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// <forward_list.h> -- C++ -- // Copyright (C) 2008-2018 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file bits/forward_list.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{forward_list} / #ifndef _FORWARD_LIST_H #define _FORWARD_LIST_H 1 #pragma GCC system_header #include <initializer_list> #include <bits/stl_iterator_base_types.h> #include <bits/stl_iterator.h> #include <bits/stl_algobase.h> #include <bits/stl_function.h> #include <bits/allocator.h> #include <ext/alloc_traits.h> #include <ext/aligned_buffer.h> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION _GLIBCXX_BEGIN_NAMESPACE_CONTAINER /* * @brief A helper basic node class for %forward_list. * This is just a linked list with nothing inside it. * There are purely list shuffling utility methods here. / struct _Fwd_list_node_base { _Fwd_list_node_base() = default; _Fwd_list_node_base(_Fwd_list_node_base&& __x) noexcept : _M_next(__x._M_next) { __x._M_next = nullptr; } _Fwd_list_node_base(const _Fwd_list_node_base&) = delete; _Fwd_list_node_base& operator=(const _Fwd_list_node_base&) = delete; _Fwd_list_node_base& operator=(_Fwd_list_node_base&& __x) noexcept { _M_next = __x._M_next; __x._M_next = nullptr; return this; } _Fwd_list_node_base* _M_next = nullptr; _Fwd_list_node_base* _M_transfer_after(_Fwd_list_node_base* __begin, _Fwd_list_node_base* __end) noexcept { _Fwd_list_node_base* __keep = __begin->_M_next; if (__end) { __begin->_M_next = __end->_M_next; __end->_M_next = _M_next; } else __begin->_M_next = nullptr; _M_next = __keep; return __end; } void _M_reverse_after() noexcept { _Fwd_list_node_base* __tail = _M_next; if (!__tail) return; while (_Fwd_list_node_base* __temp = __tail->_M_next) { _Fwd_list_node_base* __keep = _M_next; _M_next = __temp; __tail->_M_next = __temp->_M_next; _M_next->_M_next = __keep; } } }; /** * @brief A helper node class for %forward_list. * This is just a linked list with uninitialized storage for a * data value in each node. * There is a sorting utility method. / template<typename _Tp> struct _Fwd_list_node : public _Fwd_list_node_base { _Fwd_list_node() = default; __gnu_cxx::__aligned_buffer<_Tp> _M_storage; _Tp _M_valptr() noexcept { return _M_storage._M_ptr(); } const _Tp* _M_valptr() const noexcept { return _M_storage._M_ptr(); } }; /** * @brief A forward_list::iterator. * * All the functions are op overloads. / template<typename _Tp> struct _Fwd_list_iterator { typedef _Fwd_list_iterator<_Tp> _Self; typedef _Fwd_list_node<_Tp> _Node; typedef _Tp value_type; typedef _Tp pointer; typedef _Tp& reference; typedef ptrdiff_t difference_type; typedef std::forward_iterator_tag iterator_category; _Fwd_list_iterator() noexcept : _M_node() { } explicit _Fwd_list_iterator(_Fwd_list_node_base* __n) noexcept : _M_node(__n) { } reference operator() const noexcept { return static_cast<_Node>(this->_M_node)->_M_valptr(); } pointer operator->() const noexcept { return static_cast<_Node>(this->_M_node)->_M_valptr(); } _Self& operator++() noexcept { _M_node = _M_node->_M_next; return this; } _Self operator++(int) noexcept { _Self __tmp(this); _M_node = _M_node->_M_next; return __tmp; } bool operator==(const _Self& __x) const noexcept { return _M_node == __x._M_node; } bool operator!=(const _Self& __x) const noexcept { return _M_node != __x._M_node; } _Self _M_next() const noexcept { if (_M_node) return _Fwd_list_iterator(_M_node->_M_next); else return _Fwd_list_iterator(nullptr); } _Fwd_list_node_base* _M_node; }; /** * @brief A forward_list::const_iterator. * * All the functions are op overloads. / template<typename _Tp> struct _Fwd_list_const_iterator { typedef _Fwd_list_const_iterator<_Tp> _Self; typedef const _Fwd_list_node<_Tp> _Node; typedef _Fwd_list_iterator<_Tp> iterator; typedef _Tp value_type; typedef const _Tp pointer; typedef const _Tp& reference; typedef ptrdiff_t difference_type; typedef std::forward_iterator_tag iterator_category; _Fwd_list_const_iterator() noexcept : _M_node() { } explicit _Fwd_list_const_iterator(const _Fwd_list_node_base* __n) noexcept : _M_node(__n) { } _Fwd_list_const_iterator(const iterator& __iter) noexcept : _M_node(__iter._M_node) { } reference operator() const noexcept { return static_cast<_Node>(this->_M_node)->_M_valptr(); } pointer operator->() const noexcept { return static_cast<_Node>(this->_M_node)->_M_valptr(); } _Self& operator++() noexcept { _M_node = _M_node->_M_next; return this; } _Self operator++(int) noexcept { _Self __tmp(this); _M_node = _M_node->_M_next; return __tmp; } bool operator==(const _Self& __x) const noexcept { return _M_node == __x._M_node; } bool operator!=(const _Self& __x) const noexcept { return _M_node != __x._M_node; } _Self _M_next() const noexcept { if (this->_M_node) return _Fwd_list_const_iterator(_M_node->_M_next); else return _Fwd_list_const_iterator(nullptr); } const _Fwd_list_node_base* _M_node; }; /** * @brief Forward list iterator equality comparison. / template<typename _Tp> inline bool operator==(const _Fwd_list_iterator<_Tp>& __x, const _Fwd_list_const_iterator<_Tp>& __y) noexcept { return __x._M_node == __y._M_node; } /* * @brief Forward list iterator inequality comparison. / template<typename _Tp> inline bool operator!=(const _Fwd_list_iterator<_Tp>& __x, const _Fwd_list_const_iterator<_Tp>& __y) noexcept { return __x._M_node != __y._M_node; } /* * @brief Base class for %forward_list. / template<typename _Tp, typename _Alloc> struct _Fwd_list_base { protected: typedef __alloc_rebind<_Alloc, _Fwd_list_node<_Tp>> _Node_alloc_type; typedef __gnu_cxx::__alloc_traits<_Node_alloc_type> _Node_alloc_traits; struct _Fwd_list_impl : public _Node_alloc_type { _Fwd_list_node_base _M_head; _Fwd_list_impl() noexcept(is_nothrow_default_constructible<_Node_alloc_type>::value) : _Node_alloc_type(), _M_head() { } _Fwd_list_impl(_Fwd_list_impl&&) = default; _Fwd_list_impl(_Fwd_list_impl&& __fl, _Node_alloc_type&& __a) : _Node_alloc_type(std::move(__a)), _M_head(std::move(__fl._M_head)) { } _Fwd_list_impl(_Node_alloc_type&& __a) : _Node_alloc_type(std::move(__a)), _M_head() { } }; _Fwd_list_impl _M_impl; public: typedef _Fwd_list_iterator<_Tp> iterator; typedef _Fwd_list_const_iterator<_Tp> const_iterator; typedef _Fwd_list_node<_Tp> _Node; _Node_alloc_type& _M_get_Node_allocator() noexcept { return this->_M_impl; } const _Node_alloc_type& _M_get_Node_allocator() const noexcept { return this->_M_impl; } _Fwd_list_base() = default; _Fwd_list_base(_Node_alloc_type&& __a) : _M_impl(std::move(__a)) { } // When allocators are always equal. _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a, std::true_type) : _M_impl(std::move(__lst._M_impl), std::move(__a)) { } // When allocators are not always equal. _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a); _Fwd_list_base(_Fwd_list_base&&) = default; ~_Fwd_list_base() { _M_erase_after(&_M_impl._M_head, nullptr); } protected: _Node _M_get_node() { auto __ptr = _Node_alloc_traits::allocate(_M_get_Node_allocator(), 1); return std::__to_address(__ptr); } template<typename... _Args> _Node* _M_create_node(_Args&&... __args) { _Node* __node = this->_M_get_node(); __try { ::new ((void)__node) _Node; _Node_alloc_traits::construct(_M_get_Node_allocator(), __node->_M_valptr(), std::forward<_Args>(__args)...); } __catch(...) { this->_M_put_node(__node); __throw_exception_again; } return __node; } template<typename... _Args> _Fwd_list_node_base _M_insert_after(const_iterator __pos, _Args&&... __args); void _M_put_node(_Node* __p) { typedef typename _Node_alloc_traits::pointer _Ptr; auto __ptr = std::pointer_traits<_Ptr>::pointer_to(__p); _Node_alloc_traits::deallocate(_M_get_Node_allocator(), __ptr, 1); } _Fwd_list_node_base _M_erase_after(_Fwd_list_node_base* __pos); _Fwd_list_node_base* _M_erase_after(_Fwd_list_node_base* __pos, _Fwd_list_node_base* __last); }; /** * @brief A standard container with linear time access to elements, * and fixed time insertion/deletion at any point in the sequence. * * @ingroup sequences * * @tparam _Tp Type of element. * @tparam _Alloc Allocator type, defaults to allocator<_Tp>. * * Meets the requirements of a <a href="tables.html#65">container</a>, a * <a href="tables.html#67">sequence</a>, including the * <a href="tables.html#68">optional sequence requirements</a> with the * %exception of @c at and @c operator[]. * * This is a @e singly @e linked %list. Traversal up the * %list requires linear time, but adding and removing elements (or * @e nodes) is done in constant time, regardless of where the * change takes place. Unlike std::vector and std::deque, * random-access iterators are not provided, so subscripting ( @c * [] ) access is not allowed. For algorithms which only need * sequential access, this lack makes no difference. * * Also unlike the other standard containers, std::forward_list provides * specialized algorithms %unique to linked lists, such as * splicing, sorting, and in-place reversal. / template<typename _Tp, typename _Alloc = allocator<_Tp>> class forward_list : private _Fwd_list_base<_Tp, _Alloc> { static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value, "std::forward_list must have a non-const, non-volatile value_type"); #ifdef __STRICT_ANSI__ static_assert(is_same<typename _Alloc::value_type, _Tp>::value, "std::forward_list must have the same value_type as its allocator"); #endif private: typedef _Fwd_list_base<_Tp, _Alloc> _Base; typedef _Fwd_list_node<_Tp> _Node; typedef _Fwd_list_node_base _Node_base; typedef typename _Base::_Node_alloc_type _Node_alloc_type; typedef typename _Base::_Node_alloc_traits _Node_alloc_traits; typedef allocator_traits<__alloc_rebind<_Alloc, _Tp>> _Alloc_traits; public: // types: typedef _Tp value_type; typedef typename _Alloc_traits::pointer pointer; typedef typename _Alloc_traits::const_pointer const_pointer; typedef value_type& reference; typedef const value_type& const_reference; typedef _Fwd_list_iterator<_Tp> iterator; typedef _Fwd_list_const_iterator<_Tp> const_iterator; typedef std::size_t size_type; typedef std::ptrdiff_t difference_type; typedef _Alloc allocator_type; // 23.3.4.2 construct/copy/destroy: /* * @brief Creates a %forward_list with no elements. / forward_list() = default; /* * @brief Creates a %forward_list with no elements. * @param __al An allocator object. / explicit forward_list(const _Alloc& __al) noexcept : _Base(_Node_alloc_type(__al)) { } /* * @brief Copy constructor with allocator argument. * @param __list Input list to copy. * @param __al An allocator object. / forward_list(const forward_list& __list, const _Alloc& __al) : _Base(_Node_alloc_type(__al)) { _M_range_initialize(__list.begin(), __list.end()); } private: forward_list(forward_list&& __list, _Node_alloc_type&& __al, false_type) : _Base(std::move(__list), std::move(__al)) { // If __list is not empty it means its allocator is not equal to __a, // so we need to move from each element individually. insert_after(cbefore_begin(), std::__make_move_if_noexcept_iterator(__list.begin()), std::__make_move_if_noexcept_iterator(__list.end())); } forward_list(forward_list&& __list, _Node_alloc_type&& __al, true_type) noexcept : _Base(std::move(__list), _Node_alloc_type(__al), true_type{}) { } public: /* * @brief Move constructor with allocator argument. * @param __list Input list to move. * @param __al An allocator object. / forward_list(forward_list&& __list, const _Alloc& __al) noexcept(_Node_alloc_traits::_S_always_equal()) : forward_list(std::move(__list), _Node_alloc_type(__al), typename _Node_alloc_traits::is_always_equal{}) { } /* * @brief Creates a %forward_list with default constructed elements. * @param __n The number of elements to initially create. * @param __al An allocator object. * * This constructor creates the %forward_list with @a __n default * constructed elements. / explicit forward_list(size_type __n, const _Alloc& __al = _Alloc()) : _Base(_Node_alloc_type(__al)) { _M_default_initialize(__n); } /* * @brief Creates a %forward_list with copies of an exemplar element. * @param __n The number of elements to initially create. * @param __value An element to copy. * @param __al An allocator object. * * This constructor fills the %forward_list with @a __n copies of * @a __value. / forward_list(size_type __n, const _Tp& __value, const _Alloc& __al = _Alloc()) : _Base(_Node_alloc_type(__al)) { _M_fill_initialize(__n, __value); } /* * @brief Builds a %forward_list from a range. * @param __first An input iterator. * @param __last An input iterator. * @param __al An allocator object. * * Create a %forward_list consisting of copies of the elements from * [@a __first,@a __last). This is linear in N (where N is * distance(@a __first,@a __last)). / template<typename _InputIterator, typename = std::_RequireInputIter<_InputIterator>> forward_list(_InputIterator __first, _InputIterator __last, const _Alloc& __al = _Alloc()) : _Base(_Node_alloc_type(__al)) { _M_range_initialize(__first, __last); } /* * @brief The %forward_list copy constructor. * @param __list A %forward_list of identical element and allocator * types. / forward_list(const forward_list& __list) : _Base(_Node_alloc_traits::_S_select_on_copy( __list._M_get_Node_allocator())) { _M_range_initialize(__list.begin(), __list.end()); } /* * @brief