stack 、 queue的语法使用及底层实现以及deque的介绍【C++】
文章目录
- stack的使用
- queue的使用
- 适配器
- queue的模拟实现
- stack的模拟实现
- deque
stack的使用
stack是一种容器适配器，具有后进先出，只能从容器的一端进行元素的插入与提取操作
#include queue的使用
队列是一种容器适配器，具有先进先出，只能从容器的一端插入元素，另一端提取元素
#include
#include 适配器
stack和queue在STL中并没有将其划分在容器的行列，而是称为容器适配器
因为stack和queue对其他容器的接口进行了包装，STL中stack和queue默认使用deque容器。
queue的模拟实现
核心接口
front：获取对列头部（第一个元素）
back：获取队列尾部（最后一个元素）
size：获取队列中的元素个数
pop：删除队列头部元素
push：队列尾部插入元素
empty：判空
namespace cxq
{
template<class T ,class Container = deque<T> >
class queue
{
public:
void push(const T & x)
{
_con.push_back(x);
}
void pop()
{
_con.pop_front();
}
T& front()
{
return _con.front();
}
T& back()
{
return _con.back();
}
size_t size()
{
return _con.size();
}
bool empty()
{
return _con.empty();
}
private:
Container _con;
};
void test_queue1()
{
queue<int, list<int> > q ;
q.push(1);
q.push(2);
q.push(3);
q.push(4);
while (!q.empty())
{
cout << q.front() << " ";
q.pop();
}
cout << endl;
}
}
stack的模拟实现
核心接口
top：获取尾部元素
size：获取栈中的元素个数
pop：删除栈顶元素
push：栈顶插入元素
empty：判空
namespace cxq
{
template<class T , class Container = deque<T> >
class Stack
{
public:
void push( const T & x )
{
_con.push_back(x);
}
T & top()
{
return _con.back();
}
void pop()
{
_con.pop_back();
}
size_t size()
{
return _con.size();
}
bool empty()
{
return _con.empty();
}
private:
Container _con;
};
void test_Stack1()
{
stack<int> st1;
st1.push(1);
st1.push(2);
st1.push(3);
st1.push(4);
while (!st1.empty())
{
cout << st1.top() << " ";
st1.pop();
}
cout << endl;
stack<int ,list<int> > st2;
st2.push(1);
st2.push(2);
st2.push(3);
st2.push(4);
while (!st2.empty())
{
cout << st2.top() << " ";
st2.pop();
}
cout << endl;
}
}
deque
deque(双端队列)：是一种双开口的"连续"空间的数据结构，双开口的含义是：可以在头尾两端进行插入和删除操作，且时间复杂度为O(1)，与vector比较，头插效率高，不需要搬移元素；与list比较，空间利用率比较高。
deque并不是真正连续的空间，而是由一段段连续的小空间拼接而成的，实际deque类似于一个动态的二维数组。
双端队列底层是一段假象的连续空间，实际是分段连续的，为了维护其“整体连续”以及随机访问的假象，落 在了deque的迭代器身上
deque 与vector比较:
deque的头插和头删时，不需要挪动元素，效率特别高，而且在扩容时，也不需要移动大量的元素。
deque与list比较:
其底层是连续空间，空间利用率比较高，不需要存储额外字段。
但是，deque不适合遍历
因为在遍历时，deque的迭代器要频繁的去检测其是否移动到某段小空间的边界，导致效率低下，而序列式场景中，可能需要经常遍历，因此在实际中，需要线性结构时，大多数情况下优先考虑vector和list，deque的应用并不多，而目前能看到的一个应用就是，STL用其作为stack和queue的底层数据结构。
为什么STL选择deque作为stack和queue的底层默认容器
stack是一种后进先出的数据结构，因此只要具有push_back()和pop_back()操作的结构，都可以作为stack的底层容器，比如vector和list都可以。
queue是先进先出的数据结构，只要具有 push_back和pop_front操作的结构，都可以作为queue的底层容器，比如list。但是STL中对stack和 queue默认选择deque作为其底层容器，主要是因为：
1、stack和queue不需要遍历(因此stack和queue没有迭代器)，只需要在固定的一端或者两端进行操作。
2、在stack中元素增长时，deque比vector的效率高(扩容时不需要搬移大量数据)；queue中的元素增长时，deque不仅效率高，而且内存使用率高。
结合了deque的优点，而完美的避开了其缺陷。
如果想要对deque有比较深入的了解，可以阅读STL库的源码
// Deque implementation -*- C++ -*-
// Copyright (C) 2001-2018 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
// manages memory. Each deque has 4 members:
*
* - Tp** _M_map
* - size_t _M_map_size
* - iterator _M_start, _M_finish
*
* map_size is at least 8. %map is an array of map_size
* pointers-to-@a nodes. (The name %map has nothing to do with the
* std::map class, and @b nodes should not be confused with
* std::list's usage of @a node.)
*
* A @a node has no specific type name as such, but it is referred
* to as @a node in this file. It is a simple array-of-Tp. If Tp
* is very large, there will be one Tp element per node (i.e., an
* @a array of one). For non-huge Tp's, node size is inversely
* related to Tp size: the larger the Tp, the fewer Tp's will fit
* in a node. The goal here is to keep the total size of a node
* relatively small and constant over different Tp's, to improve
* allocator efficiency.
*
* Not every pointer in the %map array will point to a node. If
* the initial number of elements in the deque is small, the
* /middle/ %map pointers will be valid, and the ones at the edges
* will be unused. This same situation will arise as the %map
* grows: available %map pointers, if any, will be on the ends. As
* new nodes are created, only a subset of the %map's pointers need
* to be copied @a outward.
*
* Class invariants:
* - For any nonsingular iterator i:
* - i.node points to a member of the %map array. (Yes, you read that
* correctly: i.node does not actually point to a node.) The member of
* the %map array is what actually points to the node.
* - i.first == *(i.node) (This points to the node (first Tp element).)
* - i.last == i.first + node_size
* - i.cur is a pointer in the range [i.first, i.last). NOTE:
* the implication of this is that i.cur is always a dereferenceable
* pointer, even if i is a past-the-end iterator.
