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C++ STL 源码学习(之deque篇）
stl_deque.h
/** Class invariants:
* For any nonsingular iterator i:
* i.node is the address of an element in the map array. The
* contents of i.node is a pointer to the beginning of a node.
* i.first == *(i.node)
* 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, and that a deque
* with N elements, where N is the buffer size, must have two nodes.
* For every node other than start.node and finish.node, every element
* in the node is an initialized object. If start.node == finish.node,
* then [start.cur, finish.cur) are initialized objects, and
* the elements outside that range are uninitialized storage. Otherwise,
* [start.cur, start.last) and [finish.first, finish.cur) are initialized
* objects, and [start.first, start.cur) and [finish.cur, finish.last)
* are uninitialized storage.
* [map, map + map_size) is a valid, non-empty range.
* [start.node, finish.node] is a valid range contained within
* [map, map + map_size).
* A pointer in the range [map, map + map_size) points to an allocated node
* if and only if the pointer is in the range [start.node, finish.node].
*/
/// Note: this function is simply a kludge to work around several compilers'
/// bugs in handling constant expressions.
inline size_t __deque_buf_size(size_t __size)
{
return __size < 512 ? size_t(512 / __size) : size_t(1); ///计算deque每个区段大小
}
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;
typedef _Tp value_type;
typedef _Ptr pointer;
typedef _Ref reference;
typedef size_t size_type;
typedef ptrdiff_t difference_type;
typedef _Tp** _Map_pointer;
typedef _Deque_iterator _Self;
///指向迭代器所在区段头指针在区段中控器(一个按序存储区段头指针
///的数组,也可以理解为区段位置的索引表)中的存储位置,存储顺序决定了
///各个区段的顺序,据此来控制迭代器跨区段移动
_Map_pointer _M_node;
_Tp* _M_cur; ///指向迭代器实指位置
_Tp* _M_first; ///指向迭代器所在区段的头指针,由*_M_node可得
///指向超出迭代器所在区段的第一个指针,由_M_first与区段大小求和可得
_Tp* _M_last;
_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;
}
pointer operator->() const
{
return _M_cur;
}
difference_type operator-(const _Self& __x) const
{
///_M_node - __x._M_node-1计算x和本迭代器之间相隔的完整区段数
return difference_type(_S_buffer_size()) * (_M_node - __x._M_node - 1) +
(_M_cur - _M_first) + (__x._M_last - __x._M_cur);
}
_Self& operator++()
{
++_M_cur;
if (_M_cur == _M_last) ///已超出该区段,需要向下一个区段移动
{
_M_set_node(_M_node + 1); ///修改中控器位置记录
_M_cur = _M_first; ///指向下一个区段的头指针
}
return *this;
}
_Self operator++(int)
{
_Self __tmp = *this;
++*this;
return __tmp;
}
_Self& operator--()
{
if (_M_cur == _M_first) ///位于头指针,需要向上一个区段移动
{
_M_set_node(_M_node - 1);
_M_cur = _M_last; ///指向上一个区段超出末尾的第一个指针
}
--_M_cur; ///向前移动一位
return *this;
}
_Self operator--(int)
{
_Self __tmp = *this;
--*this;
return __tmp;
}
///为使迭代器成为随机迭代器所做的工作
_Self& operator+=(difference_type __n)
{
difference_type __offset = __n + (_M_cur - _M_first);
if (__offset >= 0 && __offset < difference_type(_S_buffer_size()))
{
///向后移动,而且并未超出目前所在区段
_M_cur += __n;
}
else
{
///计算需要前移/后移的区段数
difference_type __node_offset =