The %forward_list move constructor. * @param __list A %forward_list of identical element and allocator * types. * * The newly-created %forward_list contains the exact contents of the * moved instance. The contents of the moved instance are a valid, but * unspecified %forward_list. / forward_list(forward_list&&) = default; /* * @brief Builds a %forward_list from an initializer_list * @param __il An initializer_list of value_type. * @param __al An allocator object. * * Create a %forward_list consisting of copies of the elements * in the initializer_list @a __il. This is linear in __il.size(). / forward_list(std::initializer_list<_Tp> __il, const _Alloc& __al = _Alloc()) : _Base(_Node_alloc_type(__al)) { _M_range_initialize(__il.begin(), __il.end()); } /* * @brief The forward_list dtor. / ~forward_list() noexcept { } /* * @brief The %forward_list assignment operator. * @param __list A %forward_list of identical element and allocator * types. * * All the elements of @a __list are copied. * * Whether the allocator is copied depends on the allocator traits. / forward_list& operator=(const forward_list& __list); /* * @brief The %forward_list move assignment operator. * @param __list A %forward_list of identical element and allocator * types. * * The contents of @a __list are moved into this %forward_list * (without copying, if the allocators permit it). * * Afterwards @a __list is a valid, but unspecified %forward_list * * Whether the allocator is moved depends on the allocator traits. / forward_list& operator=(forward_list&& __list) noexcept(_Node_alloc_traits::_S_nothrow_move()) { constexpr bool __move_storage = _Node_alloc_traits::_S_propagate_on_move_assign() \|\| _Node_alloc_traits::_S_always_equal(); _M_move_assign(std::move(__list), __bool_constant<__move_storage>()); return this; } /** * @brief The %forward_list initializer list assignment operator. * @param __il An initializer_list of value_type. * * Replace the contents of the %forward_list with copies of the * elements in the initializer_list @a __il. This is linear in * __il.size(). / forward_list& operator=(std::initializer_list<_Tp> __il) { assign(__il); return this; } /** * @brief Assigns a range to a %forward_list. * @param __first An input iterator. * @param __last An input iterator. * * This function fills a %forward_list with copies of the elements * in the range [@a __first,@a __last). * * Note that the assignment completely changes the %forward_list and * that the number of elements of the resulting %forward_list is the * same as the number of elements assigned. / template<typename _InputIterator, typename = std::_RequireInputIter<_InputIterator>> void assign(_InputIterator __first, _InputIterator __last) { typedef is_assignable<_Tp, decltype(__first)> __assignable; _M_assign(__first, __last, __assignable()); } /** * @brief Assigns a given value to a %forward_list. * @param __n Number of elements to be assigned. * @param __val Value to be assigned. * * This function fills a %forward_list with @a __n copies of the * given value. Note that the assignment completely changes the * %forward_list, and that the resulting %forward_list has __n * elements. / void assign(size_type __n, const _Tp& __val) { _M_assign_n(__n, __val, is_copy_assignable<_Tp>()); } /* * @brief Assigns an initializer_list to a %forward_list. * @param __il An initializer_list of value_type. * * Replace the contents of the %forward_list with copies of the * elements in the initializer_list @a __il. This is linear in * il.size(). / void assign(std::initializer_list<_Tp> __il) { assign(__il.begin(), __il.end()); } /// Get a copy of the memory allocation object. allocator_type get_allocator() const noexcept { return allocator_type(this->_M_get_Node_allocator()); } // 23.3.4.3 iterators: /* * Returns a read/write iterator that points before the first element * in the %forward_list. Iteration is done in ordinary element order. / iterator before_begin() noexcept { return iterator(&this->_M_impl._M_head); } /* * Returns a read-only (constant) iterator that points before the * first element in the %forward_list. Iteration is done in ordinary * element order. / const_iterator before_begin() const noexcept { return const_iterator(&this->_M_impl._M_head); } /* * Returns a read/write iterator that points to the first element * in the %forward_list. Iteration is done in ordinary element order. / iterator begin() noexcept { return iterator(this->_M_impl._M_head._M_next); } /* * Returns a read-only (constant) iterator that points to the first * element in the %forward_list. Iteration is done in ordinary * element order. / const_iterator begin() const noexcept { return const_iterator(this->_M_impl._M_head._M_next); } /* * Returns a read/write iterator that points one past the last * element in the %forward_list. Iteration is done in ordinary * element order. / iterator end() noexcept { return iterator(nullptr); } /* * Returns a read-only iterator that points one past the last * element in the %forward_list. Iteration is done in ordinary * element order. / const_iterator end() const noexcept { return const_iterator(nullptr); } /* * Returns a read-only (constant) iterator that points to the * first element in the %forward_list. Iteration is done in ordinary * element order. / const_iterator cbegin() const noexcept { return const_iterator(this->_M_impl._M_head._M_next); } /* * Returns a read-only (constant) iterator that points before the * first element in the %forward_list. Iteration is done in ordinary * element order. / const_iterator cbefore_begin() const noexcept { return const_iterator(&this->_M_impl._M_head); } /* * Returns a read-only (constant) iterator that points one past * the last element in the %forward_list. Iteration is done in * ordinary element order. / const_iterator cend() const noexcept { return const_iterator(nullptr); } /* * Returns true if the %forward_list is empty. (Thus begin() would * equal end().) / bool empty() const noexcept { return this->_M_impl._M_head._M_next == nullptr; } /* * Returns the largest possible number of elements of %forward_list. / size_type max_size() const noexcept { return _Node_alloc_traits::max_size(this->_M_get_Node_allocator()); } // 23.3.4.4 element access: /* * Returns a read/write reference to the data at the first * element of the %forward_list. / reference front() { _Node __front = static_cast<_Node>(this->_M_impl._M_head._M_next); return __front->_M_valptr(); } /** * Returns a read-only (constant) reference to the data at the first * element of the %forward_list. / const_reference front() const { _Node __front = static_cast<_Node>(this->_M_impl._M_head._M_next); return __front->_M_valptr(); } // 23.3.4.5 modiﬁers: /** * @brief Constructs object in %forward_list at the front of the * list. * @param __args Arguments. * * This function will insert an object of type Tp constructed * with Tp(std::forward<Args>(args)...) at the front of the list * Due to the nature of a %forward_list this operation can * be done in constant time, and does not invalidate iterators * and references. / template<typename... _Args> #if __cplusplus > 201402L reference #else void #endif emplace_front(_Args&&... __args) { this->_M_insert_after(cbefore_begin(), std::forward<_Args>(__args)...); #if __cplusplus > 201402L return front(); #endif } /* * @brief Add data to the front of the %forward_list. * @param __val Data to be added. * * This is a typical stack operation. The function creates an * element at the front of the %forward_list and assigns the given * data to it. Due to the nature of a %forward_list this operation * can be done in constant time, and does not invalidate iterators * and references. / void push_front(const _Tp& __val) { this->_M_insert_after(cbefore_begin(), __val); } /* * / void push_front(_Tp&& __val) { this->_M_insert_after(cbefore_begin(), std::move(__val)); } /* * @brief Removes first element. * * This is a typical stack operation. It shrinks the %forward_list * by one. Due to the nature of a %forward_list this operation can * be done in constant time, and only invalidates iterators/references * to the element being removed. * * Note that no data is returned, and if the first element's data * is needed, it should be retrieved before pop_front() is * called. / void pop_front() { this->_M_erase_after(&this->_M_impl._M_head); } /* * @brief Constructs object in %forward_list after the specified * iterator. * @param __pos A const_iterator into the %forward_list. * @param __args Arguments. * @return An iterator that points to the inserted data. * * This function will insert an object of type T constructed * with T(std::forward<Args>(args)...) after the specified * location. Due to the nature of a %forward_list this operation can * be done in constant time, and does not invalidate iterators * and references. / template<typename... _Args> iterator emplace_after(const_iterator __pos, _Args&&... __args) { return iterator(this->_M_insert_after(__pos, std::forward<_Args>(__args)...)); } /* * @brief Inserts given value into %forward_list after specified * iterator. * @param __pos An iterator into the %forward_list. * @param __val Data to be inserted. * @return An iterator that points to the inserted data. * * This function will insert a copy of the given value after * the specified location. Due to the nature of a %forward_list this * operation can be done in constant time, and does not * invalidate iterators and references. / iterator insert_after(const_iterator __pos, const _Tp& __val) { return iterator(this->_M_insert_after(__pos, __val)); } /* * / iterator insert_after(const_iterator __pos, _Tp&& __val) { return iterator(this->_M_insert_after(__pos, std::move(__val))); } /* * @brief Inserts a number of copies of given data into the * %forward_list. * @param __pos An iterator into the %forward_list. * @param __n Number of elements to be inserted. * @param __val Data to be inserted. * @return An iterator pointing to the last inserted copy of * @a val or @a pos if @a n == 0. * * This function will insert a specified number of copies of the * given data after the location specified by @a pos. * * This operation is linear in the number of elements inserted and * does not invalidate iterators and references. / iterator insert_after(const_iterator __pos, size_type __n, const _Tp& __val); /* * @brief Inserts a range into the %forward_list. * @param __pos An iterator into the %forward_list. * @param __first An input iterator. * @param __last An input iterator. * @return An iterator pointing to the last inserted element or * @a __pos if @a __first == @a __last. * * This function will insert copies of the data in the range * [@a __first,@a __last) into the %forward_list after the * location specified by @a __pos. * * This operation is linear in the number of elements inserted and * does not invalidate iterators and references. / template<typename _InputIterator, typename = std::_RequireInputIter<_InputIterator>> iterator insert_after(const_iterator __pos, _InputIterator __first, _InputIterator __last); /* * @brief Inserts the contents of an initializer_list into * %forward_list after the specified iterator. * @param __pos An iterator into the %forward_list. * @param __il An initializer_list of value_type. * @return An iterator pointing to the last inserted element * or @a __pos if @a __il is empty. * * This function will insert copies of the data in the * initializer_list @a __il into the %forward_list before the location * specified by @a __pos. * * This operation is linear in the number of elements inserted and * does not invalidate iterators and references. / iterator insert_after(const_iterator __pos, std::initializer_list<_Tp> __il) { return insert_after(__pos, __il.begin(), __il.end()); } /* * @brief Removes the element pointed to by the iterator following * @c pos. * @param __pos Iterator pointing before element to be erased. * @return An iterator pointing to the element following the one * that was erased, or end() if no such element exists. * * This function will erase the element at the given position and * thus shorten the %forward_list by one. * * Due to the nature of a %forward_list this operation can be done * in constant time, and only invalidates iterators/references to * the element being removed. The user is also cautioned that * this function only erases the element, and that if the element * is itself a pointer, the pointed-to memory is not touched in * any way. Managing the pointer is the user's responsibility. / iterator erase_after(const_iterator __pos) { return iterator(this->_M_erase_after(const_cast<_Node_base> (__pos._M_node))); } /** * @brief Remove a range of elements. * @param __pos Iterator pointing before the first element to be * erased. * @param __last Iterator pointing to one past the last element to be * erased. * @return @ __last. * * This function will erase the elements in the range * @a (__pos,__last) and shorten the %forward_list accordingly. * * This operation is linear time in the size of the range and only * invalidates iterators/references to the element being removed. * The user is also cautioned that this function only erases the * elements, and that