STL deque源码剖析

deque(double-ended queue)是一种双向开口的序列容器，可以在头部和尾部进行push或pop操作，与vector不同，deque不是真正的连续线性空间，它是由分段连续空间动态组合而成。

map是一个二重指针，指向一个指针数组，数组中每个元素都为指针，指向各个相同大小的缓冲区，容器deque中的元素就放在这些缓冲区中，当map中的缓冲区满载后，就会配置一个新的map指向更大的空间。
下面详细分析SGI中的实现：
实现在stl_queue.h头文件中。

迭代器

deque也实现了随机访问迭代器，由于deque实现的是分段连续的线性空间，所以其迭代器设计相比vector比较复杂。
通过四个成员变量：

_Tp* _M_cur; //指向当前元素位置
_Tp* _M_first; //指向当前缓冲区的第一个位置
_Tp* _M_last; //指向当前缓冲区的最后一个位置
_Map_pointer _M_node; //指向中控器

template <class _Tp, class _Ref, class _Ptr>
struct _Deque_iterator {
  typedef _Deque_iterator<_Tp, _Tp&, _Tp*>             iterator;
  typedef _Deque_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;
  static size_t _S_buffer_size() { return __deque_buf_size(sizeof(_Tp)); }

  typedef random_access_iterator_tag iterator_category; //随机访问迭代器型别
  typedef _Tp value_type; //值类型
  typedef _Ptr pointer; //指针类型
  typedef _Ref reference; //指针类型
  typedef size_t size_type; //大小类型
  typedef ptrdiff_t difference_type; //指针差类型
  typedef _Tp** _Map_pointer; //二重指针类型

  typedef _Deque_iterator _Self; //deque迭代器类型

  _Tp* _M_cur; //指向当前元素位置
  _Tp* _M_first; //指向当前缓冲区的第一个位置
  _Tp* _M_last; //指向当前缓冲区的最后一个位置
  _Map_pointer _M_node; //指向中控器
//构造器
  _Deque_iterator(_Tp* __x, _Map_pointer __y) 
    : _M_cur(__x), _M_first(*__y),
      _M_last(*__y + _S_buffer_size()), _M_node(__y) {}
  _Deque_iterator() : _M_cur(0), _M_first(0), _M_last(0), _M_node(0) {}
  _Deque_iterator(const iterator& __x)
    : _M_cur(__x._M_cur), _M_first(__x._M_first), 
      _M_last(__x._M_last), _M_node(__x._M_node) {}

  reference operator*() const { return *_M_cur; } //重载*运算符
#ifndef __SGI_STL_NO_ARROW_OPERATOR
  pointer operator->() const { return _M_cur; } //重载->运算符
#endif /* __SGI_STL_NO_ARROW_OPERATOR */

  difference_type operator-(const _Self& __x) const { //重载-运算符
    return difference_type(_S_buffer_size()) * (_M_node - __x._M_node - 1) +
      (_M_cur - _M_first) + (__x._M_last - __x._M_cur); //考虑跨越不同的缓冲区块
  }

  _Self& operator++() { //重载++运算符
    ++_M_cur; //当前位置++
    if (_M_cur == _M_last) { //如果到了缓存区最后一个位置，注意缓存区最后一个位置不放置元素，只作为标志
      _M_set_node(_M_node + 1); //跳入下一个缓冲区块
      _M_cur = _M_first; //当前位置指向新区块第一个位置
    }
    return *this; 
  }
  _Self operator++(int)  {
    _Self __tmp = *this;
    ++*this;
    return __tmp;
  }

  _Self& operator--() { //重载--运算符
    if (_M_cur == _M_first) { //当前位置为当前缓存区块第一个位置时
      _M_set_node(_M_node - 1); //跳入上一个缓冲区块
      _M_cur = _M_last; //当前位置指向新区块最后一个位置
    }
    --_M_cur; //都要--，因为最后一个位置不放元素
    return *this;
  }
  _Self operator--(int) {
    _Self __tmp = *this;
    --*this;
    return __tmp;
  }