__offset > 0 ? __offset / difference_type(_S_buffer_size())
: -difference_type((-__offset - 1) / _S_buffer_size()) - 1;
_M_set_node(_M_node + __node_offset);
///计算迭代器确指位置
_M_cur = _M_first +
(__offset - __node_offset * difference_type(_S_buffer_size()));
}
return *this;
}
_Self operator+(difference_type __n) const
{
_Self __tmp = *this;
return __tmp += __n;
}
_Self& operator-=(difference_type __n)
{
return *this += -__n;
}
_Self operator-(difference_type __n) const
{
_Self __tmp = *this;
return __tmp -= __n;
}
reference operator[](difference_type __n) const
{
return *(*this + __n);
}
bool operator==(const _Self& __x) const
{
return _M_cur == __x._M_cur;
}
bool operator!=(const _Self& __x) const
{
return !(*this == __x);
}
///按迭代器所在区段头指针在中控器中的存储位置进行比较
///若在同一区段,再比较迭代器确指指针
bool operator<(const _Self& __x) const
{
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;
}
bool operator<=(const _Self& __x) const
{
return !(__x < *this);
}
bool operator>=(const _Self& __x) const
{
return !(*this < __x);
}
void _M_set_node(_Map_pointer __new_node)
{
///设置迭代器所在区段
_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)
{
return __x + __n;
}
/// Deque base class. Its constructor and destructor allocate
/// (but don't initialize) storage. This makes exception safety easier.
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);
///默认中控器大小为8,即可创建8个区段
enum { _S_initial_map_size = 8 };
protected:
_Tp** _M_map; ///中控器,一个指向_Tp类型数组指针的数组
///中控器大小,决定了不扩充中控器时最多可容纳的区段数
size_t _M_map_size;
iterator _M_start; ///起始迭代器
iterator _M_finish; ///结束迭代器,其实际指向最后一个元素的下一个位置
typedef simple_alloc<_Tp, _Alloc> _Node_alloc_type;
typedef simple_alloc<_Tp*, _Alloc> _Map_alloc_type;
///每次分配、回收一个区段
_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)));
}
///中控器内存的分配与回收,实际是Tp* 类型数组的分配、回收
_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);
}
};
/// Non-inline member functions from _Deque_base.
template <class _Tp, class _Alloc>
_Deque_base<_Tp,_Alloc>::~_Deque_base()
{
if (_M_map)
{
///回收各个区段的内存
_M_destroy_nodes(_M_start._M_node, _M_finish._M_node + 1);
///回收中控器的内存
_M_deallocate_map(_M_map, _M_map_size);
}
}
///初始化中控器
template <class _Tp, class _Alloc>
void
_Deque_base<_Tp,_Alloc>::_M_initialize_map(size_t __num_elements)
{
///计算所需的区段数目,从而决定中控器的大小
size_t __num_nodes =
__num_elements / __deque_buf_size(sizeof(_Tp)) + 1;
///计算中控器大小,并为之分配内存(至少为其分配的单元要多于区段数目两个)
///为了避免扩充过程中过多的重新分配中控器而导致的效率降低
_M_map_size = max((size_t) _S_initial_map_size, __num_nodes + 2);
_M_map = _M_allocate_map(_M_map_size);
///使用中控器的中间部分,这样可以保证前后都可以继续扩充区段
_Tp** __nstart = _M_map + (_M_map_size - __num_nodes) / 2;
_Tp** __nfinish = __nstart + __num_nodes;
try
{
_M_create_nodes(__nstart, __nfinish);
}
catch(...)
{
_M_deallocate_map(_M_map, _M_map_size);
_M_map = 0;
_M_map_size = 0;
}
///设置起始、终止迭代器的指向
_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));
}
///为各个区段分配内存
template <class _Tp, class _Alloc>
void _Deque_base<_Tp,_Alloc>::_M_create_nodes(_Tp** __nstart, _Tp** __nfinish)
{
_Tp** __cur;
try
{
for (__cur = __nstart; __cur < __nfinish; ++__cur)
*__cur = _M_allocate_node();
}
catch(...)
