ext/aligned_buffer.h>
00043 
00044 namespace std _GLIBCXX_VISIBILITY(default)
00045 {
00046 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00047 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
00048 
00049   /**
00050    *  @brief  A helper basic node class for %forward_list.
00051    *          This is just a linked list with nothing inside it.
00052    *          There are purely list shuffling utility methods here.
00053    */
00054   struct _Fwd_list_node_base
00055   {
00056     _Fwd_list_node_base() = default;
00057     _Fwd_list_node_base(_Fwd_list_node_base&& __x) noexcept
00058       : _M_next(__x._M_next)
00059     { __x._M_next = nullptr; }
00060 
00061     _Fwd_list_node_base(const _Fwd_list_node_base&) = delete;
00062     _Fwd_list_node_base& operator=(const _Fwd_list_node_base&) = delete;
00063 
00064     _Fwd_list_node_base&
00065     operator=(_Fwd_list_node_base&& __x) noexcept
00066     {
00067       _M_next = __x._M_next;
00068       __x._M_next = nullptr;
00069       return *this;
00070     }
00071 
00072     _Fwd_list_node_base* _M_next = nullptr;
00073 
00074     _Fwd_list_node_base*
00075     _M_transfer_after(_Fwd_list_node_base* __begin,
00076                       _Fwd_list_node_base* __end) noexcept
00077     {
00078       _Fwd_list_node_base* __keep = __begin->_M_next;
00079       if (__end)
00080         {
00081           __begin->_M_next = __end->_M_next;
00082           __end->_M_next = _M_next;
00083         }
00084       else
00085         __begin->_M_next = nullptr;
00086       _M_next = __keep;
00087       return __end;
00088     }
00089 
00090     void
00091     _M_reverse_after() noexcept
00092     {
00093       _Fwd_list_node_base* __tail = _M_next;
00094       if (!__tail)
00095         return;
00096       while (_Fwd_list_node_base* __temp = __tail->_M_next)
00097         {
00098           _Fwd_list_node_base* __keep = _M_next;
00099           _M_next = __temp;
00100           __tail->_M_next = __temp->_M_next;
00101           _M_next->_M_next = __keep;
00102         }
00103     }
00104   };
00105 
00106   /**
00107    *  @brief  A helper node class for %forward_list.
00108    *          This is just a linked list with uninitialized storage for a
00109    *          data value in each node.
00110    *          There is a sorting utility method.
00111    */
00112   template<typename _Tp>
00113     struct _Fwd_list_node
00114     : public _Fwd_list_node_base
00115     {
00116       _Fwd_list_node() = default;
00117 
00118       __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
00119 
00120       _Tp*
00121       _M_valptr() noexcept
00122       { return _M_storage._M_ptr(); }
00123 
00124       const _Tp*
00125       _M_valptr() const noexcept
00126       { return _M_storage._M_ptr(); }
00127     };
00128 
00129   /**
00130    *   @brief A forward_list::iterator.
00131    *
00132    *   All the functions are op overloads.
00133    */
00134   template<typename _Tp>
00135     struct _Fwd_list_iterator
00136     {
00137       typedef _Fwd_list_iterator<_Tp>           _Self;
00138       typedef _Fwd_list_node<_Tp>               _Node;
00139 
00140       typedef _Tp                               value_type;
00141       typedef _Tp*                              pointer;
00142       typedef _Tp&                              reference;
00143       typedef ptrdiff_t                         difference_type;
00144       typedef std::forward_iterator_tag         iterator_category;
00145 
00146       _Fwd_list_iterator() noexcept
00147       : _M_node() { }
00148 
00149       explicit
00150       _Fwd_list_iterator(_Fwd_list_node_base* __n) noexcept
00151       : _M_node(__n) { }
00152 
00153       reference
00154       operator*() const noexcept
00155       { return *static_cast<_Node*>(this->_M_node)->_M_valptr(); }
00156 
00157       pointer
00158       operator->() const noexcept
00159       { return static_cast<_Node*>(this->_M_node)->_M_valptr(); }
00160 
00161       _Self&
00162       operator++() noexcept
00163       {
00164         _M_node = _M_node->_M_next;
00165         return *this;
00166       }
00167 
00168       _Self
00169       operator++(int) noexcept
00170       {
00171         _Self __tmp(*this);
00172         _M_node = _M_node->_M_next;
00173         return __tmp;
00174       }
00175 
00176       bool
00177       operator==(const _Self& __x) const noexcept
00178       { return _M_node == __x._M_node; }
00179 
00180       bool
00181       operator!=(const _Self& __x) const noexcept
00182       { return _M_node != __x._M_node; }
00183 
00184       _Self
00185       _M_next() const noexcept
00186       {
00187         if (_M_node)
00188           return _Fwd_list_iterator(_M_node->_M_next);
00189         else
00190           return _Fwd_list_iterator(nullptr);
00191       }
00192 
00193       _Fwd_list_node_base* _M_node;
00194     };
00195 
00196   /**
00197    *   @brief A forward_list::const_iterator.
00198    *
00199    *   All the functions are op overloads.
00200    */
00201   template<typename _Tp>
00202     struct _Fwd_list_const_iterator
00203     {
00204       typedef _Fwd_list_const_iterator<_Tp>     _Self;
00205       typedef const _Fwd_list_node<_Tp>         _Node;
00206       typedef _Fwd_list_iterator<_Tp>           iterator;
00207 
00208       typedef _Tp                               value_type;
00209       typedef const _Tp*                        pointer;
00210       typedef const _Tp&                        reference;
00211       typedef ptrdiff_t                         difference_type;
00212       typedef std::forward_iterator_tag         iterator_category;
00213 
00214       _Fwd_list_const_iterator() noexcept
00215       : _M_node() { }
00216 
00217       explicit
00218       _Fwd_list_const_iterator(const _Fwd_list_node_base* __n)  noexcept
00219       : _M_node(__n) { }
00220 
00221       _Fwd_list_const_iterator(const iterator& __iter) noexcept
00222       : _M_node(__iter._M_node) { }
00223 
00224       reference
00225       operator*() const noexcept
00226       { return *static_cast<_Node*>(this->_M_node)->_M_valptr(); }
00227 
00228       pointer
00229       operator->() const noexcept
00230       { return static_cast<_Node*>(this->_M_node)->_M_valptr(); }
00231 
00232       _Self&
00233       operator++() noexcept
00234       {
00235         _M_node = _M_node->_M_next;
00236         return *this;
00237       }
00238 
00239       _Self
00240       operator++(int) noexcept
00241       {
00242         _Self __tmp(*this);
00243         _M_node = _M_node->_M_next;
00244         return __tmp;
00245       }
00246 
00247       bool
00248       operator==(const _Self& __x) const noexcept
00249       { return _M_node == __x._M_node; }
00250 
00251       bool
00252       operator!=(const _Self& __x) const noexcept
00253       { return _M_node != __x._M_node; }
00254 
00255       _Self
00256       _M_next() const noexcept
00257       {
00258         if (this->_M_node)
00259           return _Fwd_list_const_iterator(_M_node->_M_next);
00260         else
00261           return _Fwd_list_const_iterator(nullptr);
00262       }
00263 
00264       const _Fwd_list_node_base* _M_node;
00265     };
00266 
00267   /**
00268    *  @brief  Forward list iterator equality comparison.