  _Self& operator+=(difference_type __n) //重载+=运算符
  {
    difference_type __offset = __n + (_M_cur - _M_first); //获取偏移量
    if (__offset >= 0 && __offset < difference_type(_S_buffer_size())) //偏移在当前缓冲区块
      _M_cur += __n;
    else { //偏移超过当前区块
      difference_type __node_offset =
        __offset > 0 ? __offset / difference_type(_S_buffer_size())
                   : -difference_type((-__offset - 1) / _S_buffer_size()) - 1; //获取区块节点偏移
      _M_set_node(_M_node + __node_offset); //调到偏移缓冲区块
      _M_cur = _M_first + 
        (__offset - __node_offset * difference_type(_S_buffer_size())); //调整当前位置指针
    }
    return *this;
  }

  _Self operator+(difference_type __n) const //重载+运算符，const
  {
    _Self __tmp = *this;
    return __tmp += __n;
  }

  _Self& operator-=(difference_type __n) { return *this += -__n; } //重载-=运算符

  _Self operator-(difference_type __n) const { //重载-运算符，const
    _Self __tmp = *this;
    return __tmp -= __n;
  }

  reference operator[](difference_type __n) const { return *(*this + __n); } //重载[]运算符

  bool operator==(const _Self& __x) const { return _M_cur == __x._M_cur; } //重载==运算符
  bool operator!=(const _Self& __x) const { return !(*this == __x); }
  bool operator<(const _Self& __x) const { //重载<运算符
    return (_M_node == __x._M_node) ? 
      (_M_cur < __x._M_cur) : (_M_node < __x._M_node);
  }
  bool operator>(const _Self& __x) const  { return __x < *this; } //重载>运算符
  bool operator<=(const _Self& __x) const { return !(__x < *this); } //重载<=运算符
  bool operator>=(const _Self& __x) const { return !(*this < __x); } //重载>=运算符

  void _M_set_node(_Map_pointer __new_node) { //跳到另一缓冲区块
    _M_node = __new_node;
    _M_first = *__new_node;
    _M_last = _M_first + difference_type(_S_buffer_size());
  }
};

template <class _Tp, class _Ref, class _Ptr>
inline _Deque_iterator<_Tp, _Ref, _Ptr>
operator+(ptrdiff_t __n, const _Deque_iterator<_Tp, _Ref, _Ptr>& __x) //重载+运算符，模板函数
{
  return __x + __n;
}

#ifndef __STL_CLASS_PARTIAL_SPECIALIZATION

template <class _Tp, class _Ref, class _Ptr>
inline random_access_iterator_tag
iterator_category(const _Deque_iterator<_Tp,_Ref,_Ptr>&)
{
  return random_access_iterator_tag(); //随机访问迭代器
}

template <class _Tp, class _Ref, class _Ptr>
inline _Tp* value_type(const _Deque_iterator<_Tp,_Ref,_Ptr>&) { return 0; }

template <class _Tp, class _Ref, class _Ptr>
inline ptrdiff_t* distance_type(const _Deque_iterator<_Tp,_Ref,_Ptr>&) {
  return 0;
}

#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

空间配置器

#ifdef __STL_USE_STD_ALLOCATORS

// Base class for ordinary allocators.
template <class _Tp, class _Alloc, bool __is_static>
class _Deque_alloc_base {
public:
  typedef typename _Alloc_traits<_Tp,_Alloc>::allocator_type allocator_type;
  allocator_type get_allocator() const { return _M_node_allocator; }

  _Deque_alloc_base(const allocator_type& __a)
    : _M_node_allocator(__a), _M_map_allocator(__a),
      _M_map(0), _M_map_size(0)
  {}

protected:
  typedef typename _Alloc_traits<_Tp*, _Alloc>::allocator_type
          _Map_allocator_type;

  allocator_type      _M_node_allocator;
  _Map_allocator_type _M_map_allocator;

  _Tp* _M_allocate_node() {
    return _M_node_allocator.allocate(__deque_buf_size(sizeof(_Tp)));
  }
  void _M_deallocate_node(_Tp* __p) {
    _M_node_allocator.deallocate(__p, __deque_buf_size(sizeof(_Tp)));
  }
  _Tp** _M_allocate_map(size_t __n) 
    { return _M_map_allocator.allocate(__n); }
  void _M_deallocate_map(_Tp** __p, size_t __n) 
    { _M_map_allocator.deallocate(__p, __n); }