* - Start and Finish are always nonsingular iterators. NOTE: this
* means that an empty deque must have one node, a deque with
template<typename _Tp, typename _Alloc = std::allocator<_Tp> >
class deque : protected _Deque_base<_Tp, _Alloc>
{
#ifdef _GLIBCXX_CONCEPT_CHECKS
// concept requirements
typedef typename _Alloc::value_type _Alloc_value_type;
# if __cplusplus < 201103L
__glibcxx_class_requires(_Tp, _SGIAssignableConcept)
# endif
__glibcxx_class_requires2(_Tp, _Alloc_value_type, _SameTypeConcept)
#endif
#if __cplusplus >= 201103L
static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
"std::deque must have a non-const, non-volatile value_type");
# ifdef __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
"std::deque must have the same value_type as its allocator");
# endif
#endif
typedef _Deque_base<_Tp, _Alloc> _Base;
typedef typename _Base::_Tp_alloc_type _Tp_alloc_type;
typedef typename _Base::_Alloc_traits _Alloc_traits;
typedef typename _Base::_Map_pointer _Map_pointer;
public:
typedef _Tp value_type;
typedef typename _Alloc_traits::pointer pointer;
typedef typename _Alloc_traits::const_pointer const_pointer;
typedef typename _Alloc_traits::reference reference;
typedef typename _Alloc_traits::const_reference const_reference;
typedef typename _Base::iterator iterator;
typedef typename _Base::const_iterator const_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef size_t size_type;
typedef ptrdiff_t difference_type;
typedef _Alloc allocator_type;
protected:
static size_t _S_buffer_size() _GLIBCXX_NOEXCEPT
{ return __deque_buf_size(sizeof(_Tp)); }
// Functions controlling memory layout, and nothing else.
using _Base::_M_initialize_map;
using _Base::_M_create_nodes;
using _Base::_M_destroy_nodes;
using _Base::_M_allocate_node;
using _Base::_M_deallocate_node;
using _Base::_M_allocate_map;
using _Base::_M_deallocate_map;
using _Base::_M_get_Tp_allocator;
/**
* A total of four data members accumulated down the hierarchy.
* May be accessed via _M_impl.*
*/
using _Base::_M_impl;
public:
// [23.2.1.1] construct/copy/destroy
// (assign() and get_allocator() are also listed in this section)
/**
* @brief Creates a %deque with no elements.
*/
deque() : _Base() { }
/**
* @brief Creates a %deque with no elements.
* @param __a An allocator object.
*/
explicit
deque(const allocator_type& __a)
: _Base(__a, 0) { }
#if __cplusplus >= 201103L
/**
* @brief Creates a %deque with default constructed elements.
* @param __n The number of elements to initially create.
* @param __a An allocator.
*
* This constructor fills the %deque with @a n default
* constructed elements.
*/
explicit
deque(size_type __n, const allocator_type& __a = allocator_type())
: _Base(__a, __n)
{ _M_default_initialize(); }
/**
* @brief Creates a %deque with copies of an exemplar element.
* @param __n The number of elements to initially create.
* @param __value An element to copy.
* @param __a An allocator.
*
* This constructor fills the %deque with @a __n copies of @a __value.
*/
deque(size_type __n, const value_type& __value,
const allocator_type& __a = allocator_type())
: _Base(__a, __n)
{ _M_fill_initialize(__value); }
#else
/**
* @brief Creates a %deque with copies of an exemplar element.
* @param __n The number of elements to initially create.
* @param __value An element to copy.
* @param __a An allocator.
*
* This constructor fills the %deque with @a __n copies of @a __value.
*/
explicit
deque(size_type __n, const value_type& __value = value_type(),
const allocator_type& __a = allocator_type())
: _Base(__a, __n)
{ _M_fill_initialize(__value); }
#endif
/**
* @brief %Deque copy constructor.
* @param __x A %deque of identical element and allocator types.
*
* The newly-created %deque uses a copy of the allocator object used
* by @a __x (unless the allocator traits dictate a different object).
*/
deque(const deque& __x)
: _Base(_Alloc_traits::_S_select_on_copy(__x._M_get_Tp_allocator()),
__x.size())
{ std::__uninitialized_copy_a(__x.begin(), __x.end(),
this->_M_impl._M_start,
_M_get_Tp_allocator()); }
#if __cplusplus >= 201103L
/**
* @brief %Deque move constructor.
* @param __x A %deque of identical element and allocator types.
*
* The newly-created %deque contains the exact contents of @a __x.
* The contents of @a __x are a valid, but unspecified %deque.
*/
deque(deque&& __x)
: _Base(std::move(__x)) { }
/// Copy constructor with alternative allocator
deque(const deque& __x, const allocator_type& __a)
: _Base(__a, __x.size())
{ std::__uninitialized_copy_a(__x.begin(), __x.end(),
this->_M_impl._M_start,
_M_get_Tp_allocator()); }
/// Move constructor with alternative allocator
deque(deque&& __x, const allocator_type& __a)
: _Base(std::move(__x), __a, __x.size())
{
if (__x.get_allocator() != __a)
{
std::__uninitialized_move_a(__x.begin(), __x.end(),
this->_M_impl._M_start,
_M_get_Tp_allocator());
__x.clear();
}
}
/**
* @brief Builds a %deque from an initializer list.
* @param __l An initializer_list.
* @param __a An allocator object.
*
* Create a %deque consisting of copies of the elements in the
* initializer_list @a __l.
*
* This will call the element type's copy constructor N times
* (where N is __l.size()) and do no memory reallocation.
*/
deque(initializer_list<value_type> __l,
const allocator_type& __a = allocator_type())
: _Base(__a)
{
_M_range_initialize(__l.begin(), __l.end(),
random_access_iterator_tag());
}
#endif
/**
* @brief Builds a %deque from a range.
* @param __first An input iterator.
* @param __last An input iterator.
* @param __a An allocator object.
*
* Create a %deque consisting of copies of the elements from [__first,
* __last).