00269    */
00270   template<typename _Tp>
00271     inline bool
00272     operator==(const _Fwd_list_iterator<_Tp>& __x,
00273                const _Fwd_list_const_iterator<_Tp>& __y) noexcept
00274     { return __x._M_node == __y._M_node; }
00275 
00276   /**
00277    *  @brief  Forward list iterator inequality comparison.
00278    */
00279   template<typename _Tp>
00280     inline bool
00281     operator!=(const _Fwd_list_iterator<_Tp>& __x,
00282                const _Fwd_list_const_iterator<_Tp>& __y) noexcept
00283     { return __x._M_node != __y._M_node; }
00284 
00285   /**
00286    *  @brief  Base class for %forward_list.
00287    */
00288   template<typename _Tp, typename _Alloc>
00289     struct _Fwd_list_base
00290     {
00291     protected:
00292       typedef __alloc_rebind<_Alloc, _Fwd_list_node<_Tp>> _Node_alloc_type;
00293       typedef __gnu_cxx::__alloc_traits<_Node_alloc_type> _Node_alloc_traits;
00294 
00295       struct _Fwd_list_impl
00296       : public _Node_alloc_type
00297       {
00298         _Fwd_list_node_base _M_head;
00299 
00300         _Fwd_list_impl()
00301           noexcept( noexcept(_Node_alloc_type()) )
00302         : _Node_alloc_type(), _M_head()
00303         { }
00304 
00305         _Fwd_list_impl(_Fwd_list_impl&&) = default;
00306 
00307         _Fwd_list_impl(_Fwd_list_impl&& __fl, _Node_alloc_type&& __a)
00308         : _Node_alloc_type(std::move(__a)), _M_head(std::move(__fl._M_head))
00309         { }
00310 
00311         _Fwd_list_impl(_Node_alloc_type&& __a)
00312         : _Node_alloc_type(std::move(__a)), _M_head()
00313         { }
00314       };
00315 
00316       _Fwd_list_impl _M_impl;
00317 
00318     public:
00319       typedef _Fwd_list_iterator<_Tp>           iterator;
00320       typedef _Fwd_list_const_iterator<_Tp>     const_iterator;
00321       typedef _Fwd_list_node<_Tp>               _Node;
00322 
00323       _Node_alloc_type&
00324       _M_get_Node_allocator() noexcept
00325       { return this->_M_impl; }
00326 
00327       const _Node_alloc_type&
00328       _M_get_Node_allocator() const noexcept
00329       { return this->_M_impl; }
00330 
00331       _Fwd_list_base() = default;
00332 
00333       _Fwd_list_base(_Node_alloc_type&& __a)
00334       : _M_impl(std::move(__a)) { }
00335 
00336       // When allocators are always equal.
00337       _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a,
00338                      std::true_type)
00339       : _M_impl(std::move(__lst._M_impl), std::move(__a))
00340       { }
00341 
00342       // When allocators are not always equal.
00343       _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a);
00344 
00345       _Fwd_list_base(_Fwd_list_base&&) = default;
00346 
00347       ~_Fwd_list_base()
00348       { _M_erase_after(&_M_impl._M_head, nullptr); }
00349 
00350     protected:
00351       _Node*
00352       _M_get_node()
00353       {
00354         auto __ptr = _Node_alloc_traits::allocate(_M_get_Node_allocator(), 1);
00355         return std::__to_address(__ptr);
00356       }
00357 
00358       template<typename... _Args>
00359         _Node*
00360         _M_create_node(_Args&&... __args)
00361         {
00362           _Node* __node = this->_M_get_node();
00363           __try
00364             {
00365               ::new ((void*)__node) _Node;
00366               _Node_alloc_traits::construct(_M_get_Node_allocator(),
00367                                             __node->_M_valptr(),
00368                                             std::forward<_Args>(__args)...);
00369             }
00370           __catch(...)
00371             {
00372               this->_M_put_node(__node);
00373               __throw_exception_again;
00374             }
00375           return __node;
00376         }
00377 
00378       template<typename... _Args>
00379         _Fwd_list_node_base*
00380         _M_insert_after(const_iterator __pos, _Args&&... __args);
00381 
00382       void
00383       _M_put_node(_Node* __p)
00384       {
00385         typedef typename _Node_alloc_traits::pointer _Ptr;
00386         auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__p);
00387         _Node_alloc_traits::deallocate(_M_get_Node_allocator(), __ptr, 1);
00388       }
00389 
00390       _Fwd_list_node_base*
00391       _M_erase_after(_Fwd_list_node_base* __pos);
00392 
00393       _Fwd_list_node_base*
00394       _M_erase_after(_Fwd_list_node_base* __pos,
00395                      _Fwd_list_node_base* __last);
00396     };
00397 
00398   /**
00399    *  @brief A standard container with linear time access to elements,
00400    *  and fixed time insertion/deletion at any point in the sequence.
00401    *
00402    *  @ingroup sequences
00403    *
00404    *  @tparam _Tp  Type of element.
00405    *  @tparam _Alloc  Allocator type, defaults to allocator<_Tp>.
00406    *
00407    *  Meets the requirements of a <a href="tables.html#65">container</a>, a
00408    *  <a href="tables.html#67">sequence</a>, including the
00409    *  <a href="tables.html#68">optional sequence requirements</a> with the
00410    *  %exception of @c at and @c operator[].
00411    *
00412    *  This is a @e singly @e linked %list.  Traversal up the
00413    *  %list requires linear time, but adding and removing elements (or
00414    *  @e nodes) is done in constant time, regardless of where the
00415    *  change takes place.  Unlike std::vector and std::deque,
00416    *  random-access iterators are not provided, so subscripting ( @c
00417    *  [] ) access is not allowed.  For algorithms which only need
00418    *  sequential access, this lack makes no difference.
00419    *
00420    *  Also unlike the other standard containers, std::forward_list provides
00421    *  specialized algorithms %unique to linked lists, such as
00422    *  splicing, sorting, and in-place reversal.