  _Tp** _M_map;
  size_t _M_map_size;
};

// Specialization for instanceless allocators.
template <class _Tp, class _Alloc>
class _Deque_alloc_base<_Tp, _Alloc, true>
{
public:
  typedef typename _Alloc_traits<_Tp,_Alloc>::allocator_type allocator_type;
  allocator_type get_allocator() const { return allocator_type(); }

  _Deque_alloc_base(const allocator_type&) : _M_map(0), _M_map_size(0) {}

protected:
  typedef typename _Alloc_traits<_Tp, _Alloc>::_Alloc_type _Node_alloc_type;
  typedef typename _Alloc_traits<_Tp*, _Alloc>::_Alloc_type _Map_alloc_type;

  _Tp* _M_allocate_node() {
    return _Node_alloc_type::allocate(__deque_buf_size(sizeof(_Tp)));
  }
  void _M_deallocate_node(_Tp* __p) {
    _Node_alloc_type::deallocate(__p, __deque_buf_size(sizeof(_Tp)));
  }
  _Tp** _M_allocate_map(size_t __n) 
    { return _Map_alloc_type::allocate(__n); }
  void _M_deallocate_map(_Tp** __p, size_t __n) 
    { _Map_alloc_type::deallocate(__p, __n); }

  _Tp** _M_map;
  size_t _M_map_size;
};

template <class _Tp, class _Alloc>
class _Deque_base
  : public _Deque_alloc_base<_Tp,_Alloc,
                              _Alloc_traits<_Tp, _Alloc>::_S_instanceless>
{
public:
  typedef _Deque_alloc_base<_Tp,_Alloc,
                             _Alloc_traits<_Tp, _Alloc>::_S_instanceless>
          _Base;
  typedef typename _Base::allocator_type allocator_type;
  typedef _Deque_iterator<_Tp,_Tp&,_Tp*>             iterator;
  typedef _Deque_iterator<_Tp,const _Tp&,const _Tp*> const_iterator;

  _Deque_base(const allocator_type& __a, size_t __num_elements)
    : _Base(__a), _M_start(), _M_finish()
    { _M_initialize_map(__num_elements); }
  _Deque_base(const allocator_type& __a) 
    : _Base(__a), _M_start(), _M_finish() {}
  ~_Deque_base();    

protected:
  void _M_initialize_map(size_t);
  void _M_create_nodes(_Tp** __nstart, _Tp** __nfinish);
  void _M_destroy_nodes(_Tp** __nstart, _Tp** __nfinish);
  enum { _S_initial_map_size = 8 };

protected:
  iterator _M_start;
  iterator _M_finish;
};

#else /* __STL_USE_STD_ALLOCATORS */

template <class _Tp, class _Alloc>
class _Deque_base {
public:
  typedef _Deque_iterator<_Tp,_Tp&,_Tp*>             iterator;
  typedef _Deque_iterator<_Tp,const _Tp&,const _Tp*> const_iterator;

  typedef _Alloc allocator_type;
  allocator_type get_allocator() const { return allocator_type(); }

  _Deque_base(const allocator_type&, size_t __num_elements)
    : _M_map(0), _M_map_size(0),  _M_start(), _M_finish() {
    _M_initialize_map(__num_elements);
  }
  _Deque_base(const allocator_type&)
    : _M_map(0), _M_map_size(0),  _M_start(), _M_finish() {}
  ~_Deque_base();    

protected:
  void _M_initialize_map(size_t);
  void _M_create_nodes(_Tp** __nstart, _Tp** __nfinish);
  void _M_destroy_nodes(_Tp** __nstart, _Tp** __nfinish);
  enum { _S_initial_map_size = 8 };

protected:
  _Tp** _M_map;
  size_t _M_map_size;  
  iterator _M_start;
  iterator _M_finish;

  typedef simple_alloc<_Tp, _Alloc>  _Node_alloc_type;
  typedef simple_alloc<_Tp*, _Alloc> _Map_alloc_type;