{
_M_destroy_nodes(__nstart, __cur);
}
}
///回收各个区段的内存
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);
}
template <class _Tp, class _Alloc = Stl_Default_Alloc >
class deque : protected _Deque_base<_Tp, _Alloc>
{
/// requirements:
__STL_CLASS_REQUIRES(_Tp, _Assignable);
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;
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;
protected: /// Internal typedefs
typedef pointer* _Map_pointer;
static size_t _S_buffer_size()
{
return __deque_buf_size(sizeof(_Tp));
}
protected:
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_map;
using _Base::_M_map_size;
using _Base::_M_start;
using _Base::_M_finish;
public: /// Basic accessors
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);
}
reference operator[](size_type __n)
{
return _M_start[difference_type(__n)];
}
const_reference operator[](size_type __n) const
{
return _M_start[difference_type(__n)];
}
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;
}
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;
}
public: /// Constructor, destructor.
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());
}
/// 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)
{
///根据型别做不同的处理
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));
}
///一次析构每个对象元素,回收内存交由基类处理
~deque()
{
destroy(_M_start, _M_finish);
}
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;
}
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);
}
public:
/// assign(), a generalized assignment member function. Two
/// versions: one that takes a count, and one that takes a range.
/// The range version is a member template, so we dispatch on whether
/// or not the type is an integer.
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);
}
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)
{
///根据迭代器不同采取不同的方法,以取得最佳效率
_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());
}
public: /// push_* and pop_*
void push_back(const value_type& __t)
{
if (_M_finish._M_cur != _M_finish._M_last - 1)
{
///结束迭代器所指位置之后,该区段尚有空间
construct(_M_finish._M_cur, __t);
++_M_finish._M_cur;
}
else ///已到最后一个区段区段末尾,需另行处理
_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)
{
///起始迭代器所指为止之前该区段尚有空间
construct(_M_start._M_cur - 1, __t);
--_M_start._M_cur;
}
else ///在第一个区段头部插入,需另行处理
_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)
{
///最后一个元素不是最后一个区段的第一个元素
--_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();
}
public: /// Insert
///都是通过函数调用实现的,很清晰
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);
/// 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));
}
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());
}
public: /// Erase
iterator erase(iterator __pos)
{
iterator __next = __pos;
++__next;
difference_type __index = __pos - _M_start;
if (size_type(__index) < (this->size() >> 1)) ///位于deque前半段
{
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);
void clear();
protected: /// Internal construction/destruction
void _M_fill_initialize(const value_type& __value);
template <class _InputIterator>
void _M_range_initialize(_InputIterator __first, _InputIterator __last,
input_iterator_tag);
template <class _ForwardIterator>
void _M_range_initialize(_ForwardIterator __first, _ForwardIterator __last,
forward_iterator_tag);
protected: /// Internal push_* and pop_*
void _M_push_back_aux(const value_type&);
void _M_push_back_aux();
void _M_push_front_aux(const value_type&);
void _M_push_front_aux();
void _M_pop_back_aux();
void _M_pop_front_aux();
protected: /// Internal insert functions
template <class _InputIterator>
void insert(iterator __pos, _InputIterator __first, _InputIterator __last,
input_iterator_tag);
template <class _ForwardIterator>
void insert(iterator __pos,
_ForwardIterator __first, _ForwardIterator __last,
forward_iterator_tag);