*
* If the iterators are forward, bidirectional, or random-access, then
* this will call the elements' copy constructor N times (where N is
* distance(__first,__last)) and do no memory reallocation. But if only
* input iterators are used, then this will do at most 2N calls to the
* copy constructor, and logN memory reallocations.
*/
#if __cplusplus >= 201103L
template<typename _InputIterator,
typename = std::_RequireInputIter<_InputIterator>>
deque(_InputIterator __first, _InputIterator __last,
const allocator_type& __a = allocator_type())
: _Base(__a)
{ _M_initialize_dispatch(__first, __last, __false_type()); }
#else
template<typename _InputIterator>
deque(_InputIterator __first, _InputIterator __last,
const allocator_type& __a = allocator_type())
: _Base(__a)
{
// Check whether it's an integral type. If so, it's not an iterator.
typedef typename std::__is_integer<_InputIterator>::__type _Integral;
_M_initialize_dispatch(__first, __last, _Integral());
}
#endif
/**
* The dtor only erases the elements, and note 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.
*/
~deque()
{ _M_destroy_data(begin(), end(), _M_get_Tp_allocator()); }
/**
* @brief %Deque assignment operator.
* @param __x A %deque of identical element and allocator types.
*
* All the elements of @a x are copied.
*
* The newly-created %deque uses a copy of the allocator object used
* by @a __x (unless the allocator traits dictate a different object).
*/
deque&
operator=(const deque& __x);
#if __cplusplus >= 201103L
/**
* @brief %Deque move assignment operator.
* @param __x A %deque of identical element and allocator types.
*
* The contents of @a __x are moved into this deque (without copying,
* if the allocators permit it).
* @a __x is a valid, but unspecified %deque.
*/
deque&
operator=(deque&& __x) noexcept(_Alloc_traits::_S_always_equal())
{
using __always_equal = typename _Alloc_traits::is_always_equal;
_M_move_assign1(std::move(__x), __always_equal{});
return *this;
}
/**
* @brief Assigns an initializer list to a %deque.
* @param __l An initializer_list.
*
* This function fills a %deque with copies of the elements in the
* initializer_list @a __l.
*
* Note that the assignment completely changes the %deque and that the
* resulting %deque's size is the same as the number of elements
* assigned.
*/
deque&
operator=(initializer_list<value_type> __l)
{
_M_assign_aux(__l.begin(), __l.end(),
random_access_iterator_tag());
return *this;
}
#endif
/**
* @brief Assigns a given value to a %deque.
* @param __n Number of elements to be assigned.
* @param __val Value to be assigned.
*
* This function fills a %deque with @a n copies of the given
* value. Note that the assignment completely changes the
* %deque and that the resulting %deque's size is the same as
* the number of elements assigned.
*/
void
assign(size_type __n, const value_type& __val)
{ _M_fill_assign(__n, __val); }
/**
* @brief Assigns a range to a %deque.
* @param __first An input iterator.
* @param __last An input iterator.
*
* This function fills a %deque with copies of the elements in the
* range [__first,__last).
*
* Note that the assignment completely changes the %deque and that the
* resulting %deque's size is the same as the number of elements
* assigned.
*/
#if __cplusplus >= 201103L
template<typename _InputIterator,
typename = std::_RequireInputIter<_InputIterator>>
void
assign(_InputIterator __first, _InputIterator __last)
{ _M_assign_dispatch(__first, __last, __false_type()); }
#else
template<typename _InputIterator>
void
assign(_InputIterator __first, _InputIterator __last)
{
typedef typename std::__is_integer<_InputIterator>::__type _Integral;
_M_assign_dispatch(__first, __last, _Integral());
}
#endif
#if __cplusplus >= 201103L
/**
* @brief Assigns an initializer list to a %deque.
* @param __l An initializer_list.
*
* This function fills a %deque with copies of the elements in the
* initializer_list @a __l.
*
* Note that the assignment completely changes the %deque and that the
* resulting %deque's size is the same as the number of elements
* assigned.
*/
void
assign(initializer_list<value_type> __l)
{ _M_assign_aux(__l.begin(), __l.end(), random_access_iterator_tag()); }
#endif
/// Get a copy of the memory allocation object.
allocator_type
get_allocator() const _GLIBCXX_NOEXCEPT
{ return _Base::get_allocator(); }
// iterators
/**
* Returns a read/write iterator that points to the first element in the
* %deque. Iteration is done in ordinary element order.
*/
iterator
begin() _GLIBCXX_NOEXCEPT
{ return this->_M_impl._M_start; }
/**
* Returns a read-only (constant) iterator that points to the first
* element in the %deque. Iteration is done in ordinary element order.
*/
const_iterator
begin() const _GLIBCXX_NOEXCEPT
{ return this->_M_impl._M_start; }
/**
* Returns a read/write iterator that points one past the last
* element in the %deque. Iteration is done in ordinary
* element order.
*/
iterator
end() _GLIBCXX_NOEXCEPT
{ return this->_M_impl._M_finish; }
/**
* Returns a read-only (constant) iterator that points one past
* the last element in the %deque. Iteration is done in
* ordinary element order.
*/
const_iterator
end() const _GLIBCXX_NOEXCEPT
{ return this->_M_impl._M_finish; }
/**
* Returns a read/write reverse iterator that points to the
* last element in the %deque. Iteration is done in reverse
* element order.
*/
reverse_iterator
rbegin() _GLIBCXX_NOEXCEPT
{ return reverse_iterator(this->_M_impl._M_finish); }
/**
* Returns a read-only (constant) reverse iterator that points
* to the last element in the %deque. Iteration is done in
* reverse element order.
*/
const_reverse_iterator
rbegin() const _GLIBCXX_NOEXCEPT
{ return const_reverse_iterator(this->_M_impl._M_finish); }
/**
* Returns a read/write reverse iterator that points to one
* before the first element in the %deque. Iteration is done
* in reverse element order.
*/
reverse_iterator
rend() _GLIBCXX_NOEXCEPT
{ return reverse_iterator(this->_M_impl._M_start); }
/**
* Returns a read-only (constant) reverse iterator that points
* to one before the first element in the %deque. Iteration is
* done in reverse element order.