00423    */
00424   template<typename _Tp, typename _Alloc = allocator<_Tp>>
00425     class forward_list : private _Fwd_list_base<_Tp, _Alloc>
00426     {
00427       static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
00428           "std::forward_list must have a non-const, non-volatile value_type");
00429 #ifdef __STRICT_ANSI__
00430       static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
00431           "std::forward_list must have the same value_type as its allocator");
00432 #endif
00433 
00434     private:
00435       typedef _Fwd_list_base<_Tp, _Alloc>               _Base;
00436       typedef _Fwd_list_node<_Tp>                       _Node;
00437       typedef _Fwd_list_node_base                       _Node_base;
00438       typedef typename _Base::_Node_alloc_type          _Node_alloc_type;
00439       typedef typename _Base::_Node_alloc_traits        _Node_alloc_traits;
00440       typedef allocator_traits<__alloc_rebind<_Alloc, _Tp>>     _Alloc_traits;
00441 
00442     public:
00443       // types:
00444       typedef _Tp                                       value_type;
00445       typedef typename _Alloc_traits::pointer           pointer;
00446       typedef typename _Alloc_traits::const_pointer     const_pointer;
00447       typedef value_type&                               reference;
00448       typedef const value_type&                         const_reference;
00449 
00450       typedef _Fwd_list_iterator<_Tp>                   iterator;
00451       typedef _Fwd_list_const_iterator<_Tp>             const_iterator;
00452       typedef std::size_t                               size_type;
00453       typedef std::ptrdiff_t                            difference_type;
00454       typedef _Alloc                                    allocator_type;
00455 
00456       // 23.3.4.2 construct/copy/destroy:
00457 
00458       /**
00459        *  @brief  Creates a %forward_list with no elements.
00460        */
00461       forward_list() = default;
00462 
00463       /**
00464        *  @brief  Creates a %forward_list with no elements.
00465        *  @param  __al  An allocator object.
00466        */
00467       explicit
00468       forward_list(const _Alloc& __al) noexcept
00469       : _Base(_Node_alloc_type(__al))
00470       { }
00471 
00472       /**
00473        *  @brief  Copy constructor with allocator argument.
00474        *  @param  __list  Input list to copy.
00475        *  @param  __al    An allocator object.
00476        */
00477       forward_list(const forward_list& __list, const _Alloc& __al)
00478       : _Base(_Node_alloc_type(__al))
00479       { _M_range_initialize(__list.begin(), __list.end()); }
00480 
00481     private:
00482       forward_list(forward_list&& __list, _Node_alloc_type&& __al,
00483                    false_type)
00484       : _Base(std::move(__list), std::move(__al))
00485       {
00486         // If __list is not empty it means its allocator is not equal to __a,
00487         // so we need to move from each element individually.
00488         insert_after(cbefore_begin(),
00489                      std::__make_move_if_noexcept_iterator(__list.begin()),
00490                      std::__make_move_if_noexcept_iterator(__list.end()));
00491       }
00492 
00493       forward_list(forward_list&& __list, _Node_alloc_type&& __al,
00494                    true_type)
00495       noexcept
00496       : _Base(std::move(__list), _Node_alloc_type(__al), true_type{})
00497       { }
00498 
00499     public:
00500       /**
00501        *  @brief  Move constructor with allocator argument.
00502        *  @param  __list  Input list to move.
00503        *  @param  __al    An allocator object.
00504        */
00505       forward_list(forward_list&& __list, const _Alloc& __al)
00506       noexcept(_Node_alloc_traits::_S_always_equal())
00507       : forward_list(std::move(__list), _Node_alloc_type(__al),
00508                      typename _Node_alloc_traits::is_always_equal{})
00509       { }
00510 
00511       /**
00512        *  @brief  Creates a %forward_list with default constructed elements.
00513        *  @param  __n   The number of elements to initially create.
00514        *  @param  __al  An allocator object.
00515        *
00516        *  This constructor creates the %forward_list with @a __n default
00517        *  constructed elements.
00518        */
00519       explicit
00520       forward_list(size_type __n, const _Alloc& __al = _Alloc())
00521       : _Base(_Node_alloc_type(__al))
00522       { _M_default_initialize(__n); }
00523 
00524       /**
00525        *  @brief  Creates a %forward_list with copies of an exemplar element.
00526        *  @param  __n      The number of elements to initially create.
00527        *  @param  __value  An element to copy.
00528        *  @param  __al     An allocator object.
00529        *
00530        *  This constructor fills the %forward_list with @a __n copies of
00531        *  @a __value.
00532        */
00533       forward_list(size_type __n, const _Tp& __value,
00534                    const _Alloc& __al = _Alloc())
00535       : _Base(_Node_alloc_type(__al))
00536       { _M_fill_initialize(__n, __value); }
00537 
00538       /**
00539        *  @brief  Builds a %forward_list from a range.
00540        *  @param  __first  An input iterator.
00541        *  @param  __last   An input iterator.
00542        *  @param  __al     An allocator object.
00543        *
00544        *  Create a %forward_list consisting of copies of the elements from
00545        *  [@a __first,@a __last).  This is linear in N (where N is
00546        *  distance(@a __first,@a __last)).
00547        */
00548       template<typename _InputIterator,
00549                typename = std::_RequireInputIter<_InputIterator>>
00550         forward_list(_InputIterator __first, _InputIterator __last,
00551                      const _Alloc& __al = _Alloc())
00552         : _Base(_Node_alloc_type(__al))
00553         { _M_range_initialize(__first, __last); }
00554 
00555       /**
00556        *  @brief  The %forward_list copy constructor.
00557        *  @param  __list  A %forward_list of identical element and allocator
00558        *                  types.
00559        */
00560       forward_list(const forward_list& __list)
00561       : _Base(_Node_alloc_traits::_S_select_on_copy(
00562                 __list._M_get_Node_allocator()))
00563       { _M_range_initialize(__list.begin(), __list.end()); }
00564 
00565       /**
00566        *  @brief  The %forward_list move constructor.
00567        *  @param  __list  A %forward_list of identical element and allocator
00568        *                  types.
00569        *
00570        *  The newly-created %forward_list contains the exact contents of the
00571        *  moved instance. The contents of the moved instance are a valid, but
00572        *  unspecified %forward_list.
00573        */
00574       forward_list(forward_list&&) = default;
00575 
00576       /**
00577        *  @brief  Builds a %forward_list from an initializer_list
00578        *  @param  __il  An initializer_list of value_type.
00579        *  @param  __al  An allocator object.
00580        *
00581        *  Create a %forward_list consisting of copies of the elements
00582        *  in the initializer_list @a __il.  This is linear in __il.size().