if the elements themselves are pointers, the * pointed-to memory is not touched in any way. Managing the pointer * is the user's responsibility. / iterator erase_after(const_iterator __pos, const_iterator __last) { return iterator(this->_M_erase_after(const_cast<_Node_base> (__pos._M_node), const_cast<_Node_base> (__last._M_node))); } /* * @brief Swaps data with another %forward_list. * @param __list A %forward_list of the same element and allocator * types. * * This exchanges the elements between two lists in constant * time. Note that the global std::swap() function is * specialized such that std::swap(l1,l2) will feed to this * function. * * Whether the allocators are swapped depends on the allocator traits. / void swap(forward_list& __list) noexcept { std::swap(this->_M_impl._M_head._M_next, __list._M_impl._M_head._M_next); _Node_alloc_traits::_S_on_swap(this->_M_get_Node_allocator(), __list._M_get_Node_allocator()); } /* * @brief Resizes the %forward_list to the specified number of * elements. * @param __sz Number of elements the %forward_list should contain. * * This function will %resize the %forward_list to the specified * number of elements. If the number is smaller than the * %forward_list's current number of elements the %forward_list * is truncated, otherwise the %forward_list is extended and the * new elements are default constructed. / void resize(size_type __sz); /* * @brief Resizes the %forward_list to the specified number of * elements. * @param __sz Number of elements the %forward_list should contain. * @param __val Data with which new elements should be populated. * * This function will %resize the %forward_list to the specified * number of elements. If the number is smaller than the * %forward_list's current number of elements the %forward_list * is truncated, otherwise the %forward_list is extended and new * elements are populated with given data. / void resize(size_type __sz, const value_type& __val); /* * @brief Erases all the elements. * * Note that this function only erases * the elements, and that if the elements themselves are * pointers, the pointed-to memory is not touched in any way. * Managing the pointer is the user's responsibility. / void clear() noexcept { this->_M_erase_after(&this->_M_impl._M_head, nullptr); } // 23.3.4.6 forward_list operations: /* * @brief Insert contents of another %forward_list. * @param __pos Iterator referencing the element to insert after. * @param __list Source list. * * The elements of @a list are inserted in constant time after * the element referenced by @a pos. @a list becomes an empty * list. * * Requires this != @a x. / void splice_after(const_iterator __pos, forward_list&& __list) noexcept { if (!__list.empty()) _M_splice_after(__pos, __list.before_begin(), __list.end()); } void splice_after(const_iterator __pos, forward_list& __list) noexcept { splice_after(__pos, std::move(__list)); } /* * @brief Insert element from another %forward_list. * @param __pos Iterator referencing the element to insert after. * @param __list Source list. * @param __i Iterator referencing the element before the element * to move. * * Removes the element in list @a list referenced by @a i and * inserts it into the current list after @a pos. / void splice_after(const_iterator __pos, forward_list&& __list, const_iterator __i) noexcept; void splice_after(const_iterator __pos, forward_list& __list, const_iterator __i) noexcept { splice_after(__pos, std::move(__list), __i); } /* * @brief Insert range from another %forward_list. * @param __pos Iterator referencing the element to insert after. * @param __list Source list. * @param __before Iterator referencing before the start of range * in list. * @param __last Iterator referencing the end of range in list. * * Removes elements in the range (__before,__last) and inserts them * after @a __pos in constant time. * * Undefined if @a __pos is in (__before,__last). * @{ / void splice_after(const_iterator __pos, forward_list&&, const_iterator __before, const_iterator __last) noexcept { _M_splice_after(__pos, __before, __last); } void splice_after(const_iterator __pos, forward_list&, const_iterator __before, const_iterator __last) noexcept { _M_splice_after(__pos, __before, __last); } // @} /* * @brief Remove all elements equal to value. * @param __val The value to remove. * * Removes every element in the list equal to @a __val. * Remaining elements stay in list order. Note that this * function only erases the elements, and that if the elements * themselves are pointers, the pointed-to memory is not * touched in any way. Managing the pointer is the user's * responsibility. / void remove(const _Tp& __val); /* * @brief Remove all elements satisfying a predicate. * @param __pred Unary predicate function or object. * * Removes every element in the list for which the predicate * returns true. Remaining elements stay in list order. Note * that this function only erases the elements, and that if the * elements themselves are pointers, the pointed-to memory is * not touched in any way. Managing the pointer is the user's * responsibility. / template<typename _Pred> void remove_if(_Pred __pred); /* * @brief Remove consecutive duplicate elements. * * For each consecutive set of elements with the same value, * remove all but the first one. Remaining elements stay in * list order. Note that this function only erases the * elements, and that if the elements themselves are pointers, * the pointed-to memory is not touched in any way. Managing * the pointer is the user's responsibility. / void unique() { unique(std::equal_to<_Tp>()); } /* * @brief Remove consecutive elements satisfying a predicate. * @param __binary_pred Binary predicate function or object. * * For each consecutive set of elements [first,last) that * satisfy predicate(first,i) where i is an iterator in * [first,last), remove all but the first one. Remaining * elements stay in list order. Note that this function only * erases the elements, and that if the elements themselves are * pointers, the pointed-to memory is not touched in any way. * Managing the pointer is the user's responsibility. / template<typename _BinPred> void unique(_BinPred __binary_pred); /* * @brief Merge sorted lists. * @param __list Sorted list to merge. * * Assumes that both @a list and this list are sorted according to * operator<(). Merges elements of @a __list into this list in * sorted order, leaving @a __list empty when complete. Elements in * this list precede elements in @a __list that are equal. / void merge(forward_list&& __list) { merge(std::move(__list), std::less<_Tp>()); } void merge(forward_list& __list) { merge(std::move(__list)); } /* * @brief Merge sorted lists according to comparison function. * @param __list Sorted list to merge. * @param __comp Comparison function defining sort order. * * Assumes that both @a __list and this list are sorted according to * comp. Merges elements of @a __list into this list * in sorted order, leaving @a __list empty when complete. Elements * in this list precede elements in @a __list that are equivalent * according to comp(). / template<typename _Comp> void merge(forward_list&& __list, _Comp __comp); template<typename _Comp> void merge(forward_list& __list, _Comp __comp) { merge(std::move(__list), __comp); } /* * @brief Sort the elements of the list. * * Sorts the elements of this list in NlogN time. Equivalent * elements remain in list order. / void sort() { sort(std::less<_Tp>()); } /* * @brief Sort the forward_list using a comparison function. * * Sorts the elements of this list in NlogN time. Equivalent * elements remain in list order. / template<typename _Comp> void sort(_Comp __comp); /* * @brief Reverse the elements in list. * * Reverse the order of elements in the list in linear time. / void reverse() noexcept { this->_M_impl._M_head._M_reverse_after(); } private: // Called by the range constructor to implement [23.3.4.2]/9 template<typename _InputIterator> void _M_range_initialize(_InputIterator __first, _InputIterator __last); // Called by forward_list(n,v,a), and the range constructor when it // turns out to be the same thing. void _M_fill_initialize(size_type __n, const value_type& __value); // Called by splice_after and insert_after. iterator _M_splice_after(const_iterator __pos, const_iterator __before, const_iterator __last); // Called by forward_list(n). void _M_default_initialize(size_type __n); // Called by resize(sz). void _M_default_insert_after(const_iterator __pos, size_type __n); // Called by operator=(forward_list&&) void _M_move_assign(forward_list&& __list, true_type) noexcept { clear(); this->_M_impl._M_head._M_next = __list._M_impl._M_head._M_next; __list._M_impl._M_head._M_next = nullptr; std::__alloc_on_move(this->_M_get_Node_allocator(), __list._M_get_Node_allocator()); } // Called by operator=(forward_list&&) void _M_move_assign(forward_list&& __list, false_type) { if (__list._M_get_Node_allocator() == this->_M_get_Node_allocator()) _M_move_assign(std::move(__list), true_type()); else // The rvalue's allocator cannot be moved, or is not equal, // so we need to individually move each element. this->assign(std::__make_move_if_noexcept_iterator(__list.begin()), std::__make_move_if_noexcept_iterator(__list.end())); } // Called by assign(_InputIterator, _InputIterator) if _Tp is // CopyAssignable. template<typename _InputIterator> void _M_assign(_InputIterator __first, _InputIterator __last, true_type) { auto __prev = before_begin(); auto __curr = begin(); auto __end = end(); while (__curr != __end && __first != __last) { __curr = __first; ++__prev; ++__curr; ++__first; } if (__first != __last) insert_after(__prev, __first, __last); else if (__curr != __end) erase_after(__prev, __end); } // Called by assign(_InputIterator, _InputIterator) if _Tp is not // CopyAssignable. template<typename _InputIterator> void _M_assign(_InputIterator __first, _InputIterator __last, false_type) { clear(); insert_after(cbefore_begin(), __first, __last); } // Called by assign(size_type, const _Tp&) if Tp is CopyAssignable void _M_assign_n(size_type __n, const _Tp& __val, true_type) { auto __prev = before_begin(); auto __curr = begin(); auto __end = end(); while (__curr != __end && __n > 0) { __curr = __val; ++__prev; ++__curr; --__n; } if (__n > 0) insert_after(__prev, __n, __val); else if (__curr != __end) erase_after(__prev, __end); } // Called by assign(size_type, const _Tp&) if Tp is non-CopyAssignable void _M_assign_n(size_type __n, const _Tp& __val, false_type) { clear(); insert_after(cbefore_begin(), __n, __val); } }; #if __cpp_deduction_guides >= 201606 template<typename _InputIterator, typename _ValT = typename iterator_traits<_InputIterator>::value_type, typename _Allocator = allocator<_ValT>, typename = _RequireInputIter<_InputIterator>, typename = _RequireAllocator<_Allocator>> forward_list(_InputIterator, _InputIterator, _Allocator = _Allocator()) -> forward_list<_ValT, _Allocator>; #endif /** * @brief Forward list equality comparison. * @param __lx A %forward_list * @param __ly A %forward_list of the same type as @a __lx. * @return True iff the elements of the forward lists are equal. * * This is an equivalence relation. It is linear in the number of * elements of the forward lists. Deques are considered equivalent * if corresponding elements compare equal. / template<typename _Tp, typename _Alloc> bool operator==(const forward_list<_Tp, _Alloc>& __lx, const forward_list<_Tp, _Alloc>& __ly); /* * @brief Forward list ordering relation. * @param __lx A %forward_list. * @param __ly A %forward_list of the same type as @a __lx. * @return True iff @a __lx is lexicographically less than @a __ly. * * This is a total ordering relation. It is linear in the number of * elements of the forward lists. The elements must be comparable * with @c <. * * See std::lexicographical_compare() for how the determination is made. */ template<typename _Tp, typename _Alloc> inline bool operator<(const forward_list<_Tp, _Alloc>& __lx, const forward_list<_Tp, _Alloc>& __ly) { return std::lexicographical_compare(__lx.cbegin(), __lx.cend(), __ly.cbegin(), __ly.cend()); } /// Based on operator== template<typename _Tp, typename _Alloc> inline bool operator!=(const forward_list<_Tp, _Alloc>& __lx, const forward_list<_Tp, _Alloc>& __ly) { return !(__lx == __ly); } /// Based on operator< template<typename _Tp, typename _Alloc> inline bool operator>(const forward_list<_Tp, _Alloc>& __lx, const forward_list<_Tp, _Alloc>& __ly) { return (__ly < __lx); } /// Based on operator< template<typename _Tp, typename _Alloc> inline bool operator>=(const forward_list<_Tp, _Alloc>& __lx, const forward_list<_Tp, _Alloc>& __ly) { return !(__lx < __ly); } /// Based on operator< template<typename _Tp, typename _Alloc> inline bool operator<=(const forward_list<_Tp, _Alloc>& __lx, const forward_list<_Tp, _Alloc>& __ly) { return !(__ly < __lx); } /// See std::forward_list::swap(). template<typename _Tp, typename _Alloc> inline void swap(forward_list<_Tp, _Alloc>& __lx, forward_list<_Tp, _Alloc>& __ly) noexcept(noexcept(__lx.swap(__ly))) { __lx.swap(__ly); } _GLIBCXX_END_NAMESPACE_CONTAINER _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif // _FORWARD_LIST_H Back