*/
const_reverse_iterator
rend() const _GLIBCXX_NOEXCEPT
{ return const_reverse_iterator(this->_M_impl._M_start); }
#if __cplusplus >= 201103L
/**
* Returns a read-only (constant) iterator that points to the first
* element in the %deque. Iteration is done in ordinary element order.
*/
const_iterator
cbegin() const noexcept
{ return this->_M_impl._M_start; }
/**
* Returns a read-only (constant) iterator that points one past
* the last element in the %deque. Iteration is done in
* ordinary element order.
*/
const_iterator
cend() const noexcept
{ return this->_M_impl._M_finish; }
/**
* Returns a read-only (constant) reverse iterator that points
* to the last element in the %deque. Iteration is done in
* reverse element order.
*/
const_reverse_iterator
crbegin() const noexcept
{ return const_reverse_iterator(this->_M_impl._M_finish); }
/**
* Returns a read-only (constant) reverse iterator that points
* to one before the first element in the %deque. Iteration is
* done in reverse element order.
*/
const_reverse_iterator
crend() const noexcept
{ return const_reverse_iterator(this->_M_impl._M_start); }
#endif
// [23.2.1.2] capacity
/** Returns the number of elements in the %deque. */
size_type
size() const _GLIBCXX_NOEXCEPT
{ return this->_M_impl._M_finish - this->_M_impl._M_start; }
/** Returns the size() of the largest possible %deque. */
size_type
max_size() const _GLIBCXX_NOEXCEPT
{ return _Alloc_traits::max_size(_M_get_Tp_allocator()); }
#if __cplusplus >= 201103L
/**
* @brief Resizes the %deque to the specified number of elements.
* @param __new_size Number of elements the %deque should contain.
*
* This function will %resize the %deque to the specified
* number of elements. If the number is smaller than the
* %deque's current size the %deque is truncated, otherwise
* default constructed elements are appended.
*/
void
resize(size_type __new_size)
{
const size_type __len = size();
if (__new_size > __len)
_M_default_append(__new_size - __len);
else if (__new_size < __len)
_M_erase_at_end(this->_M_impl._M_start
+ difference_type(__new_size));
}
/**
* @brief Resizes the %deque to the specified number of elements.
* @param __new_size Number of elements the %deque should contain.
* @param __x Data with which new elements should be populated.
*
* This function will %resize the %deque to the specified
* number of elements. If the number is smaller than the
* %deque's current size the %deque is truncated, otherwise the
* %deque is extended and new elements are populated with given
* data.
*/
void
resize(size_type __new_size, const value_type& __x)
{
const size_type __len = size();
if (__new_size > __len)
_M_fill_insert(this->_M_impl._M_finish, __new_size - __len, __x);
else if (__new_size < __len)
_M_erase_at_end(this->_M_impl._M_start
+ difference_type(__new_size));
}
#else
/**
* @brief Resizes the %deque to the specified number of elements.
* @param __new_size Number of elements the %deque should contain.
* @param __x Data with which new elements should be populated.
*
* This function will %resize the %deque to the specified
* number of elements. If the number is smaller than the
* %deque's current size the %deque is truncated, otherwise the
* %deque is extended and new elements are populated with given
* data.
*/
void
resize(size_type __new_size, value_type __x = value_type())
{
const size_type __len = size();
if (__new_size > __len)
_M_fill_insert(this->_M_impl._M_finish, __new_size - __len, __x);
else if (__new_size < __len)
_M_erase_at_end(this->_M_impl._M_start
+ difference_type(__new_size));
}
#endif
#if __cplusplus >= 201103L
/** A non-binding request to reduce memory use. */
void
shrink_to_fit() noexcept
{ _M_shrink_to_fit(); }
#endif
/**
* Returns true if the %deque is empty. (Thus begin() would
* equal end().)
*/
bool
empty() const _GLIBCXX_NOEXCEPT
{ return this->_M_impl._M_finish == this->_M_impl._M_start; }
// element access
/**
* @brief Subscript access to the data contained in the %deque.
* @param __n The index of the element for which data should be
* accessed.
* @return Read/write reference to data.
*
* This operator allows for easy, array-style, data access.
* Note that data access with this operator is unchecked and
* out_of_range lookups are not defined. (For checked lookups
* see at().)
*/
reference
operator[](size_type __n) _GLIBCXX_NOEXCEPT
{
__glibcxx_requires_subscript(__n);
return this->_M_impl._M_start[difference_type(__n)];
}
/**
* @brief Subscript access to the data contained in the %deque.
* @param __n The index of the element for which data should be
* accessed.
* @return Read-only (constant) reference to data.
*
* This operator allows for easy, array-style, data access.
* Note that data access with this operator is unchecked and
* out_of_range lookups are not defined. (For checked lookups
* see at().)
*/
const_reference
operator[](size_type __n) const _GLIBCXX_NOEXCEPT
{
__glibcxx_requires_subscript(__n);
return this->_M_impl._M_start[difference_type(__n)];
}
protected:
/// Safety check used only from at().
void
_M_range_check(size_type __n) const
{
if (__n >= this->size())
__throw_out_of_range_fmt(__N("deque::_M_range_check: __n "
"(which is %zu)>= this->size() "
"(which is %zu)"),
__n, this->size());
}
public:
/**
* @brief Provides access to the data contained in the %deque.
* @param __n The index of the element for which data should be
* accessed.
* @return Read/write reference to data.
* @throw std::out_of_range If @a __n is an invalid index.
*
* This function provides for safer data access. The parameter
* is first checked that it is in the range of the deque. The
* function throws out_of_range if the check fails.
*/
reference
at(size_type __n)
{
_M_range_check(__n);
return (*this)[__n];
}
/**
* @brief Provides access to the data contained in the %deque.
* @param __n The index of the element for which data should be
* accessed.
* @return Read-only (constant) reference to data.
* @throw std::out_of_range If @a __n is an invalid index.
*
* This function provides for safer data access. The parameter is first
* checked that it is in the range of the deque. The function throws
* out_of_range if the check fails.
*/
const_reference
at(size_type __n) const
{
_M_range_check(__n);
return (*this)[__n];
}
/**
* Returns a read/write reference to the data at the first
* element of the %deque.