00583        */
00584       forward_list(std::initializer_list<_Tp> __il,
00585                    const _Alloc& __al = _Alloc())
00586       : _Base(_Node_alloc_type(__al))
00587       { _M_range_initialize(__il.begin(), __il.end()); }
00588 
00589       /**
00590        *  @brief  The forward_list dtor.
00591        */
00592       ~forward_list() noexcept
00593       { }
00594 
00595       /**
00596        *  @brief  The %forward_list assignment operator.
00597        *  @param  __list  A %forward_list of identical element and allocator
00598        *                types.
00599        *
00600        *  All the elements of @a __list are copied.
00601        *
00602        *  Whether the allocator is copied depends on the allocator traits.
00603        */
00604       forward_list&
00605       operator=(const forward_list& __list);
00606 
00607       /**
00608        *  @brief  The %forward_list move assignment operator.
00609        *  @param  __list  A %forward_list of identical element and allocator
00610        *                types.
00611        *
00612        *  The contents of @a __list are moved into this %forward_list
00613        *  (without copying, if the allocators permit it).
00614        *
00615        *  Afterwards @a __list is a valid, but unspecified %forward_list
00616        *
00617        *  Whether the allocator is moved depends on the allocator traits.
00618        */
00619       forward_list&
00620       operator=(forward_list&& __list)
00621       noexcept(_Node_alloc_traits::_S_nothrow_move())
00622       {
00623         constexpr bool __move_storage =
00624           _Node_alloc_traits::_S_propagate_on_move_assign()
00625           || _Node_alloc_traits::_S_always_equal();
00626         _M_move_assign(std::move(__list), __bool_constant<__move_storage>());
00627         return *this;
00628       }
00629 
00630       /**
00631        *  @brief  The %forward_list initializer list assignment operator.
00632        *  @param  __il  An initializer_list of value_type.
00633        *
00634        *  Replace the contents of the %forward_list with copies of the
00635        *  elements in the initializer_list @a __il.  This is linear in
00636        *  __il.size().
00637        */
00638       forward_list&
00639       operator=(std::initializer_list<_Tp> __il)
00640       {
00641         assign(__il);
00642         return *this;
00643       }
00644 
00645       /**
00646        *  @brief  Assigns a range to a %forward_list.
00647        *  @param  __first  An input iterator.
00648        *  @param  __last   An input iterator.
00649        *
00650        *  This function fills a %forward_list with copies of the elements
00651        *  in the range [@a __first,@a __last).
00652        *
00653        *  Note that the assignment completely changes the %forward_list and
00654        *  that the number of elements of the resulting %forward_list is the
00655        *  same as the number of elements assigned.
00656        */
00657       template<typename _InputIterator,
00658                typename = std::_RequireInputIter<_InputIterator>>
00659         void
00660         assign(_InputIterator __first, _InputIterator __last)
00661         {
00662           typedef is_assignable<_Tp, decltype(*__first)> __assignable;
00663           _M_assign(__first, __last, __assignable());
00664         }
00665 
00666       /**
00667        *  @brief  Assigns a given value to a %forward_list.
00668        *  @param  __n  Number of elements to be assigned.
00669        *  @param  __val  Value to be assigned.
00670        *
00671        *  This function fills a %forward_list with @a __n copies of the
00672        *  given value.  Note that the assignment completely changes the
00673        *  %forward_list, and that the resulting %forward_list has __n
00674        *  elements.
00675        */
00676       void
00677       assign(size_type __n, const _Tp& __val)
00678       { _M_assign_n(__n, __val, is_copy_assignable<_Tp>()); }
00679 
00680       /**
00681        *  @brief  Assigns an initializer_list to a %forward_list.
00682        *  @param  __il  An initializer_list of value_type.
00683        *
00684        *  Replace the contents of the %forward_list with copies of the
00685        *  elements in the initializer_list @a __il.  This is linear in
00686        *  il.size().
00687        */
00688       void
00689       assign(std::initializer_list<_Tp> __il)
00690       { assign(__il.begin(), __il.end()); }
00691 
00692       /// Get a copy of the memory allocation object.
00693       allocator_type
00694       get_allocator() const noexcept
00695       { return allocator_type(this->_M_get_Node_allocator()); }
00696 
00697       // 23.3.4.3 iterators:
00698 
00699       /**
00700        *  Returns a read/write iterator that points before the first element
00701        *  in the %forward_list.  Iteration is done in ordinary element order.
00702        */
00703       iterator
00704       before_begin() noexcept
00705       { return iterator(&this->_M_impl._M_head); }
00706 
00707       /**
00708        *  Returns a read-only (constant) iterator that points before the
00709        *  first element in the %forward_list.  Iteration is done in ordinary
00710        *  element order.
00711        */
00712       const_iterator
00713       before_begin() const noexcept
00714       { return const_iterator(&this->_M_impl._M_head); }
00715 
00716       /**
00717        *  Returns a read/write iterator that points to the first element
00718        *  in the %forward_list.  Iteration is done in ordinary element order.
00719        */
00720       iterator
00721       begin() noexcept
00722       { return iterator(this->_M_impl._M_head._M_next); }
00723 
00724       /**
00725        *  Returns a read-only (constant) iterator that points to the first
00726        *  element in the %forward_list.  Iteration is done in ordinary
00727        *  element order.
00728        */
00729       const_iterator
00730       begin() const noexcept
00731       { return const_iterator(this->_M_impl._M_head._M_next); }
00732 
00733       /**
00734        *  Returns a read/write iterator that points one past the last
00735        *  element in the %forward_list.  Iteration is done in ordinary
00736        *  element order.
00737        */
00738       iterator
00739       end() noexcept
00740       { return iterator(nullptr); }
00741 
00742       /**
00743        *  Returns a read-only iterator that points one past the last
00744        *  element in the %forward_list.  Iteration is done in ordinary
00745        *  element order.
00746        */
00747       const_iterator
00748       end() const noexcept
00749       { return const_iterator(nullptr); }
00750 
00751       /**
00752        *  Returns a read-only (constant) iterator that points to the
00753        *  first element in the %forward_list.  Iteration is done in ordinary
00754        *  element order.
00755        */
00756       const_iterator
00757       cbegin() const noexcept
00758       { return const_iterator(this->_M_impl._M_head._M_next); }
00759 
00760       /**
00761        *  Returns a read-only (constant) iterator that points before the
00762        *  first element in the %forward_list.  Iteration is done in ordinary
00763        *  element order.
00764        */
00765       const_iterator
00766       cbefore_begin() const noexcept
00767       { return const_iterator(&this->_M_impl._M_head); }
00768 
00769       /**
00770        *  Returns a read-only (constant) iterator that points one past
00771        *  the last element in the %forward_list.  Iteration is done in
00772        *  ordinary element order.