  _Tp* _M_allocate_node()
    { return _Node_alloc_type::allocate(__deque_buf_size(sizeof(_Tp))); }
  void _M_deallocate_node(_Tp* __p)
    { _Node_alloc_type::deallocate(__p, __deque_buf_size(sizeof(_Tp))); }
  _Tp** _M_allocate_map(size_t __n) 
    { return _Map_alloc_type::allocate(__n); }
  void _M_deallocate_map(_Tp** __p, size_t __n) 
    { _Map_alloc_type::deallocate(__p, __n); }
};

#endif /* __STL_USE_STD_ALLOCATORS */

// Non-inline member functions from _Deque_base.

template <class _Tp, class _Alloc>
_Deque_base<_Tp,_Alloc>::~_Deque_base() {
  if (_M_map) {
    _M_destroy_nodes(_M_start._M_node, _M_finish._M_node + 1);
    _M_deallocate_map(_M_map, _M_map_size);
  }
}

template <class _Tp, class _Alloc>
void
_Deque_base<_Tp,_Alloc>::_M_initialize_map(size_t __num_elements)
{
  size_t __num_nodes = 
    __num_elements / __deque_buf_size(sizeof(_Tp)) + 1;

  _M_map_size = max((size_t) _S_initial_map_size, __num_nodes + 2);
  _M_map = _M_allocate_map(_M_map_size);

  _Tp** __nstart = _M_map + (_M_map_size - __num_nodes) / 2;
  _Tp** __nfinish = __nstart + __num_nodes;

  __STL_TRY {
    _M_create_nodes(__nstart, __nfinish);
  }
  __STL_UNWIND((_M_deallocate_map(_M_map, _M_map_size), 
                _M_map = 0, _M_map_size = 0));
  _M_start._M_set_node(__nstart);
  _M_finish._M_set_node(__nfinish - 1);
  _M_start._M_cur = _M_start._M_first;
  _M_finish._M_cur = _M_finish._M_first +
               __num_elements % __deque_buf_size(sizeof(_Tp));
}

template <class _Tp, class _Alloc>
void _Deque_base<_Tp,_Alloc>::_M_create_nodes(_Tp** __nstart, _Tp** __nfinish)
{
  _Tp** __cur;
  __STL_TRY {
    for (__cur = __nstart; __cur < __nfinish; ++__cur)
      *__cur = _M_allocate_node();
  }
  __STL_UNWIND(_M_destroy_nodes(__nstart, __cur));
}

template <class _Tp, class _Alloc>
void
_Deque_base<_Tp,_Alloc>::_M_destroy_nodes(_Tp** __nstart, _Tp** __nfinish)
{
  for (_Tp** __n = __nstart; __n < __nfinish; ++__n)
    _M_deallocate_node(*__n);
}

deque类实现

template <class _Tp, class _Alloc = __STL_DEFAULT_ALLOCATOR(_Tp) >
class deque : protected _Deque_base<_Tp, _Alloc> {
    ...
}

接受两个模板参数：_Tp（元素类型），_Alloc（空间配置器类型）。继承自deque基类_Deque_base。

• 型别定义

typedef _Deque_base<_Tp, _Alloc> _Base;
public:                         // Basic types
  typedef _Tp value_type;
  typedef value_type* pointer;
  typedef const value_type* const_pointer;
  typedef value_type& reference;
  typedef const value_type& const_reference;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;

  typedef typename _Base::allocator_type allocator_type;
  allocator_type get_allocator() const { return _Base::get_allocator(); }

public:                         // Iterators
  typedef typename _Base::iterator       iterator;
  typedef typename _Base::const_iterator const_iterator;

#ifdef __STL_CLASS_PARTIAL_SPECIALIZATION
  typedef reverse_iterator<const_iterator> const_reverse_iterator;
  typedef reverse_iterator<iterator> reverse_iterator;
#else /* __STL_CLASS_PARTIAL_SPECIALIZATION */
  typedef reverse_iterator<const_iterator, value_type, const_reference, 
                           difference_type>  
          const_reverse_iterator;
  typedef reverse_iterator<iterator, value_type, reference, difference_type>
          reverse_iterator; 
#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

protected:                      // Internal typedefs
  typedef pointer* _Map_pointer;
  static size_t _S_buffer_size() { return __deque_buf_size(sizeof(_Tp)); }