*/
reference
front() _GLIBCXX_NOEXCEPT
{
__glibcxx_requires_nonempty();
return *begin();
}
/**
* Returns a read-only (constant) reference to the data at the first
* element of the %deque.
*/
const_reference
front() const _GLIBCXX_NOEXCEPT
{
__glibcxx_requires_nonempty();
return *begin();
}
/**
* Returns a read/write reference to the data at the last element of the
* %deque.
*/
reference
back() _GLIBCXX_NOEXCEPT
{
__glibcxx_requires_nonempty();
iterator __tmp = end();
--__tmp;
return *__tmp;
}
/**
* Returns a read-only (constant) reference to the data at the last
* element of the %deque.
*/
const_reference
back() const _GLIBCXX_NOEXCEPT
{
__glibcxx_requires_nonempty();
const_iterator __tmp = end();
--__tmp;
return *__tmp;
}
// [23.2.1.2] modifiers
/**
* @brief Add data to the front of the %deque.
* @param __x Data to be added.
*
* This is a typical stack operation. The function creates an
* element at the front of the %deque and assigns the given
* data to it. Due to the nature of a %deque this operation
* can be done in constant time.
*/
void
push_front(const value_type& __x)
{
if (this->_M_impl._M_start._M_cur != this->_M_impl._M_start._M_first)
{
_Alloc_traits::construct(this->_M_impl,
this->_M_impl._M_start._M_cur - 1,
__x);
--this->_M_impl._M_start._M_cur;
}
else
_M_push_front_aux(__x);
}
#if __cplusplus >= 201103L
void
push_front(value_type&& __x)
{ emplace_front(std::move(__x)); }
template<typename... _Args>
#if __cplusplus > 201402L
reference
#else
void
#endif
emplace_front(_Args&&... __args);
#endif
/**
* @brief Add data to the end of the %deque.
* @param __x Data to be added.
*
* This is a typical stack operation. The function creates an
* element at the end of the %deque and assigns the given data
* to it. Due to the nature of a %deque this operation can be
* done in constant time.
*/
void
push_back(const value_type& __x)
{
if (this->_M_impl._M_finish._M_cur
!= this->_M_impl._M_finish._M_last - 1)
{
_Alloc_traits::construct(this->_M_impl,
this->_M_impl._M_finish._M_cur, __x);
++this->_M_impl._M_finish._M_cur;
}
else
_M_push_back_aux(__x);
}
#if __cplusplus >= 201103L
void
push_back(value_type&& __x)
{ emplace_back(std::move(__x)); }
template<typename... _Args>
#if __cplusplus > 201402L
reference
#else
void
#endif
emplace_back(_Args&&... __args);
#endif
/**
* @brief Removes first element.
*
* This is a typical stack operation. It shrinks the %deque by one.
*
* 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() _GLIBCXX_NOEXCEPT
{
__glibcxx_requires_nonempty();
if (this->_M_impl._M_start._M_cur
!= this->_M_impl._M_start._M_last - 1)
{
_Alloc_traits::destroy(this->_M_impl,
this->_M_impl._M_start._M_cur);
++this->_M_impl._M_start._M_cur;
}
else
_M_pop_front_aux();
}
/**
* @brief Removes last element.
*
* This is a typical stack operation. It shrinks the %deque by one.
*
* Note that no data is returned, and if the last element's data is
* needed, it should be retrieved before pop_back() is called.
*/
void
pop_back() _GLIBCXX_NOEXCEPT
{
__glibcxx_requires_nonempty();
if (this->_M_impl._M_finish._M_cur
!= this->_M_impl._M_finish._M_first)
{
--this->_M_impl._M_finish._M_cur;
_Alloc_traits::destroy(this->_M_impl,
this->_M_impl._M_finish._M_cur);
}
else
_M_pop_back_aux();
}
#if __cplusplus >= 201103L
/**
* @brief Inserts an object in %deque before specified iterator.
* @param __position A const_iterator into the %deque.
* @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)...) before the specified location.
*/
template<typename... _Args>
iterator
emplace(const_iterator __position, _Args&&... __args);
/**
* @brief Inserts given value into %deque before specified iterator.
* @param __position A const_iterator into the %deque.
* @param __x Data to be inserted.
* @return An iterator that points to the inserted data.
*
* This function will insert a copy of the given value before the
* specified location.
*/
iterator
insert(const_iterator __position, const value_type& __x);
#else
/**
* @brief Inserts given value into %deque before specified iterator.
* @param __position An iterator into the %deque.
* @param __x Data to be inserted.
* @return An iterator that points to the inserted data.
*
* This function will insert a copy of the given value before the
* specified location.
*/
iterator
insert(iterator __position, const value_type& __x);
#endif
#if __cplusplus >= 201103L
/**
* @brief Inserts given rvalue into %deque before specified iterator.
* @param __position A const_iterator into the %deque.
* @param __x Data to be inserted.
* @return An iterator that points to the inserted data.
*
* This function will insert a copy of the given rvalue before the
* specified location.
*/
iterator
insert(const_iterator __position, value_type&& __x)
{ return emplace(__position, std::move(__x)); }
/**
* @brief Inserts an initializer list into the %deque.
* @param __p An iterator into the %deque.
* @param __l An initializer_list.
*
* This function will insert copies of the data in the
* initializer_list @a __l into the %deque before the location
* specified by @a __p. This is known as list insert.
*/
iterator
insert(const_iterator __p, initializer_list<value_type> __l)
{
auto __offset = __p - cbegin();
_M_range_insert_aux(__p._M_const_cast(), __l.begin(), __l.end(),
std::random_access_iterator_tag());
return begin() + __offset;
}
#endif
#if __cplusplus >= 201103L
/**
* @brief Inserts a number of copies of given data into the %deque.
* @param __position A const_iterator into the %deque.
* @param __n Number of elements to be inserted.
* @param __x Data to be inserted.
* @return An iterator that points to the inserted data.
*
* This function will insert a specified number of copies of the given
* data before the location specified by @a __position.