00773        */
00774       const_iterator
00775       cend() const noexcept
00776       { return const_iterator(nullptr); }
00777 
00778       /**
00779        *  Returns true if the %forward_list is empty.  (Thus begin() would
00780        *  equal end().)
00781        */
00782       bool
00783       empty() const noexcept
00784       { return this->_M_impl._M_head._M_next == nullptr; }
00785 
00786       /**
00787        *  Returns the largest possible number of elements of %forward_list.
00788        */
00789       size_type
00790       max_size() const noexcept
00791       { return _Node_alloc_traits::max_size(this->_M_get_Node_allocator()); }
00792 
00793       // 23.3.4.4 element access:
00794 
00795       /**
00796        *  Returns a read/write reference to the data at the first
00797        *  element of the %forward_list.
00798        */
00799       reference
00800       front()
00801       {
00802         _Node* __front = static_cast<_Node*>(this->_M_impl._M_head._M_next);
00803         return *__front->_M_valptr();
00804       }
00805 
00806       /**
00807        *  Returns a read-only (constant) reference to the data at the first
00808        *  element of the %forward_list.
00809        */
00810       const_reference
00811       front() const
00812       {
00813         _Node* __front = static_cast<_Node*>(this->_M_impl._M_head._M_next);
00814         return *__front->_M_valptr();
00815       }
00816 
00817       // 23.3.4.5 modifiers:
00818 
00819       /**
00820        *  @brief  Constructs object in %forward_list at the front of the
00821        *          list.
00822        *  @param  __args  Arguments.
00823        *
00824        *  This function will insert an object of type Tp constructed
00825        *  with Tp(std::forward<Args>(args)...) at the front of the list
00826        *  Due to the nature of a %forward_list this operation can
00827        *  be done in constant time, and does not invalidate iterators
00828        *  and references.
00829        */
00830       template<typename... _Args>
00831 #if __cplusplus > 201402L
00832         reference
00833 #else
00834         void
00835 #endif
00836         emplace_front(_Args&&... __args)
00837         {
00838           this->_M_insert_after(cbefore_begin(),
00839                                 std::forward<_Args>(__args)...);
00840 #if __cplusplus > 201402L
00841           return front();
00842 #endif
00843         }
00844 
00845       /**
00846        *  @brief  Add data to the front of the %forward_list.
00847        *  @param  __val  Data to be added.
00848        *
00849        *  This is a typical stack operation.  The function creates an
00850        *  element at the front of the %forward_list and assigns the given
00851        *  data to it.  Due to the nature of a %forward_list this operation
00852        *  can be done in constant time, and does not invalidate iterators
00853        *  and references.
00854        */
00855       void
00856       push_front(const _Tp& __val)
00857       { this->_M_insert_after(cbefore_begin(), __val); }
00858 
00859       /**
00860        *
00861        */
00862       void
00863       push_front(_Tp&& __val)
00864       { this->_M_insert_after(cbefore_begin(), std::move(__val)); }
00865 
00866       /**
00867        *  @brief  Removes first element.
00868        *
00869        *  This is a typical stack operation.  It shrinks the %forward_list
00870        *  by one.  Due to the nature of a %forward_list this operation can
00871        *  be done in constant time, and only invalidates iterators/references
00872        *  to the element being removed.
00873        *
00874        *  Note that no data is returned, and if the first element's data
00875        *  is needed, it should be retrieved before pop_front() is
00876        *  called.
00877        */
00878       void
00879       pop_front()
00880       { this->_M_erase_after(&this->_M_impl._M_head); }
00881 
00882       /**
00883        *  @brief  Constructs object in %forward_list after the specified
00884        *          iterator.
00885        *  @param  __pos  A const_iterator into the %forward_list.
00886        *  @param  __args  Arguments.
00887        *  @return  An iterator that points to the inserted data.
00888        *
00889        *  This function will insert an object of type T constructed
00890        *  with T(std::forward<Args>(args)...) after the specified
00891        *  location.  Due to the nature of a %forward_list this operation can
00892        *  be done in constant time, and does not invalidate iterators
00893        *  and references.
00894        */
00895       template<typename... _Args>
00896         iterator
00897         emplace_after(const_iterator __pos, _Args&&... __args)
00898         { return iterator(this->_M_insert_after(__pos,
00899                                           std::forward<_Args>(__args)...)); }
00900 
00901       /**
00902        *  @brief  Inserts given value into %forward_list after specified
00903        *          iterator.
00904        *  @param  __pos  An iterator into the %forward_list.
00905        *  @param  __val  Data to be inserted.
00906        *  @return  An iterator that points to the inserted data.
00907        *
00908        *  This function will insert a copy of the given value after
00909        *  the specified location.  Due to the nature of a %forward_list this
00910        *  operation can be done in constant time, and does not
00911        *  invalidate iterators and references.
00912        */
00913       iterator
00914       insert_after(const_iterator __pos, const _Tp& __val)
00915       { return iterator(this->_M_insert_after(__pos, __val)); }
00916 
00917       /**
00918        *
00919        */
00920       iterator
00921       insert_after(const_iterator __pos, _Tp&& __val)
00922       { return iterator(this->_M_insert_after(__pos, std::move(__val))); }
00923 
00924       /**
00925        *  @brief  Inserts a number of copies of given data into the
00926        *          %forward_list.
00927        *  @param  __pos  An iterator into the %forward_list.
00928        *  @param  __n  Number of elements to be inserted.
00929        *  @param  __val  Data to be inserted.
00930        *  @return  An iterator pointing to the last inserted copy of
00931        *           @a val or @a pos if @a n == 0.
00932        *
00933        *  This function will insert a specified number of copies of the
00934        *  given data after the location specified by @a pos.
00935        *
00936        *  This operation is linear in the number of elements inserted and
00937        *  does not invalidate iterators and references.
00938        */
00939       iterator
00940       insert_after(const_iterator __pos, size_type __n, const _Tp& __val);
00941 
00942       /**
00943        *  @brief  Inserts a range into the %forward_list.
00944        *  @param  __pos  An iterator into the %forward_list.
00945        *  @param  __first  An input iterator.
00946        *  @param  __last   An input iterator.
00947        *  @return  An iterator pointing to the last inserted element or
00948        *           @a __pos if @a __first == @a __last.
00949        *
00950        *  This function will insert copies of the data in the range
00951        *  [@a __first,@a __last) into the %forward_list after the
00952        *  location specified by @a __pos.
00953        *
00954        *  This operation is linear in the number of elements inserted and
00955        *  does not invalidate iterators and references.