Edit File : forward_list.h | Size : 47.77 KB

// <forward_list.h> -*- C++ -*-

// Copyright (C) 2008-2018 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file bits/forward_list.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{forward_list}
 */

#ifndef _FORWARD_LIST_H
#define _FORWARD_LIST_H 1

#pragma GCC system_header

#include <initializer_list>
#include <bits/stl_iterator_base_types.h>
#include <bits/stl_iterator.h>
#include <bits/stl_algobase.h>
#include <bits/stl_function.h>
#include <bits/allocator.h>
#include <ext/alloc_traits.h>
#include <ext/aligned_buffer.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
_GLIBCXX_BEGIN_NAMESPACE_CONTAINER

/**
   *  @brief  A helper basic node class for %forward_list.
   *          This is just a linked list with nothing inside it.
   *          There are purely list shuffling utility methods here.
   */
  struct _Fwd_list_node_base
  {
    _Fwd_list_node_base() = default;
    _Fwd_list_node_base(_Fwd_list_node_base&& __x) noexcept
      : _M_next(__x._M_next)
    { __x._M_next = nullptr; }

_Fwd_list_node_base(const _Fwd_list_node_base&) = delete;
    _Fwd_list_node_base& operator=(const _Fwd_list_node_base&) = delete;

_Fwd_list_node_base&
    operator=(_Fwd_list_node_base&& __x) noexcept
    {
      _M_next = __x._M_next;
      __x._M_next = nullptr;
      return *this;
    }

_Fwd_list_node_base* _M_next = nullptr;

_Fwd_list_node_base*
    _M_transfer_after(_Fwd_list_node_base* __begin,
		      _Fwd_list_node_base* __end) noexcept
    {
      _Fwd_list_node_base* __keep = __begin->_M_next;
      if (__end)
	{
	  __begin->_M_next = __end->_M_next;
	  __end->_M_next = _M_next;
	}
      else
	__begin->_M_next = nullptr;
      _M_next = __keep;
      return __end;
    }

void
    _M_reverse_after() noexcept
    {
      _Fwd_list_node_base* __tail = _M_next;
      if (!__tail)
	return;
      while (_Fwd_list_node_base* __temp = __tail->_M_next)
	{
	  _Fwd_list_node_base* __keep = _M_next;
	  _M_next = __temp;
	  __tail->_M_next = __temp->_M_next;
	  _M_next->_M_next = __keep;
	}
    }
  };

/**
   *  @brief  A helper node class for %forward_list.
   *          This is just a linked list with uninitialized storage for a
   *          data value in each node.
   *          There is a sorting utility method.
   */
  template<typename _Tp>
    struct _Fwd_list_node
    : public _Fwd_list_node_base
    {
      _Fwd_list_node() = default;

__gnu_cxx::__aligned_buffer<_Tp> _M_storage;

_Tp*
      _M_valptr() noexcept
      { return _M_storage._M_ptr(); }

const _Tp*
      _M_valptr() const noexcept
      { return _M_storage._M_ptr(); }
    };

/**
   *   @brief A forward_list::iterator.
   *
   *   All the functions are op overloads.
   */
  template<typename _Tp>
    struct _Fwd_list_iterator
    {
      typedef _Fwd_list_iterator<_Tp>		_Self;
      typedef _Fwd_list_node<_Tp>		_Node;

typedef _Tp				value_type;
      typedef _Tp*				pointer;
      typedef _Tp&				reference;
      typedef ptrdiff_t				difference_type;
      typedef std::forward_iterator_tag		iterator_category;

_Fwd_list_iterator() noexcept
      : _M_node() { }

explicit
      _Fwd_list_iterator(_Fwd_list_node_base* __n) noexcept
      : _M_node(__n) { }

reference
      operator*() const noexcept
      { return *static_cast<_Node*>(this->_M_node)->_M_valptr(); }

pointer
      operator->() const noexcept
      { return static_cast<_Node*>(this->_M_node)->_M_valptr(); }