*/
iterator
insert(const_iterator __position, size_type __n, const value_type& __x)
{
difference_type __offset = __position - cbegin();
_M_fill_insert(__position._M_const_cast(), __n, __x);
return begin() + __offset;
}
#else
/**
* @brief Inserts a number of copies of given data into the %deque.
* @param __position An iterator into the %deque.
* @param __n Number of elements to be inserted.
* @param __x Data to be inserted.
*
* This function will insert a specified number of copies of the given
* data before the location specified by @a __position.
*/
void
insert(iterator __position, size_type __n, const value_type& __x)
{ _M_fill_insert(__position, __n, __x); }
#endif
#if __cplusplus >= 201103L
/**
* @brief Inserts a range into the %deque.
* @param __position A const_iterator into the %deque.
* @param __first An input iterator.
* @param __last An input iterator.
* @return An iterator that points to the inserted data.
*
* This function will insert copies of the data in the range
* [__first,__last) into the %deque before the location specified
* by @a __position. This is known as range insert.
*/
template<typename _InputIterator,
typename = std::_RequireInputIter<_InputIterator>>
iterator
insert(const_iterator __position, _InputIterator __first,
_InputIterator __last)
{
difference_type __offset = __position - cbegin();
_M_insert_dispatch(__position._M_const_cast(),
__first, __last, __false_type());
return begin() + __offset;
}
#else
/**
* @brief Inserts a range into the %deque.
* @param __position An iterator into the %deque.
* @param __first An input iterator.
* @param __last An input iterator.
*
* This function will insert copies of the data in the range
* [__first,__last) into the %deque before the location specified
* by @a __position. This is known as range insert.
*/
template<typename _InputIterator>
void
insert(iterator __position, _InputIterator __first,
_InputIterator __last)
{
// Check whether it's an integral type. If so, it's not an iterator.
typedef typename std::__is_integer<_InputIterator>::__type _Integral;
_M_insert_dispatch(__position, __first, __last, _Integral());
}
#endif
/**
* @brief Remove element at given position.
* @param __position Iterator pointing to element to be erased.
* @return An iterator pointing to the next element (or end()).
*
* This function will erase the element at the given position and thus
* shorten the %deque by one.
*
* The user is 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
#if __cplusplus >= 201103L
erase(const_iterator __position)
#else
erase(iterator __position)
#endif
{ return _M_erase(__position._M_const_cast()); }
/**
* @brief Remove a range of elements.
* @param __first Iterator pointing to the first element to be erased.
* @param __last Iterator pointing to one past the last element to be
* erased.
* @return An iterator pointing to the element pointed to by @a last
* prior to erasing (or end()).
*
* This function will erase the elements in the range
* [__first,__last) and shorten the %deque accordingly.
*
* The user is 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
#if __cplusplus >= 201103L
erase(const_iterator __first, const_iterator __last)
#else
erase(iterator __first, iterator __last)
#endif
{ return _M_erase(__first._M_const_cast(), __last._M_const_cast()); }
/**
* @brief Swaps data with another %deque.
* @param __x A %deque of the same element and allocator types.
*
* This exchanges the elements between two deques in constant time.
* (Four pointers, so it should be quite fast.)
* Note that the global std::swap() function is specialized such that
* std::swap(d1,d2) will feed to this function.
*
* Whether the allocators are swapped depends on the allocator traits.
*/
void
swap(deque& __x) _GLIBCXX_NOEXCEPT
{
#if __cplusplus >= 201103L
__glibcxx_assert(_Alloc_traits::propagate_on_container_swap::value
|| _M_get_Tp_allocator() == __x._M_get_Tp_allocator());
#endif
_M_impl._M_swap_data(__x._M_impl);
_Alloc_traits::_S_on_swap(_M_get_Tp_allocator(),
__x._M_get_Tp_allocator());
}
/**
* 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() _GLIBCXX_NOEXCEPT
{ _M_erase_at_end(begin()); }
protected:
// Internal constructor functions follow.
// called by the range constructor to implement [23.1.1]/9
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 438. Ambiguity in the "do the right thing" clause
template<typename _Integer>
void
_M_initialize_dispatch(_Integer __n, _Integer __x, __true_type)
{
_M_initialize_map(static_cast<size_type>(__n));
_M_fill_initialize(__x);
}
// called by the range constructor to implement [23.1.1]/9
template<typename _InputIterator>
void
_M_initialize_dispatch(_InputIterator __first, _InputIterator __last,
__false_type)
{
_M_range_initialize(__first, __last,
std::__iterator_category(__first));
}
// called by the second initialize_dispatch above
//@{
/**
* @brief Fills the deque with whatever is in [first,last).
* @param __first An input iterator.
* @param __last An input iterator.
* @return Nothing.
*
* If the iterators are actually forward iterators (or better), then the
* memory layout can be done all at once. Else we move forward using
* push_back on each value from the iterator.
*/
template<typename _InputIterator>
void
_M_range_initialize(_InputIterator __first, _InputIterator __last,
std::input_iterator_tag);
// called by the second initialize_dispatch above
template<typename _ForwardIterator>
void
_M_range_initialize(_ForwardIterator __first, _ForwardIterator __last,
std::forward_iterator_tag);
//@}
/**
* @brief Fills the %deque with copies of value.
* @param __value Initial value.
* @return Nothing.
* @pre _M_start and _M_finish have already been initialized,
* but none of the %deque's elements have yet been constructed.
*
* This function is called only when the user provides an explicit size
* (with or without an explicit exemplar value).
*/
void
_M_fill_initialize(const value_type& __value);
#if __cplusplus >= 201103L
// called by deque(n).
void
_M_default_initialize();
#endif
// Internal assign functions follow. The *_aux functions do the actual
// assignment work for the range versions.