00956        */
00957       template<typename _InputIterator,
00958                typename = std::_RequireInputIter<_InputIterator>>
00959         iterator
00960         insert_after(const_iterator __pos,
00961                      _InputIterator __first, _InputIterator __last);
00962 
00963       /**
00964        *  @brief  Inserts the contents of an initializer_list into
00965        *          %forward_list after the specified iterator.
00966        *  @param  __pos  An iterator into the %forward_list.
00967        *  @param  __il  An initializer_list of value_type.
00968        *  @return  An iterator pointing to the last inserted element
00969        *           or @a __pos if @a __il is empty.
00970        *
00971        *  This function will insert copies of the data in the
00972        *  initializer_list @a __il into the %forward_list before the location
00973        *  specified by @a __pos.
00974        *
00975        *  This operation is linear in the number of elements inserted and
00976        *  does not invalidate iterators and references.
00977        */
00978       iterator
00979       insert_after(const_iterator __pos, std::initializer_list<_Tp> __il)
00980       { return insert_after(__pos, __il.begin(), __il.end()); }
00981 
00982       /**
00983        *  @brief  Removes the element pointed to by the iterator following
00984        *          @c pos.
00985        *  @param  __pos  Iterator pointing before element to be erased.
00986        *  @return  An iterator pointing to the element following the one
00987        *           that was erased, or end() if no such element exists.
00988        *
00989        *  This function will erase the element at the given position and
00990        *  thus shorten the %forward_list by one.
00991        *
00992        *  Due to the nature of a %forward_list this operation can be done
00993        *  in constant time, and only invalidates iterators/references to
00994        *  the element being removed.  The user is also cautioned that
00995        *  this function only erases the element, and that if the element
00996        *  is itself a pointer, the pointed-to memory is not touched in
00997        *  any way.  Managing the pointer is the user's responsibility.
00998        */
00999       iterator
01000       erase_after(const_iterator __pos)
01001       { return iterator(this->_M_erase_after(const_cast<_Node_base*>
01002                                              (__pos._M_node))); }
01003 
01004       /**
01005        *  @brief  Remove a range of elements.
01006        *  @param  __pos  Iterator pointing before the first element to be
01007        *                 erased.
01008        *  @param  __last  Iterator pointing to one past the last element to be
01009        *                  erased.
01010        *  @return  @ __last.
01011        *
01012        *  This function will erase the elements in the range
01013        *  @a (__pos,__last) and shorten the %forward_list accordingly.
01014        *
01015        *  This operation is linear time in the size of the range and only
01016        *  invalidates iterators/references to the element being removed.
01017        *  The user is also cautioned that this function only erases the
01018        *  elements, and that if the elements themselves are pointers, the
01019        *  pointed-to memory is not touched in any way.  Managing the pointer
01020        *  is the user's responsibility.
01021        */
01022       iterator
01023       erase_after(const_iterator __pos, const_iterator __last)
01024       { return iterator(this->_M_erase_after(const_cast<_Node_base*>
01025                                              (__pos._M_node),
01026                                              const_cast<_Node_base*>
01027                                              (__last._M_node))); }
01028 
01029       /**
01030        *  @brief  Swaps data with another %forward_list.
01031        *  @param  __list  A %forward_list of the same element and allocator
01032        *                  types.
01033        *
01034        *  This exchanges the elements between two lists in constant
01035        *  time.  Note that the global std::swap() function is
01036        *  specialized such that std::swap(l1,l2) will feed to this
01037        *  function.
01038        *
01039        *  Whether the allocators are swapped depends on the allocator traits.
01040        */
01041       void
01042       swap(forward_list& __list) noexcept
01043       {
01044         std::swap(this->_M_impl._M_head._M_next,
01045                   __list._M_impl._M_head._M_next);
01046         _Node_alloc_traits::_S_on_swap(this->_M_get_Node_allocator(),
01047                                        __list._M_get_Node_allocator());
01048       }
01049 
01050       /**
01051        *  @brief Resizes the %forward_list to the specified number of
01052        *         elements.
01053        *  @param __sz Number of elements the %forward_list should contain.
01054        *
01055        *  This function will %resize the %forward_list to the specified
01056        *  number of elements.  If the number is smaller than the
01057        *  %forward_list's current number of elements the %forward_list
01058        *  is truncated, otherwise the %forward_list is extended and the
01059        *  new elements are default constructed.
01060        */
01061       void
01062       resize(size_type __sz);
01063 
01064       /**
01065        *  @brief Resizes the %forward_list to the specified number of
01066        *         elements.
01067        *  @param __sz Number of elements the %forward_list should contain.
01068        *  @param __val Data with which new elements should be populated.
01069        *
01070        *  This function will %resize the %forward_list to the specified
01071        *  number of elements.  If the number is smaller than the
01072        *  %forward_list's current number of elements the %forward_list
01073        *  is truncated, otherwise the %forward_list is extended and new
01074        *  elements are populated with given data.
01075        */
01076       void
01077       resize(size_type __sz, const value_type& __val);
01078 
01079       /**
01080        *  @brief  Erases all the elements.
01081        *
01082        *  Note that this function only erases
01083        *  the elements, and that if the elements themselves are
01084        *  pointers, the pointed-to memory is not touched in any way.
01085        *  Managing the pointer is the user's responsibility.
01086        */
01087       void
01088       clear() noexcept
01089       { this->_M_erase_after(&this->_M_impl._M_head, nullptr); }
01090 
01091       // 23.3.4.6 forward_list operations:
01092 
01093       /**
01094        *  @brief  Insert contents of another %forward_list.
01095        *  @param  __pos  Iterator referencing the element to insert after.
01096        *  @param  __list  Source list.
01097        *
01098        *  The elements of @a list are inserted in constant time after
01099        *  the element referenced by @a pos.  @a list becomes an empty
01100        *  list.
01101        *
01102        *  Requires this != @a x.
01103        */
01104       void
01105       splice_after(const_iterator __pos, forward_list&& __list) noexcept
01106       {
01107         if (!__list.empty())
01108           _M_splice_after(__pos, __list.before_begin(), __list.end());
01109       }
01110 
01111       void
01112       splice_after(const_iterator __pos, forward_list& __list) noexcept
01113       { splice_after(__pos, std::move(__list)); }
01114 
01115       /**
01116        *  @brief  Insert element from another %forward_list.
01117        *  @param  __pos  Iterator referencing the element to insert after.
01118        *  @param  __list  Source list.
01119        *  @param  __i   Iterator referencing the element before the element
01120        *                to move.
01121        *
01122        *  Removes the element in list @a list referenced by @a i and
01123        *  inserts it into the current list after @a pos.