• 构造器

explicit deque(const allocator_type& __a = allocator_type()) 
    : _Base(__a, 0) {}
  deque(const deque& __x) : _Base(__x.get_allocator(), __x.size()) 
    { uninitialized_copy(__x.begin(), __x.end(), _M_start); }
  deque(size_type __n, const value_type& __value,
        const allocator_type& __a = allocator_type()) : _Base(__a, __n)
    { _M_fill_initialize(__value); }
  explicit deque(size_type __n) : _Base(allocator_type(), __n)
    { _M_fill_initialize(value_type()); }

#ifdef __STL_MEMBER_TEMPLATES

  // Check whether it's an integral type.  If so, it's not an iterator.
  template <class _InputIterator>
  deque(_InputIterator __first, _InputIterator __last,
        const allocator_type& __a = allocator_type()) : _Base(__a) {
    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
    _M_initialize_dispatch(__first, __last, _Integral());
  }

  template <class _Integer>
  void _M_initialize_dispatch(_Integer __n, _Integer __x, __true_type) {
    _M_initialize_map(__n);
    _M_fill_initialize(__x);
  }

  template <class _InputIter>
  void _M_initialize_dispatch(_InputIter __first, _InputIter __last,
                              __false_type) {
    _M_range_initialize(__first, __last, __ITERATOR_CATEGORY(__first));
  }

#else /* __STL_MEMBER_TEMPLATES */

  deque(const value_type* __first, const value_type* __last,
        const allocator_type& __a = allocator_type()) 
    : _Base(__a, __last - __first)
    { uninitialized_copy(__first, __last, _M_start); }
  deque(const_iterator __first, const_iterator __last,
        const allocator_type& __a = allocator_type()) 
    : _Base(__a, __last - __first)
    { uninitialized_copy(__first, __last, _M_start); }

#endif /* __STL_MEMBER_TEMPLATES */

• 析构器

~deque() { destroy(_M_start, _M_finish); }

• 拷贝赋值运算符

 deque& operator= (const deque& __x) {
    const size_type __len = size();
    if (&__x != this) {
      if (__len >= __x.size())
        erase(copy(__x.begin(), __x.end(), _M_start), _M_finish);
      else {
        const_iterator __mid = __x.begin() + difference_type(__len);
        copy(__x.begin(), __mid, _M_start);
        insert(_M_finish, __mid, __x.end());
      }
    }
    return *this;
  }        

• 迭代器

iterator begin() { return _M_start; }
iterator end() { return _M_finish; }
const_iterator begin() const { return _M_start; }
const_iterator end() const { return _M_finish; }

reverse_iterator rbegin() { return reverse_iterator(_M_finish); }
reverse_iterator rend() { return reverse_iterator(_M_start); }
const_reverse_iterator rbegin() const 
    { return const_reverse_iterator(_M_finish); }
const_reverse_iterator rend() const 
    { return const_reverse_iterator(_M_start); }

• 容量

size_type size() const { return _M_finish - _M_start; }
size_type max_size() const { return size_type(-1); }
bool empty() const { return _M_finish == _M_start; }
void resize(size_type __new_size, const value_type& __x) {
    const size_type __len = size();
    if (__new_size < __len) 
      erase(_M_start + __new_size, _M_finish);
    else
      insert(_M_finish, __new_size - __len, __x);
}

void resize(size_type new_size) { resize(new_size, value_type()); }

• 元素访问

reference operator[](size_type __n)
    { return _M_start[difference_type(__n)]; }
  const_reference operator[](size_type __n) const 
    { return _M_start[difference_type(__n)]; }