// called by the range assign to implement [23.1.1]/9
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 438. Ambiguity in the "do the right thing" clause
template<typename _Integer>
void
_M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
{ _M_fill_assign(__n, __val); }
// called by the range assign to implement [23.1.1]/9
template<typename _InputIterator>
void
_M_assign_dispatch(_InputIterator __first, _InputIterator __last,
__false_type)
{ _M_assign_aux(__first, __last, std::__iterator_category(__first)); }
// called by the second assign_dispatch above
template<typename _InputIterator>
void
_M_assign_aux(_InputIterator __first, _InputIterator __last,
std::input_iterator_tag);
// called by the second assign_dispatch above
template<typename _ForwardIterator>
void
_M_assign_aux(_ForwardIterator __first, _ForwardIterator __last,
std::forward_iterator_tag)
{
const size_type __len = std::distance(__first, __last);
if (__len > size())
{
_ForwardIterator __mid = __first;
std::advance(__mid, size());
std::copy(__first, __mid, begin());
_M_range_insert_aux(end(), __mid, __last,
std::__iterator_category(__first));
}
else
_M_erase_at_end(std::copy(__first, __last, begin()));
}
// Called by assign(n,t), and the range assign when it turns out
// to be the same thing.
void
_M_fill_assign(size_type __n, const value_type& __val)
{
if (__n > size())
{
std::fill(begin(), end(), __val);
_M_fill_insert(end(), __n - size(), __val);
}
else
{
_M_erase_at_end(begin() + difference_type(__n));
std::fill(begin(), end(), __val);
}
}
//@{
/// Helper functions for push_* and pop_*.
#if __cplusplus < 201103L
void _M_push_back_aux(const value_type&);
void _M_push_front_aux(const value_type&);
#else
template<typename... _Args>
void _M_push_back_aux(_Args&&... __args);
template<typename... _Args>
void _M_push_front_aux(_Args&&... __args);
#endif
void _M_pop_back_aux();
void _M_pop_front_aux();
//@}
// Internal insert functions follow. The *_aux functions do the actual
// insertion work when all shortcuts fail.
// called by the range insert to implement [23.1.1]/9
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 438. Ambiguity in the "do the right thing" clause
template<typename _Integer>
void
_M_insert_dispatch(iterator __pos,
_Integer __n, _Integer __x, __true_type)
{ _M_fill_insert(__pos, __n, __x); }
// called by the range insert to implement [23.1.1]/9
template<typename _InputIterator>
void
_M_insert_dispatch(iterator __pos,
_InputIterator __first, _InputIterator __last,
__false_type)
{
_M_range_insert_aux(__pos, __first, __last,
std::__iterator_category(__first));
}
// called by the second insert_dispatch above
template<typename _InputIterator>
void
_M_range_insert_aux(iterator __pos, _InputIterator __first,
_InputIterator __last, std::input_iterator_tag);
// called by the second insert_dispatch above
template<typename _ForwardIterator>
void
_M_range_insert_aux(iterator __pos, _ForwardIterator __first,
_ForwardIterator __last, std::forward_iterator_tag);
// Called by insert(p,n,x), and the range insert when it turns out to be
// the same thing. Can use fill functions in optimal situations,
// otherwise passes off to insert_aux(p,n,x).
void
_M_fill_insert(iterator __pos, size_type __n, const value_type& __x);
// called by insert(p,x)
#if __cplusplus < 201103L
iterator
_M_insert_aux(iterator __pos, const value_type& __x);
#else
template<typename... _Args>
iterator
_M_insert_aux(iterator __pos, _Args&&... __args);
#endif
// called by insert(p,n,x) via fill_insert
void
_M_insert_aux(iterator __pos, size_type __n, const value_type& __x);
// called by range_insert_aux for forward iterators
template<typename _ForwardIterator>
void
_M_insert_aux(iterator __pos,
_ForwardIterator __first, _ForwardIterator __last,
size_type __n);
// Internal erase functions follow.
void
_M_destroy_data_aux(iterator __first, iterator __last);
// Called by ~deque().
// NB: Doesn't deallocate the nodes.
template<typename _Alloc1>
void
_M_destroy_data(iterator __first, iterator __last, const _Alloc1&)
{ _M_destroy_data_aux(__first, __last); }
void
_M_destroy_data(iterator __first, iterator __last,
const std::allocator<_Tp>&)
{
if (!__has_trivial_destructor(value_type))
_M_destroy_data_aux(__first, __last);
}
// Called by erase(q1, q2).
void
_M_erase_at_begin(iterator __pos)
{
_M_destroy_data(begin(), __pos, _M_get_Tp_allocator());
_M_destroy_nodes(this->_M_impl._M_start._M_node, __pos._M_node);
this->_M_impl._M_start = __pos;
}
// Called by erase(q1, q2), resize(), clear(), _M_assign_aux,
// _M_fill_assign, operator=.
void
_M_erase_at_end(iterator __pos)
{
_M_destroy_data(__pos, end(), _M_get_Tp_allocator());
_M_destroy_nodes(__pos._M_node + 1,
this->_M_impl._M_finish._M_node + 1);
this->_M_impl._M_finish = __pos;
}
iterator
_M_erase(iterator __pos);
iterator
_M_erase(iterator __first, iterator __last);
#if __cplusplus >= 201103L
// Called by resize(sz).
void
_M_default_append(size_type __n);
bool
_M_shrink_to_fit();
#endif
//@{
/// Memory-handling helpers for the previous internal insert functions.
iterator
_M_reserve_elements_at_front(size_type __n)
{
const size_type __vacancies = this->_M_impl._M_start._M_cur
- this->_M_impl._M_start._M_first;
if (__n > __vacancies)
_M_new_elements_at_front(__n - __vacancies);
return this->_M_impl._M_start - difference_type(__n);
}
iterator
_M_reserve_elements_at_back(size_type __n)
{
const size_type __vacancies = (this->_M_impl._M_finish._M_last
- this->_M_impl._M_finish._M_cur) - 1;
if (__n > __vacancies)
_M_new_elements_at_back(__n - __vacancies);
return this->_M_impl._M_finish + difference_type(__n);
}
void
_M_new_elements_at_front(size_type __new_elements);
void
_M_new_elements_at_back(size_type __new_elements);
//@}
//@{
/**
* @brief Memory-handling helpers for the major %map.
*
* Makes sure the _M_map has space for new nodes. Does not
* actually add the nodes. Can invalidate _M_map pointers.
* (And consequently, %deque iterators.)