_Self&
      operator++() noexcept
      {
	_M_node = _M_node->_M_next;
	return *this;
      }

_Self
      operator++(int) noexcept
      {
	_Self __tmp(*this);
	_M_node = _M_node->_M_next;
	return __tmp;
      }

bool
      operator==(const _Self& __x) const noexcept
      { return _M_node == __x._M_node; }

bool
      operator!=(const _Self& __x) const noexcept
      { return _M_node != __x._M_node; }

_Self
      _M_next() const noexcept
      {
	if (_M_node)
	  return _Fwd_list_iterator(_M_node->_M_next);
	else
	  return _Fwd_list_iterator(nullptr);
      }

_Fwd_list_node_base* _M_node;
    };

/**
   *   @brief A forward_list::const_iterator.
   *
   *   All the functions are op overloads.
   */
  template<typename _Tp>
    struct _Fwd_list_const_iterator
    {
      typedef _Fwd_list_const_iterator<_Tp>	_Self;
      typedef const _Fwd_list_node<_Tp>		_Node;
      typedef _Fwd_list_iterator<_Tp>		iterator;

typedef _Tp				value_type;
      typedef const _Tp*			pointer;
      typedef const _Tp&			reference;
      typedef ptrdiff_t				difference_type;
      typedef std::forward_iterator_tag		iterator_category;

_Fwd_list_const_iterator() noexcept
      : _M_node() { }

explicit
      _Fwd_list_const_iterator(const _Fwd_list_node_base* __n)  noexcept
      : _M_node(__n) { }

_Fwd_list_const_iterator(const iterator& __iter) noexcept
      : _M_node(__iter._M_node) { }

reference
      operator*() const noexcept
      { return *static_cast<_Node*>(this->_M_node)->_M_valptr(); }

pointer
      operator->() const noexcept
      { return static_cast<_Node*>(this->_M_node)->_M_valptr(); }

_Self&
      operator++() noexcept
      {
	_M_node = _M_node->_M_next;
	return *this;
      }

_Self
      operator++(int) noexcept
      {
	_Self __tmp(*this);
	_M_node = _M_node->_M_next;
	return __tmp;
      }

bool
      operator==(const _Self& __x) const noexcept
      { return _M_node == __x._M_node; }

bool
      operator!=(const _Self& __x) const noexcept
      { return _M_node != __x._M_node; }

_Self
      _M_next() const noexcept
      {
	if (this->_M_node)
	  return _Fwd_list_const_iterator(_M_node->_M_next);
	else
	  return _Fwd_list_const_iterator(nullptr);
      }

const _Fwd_list_node_base* _M_node;
    };

/**
   *  @brief  Forward list iterator equality comparison.
   */
  template<typename _Tp>
    inline bool
    operator==(const _Fwd_list_iterator<_Tp>& __x,
	       const _Fwd_list_const_iterator<_Tp>& __y) noexcept
    { return __x._M_node == __y._M_node; }

/**
   *  @brief  Forward list iterator inequality comparison.
   */
  template<typename _Tp>
    inline bool
    operator!=(const _Fwd_list_iterator<_Tp>& __x,
	       const _Fwd_list_const_iterator<_Tp>& __y) noexcept
    { return __x._M_node != __y._M_node; }

/**
   *  @brief  Base class for %forward_list.
   */
  template<typename _Tp, typename _Alloc>
    struct _Fwd_list_base
    {
    protected:
      typedef __alloc_rebind<_Alloc, _Fwd_list_node<_Tp>> _Node_alloc_type;
      typedef __gnu_cxx::__alloc_traits<_Node_alloc_type> _Node_alloc_traits;

struct _Fwd_list_impl
      : public _Node_alloc_type
      {
	_Fwd_list_node_base _M_head;

_Fwd_list_impl()
	  noexcept(is_nothrow_default_constructible<_Node_alloc_type>::value)
	: _Node_alloc_type(), _M_head()
	{ }

_Fwd_list_impl(_Fwd_list_impl&&) = default;

_Fwd_list_impl(_Fwd_list_impl&& __fl, _Node_alloc_type&& __a)
	: _Node_alloc_type(std::move(__a)), _M_head(std::move(__fl._M_head))
	{ }

_Fwd_list_impl(_Node_alloc_type&& __a)
	: _Node_alloc_type(std::move(__a)), _M_head()
	{ }
      };

_Fwd_list_impl _M_impl;

public:
      typedef _Fwd_list_iterator<_Tp>		iterator;
      typedef _Fwd_list_const_iterator<_Tp>	const_iterator;
      typedef _Fwd_list_node<_Tp>		_Node;

_Node_alloc_type&
      _M_get_Node_allocator() noexcept
      { return this->_M_impl; }

const _Node_alloc_type&
      _M_get_Node_allocator() const noexcept
      { return this->_M_impl; }

_Fwd_list_base() = default;

_Fwd_list_base(_Node_alloc_type&& __a)
      : _M_impl(std::move(__a)) { }

// When allocators are always equal.
      _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a,
		     std::true_type)
      : _M_impl(std::move(__lst._M_impl), std::move(__a))
      { }

// When allocators are not always equal.
      _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a);

_Fwd_list_base(_Fwd_list_base&&) = default;

~_Fwd_list_base()
      { _M_erase_after(&_M_impl._M_head, nullptr); }

protected:
      _Node*
      _M_get_node()
      {
	auto __ptr = _Node_alloc_traits::allocate(_M_get_Node_allocator(), 1);
	return std::__to_address(__ptr);
      }

template<typename... _Args>
	_Node*
	_M_create_node(_Args&&... __args)
	{
	  _Node* __node = this->_M_get_node();
	  __try
	    {
	      ::new ((void*)__node) _Node;
	      _Node_alloc_traits::construct(_M_get_Node_allocator(),
					    __node->_M_valptr(),
					    std::forward<_Args>(__args)...);
	    }
	  __catch(...)
	    {
	      this->_M_put_node(__node);
	      __throw_exception_again;
	    }
	  return __node;
	}

template<typename... _Args>
	_Fwd_list_node_base*
	_M_insert_after(const_iterator __pos, _Args&&... __args);

void
      _M_put_node(_Node* __p)
      {
	typedef typename _Node_alloc_traits::pointer _Ptr;
	auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__p);
	_Node_alloc_traits::deallocate(_M_get_Node_allocator(), __ptr, 1);
      }

_Fwd_list_node_base*
      _M_erase_after(_Fwd_list_node_base* __pos);

_Fwd_list_node_base*
      _M_erase_after(_Fwd_list_node_base* __pos,
		     _Fwd_list_node_base* __last);
    };

/**
   *  @brief A standard container with linear time access to elements,
   *  and fixed time insertion/deletion at any point in the sequence.
   *
   *  @ingroup sequences
   *
   *  @tparam _Tp  Type of element.
   *  @tparam _Alloc  Allocator type, defaults to allocator<_Tp>.
   *
   *  Meets the requirements of a <a href="tables.html#65">container</a>, a
   *  <a href="tables.html#67">sequence</a>, including the
   *  <a href="tables.html#68">optional sequence requirements</a> with the
   *  %exception of @c at and @c operator[].
   *
   *  This is a @e singly @e linked %list.  Traversal up the
   *  %list requires linear time, but adding and removing elements (or
   *  @e nodes) is done in constant time, regardless of where the
   *  change takes place.  Unlike std::vector and std::deque,
   *  random-access iterators are not provided, so subscripting ( @c
   *  [] ) access is not allowed.  For algorithms which only need
   *  sequential access, this lack makes no difference.
   *
   *  Also unlike the other standard containers, std::forward_list provides
   *  specialized algorithms %unique to linked lists, such as
   *  splicing, sorting, and in-place reversal.
   */
  template<typename _Tp, typename _Alloc = allocator<_Tp>>
    class forward_list : private _Fwd_list_base<_Tp, _Alloc>
    {
      static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
	  "std::forward_list must have a non-const, non-volatile value_type");
#ifdef __STRICT_ANSI__
      static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
	  "std::forward_list must have the same value_type as its allocator");
#endif

private:
      typedef _Fwd_list_base<_Tp, _Alloc>		_Base;
      typedef _Fwd_list_node<_Tp>			_Node;
      typedef _Fwd_list_node_base			_Node_base;
      typedef typename _Base::_Node_alloc_type		_Node_alloc_type;
      typedef typename _Base::_Node_alloc_traits	_Node_alloc_traits;
      typedef allocator_traits<__alloc_rebind<_Alloc, _Tp>>	_Alloc_traits;

public:
      // types:
      typedef _Tp					value_type;
      typedef typename _Alloc_traits::pointer		pointer;
      typedef typename _Alloc_traits::const_pointer	const_pointer;
      typedef value_type&				reference;
      typedef const value_type&				const_reference;

typedef _Fwd_list_iterator<_Tp>			iterator;
      typedef _Fwd_list_const_iterator<_Tp>		const_iterator;
      typedef std::size_t				size_type;
      typedef std::ptrdiff_t				difference_type;
      typedef _Alloc					allocator_type;

// 23.3.4.2 construct/copy/destroy:

/**
       *  @brief  Creates a %forward_list with no elements.
       */
      forward_list() = default;

/**
       *  @brief  Creates a %forward_list with no elements.
       *  @param  __al  An allocator object.
       */
      explicit
      forward_list(const _Alloc& __al) noexcept
      : _Base(_Node_alloc_type(__al))
      { }

/**
       *  @brief  Copy constructor with allocator argument.
       *  @param  __list  Input list to copy.
       *  @param  __al    An allocator object.
       */
      forward_list(const forward_list& __list, const _Alloc& __al)
      : _Base(_Node_alloc_type(__al))
      { _M_range_initialize(__list.begin(), __list.end()); }

private:
      forward_list(forward_list&& __list, _Node_alloc_type&& __al,
		   false_type)
      : _Base(std::move(__list), std::move(__al))
      {
	// If __list is not empty it means its allocator is not equal to __a,
	// so we need to move from each element individually.
	insert_after(cbefore_begin(),
		     std::__make_move_if_noexcept_iterator(__list.begin()),
		     std::__make_move_if_noexcept_iterator(__list.end()));
      }

forward_list(forward_list&& __list, _Node_alloc_type&& __al,
		   true_type)
      noexcept
      : _Base(std::move(__list), _Node_alloc_type(__al), true_type{})
      { }

public:
      /**
       *  @brief  Move constructor with allocator argument.
       *  @param  __list  Input list to move.
       *  @param  __al    An allocator object.
       */
      forward_list(forward_list&& __list, const _Alloc& __al)
      noexcept(_Node_alloc_traits::_S_always_equal())
      : forward_list(std::move(__list), _Node_alloc_type(__al),
		     typename _Node_alloc_traits::is_always_equal{})
      { }