#ifdef __STL_THROW_RANGE_ERRORS
  void _M_range_check(size_type __n) const {
    if (__n >= this->size())
      __stl_throw_range_error("deque");
  }

  reference at(size_type __n)
    { _M_range_check(__n); return (*this)[__n]; }
  const_reference at(size_type __n) const
    { _M_range_check(__n); return (*this)[__n]; }
#endif /* __STL_THROW_RANGE_ERRORS */

  reference front() { return *_M_start; }
  reference back() {
    iterator __tmp = _M_finish;
    --__tmp;
    return *__tmp;
  }
  const_reference front() const { return *_M_start; }
  const_reference back() const {
    const_iterator __tmp = _M_finish;
    --__tmp;
    return *__tmp;
  }

• 修改器

assign

void _M_fill_assign(size_type __n, const _Tp& __val) {
    if (__n > size()) {
      fill(begin(), end(), __val);
      insert(end(), __n - size(), __val);
    }
    else {
      erase(begin() + __n, end());
      fill(begin(), end(), __val);
    }
  }

  void assign(size_type __n, const _Tp& __val) {
    _M_fill_assign(__n, __val);
  }

#ifdef __STL_MEMBER_TEMPLATES

  template <class _InputIterator>
  void assign(_InputIterator __first, _InputIterator __last) {
    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
    _M_assign_dispatch(__first, __last, _Integral());
  }

private:                        // helper functions for assign() 

  template <class _Integer>
  void _M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
    { _M_fill_assign((size_type) __n, (_Tp) __val); }

  template <class _InputIterator>
  void _M_assign_dispatch(_InputIterator __first, _InputIterator __last,
                          __false_type) {
    _M_assign_aux(__first, __last, __ITERATOR_CATEGORY(__first));
  }

  template <class _InputIterator>
  void _M_assign_aux(_InputIterator __first, _InputIterator __last,
                     input_iterator_tag);

  template <class _ForwardIterator>
  void _M_assign_aux(_ForwardIterator __first, _ForwardIterator __last,
                     forward_iterator_tag) {
    size_type __len = 0;
    distance(__first, __last, __len);
    if (__len > size()) {
      _ForwardIterator __mid = __first;
      advance(__mid, size());
      copy(__first, __mid, begin());
      insert(end(), __mid, __last);
    }
    else
      erase(copy(__first, __last, begin()), end());
  }

#endif /* __STL_MEMBER_TEMPLATES */

push_back,push_front,pop_back,pop_front

void push_back(const value_type& __t) {
    if (_M_finish._M_cur != _M_finish._M_last - 1) {
      construct(_M_finish._M_cur, __t);
      ++_M_finish._M_cur;
    }
    else
      _M_push_back_aux(__t);
  }

  void push_back() {
    if (_M_finish._M_cur != _M_finish._M_last - 1) {
      construct(_M_finish._M_cur);
      ++_M_finish._M_cur;
    }
    else
      _M_push_back_aux();
  }

  void push_front(const value_type& __t) {
    if (_M_start._M_cur != _M_start._M_first) {
      construct(_M_start._M_cur - 1, __t);
      --_M_start._M_cur;
    }
    else
      _M_push_front_aux(__t);
  }

  void push_front() {
    if (_M_start._M_cur != _M_start._M_first) {
      construct(_M_start._M_cur - 1);
      --_M_start._M_cur;
    }
    else
      _M_push_front_aux();
  }


  void pop_back() {
    if (_M_finish._M_cur != _M_finish._M_first) {
      --_M_finish._M_cur;
      destroy(_M_finish._M_cur);
    }
    else
      _M_pop_back_aux();
  }

  void pop_front() {
    if (_M_start._M_cur != _M_start._M_last - 1) {
      destroy(_M_start._M_cur);
      ++_M_start._M_cur;
    }
    else 
      _M_pop_front_aux();
  }

insert

iterator insert(iterator position, const value_type& __x) {
    if (position._M_cur == _M_start._M_cur) {
      push_front(__x);
      return _M_start;
    }
    else if (position._M_cur == _M_finish._M_cur) {
      push_back(__x);
      iterator __tmp = _M_finish;
      --__tmp;
      return __tmp;
    }
    else {
      return _M_insert_aux(position, __x);
    }
  }

  iterator insert(iterator __position)
    { return insert(__position, value_type()); }

  void insert(iterator __pos, size_type __n, const value_type& __x)
    { _M_fill_insert(__pos, __n, __x); }

  void _M_fill_insert(iterator __pos, size_type __n, const value_type& __x); 