*/
void
_M_reserve_map_at_back(size_type __nodes_to_add = 1)
{
if (__nodes_to_add + 1 > this->_M_impl._M_map_size
- (this->_M_impl._M_finish._M_node - this->_M_impl._M_map))
_M_reallocate_map(__nodes_to_add, false);
}
void
_M_reserve_map_at_front(size_type __nodes_to_add = 1)
{
if (__nodes_to_add > size_type(this->_M_impl._M_start._M_node
- this->_M_impl._M_map))
_M_reallocate_map(__nodes_to_add, true);
}
void
_M_reallocate_map(size_type __nodes_to_add, bool __add_at_front);
//@}
#if __cplusplus >= 201103L
// Constant-time, nothrow move assignment when source object's memory
// can be moved because the allocators are equal.
void
_M_move_assign1(deque&& __x, /* always equal: */ true_type) noexcept
{
this->_M_impl._M_swap_data(__x._M_impl);
__x.clear();
std::__alloc_on_move(_M_get_Tp_allocator(), __x._M_get_Tp_allocator());
}
// When the allocators are not equal the operation could throw, because
// we might need to allocate a new map for __x after moving from it
// or we might need to allocate new elements for *this.
void
_M_move_assign1(deque&& __x, /* always equal: */ false_type)
{
constexpr bool __move_storage =
_Alloc_traits::_S_propagate_on_move_assign();
_M_move_assign2(std::move(__x), __bool_constant<__move_storage>());
}
// Destroy all elements and deallocate all memory, then replace
// with elements created from __args.
template<typename... _Args>
void
_M_replace_map(_Args&&... __args)
{
// Create new data first, so if allocation fails there are no effects.
deque __newobj(std::forward<_Args>(__args)...);
// Free existing storage using existing allocator.
clear();
_M_deallocate_node(*begin()._M_node); // one node left after clear()
_M_deallocate_map(this->_M_impl._M_map, this->_M_impl._M_map_size);
this->_M_impl._M_map = nullptr;
this->_M_impl._M_map_size = 0;
// Take ownership of replacement memory.
this->_M_impl._M_swap_data(__newobj._M_impl);
}
// Do move assignment when the allocator propagates.
void
_M_move_assign2(deque&& __x, /* propagate: */ true_type)
{
// Make a copy of the original allocator state.
auto __alloc = __x._M_get_Tp_allocator();
// The allocator propagates so storage can be moved from __x,
// leaving __x in a valid empty state with a moved-from allocator.
_M_replace_map(std::move(__x));
// Move the corresponding allocator state too.
_M_get_Tp_allocator() = std::move(__alloc);
}
// Do move assignment when it may not be possible to move source
// object's memory, resulting in a linear-time operation.
void
_M_move_assign2(deque&& __x, /* propagate: */ false_type)
{
if (__x._M_get_Tp_allocator() == this->_M_get_Tp_allocator())
{
// The allocators are equal so storage can be moved from __x,
// leaving __x in a valid empty state with its current allocator.
_M_replace_map(std::move(__x), __x.get_allocator());
}
else
{
// The rvalue's allocator cannot be moved and is not equal,
// so we need to individually move each element.
_M_assign_aux(std::__make_move_if_noexcept_iterator(__x.begin()),
std::__make_move_if_noexcept_iterator(__x.end()),
std::random_access_iterator_tag());
__x.clear();
}
}
#endif
};
#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>>
deque(_InputIterator, _InputIterator, _Allocator = _Allocator())
-> deque<_ValT, _Allocator>;
#endif
/**
* @brief Deque equality comparison.
* @param __x A %deque.
* @param __y A %deque of the same type as @a __x.
* @return True iff the size and elements of the deques are equal.
*
* This is an equivalence relation. It is linear in the size of the
* deques. Deques are considered equivalent if their sizes are equal,
* and if corresponding elements compare equal.
*/
template<typename _Tp, typename _Alloc>
inline bool
operator==(const deque<_Tp, _Alloc>& __x,
const deque<_Tp, _Alloc>& __y)
{ return __x.size() == __y.size()
&& std::equal(__x.begin(), __x.end(), __y.begin()); }
/**
* @brief Deque ordering relation.
* @param __x A %deque.
* @param __y A %deque of the same type as @a __x.
* @return True iff @a x is lexicographically less than @a __y.
*
* This is a total ordering relation. It is linear in the size of the
* deques. 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 deque<_Tp, _Alloc>& __x,
const deque<_Tp, _Alloc>& __y)
{ return std::lexicographical_compare(__x.begin(), __x.end(),
__y.begin(), __y.end()); }
/// Based on operator==
template<typename _Tp, typename _Alloc>
inline bool
operator!=(const deque<_Tp, _Alloc>& __x,
const deque<_Tp, _Alloc>& __y)
{ return !(__x == __y); }
/// Based on operator<
template<typename _Tp, typename _Alloc>
inline bool
operator>(const deque<_Tp, _Alloc>& __x,
const deque<_Tp, _Alloc>& __y)
{ return __y < __x; }
/// Based on operator<
template<typename _Tp, typename _Alloc>
inline bool
operator<=(const deque<_Tp, _Alloc>& __x,
const deque<_Tp, _Alloc>& __y)
{ return !(__y < __x); }
/// Based on operator<
template<typename _Tp, typename _Alloc>
inline bool
operator>=(const deque<_Tp, _Alloc>& __x,
const deque<_Tp, _Alloc>& __y)
{ return !(__x < __y); }
/// See std::deque::swap().
template<typename _Tp, typename _Alloc>
inline void
swap(deque<_Tp,_Alloc>& __x, deque<_Tp,_Alloc>& __y)
_GLIBCXX_NOEXCEPT_IF(noexcept(__x.swap(__y)))
{ __x.swap(__y); }
#undef _GLIBCXX_DEQUE_BUF_SIZE
_GLIBCXX_END_NAMESPACE_CONTAINER
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif /* _STL_DEQUE_H */
如果你觉得这篇文章对你有帮助，不妨动动手指给点赞收藏加转发，给鄃鳕一个大大的关注你们的每一次支持都将转化为我前进的动力！！！