/**
       *  @brief  Creates a %forward_list with default constructed elements.
       *  @param  __n   The number of elements to initially create.
       *  @param  __al  An allocator object.
       *
       *  This constructor creates the %forward_list with @a __n default
       *  constructed elements.
       */
      explicit
      forward_list(size_type __n, const _Alloc& __al = _Alloc())
      : _Base(_Node_alloc_type(__al))
      { _M_default_initialize(__n); }

/**
       *  @brief  Creates a %forward_list with copies of an exemplar element.
       *  @param  __n      The number of elements to initially create.
       *  @param  __value  An element to copy.
       *  @param  __al     An allocator object.
       *
       *  This constructor fills the %forward_list with @a __n copies of
       *  @a __value.
       */
      forward_list(size_type __n, const _Tp& __value,
		   const _Alloc& __al = _Alloc())
      : _Base(_Node_alloc_type(__al))
      { _M_fill_initialize(__n, __value); }

/**
       *  @brief  Builds a %forward_list from a range.
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @param  __al     An allocator object.
       *
       *  Create a %forward_list consisting of copies of the elements from
       *  [@a __first,@a __last).  This is linear in N (where N is
       *  distance(@a __first,@a __last)).
       */
      template<typename _InputIterator,
	       typename = std::_RequireInputIter<_InputIterator>>
	forward_list(_InputIterator __first, _InputIterator __last,
		     const _Alloc& __al = _Alloc())
	: _Base(_Node_alloc_type(__al))
	{ _M_range_initialize(__first, __last); }

/**
       *  @brief  The %forward_list copy constructor.
       *  @param  __list  A %forward_list of identical element and allocator
       *                  types.
       */
      forward_list(const forward_list& __list)
      : _Base(_Node_alloc_traits::_S_select_on_copy(
		__list._M_get_Node_allocator()))
      { _M_range_initialize(__list.begin(), __list.end()); }

/**
       *  @brief  The %forward_list move constructor.
       *  @param  __list  A %forward_list of identical element and allocator
       *                  types.
       *
       *  The newly-created %forward_list contains the exact contents of the
       *  moved instance. The contents of the moved instance are a valid, but
       *  unspecified %forward_list.
       */
      forward_list(forward_list&&) = default;

/**
       *  @brief  Builds a %forward_list from an initializer_list
       *  @param  __il  An initializer_list of value_type.
       *  @param  __al  An allocator object.
       *
       *  Create a %forward_list consisting of copies of the elements
       *  in the initializer_list @a __il.  This is linear in __il.size().
       */
      forward_list(std::initializer_list<_Tp> __il,
		   const _Alloc& __al = _Alloc())
      : _Base(_Node_alloc_type(__al))
      { _M_range_initialize(__il.begin(), __il.end()); }

/**
       *  @brief  The forward_list dtor.
       */
      ~forward_list() noexcept
      { }

/**
       *  @brief  The %forward_list assignment operator.
       *  @param  __list  A %forward_list of identical element and allocator
       *                types.
       *
       *  All the elements of @a __list are copied.
       *
       *  Whether the allocator is copied depends on the allocator traits.
       */
      forward_list&
      operator=(const forward_list& __list);

/**
       *  @brief  The %forward_list move assignment operator.
       *  @param  __list  A %forward_list of identical element and allocator
       *                types.
       *
       *  The contents of @a __list are moved into this %forward_list
       *  (without copying, if the allocators permit it).
       *
       *  Afterwards @a __list is a valid, but unspecified %forward_list
       *
       *  Whether the allocator is moved depends on the allocator traits.
       */
      forward_list&
      operator=(forward_list&& __list)
      noexcept(_Node_alloc_traits::_S_nothrow_move())
      {
	constexpr bool __move_storage =
	  _Node_alloc_traits::_S_propagate_on_move_assign()
	  || _Node_alloc_traits::_S_always_equal();
	_M_move_assign(std::move(__list), __bool_constant<__move_storage>());
	return *this;
      }

/**
       *  @brief  The %forward_list initializer list assignment operator.
       *  @param  __il  An initializer_list of value_type.
       *
       *  Replace the contents of the %forward_list with copies of the
       *  elements in the initializer_list @a __il.  This is linear in
       *  __il.size().
       */
      forward_list&
      operator=(std::initializer_list<_Tp> __il)
      {
	assign(__il);
	return *this;
      }

/**
       *  @brief  Assigns a range to a %forward_list.
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *
       *  This function fills a %forward_list with copies of the elements
       *  in the range [@a __first,@a __last).
       *
       *  Note that the assignment completely changes the %forward_list and
       *  that the number of elements of the resulting %forward_list is the
       *  same as the number of elements assigned.
       */
      template<typename _InputIterator,
	       typename = std::_RequireInputIter<_InputIterator>>
	void
	assign(_InputIterator __first, _InputIterator __last)
	{
	  typedef is_assignable<_Tp, decltype(*__first)> __assignable;
	  _M_assign(__first, __last, __assignable());
	}

/**
       *  @brief  Assigns a given value to a %forward_list.
       *  @param  __n  Number of elements to be assigned.
       *  @param  __val  Value to be assigned.
       *
       *  This function fills a %forward_list with @a __n copies of the
       *  given value.  Note that the assignment completely changes the
       *  %forward_list, and that the resulting %forward_list has __n
       *  elements.
       */
      void
      assign(size_type __n, const _Tp& __val)
      { _M_assign_n(__n, __val, is_copy_assignable<_Tp>()); }

/**
       *  @brief  Assigns an initializer_list to a %forward_list.
       *  @param  __il  An initializer_list of value_type.
       *
       *  Replace the contents of the %forward_list with copies of the
       *  elements in the initializer_list @a __il.  This is linear in
       *  il.size().
       */
      void
      assign(std::initializer_list<_Tp> __il)
      { assign(__il.begin(), __il.end()); }

/// Get a copy of the memory allocation object.
      allocator_type
      get_allocator() const noexcept
      { return allocator_type(this->_M_get_Node_allocator()); }

// 23.3.4.3 iterators:

/**
       *  Returns a read/write iterator that points before the first element
       *  in the %forward_list.  Iteration is done in ordinary element order.
       */
      iterator
      before_begin() noexcept
      { return iterator(&this->_M_impl._M_head); }

/**
       *  Returns a read-only (constant) iterator that points before the
       *  first element in the %forward_list.  Iteration is done in ordinary
       *  element order.
       */
      const_iterator
      before_begin() const noexcept
      { return const_iterator(&this->_M_impl._M_head); }

/**
       *  Returns a read/write iterator that points to the first element
       *  in the %forward_list.  Iteration is done in ordinary element order.
       */
      iterator
      begin() noexcept
      { return iterator(this->_M_impl._M_head._M_next); }

/**
       *  Returns a read-only (constant) iterator that points to the first
       *  element in the %forward_list.  Iteration is done in ordinary
       *  element order.
       */
      const_iterator
      begin() const noexcept
      { return const_iterator(this->_M_impl._M_head._M_next); }

/**
       *  Returns a read/write iterator that points one past the last
       *  element in the %forward_list.  Iteration is done in ordinary
       *  element order.
       */
      iterator
      end() noexcept
      { return iterator(nullptr); }

/**
       *  Returns a read-only iterator that points one past the last
       *  element in the %forward_list.  Iteration is done in ordinary
       *  element order.
       */
      const_iterator
      end() const noexcept
      { return const_iterator(nullptr); }

/**
       *  Returns a read-only (constant) iterator that points to the
       *  first element in the %forward_list.  Iteration is done in ordinary
       *  element order.
       */
      const_iterator
      cbegin() const noexcept
      { return const_iterator(this->_M_impl._M_head._M_next); }

/**
       *  Returns a read-only (constant) iterator that points before the
       *  first element in the %forward_list.  Iteration is done in ordinary
       *  element order.
       */
      const_iterator
      cbefore_begin() const noexcept
      { return const_iterator(&this->_M_impl._M_head); }

/**
       *  Returns a read-only (constant) iterator that points one past
       *  the last element in the %forward_list.  Iteration is done in
       *  ordinary element order.
       */
      const_iterator
      cend() const noexcept
      { return const_iterator(nullptr); }

/**
       *  Returns true if the %forward_list is empty.  (Thus begin() would
       *  equal end().)
       */
      bool
      empty() const noexcept
      { return this->_M_impl._M_head._M_next == nullptr; }

/**
       *  Returns the largest possible number of elements of %forward_list.
       */
      size_type
      max_size() const noexcept
      { return _Node_alloc_traits::max_size(this->_M_get_Node_allocator()); }

// 23.3.4.4 element access:

/**
       *  Returns a read/write reference to the data at the first
       *  element of the %forward_list.
       */
      reference
      front()
      {
	_Node* __front = static_cast<_Node*>(this->_M_impl._M_head._M_next);
	return *__front->_M_valptr();
      }

/**
       *  Returns a read-only (constant) reference to the data at the first
       *  element of the %forward_list.
       */
      const_reference
      front() const
      {
	_Node* __front = static_cast<_Node*>(this->_M_impl._M_head._M_next);
	return *__front->_M_valptr();
      }

// 23.3.4.5 modiﬁers:

/**
       *  @brief  Constructs object in %forward_list at the front of the
       *          list.
       *  @param  __args  Arguments.
       *
       *  This function will insert an object of type Tp constructed
       *  with Tp(std::forward<Args>(args)...) at the front of the list
       *  Due to the nature of a %forward_list this operation can
       *  be done in constant time, and does not invalidate iterators
       *  and references.
       */
      template<typename... _Args>
#if __cplusplus > 201402L
	reference
#else
	void
#endif
	emplace_front(_Args&&... __args)
	{
	  this->_M_insert_after(cbefore_begin(),
				std::forward<_Args>(__args)...);
#if __cplusplus > 201402L
	  return front();
#endif
	}