#ifdef __STL_MEMBER_TEMPLATES  

  // Check whether it's an integral type.  If so, it's not an iterator.
  template <class _InputIterator>
  void insert(iterator __pos, _InputIterator __first, _InputIterator __last) {
    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
    _M_insert_dispatch(__pos, __first, __last, _Integral());
  }

  template <class _Integer>
  void _M_insert_dispatch(iterator __pos, _Integer __n, _Integer __x,
                          __true_type) {
    _M_fill_insert(__pos, (size_type) __n, (value_type) __x);
  }

  template <class _InputIterator>
  void _M_insert_dispatch(iterator __pos,
                          _InputIterator __first, _InputIterator __last,
                          __false_type) {
    insert(__pos, __first, __last, __ITERATOR_CATEGORY(__first));
  }

#else /* __STL_MEMBER_TEMPLATES */

  void insert(iterator __pos,
              const value_type* __first, const value_type* __last);
  void insert(iterator __pos,
              const_iterator __first, const_iterator __last);

#endif /* __STL_MEMBER_TEMPLATES */

erase

iterator erase(iterator __pos) {
    iterator __next = __pos;
    ++__next;
    difference_type __index = __pos - _M_start;
    if (size_type(__index) < (this->size() >> 1)) {
      copy_backward(_M_start, __pos, __next);
      pop_front();
    }
    else {
      copy(__next, _M_finish, __pos);
      pop_back();
    }
    return _M_start + __index;
  }

  iterator erase(iterator __first, iterator __last);

swap

  void swap(deque& __x) {
    __STD::swap(_M_start, __x._M_start);
    __STD::swap(_M_finish, __x._M_finish);
    __STD::swap(_M_map, __x._M_map);
    __STD::swap(_M_map_size, __x._M_map_size);
  }

template <class _Tp, class _Alloc>
inline void swap(deque<_Tp,_Alloc>& __x, deque<_Tp,_Alloc>& __y) {
  __x.swap(__y);
}

clear

template <class _Tp, class _Alloc> 
void deque<_Tp,_Alloc>::clear()
{
  for (_Map_pointer __node = _M_start._M_node + 1;
       __node < _M_finish._M_node;
       ++__node) {
    destroy(*__node, *__node + _S_buffer_size());
    _M_deallocate_node(*__node);
  }

  if (_M_start._M_node != _M_finish._M_node) {
    destroy(_M_start._M_cur, _M_start._M_last);
    destroy(_M_finish._M_first, _M_finish._M_cur);
    _M_deallocate_node(_M_finish._M_first);
  }
  else
    destroy(_M_start._M_cur, _M_finish._M_cur);

  _M_finish = _M_start;
}

• 关系运算符重载

template <class _Tp, class _Alloc>
inline bool operator==(const deque<_Tp, _Alloc>& __x,
                       const deque<_Tp, _Alloc>& __y) {
  return __x.size() == __y.size() &&
         equal(__x.begin(), __x.end(), __y.begin());
}

template <class _Tp, class _Alloc>
inline bool operator<(const deque<_Tp, _Alloc>& __x,
                      const deque<_Tp, _Alloc>& __y) {
  return lexicographical_compare(__x.begin(), __x.end(), 
                                 __y.begin(), __y.end());
}

#ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER

template <class _Tp, class _Alloc>
inline bool operator!=(const deque<_Tp, _Alloc>& __x,
                       const deque<_Tp, _Alloc>& __y) {
  return !(__x == __y);
}

template <class _Tp, class _Alloc>
inline bool operator>(const deque<_Tp, _Alloc>& __x,
                      const deque<_Tp, _Alloc>& __y) {
  return __y < __x;
}

template <class _Tp, class _Alloc>
inline bool operator<=(const deque<_Tp, _Alloc>& __x,
                       const deque<_Tp, _Alloc>& __y) {
  return !(__y < __x);
}
template <class _Tp, class _Alloc>
inline bool operator>=(const deque<_Tp, _Alloc>& __x,
                       const deque<_Tp, _Alloc>& __y) {
  return !(__x < __y);
}