01124        */
01125       void
01126       splice_after(const_iterator __pos, forward_list&& __list,
01127                    const_iterator __i) noexcept;
01128 
01129       void
01130       splice_after(const_iterator __pos, forward_list& __list,
01131                    const_iterator __i) noexcept
01132       { splice_after(__pos, std::move(__list), __i); }
01133 
01134       /**
01135        *  @brief  Insert range from another %forward_list.
01136        *  @param  __pos  Iterator referencing the element to insert after.
01137        *  @param  __list  Source list.
01138        *  @param  __before  Iterator referencing before the start of range
01139        *                    in list.
01140        *  @param  __last  Iterator referencing the end of range in list.
01141        *
01142        *  Removes elements in the range (__before,__last) and inserts them
01143        *  after @a __pos in constant time.
01144        *
01145        *  Undefined if @a __pos is in (__before,__last).
01146        *  @{
01147        */
01148       void
01149       splice_after(const_iterator __pos, forward_list&&,
01150                    const_iterator __before, const_iterator __last) noexcept
01151       { _M_splice_after(__pos, __before, __last); }
01152 
01153       void
01154       splice_after(const_iterator __pos, forward_list&,
01155                    const_iterator __before, const_iterator __last) noexcept
01156       { _M_splice_after(__pos, __before, __last); }
01157       // @}
01158 
01159       /**
01160        *  @brief  Remove all elements equal to value.
01161        *  @param  __val  The value to remove.
01162        *
01163        *  Removes every element in the list equal to @a __val.
01164        *  Remaining elements stay in list order.  Note that this
01165        *  function only erases the elements, and that if the elements
01166        *  themselves are pointers, the pointed-to memory is not
01167        *  touched in any way.  Managing the pointer is the user's
01168        *  responsibility.
01169        */
01170       void
01171       remove(const _Tp& __val);
01172 
01173       /**
01174        *  @brief  Remove all elements satisfying a predicate.
01175        *  @param  __pred  Unary predicate function or object.
01176        *
01177        *  Removes every element in the list for which the predicate
01178        *  returns true.  Remaining elements stay in list order.  Note
01179        *  that this function only erases the elements, and that if the
01180        *  elements themselves are pointers, the pointed-to memory is
01181        *  not touched in any way.  Managing the pointer is the user's
01182        *  responsibility.
01183        */
01184       template<typename _Pred>
01185         void
01186         remove_if(_Pred __pred);
01187 
01188       /**
01189        *  @brief  Remove consecutive duplicate elements.
01190        *
01191        *  For each consecutive set of elements with the same value,
01192        *  remove all but the first one.  Remaining elements stay in
01193        *  list order.  Note that this function only erases the
01194        *  elements, and that if the elements themselves are pointers,
01195        *  the pointed-to memory is not touched in any way.  Managing
01196        *  the pointer is the user's responsibility.
01197        */
01198       void
01199       unique()
01200       { unique(std::equal_to<_Tp>()); }
01201 
01202       /**
01203        *  @brief  Remove consecutive elements satisfying a predicate.
01204        *  @param  __binary_pred  Binary predicate function or object.
01205        *
01206        *  For each consecutive set of elements [first,last) that
01207        *  satisfy predicate(first,i) where i is an iterator in
01208        *  [first,last), remove all but the first one.  Remaining
01209        *  elements stay in list order.  Note that this function only
01210        *  erases the elements, and that if the elements themselves are
01211        *  pointers, the pointed-to memory is not touched in any way.
01212        *  Managing the pointer is the user's responsibility.
01213        */
01214       template<typename _BinPred>
01215         void
01216         unique(_BinPred __binary_pred);
01217 
01218       /**
01219        *  @brief  Merge sorted lists.
01220        *  @param  __list  Sorted list to merge.
01221        *
01222        *  Assumes that both @a list and this list are sorted according to
01223        *  operator<().  Merges elements of @a __list into this list in
01224        *  sorted order, leaving @a __list empty when complete.  Elements in
01225        *  this list precede elements in @a __list that are equal.
01226        */
01227       void
01228       merge(forward_list&& __list)
01229       { merge(std::move(__list), std::less<_Tp>()); }
01230 
01231       void
01232       merge(forward_list& __list)
01233       { merge(std::move(__list)); }
01234 
01235       /**
01236        *  @brief  Merge sorted lists according to comparison function.
01237        *  @param  __list  Sorted list to merge.
01238        *  @param  __comp Comparison function defining sort order.
01239        *
01240        *  Assumes that both @a __list and this list are sorted according to
01241        *  comp.  Merges elements of @a __list into this list
01242        *  in sorted order, leaving @a __list empty when complete.  Elements
01243        *  in this list precede elements in @a __list that are equivalent
01244        *  according to comp().
01245        */
01246       template<typename _Comp>
01247         void
01248         merge(forward_list&& __list, _Comp __comp);
01249 
01250       template<typename _Comp>
01251         void
01252         merge(forward_list& __list, _Comp __comp)
01253         { merge(std::move(__list), __comp); }
01254 
01255       /**
01256        *  @brief  Sort the elements of the list.
01257        *
01258        *  Sorts the elements of this list in NlogN time.  Equivalent
01259        *  elements remain in list order.
01260        */
01261       void
01262       sort()
01263       { sort(std::less<_Tp>()); }
01264 
01265       /**
01266        *  @brief  Sort the forward_list using a comparison function.
01267        *
01268        *  Sorts the elements of this list in NlogN time.  Equivalent
01269        *  elements remain in list order.
01270        */
01271       template<typename _Comp>
01272         void
01273         sort(_Comp __comp);
01274 
01275       /**
01276        *  @brief  Reverse the elements in list.
01277        *
01278        *  Reverse the order of elements in the list in linear time.
01279        */
01280       void
01281       reverse() noexcept
01282       { this->_M_impl._M_head._M_reverse_after(); }
01283 
01284     private:
01285       // Called by the range constructor to implement [23.3.4.2]/9
01286       template<typename _InputIterator>
01287         void
01288         _M_range_initialize(_InputIterator __first, _InputIterator __last);
01289 
01290       // Called by forward_list(n,v,a), and the range constructor when it
01291       // turns out to be the same thing.
01292       void
01293       _M_fill_initialize(size_type __n, const value_type& __value);
01294 
01295       // Called by splice_after and insert_after.
01296       iterator
01297       _M_splice_after(const_iterator __pos, const_iterator __before,
01298                       const_iterator __last);
01299 
01300       // Called by forward_list(n).
01301       void
01302       _M_default_initialize(size_type __n);
01303 
01304       // Called by resize(sz).