/**
       *  @brief  Add data to the front of the %forward_list.
       *  @param  __val  Data to be added.
       *
       *  This is a typical stack operation.  The function creates an
       *  element at the front of the %forward_list and assigns the given
       *  data to it.  Due to the nature of a %forward_list this operation
       *  can be done in constant time, and does not invalidate iterators
       *  and references.
       */
      void
      push_front(const _Tp& __val)
      { this->_M_insert_after(cbefore_begin(), __val); }

/**
       *
       */
      void
      push_front(_Tp&& __val)
      { this->_M_insert_after(cbefore_begin(), std::move(__val)); }

/**
       *  @brief  Removes first element.
       *
       *  This is a typical stack operation.  It shrinks the %forward_list
       *  by one.  Due to the nature of a %forward_list this operation can
       *  be done in constant time, and only invalidates iterators/references
       *  to the element being removed.
       *
       *  Note that no data is returned, and if the first element's data
       *  is needed, it should be retrieved before pop_front() is
       *  called.
       */
      void
      pop_front()
      { this->_M_erase_after(&this->_M_impl._M_head); }

/**
       *  @brief  Constructs object in %forward_list after the specified
       *          iterator.
       *  @param  __pos  A const_iterator into the %forward_list.
       *  @param  __args  Arguments.
       *  @return  An iterator that points to the inserted data.
       *
       *  This function will insert an object of type T constructed
       *  with T(std::forward<Args>(args)...) after the specified
       *  location.  Due to the nature of a %forward_list this operation can
       *  be done in constant time, and does not invalidate iterators
       *  and references.
       */
      template<typename... _Args>
	iterator
	emplace_after(const_iterator __pos, _Args&&... __args)
	{ return iterator(this->_M_insert_after(__pos,
					  std::forward<_Args>(__args)...)); }

/**
       *  @brief  Inserts given value into %forward_list after specified
       *          iterator.
       *  @param  __pos  An iterator into the %forward_list.
       *  @param  __val  Data to be inserted.
       *  @return  An iterator that points to the inserted data.
       *
       *  This function will insert a copy of the given value after
       *  the specified location.  Due to the nature of a %forward_list this
       *  operation can be done in constant time, and does not
       *  invalidate iterators and references.
       */
      iterator
      insert_after(const_iterator __pos, const _Tp& __val)
      { return iterator(this->_M_insert_after(__pos, __val)); }

/**
       *
       */
      iterator
      insert_after(const_iterator __pos, _Tp&& __val)
      { return iterator(this->_M_insert_after(__pos, std::move(__val))); }

/**
       *  @brief  Inserts a number of copies of given data into the
       *          %forward_list.
       *  @param  __pos  An iterator into the %forward_list.
       *  @param  __n  Number of elements to be inserted.
       *  @param  __val  Data to be inserted.
       *  @return  An iterator pointing to the last inserted copy of
       *           @a val or @a pos if @a n == 0.
       *
       *  This function will insert a specified number of copies of the
       *  given data after the location specified by @a pos.
       *
       *  This operation is linear in the number of elements inserted and
       *  does not invalidate iterators and references.
       */
      iterator
      insert_after(const_iterator __pos, size_type __n, const _Tp& __val);

/**
       *  @brief  Inserts a range into the %forward_list.
       *  @param  __pos  An iterator into the %forward_list.
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @return  An iterator pointing to the last inserted element or
       *           @a __pos if @a __first == @a __last.
       *
       *  This function will insert copies of the data in the range
       *  [@a __first,@a __last) into the %forward_list after the
       *  location specified by @a __pos.
       *
       *  This operation is linear in the number of elements inserted and
       *  does not invalidate iterators and references.
       */
      template<typename _InputIterator,
	       typename = std::_RequireInputIter<_InputIterator>>
	iterator
	insert_after(const_iterator __pos,
		     _InputIterator __first, _InputIterator __last);

/**
       *  @brief  Inserts the contents of an initializer_list into
       *          %forward_list after the specified iterator.
       *  @param  __pos  An iterator into the %forward_list.
       *  @param  __il  An initializer_list of value_type.
       *  @return  An iterator pointing to the last inserted element
       *           or @a __pos if @a __il is empty.
       *
       *  This function will insert copies of the data in the
       *  initializer_list @a __il into the %forward_list before the location
       *  specified by @a __pos.
       *
       *  This operation is linear in the number of elements inserted and
       *  does not invalidate iterators and references.
       */
      iterator
      insert_after(const_iterator __pos, std::initializer_list<_Tp> __il)
      { return insert_after(__pos, __il.begin(), __il.end()); }

/**
       *  @brief  Removes the element pointed to by the iterator following
       *          @c pos.
       *  @param  __pos  Iterator pointing before element to be erased.
       *  @return  An iterator pointing to the element following the one
       *           that was erased, or end() if no such element exists.
       *
       *  This function will erase the element at the given position and
       *  thus shorten the %forward_list by one.
       *
       *  Due to the nature of a %forward_list this operation can be done
       *  in constant time, and only invalidates iterators/references to
       *  the element being removed.  The user is also cautioned that
       *  this function only erases the element, and that if the element
       *  is itself a pointer, the pointed-to memory is not touched in
       *  any way.  Managing the pointer is the user's responsibility.
       */
      iterator
      erase_after(const_iterator __pos)
      { return iterator(this->_M_erase_after(const_cast<_Node_base*>
					     (__pos._M_node))); }

/**
       *  @brief  Remove a range of elements.
       *  @param  __pos  Iterator pointing before the first element to be
       *                 erased.
       *  @param  __last  Iterator pointing to one past the last element to be
       *                  erased.
       *  @return  @ __last.
       *
       *  This function will erase the elements in the range
       *  @a (__pos,__last) and shorten the %forward_list accordingly.
       *
       *  This operation is linear time in the size of the range and only
       *  invalidates iterators/references to the element being removed.
       *  The user is also cautioned that this function only erases the
       *  elements, and that if the elements themselves are pointers, the
       *  pointed-to memory is not touched in any way.  Managing the pointer
       *  is the user's responsibility.
       */
      iterator
      erase_after(const_iterator __pos, const_iterator __last)
      { return iterator(this->_M_erase_after(const_cast<_Node_base*>
					     (__pos._M_node),
					     const_cast<_Node_base*>
					     (__last._M_node))); }

/**
       *  @brief  Swaps data with another %forward_list.
       *  @param  __list  A %forward_list of the same element and allocator
       *                  types.
       *
       *  This exchanges the elements between two lists in constant
       *  time.  Note that the global std::swap() function is
       *  specialized such that std::swap(l1,l2) will feed to this
       *  function.
       *
       *  Whether the allocators are swapped depends on the allocator traits.
       */
      void
      swap(forward_list& __list) noexcept
      {
	std::swap(this->_M_impl._M_head._M_next,
		  __list._M_impl._M_head._M_next);
	_Node_alloc_traits::_S_on_swap(this->_M_get_Node_allocator(),
				       __list._M_get_Node_allocator());
      }

/**
       *  @brief Resizes the %forward_list to the specified number of
       *         elements.
       *  @param __sz Number of elements the %forward_list should contain.
       *
       *  This function will %resize the %forward_list to the specified
       *  number of elements.  If the number is smaller than the
       *  %forward_list's current number of elements the %forward_list
       *  is truncated, otherwise the %forward_list is extended and the
       *  new elements are default constructed.
       */
      void
      resize(size_type __sz);

/**
       *  @brief Resizes the %forward_list to the specified number of
       *         elements.
       *  @param __sz Number of elements the %forward_list should contain.
       *  @param __val Data with which new elements should be populated.
       *
       *  This function will %resize the %forward_list to the specified
       *  number of elements.  If the number is smaller than the
       *  %forward_list's current number of elements the %forward_list
       *  is truncated, otherwise the %forward_list is extended and new
       *  elements are populated with given data.
       */
      void
      resize(size_type __sz, const value_type& __val);

/**
       *  @brief  Erases all the elements.
       *
       *  Note that this function only erases
       *  the elements, and that if the elements themselves are
       *  pointers, the pointed-to memory is not touched in any way.
       *  Managing the pointer is the user's responsibility.
       */
      void
      clear() noexcept
      { this->_M_erase_after(&this->_M_impl._M_head, nullptr); }

// 23.3.4.6 forward_list operations:

/**
       *  @brief  Insert contents of another %forward_list.
       *  @param  __pos  Iterator referencing the element to insert after.
       *  @param  __list  Source list.
       *
       *  The elements of @a list are inserted in constant time after
       *  the element referenced by @a pos.  @a list becomes an empty
       *  list.
       *
       *  Requires this != @a x.
       */
      void
      splice_after(const_iterator __pos, forward_list&& __list) noexcept
      {
	if (!__list.empty())
	  _M_splice_after(__pos, __list.before_begin(), __list.end());
      }

void
      splice_after(const_iterator __pos, forward_list& __list) noexcept
      { splice_after(__pos, std::move(__list)); }

/**
       *  @brief  Insert element from another %forward_list.
       *  @param  __pos  Iterator referencing the element to insert after.
       *  @param  __list  Source list.
       *  @param  __i   Iterator referencing the element before the element
       *                to move.
       *
       *  Removes the element in list @a list referenced by @a i and
       *  inserts it into the current list after @a pos.
       */
      void
      splice_after(const_iterator __pos, forward_list&& __list,
		   const_iterator __i) noexcept;

void
      splice_after(const_iterator __pos, forward_list& __list,
		   const_iterator __i) noexcept
      { splice_after(__pos, std::move(__list), __i); }

/**
       *  @brief  Insert range from another %forward_list.
       *  @param  __pos  Iterator referencing the element to insert after.
       *  @param  __list  Source list.
       *  @param  __before  Iterator referencing before the start of range
       *                    in list.
       *  @param  __last  Iterator referencing the end of range in list.
       *
       *  Removes elements in the range (__before,__last) and inserts them
       *  after @a __pos in constant time.
       *
       *  Undefined if @a __pos is in (__before,__last).
       *  @{
       */
      void
      splice_after(const_iterator __pos, forward_list&&,
		   const_iterator __before, const_iterator __last) noexcept
      { _M_splice_after(__pos, __before, __last); }

void
      splice_after(const_iterator __pos, forward_list&,
		   const_iterator __before, const_iterator __last) noexcept
      { _M_splice_after(__pos, __before, __last); }
      // @}

/**
       *  @brief  Remove all elements equal to value.
       *  @param  __val  The value to remove.
       *
       *  Removes every element in the list equal to @a __val.
       *  Remaining elements stay in list order.  Note that this
       *  function only erases the elements, and that if the elements
       *  themselves are pointers, the pointed-to memory is not
       *  touched in any way.  Managing the pointer is the user's
       *  responsibility.
       */
      void
      remove(const _Tp& __val);

/**
       *  @brief  Remove all elements satisfying a predicate.
       *  @param  __pred  Unary predicate function or object.
       *
       *  Removes every element in the list for which the predicate
       *  returns true.  Remaining elements stay in list order.  Note
       *  that this function only erases the elements, and that if the
       *  elements themselves are pointers, the pointed-to memory is
       *  not touched in any way.  Managing the pointer is the user's
       *  responsibility.
       */
      template<typename _Pred>
	void
	remove_if(_Pred __pred);

/**
       *  @brief  Remove consecutive duplicate elements.
       *
       *  For each consecutive set of elements with the same value,
       *  remove all but the first one.  Remaining elements stay in
       *  list order.  Note that this function only erases the
       *  elements, and that if the elements themselves are pointers,
       *  the pointed-to memory is not touched in any way.  Managing
       *  the pointer is the user's responsibility.
       */
      void
      unique()
      { unique(std::equal_to<_Tp>()); }

/**
       *  @brief  Remove consecutive elements satisfying a predicate.
       *  @param  __binary_pred  Binary predicate function or object.
       *
       *  For each consecutive set of elements [first,last) that
       *  satisfy predicate(first,i) where i is an iterator in
       *  [first,last), remove all but the first one.  Remaining
       *  elements stay in list order.  Note that this function only
       *  erases the elements, and that if the elements themselves are
       *  pointers, the pointed-to memory is not touched in any way.
       *  Managing the pointer is the user's responsibility.
       */
      template<typename _BinPred>
	void
	unique(_BinPred __binary_pred);

/**
       *  @brief  Merge sorted lists.
       *  @param  __list  Sorted list to merge.
       *
       *  Assumes that both @a list and this list are sorted according to
       *  operator<().  Merges elements of @a __list into this list in
       *  sorted order, leaving @a __list empty when complete.  Elements in
       *  this list precede elements in @a __list that are equal.
       */
      void
      merge(forward_list&& __list)
      { merge(std::move(__list), std::less<_Tp>()); }

void
      merge(forward_list& __list)
      { merge(std::move(__list)); }

/**
       *  @brief  Merge sorted lists according to comparison function.
       *  @param  __list  Sorted list to merge.
       *  @param  __comp Comparison function defining sort order.
       *
       *  Assumes that both @a __list and this list are sorted according to
       *  comp.  Merges elements of @a __list into this list
       *  in sorted order, leaving @a __list empty when complete.  Elements
       *  in this list precede elements in @a __list that are equivalent
       *  according to comp().
       */
      template<typename _Comp>
	void
	merge(forward_list&& __list, _Comp __comp);

template<typename _Comp>
	void
	merge(forward_list& __list, _Comp __comp)
	{ merge(std::move(__list), __comp); }

/**
       *  @brief  Sort the elements of the list.
       *
       *  Sorts the elements of this list in NlogN time.  Equivalent
       *  elements remain in list order.
       */
      void
      sort()
      { sort(std::less<_Tp>()); }

/**
       *  @brief  Sort the forward_list using a comparison function.
       *
       *  Sorts the elements of this list in NlogN time.  Equivalent
       *  elements remain in list order.
       */
      template<typename _Comp>
	void
	sort(_Comp __comp);

/**
       *  @brief  Reverse the elements in list.
       *
       *  Reverse the order of elements in the list in linear time.
       */
      void
      reverse() noexcept
      { this->_M_impl._M_head._M_reverse_after(); }

private:
      // Called by the range constructor to implement [23.3.4.2]/9
      template<typename _InputIterator>
	void
	_M_range_initialize(_InputIterator __first, _InputIterator __last);

// Called by forward_list(n,v,a), and the range constructor when it
      // turns out to be the same thing.
      void
      _M_fill_initialize(size_type __n, const value_type& __value);

// Called by splice_after and insert_after.
      iterator
      _M_splice_after(const_iterator __pos, const_iterator __before,
		      const_iterator __last);

// Called by forward_list(n).
      void
      _M_default_initialize(size_type __n);

// Called by resize(sz).
      void
      _M_default_insert_after(const_iterator __pos, size_type __n);

// Called by operator=(forward_list&&)
      void
      _M_move_assign(forward_list&& __list, true_type) noexcept
      {
	clear();
	this->_M_impl._M_head._M_next = __list._M_impl._M_head._M_next;
	__list._M_impl._M_head._M_next = nullptr;
	std::__alloc_on_move(this->_M_get_Node_allocator(),
			     __list._M_get_Node_allocator());
      }

// Called by operator=(forward_list&&)
      void
      _M_move_assign(forward_list&& __list, false_type)
      {
	if (__list._M_get_Node_allocator() == this->_M_get_Node_allocator())
	  _M_move_assign(std::move(__list), true_type());
	else
	  // The rvalue's allocator cannot be moved, or is not equal,
	  // so we need to individually move each element.
	  this->assign(std::__make_move_if_noexcept_iterator(__list.begin()),
		       std::__make_move_if_noexcept_iterator(__list.end()));
      }

// Called by assign(_InputIterator, _InputIterator) if _Tp is
      // CopyAssignable.
      template<typename _InputIterator>
	void
	_M_assign(_InputIterator __first, _InputIterator __last, true_type)
	{
	  auto __prev = before_begin();
	  auto __curr = begin();
	  auto __end = end();
	  while (__curr != __end && __first != __last)
	    {
	      *__curr = *__first;
	      ++__prev;
	      ++__curr;
	      ++__first;
	    }
	  if (__first != __last)
	    insert_after(__prev, __first, __last);
	  else if (__curr != __end)
	    erase_after(__prev, __end);
	}

// Called by assign(_InputIterator, _InputIterator) if _Tp is not
      // CopyAssignable.
      template<typename _InputIterator>
	void
	_M_assign(_InputIterator __first, _InputIterator __last, false_type)
	{
	  clear();
	  insert_after(cbefore_begin(), __first, __last);
	}

// Called by assign(size_type, const _Tp&) if Tp is CopyAssignable
      void
      _M_assign_n(size_type __n, const _Tp& __val, true_type)
      {
	auto __prev = before_begin();
	auto __curr = begin();
	auto __end = end();
	while (__curr != __end && __n > 0)
	  {
	    *__curr = __val;
	    ++__prev;
	    ++__curr;
	    --__n;
	  }
	if (__n > 0)
	  insert_after(__prev, __n, __val);
	else if (__curr != __end)
	  erase_after(__prev, __end);
      }

// Called by assign(size_type, const _Tp&) if Tp is non-CopyAssignable
      void
      _M_assign_n(size_type __n, const _Tp& __val, false_type)
      {
	clear();
	insert_after(cbefore_begin(), __n, __val);
      }
    };

#if __cpp_deduction_guides >= 201606
  template<typename _InputIterator, typename _ValT
	     = typename iterator_traits<_InputIterator>::value_type,
	   typename _Allocator = allocator<_ValT>,
	   typename = _RequireInputIter<_InputIterator>,
	   typename = _RequireAllocator<_Allocator>>
    forward_list(_InputIterator, _InputIterator, _Allocator = _Allocator())
      -> forward_list<_ValT, _Allocator>;
#endif

/**
   *  @brief  Forward list equality comparison.
   *  @param  __lx  A %forward_list
   *  @param  __ly  A %forward_list of the same type as @a __lx.
   *  @return  True iff the elements of the forward lists are equal.
   *
   *  This is an equivalence relation.  It is linear in the number of
   *  elements of the forward lists.  Deques are considered equivalent
   *  if corresponding elements compare equal.
   */
  template<typename _Tp, typename _Alloc>
    bool
    operator==(const forward_list<_Tp, _Alloc>& __lx,
	       const forward_list<_Tp, _Alloc>& __ly);

/**
   *  @brief  Forward list ordering relation.
   *  @param  __lx  A %forward_list.
   *  @param  __ly  A %forward_list of the same type as @a __lx.
   *  @return  True iff @a __lx is lexicographically less than @a __ly.
   *
   *  This is a total ordering relation.  It is linear in the number of
   *  elements of the forward lists.  The elements must be comparable
   *  with @c <.
   *
   *  See std::lexicographical_compare() for how the determination is made.
   */
  template<typename _Tp, typename _Alloc>
    inline bool
    operator<(const forward_list<_Tp, _Alloc>& __lx,
	      const forward_list<_Tp, _Alloc>& __ly)
    { return std::lexicographical_compare(__lx.cbegin(), __lx.cend(),
					  __ly.cbegin(), __ly.cend()); }

/// Based on operator==
  template<typename _Tp, typename _Alloc>
    inline bool
    operator!=(const forward_list<_Tp, _Alloc>& __lx,
	       const forward_list<_Tp, _Alloc>& __ly)
    { return !(__lx == __ly); }

/// Based on operator<
  template<typename _Tp, typename _Alloc>
    inline bool
    operator>(const forward_list<_Tp, _Alloc>& __lx,
	      const forward_list<_Tp, _Alloc>& __ly)
    { return (__ly < __lx); }

/// Based on operator<
  template<typename _Tp, typename _Alloc>
    inline bool
    operator>=(const forward_list<_Tp, _Alloc>& __lx,
	       const forward_list<_Tp, _Alloc>& __ly)
    { return !(__lx < __ly); }

/// Based on operator<
  template<typename _Tp, typename _Alloc>
    inline bool
    operator<=(const forward_list<_Tp, _Alloc>& __lx,
	       const forward_list<_Tp, _Alloc>& __ly)
    { return !(__ly < __lx); }

/// See std::forward_list::swap().
  template<typename _Tp, typename _Alloc>
    inline void
    swap(forward_list<_Tp, _Alloc>& __lx,
	 forward_list<_Tp, _Alloc>& __ly)
    noexcept(noexcept(__lx.swap(__ly)))
    { __lx.swap(__ly); }

_GLIBCXX_END_NAMESPACE_CONTAINER
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // _FORWARD_LIST_H

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