01305       void
01306       _M_default_insert_after(const_iterator __pos, size_type __n);
01307 
01308       // Called by operator=(forward_list&&)
01309       void
01310       _M_move_assign(forward_list&& __list, true_type) noexcept
01311       {
01312         clear();
01313         this->_M_impl._M_head._M_next = __list._M_impl._M_head._M_next;
01314         __list._M_impl._M_head._M_next = nullptr;
01315         std::__alloc_on_move(this->_M_get_Node_allocator(),
01316                              __list._M_get_Node_allocator());
01317       }
01318 
01319       // Called by operator=(forward_list&&)
01320       void
01321       _M_move_assign(forward_list&& __list, false_type)
01322       {
01323         if (__list._M_get_Node_allocator() == this->_M_get_Node_allocator())
01324           _M_move_assign(std::move(__list), true_type());
01325         else
01326           // The rvalue's allocator cannot be moved, or is not equal,
01327           // so we need to individually move each element.
01328           this->assign(std::__make_move_if_noexcept_iterator(__list.begin()),
01329                        std::__make_move_if_noexcept_iterator(__list.end()));
01330       }
01331 
01332       // Called by assign(_InputIterator, _InputIterator) if _Tp is
01333       // CopyAssignable.
01334       template<typename _InputIterator>
01335         void
01336         _M_assign(_InputIterator __first, _InputIterator __last, true_type)
01337         {
01338           auto __prev = before_begin();
01339           auto __curr = begin();
01340           auto __end = end();
01341           while (__curr != __end && __first != __last)
01342             {
01343               *__curr = *__first;
01344               ++__prev;
01345               ++__curr;
01346               ++__first;
01347             }
01348           if (__first != __last)
01349             insert_after(__prev, __first, __last);
01350           else if (__curr != __end)
01351             erase_after(__prev, __end);
01352         }
01353 
01354       // Called by assign(_InputIterator, _InputIterator) if _Tp is not
01355       // CopyAssignable.
01356       template<typename _InputIterator>
01357         void
01358         _M_assign(_InputIterator __first, _InputIterator __last, false_type)
01359         {
01360           clear();
01361           insert_after(cbefore_begin(), __first, __last);
01362         }
01363 
01364       // Called by assign(size_type, const _Tp&) if Tp is CopyAssignable
01365       void
01366       _M_assign_n(size_type __n, const _Tp& __val, true_type)
01367       {
01368         auto __prev = before_begin();
01369         auto __curr = begin();
01370         auto __end = end();
01371         while (__curr != __end && __n > 0)
01372           {
01373             *__curr = __val;
01374             ++__prev;
01375             ++__curr;
01376             --__n;
01377           }
01378         if (__n > 0)
01379           insert_after(__prev, __n, __val);
01380         else if (__curr != __end)
01381           erase_after(__prev, __end);
01382       }
01383 
01384       // Called by assign(size_type, const _Tp&) if Tp is non-CopyAssignable
01385       void
01386       _M_assign_n(size_type __n, const _Tp& __val, false_type)
01387       {
01388         clear();
01389         insert_after(cbefore_begin(), __n, __val);
01390       }
01391     };
01392 
01393 #if __cpp_deduction_guides >= 201606
01394   template<typename _InputIterator, typename _ValT
01395              = typename iterator_traits<_InputIterator>::value_type,
01396            typename _Allocator = allocator<_ValT>,
01397            typename = _RequireInputIter<_InputIterator>,
01398            typename = _RequireAllocator<_Allocator>>
01399     forward_list(_InputIterator, _InputIterator, _Allocator = _Allocator())
01400       -> forward_list<_ValT, _Allocator>;
01401 #endif
01402 
01403   /**
01404    *  @brief  Forward list equality comparison.
01405    *  @param  __lx  A %forward_list
01406    *  @param  __ly  A %forward_list of the same type as @a __lx.
01407    *  @return  True iff the elements of the forward lists are equal.
01408    *
01409    *  This is an equivalence relation.  It is linear in the number of
01410    *  elements of the forward lists.  Deques are considered equivalent
01411    *  if corresponding elements compare equal.
01412    */
01413   template<typename _Tp, typename _Alloc>
01414     bool
01415     operator==(const forward_list<_Tp, _Alloc>& __lx,
01416                const forward_list<_Tp, _Alloc>& __ly);
01417 
01418   /**
01419    *  @brief  Forward list ordering relation.
01420    *  @param  __lx  A %forward_list.
01421    *  @param  __ly  A %forward_list of the same type as @a __lx.
01422    *  @return  True iff @a __lx is lexicographically less than @a __ly.
01423    *
01424    *  This is a total ordering relation.  It is linear in the number of
01425    *  elements of the forward lists.  The elements must be comparable
01426    *  with @c <.
01427    *
01428    *  See std::lexicographical_compare() for how the determination is made.
01429    */
01430   template<typename _Tp, typename _Alloc>
01431     inline bool
01432     operator<(const forward_list<_Tp, _Alloc>& __lx,
01433               const forward_list<_Tp, _Alloc>& __ly)
01434     { return std::lexicographical_compare(__lx.cbegin(), __lx.cend(),
01435                                           __ly.cbegin(), __ly.cend()); }
01436 
01437   /// Based on operator==
01438   template<typename _Tp, typename _Alloc>
01439     inline bool
01440     operator!=(const forward_list<_Tp, _Alloc>& __lx,
01441                const forward_list<_Tp, _Alloc>& __ly)
01442     { return !(__lx == __ly); }
01443 
01444   /// Based on operator<
01445   template<typename _Tp, typename _Alloc>
01446     inline bool
01447     operator>(const forward_list<_Tp, _Alloc>& __lx,
01448               const forward_list<_Tp, _Alloc>& __ly)
01449     { return (__ly < __lx); }
01450 
01451   /// Based on operator<
01452   template<typename _Tp, typename _Alloc>
01453     inline bool
01454     operator>=(const forward_list<_Tp, _Alloc>& __lx,
01455                const forward_list<_Tp, _Alloc>& __ly)
01456     { return !(__lx < __ly); }
01457 
01458   /// Based on operator<
01459   template<typename _Tp, typename _Alloc>
01460     inline bool
01461     operator<=(const forward_list<_Tp, _Alloc>& __lx,
01462                const forward_list<_Tp, _Alloc>& __ly)
01463     { return !(__ly < __lx); }
01464 
01465   /// See std::forward_list::swap().
01466   template<typename _Tp, typename _Alloc>
01467     inline void
01468     swap(forward_list<_Tp, _Alloc>& __lx,
01469          forward_list<_Tp, _Alloc>& __ly)
01470     noexcept(noexcept(__lx.swap(__ly)))
01471     { __lx.swap(__ly); }
01472 
01473 _GLIBCXX_END_NAMESPACE_CONTAINER
01474 _GLIBCXX_END_NAMESPACE_VERSION
01475 } // namespace std
01476 
01477 #endif // _FORWARD_LIST_H