iterator _M_insert_aux(iterator __pos, const value_type& __x);
iterator _M_insert_aux(iterator __pos);
void _M_insert_aux(iterator __pos, size_type __n, const value_type& __x);
template <class _ForwardIterator>
void _M_insert_aux(iterator __pos,
_ForwardIterator __first, _ForwardIterator __last,
size_type __n);
void _M_insert_aux(iterator __pos,
const value_type* __first, const value_type* __last,
size_type __n);
void _M_insert_aux(iterator __pos,
const_iterator __first, const_iterator __last,
size_type __n);
iterator _M_reserve_elements_at_front(size_type __n)
{
size_type __vacancies = _M_start._M_cur - _M_start._M_first;
if (__n > __vacancies)
_M_new_elements_at_front(__n - __vacancies);
return _M_start - difference_type(__n);
}
iterator _M_reserve_elements_at_back(size_type __n)
{
size_type __vacancies = (_M_finish._M_last - _M_finish._M_cur) - 1;
if (__n > __vacancies)
_M_new_elements_at_back(__n - __vacancies);
return _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);
protected: /// Allocation of _M_map and nodes
/// 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 > _M_map_size - (_M_finish._M_node - _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(_M_start._M_node - _M_map))
_M_reallocate_map(__nodes_to_add, true);
}
void _M_reallocate_map(size_type __nodes_to_add, bool __add_at_front);
};
/// Non-inline member functions
template <class _Tp, class _Alloc>
template <class _InputIter>
void deque<_Tp, _Alloc>
::_M_assign_aux(_InputIter __first, _InputIter __last, input_iterator_tag)
{
iterator __cur = begin();
for ( ; __first != __last && __cur != end(); ++__cur, ++__first)
*__cur = *__first;
if (__first == __last)
erase(__cur, end());
else
insert(end(), __first, __last);
}
template <class _Tp, class _Alloc>
void deque<_Tp, _Alloc>::_M_fill_insert(iterator __pos,
size_type __n, const value_type& __x)
{
if (__pos._M_cur == _M_start._M_cur)
{
iterator __new_start = _M_reserve_elements_at_front(__n);
try
{
uninitialized_fill(__new_start, _M_start, __x);
_M_start = __new_start;
}
catch(...)
{
_M_destroy_nodes(__new_start._M_node, _M_start._M_node);
throw;
}
}
else if (__pos._M_cur == _M_finish._M_cur)
{
iterator __new_finish = _M_reserve_elements_at_back(__n);
try
{
uninitialized_fill(_M_finish, __new_finish, __x);
_M_finish = __new_finish;
}
catch(...)
{
_M_destroy_nodes(_M_finish._M_node + 1,
__new_finish._M_node + 1);
throw;
}
}
else
_M_insert_aux(__pos, __n, __x);
}
template <class _Tp, class _Alloc>
void deque<_Tp, _Alloc>::insert(iterator __pos,
const value_type* __first,
const value_type* __last)
{
size_type __n = __last - __first;
if (__pos._M_cur == _M_start._M_cur)
{
iterator __new_start = _M_reserve_elements_at_front(__n);
try
{
uninitialized_copy(__first, __last, __new_start);
_M_start = __new_start;
}
catch(...)
{
_M_destroy_nodes(__new_start._M_node, _M_start._M_node);
throw;
}
}
else if (__pos._M_cur == _M_finish._M_cur)
{
iterator __new_finish = _M_reserve_elements_at_back(__n);
try
{
uninitialized_copy(__first, __last, _M_finish);
_M_finish = __new_finish;
}
catch(...)
{
_M_destroy_nodes(_M_finish._M_node + 1,
__new_finish._M_node + 1);
throw;
}
}
else
_M_insert_aux(__pos, __first, __last, __n);
}
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::insert(iterator __pos,
const_iterator __first, const_iterator __last)
{
size_type __n = __last - __first;
if (__pos._M_cur == _M_start._M_cur)
{
iterator __new_start = _M_reserve_elements_at_front(__n);
try
{
uninitialized_copy(__first, __last, __new_start);
_M_start = __new_start;
}
catch(...)
{
_M_destroy_nodes(__new_start._M_node, _M_start._M_node);
throw;
}
}
else if (__pos._M_cur == _M_finish._M_cur)
{
iterator __new_finish = _M_reserve_elements_at_back(__n);
try
{
uninitialized_copy(__first, __last, _M_finish);
_M_finish = __new_finish;
}
catch(...)
{
_M_destroy_nodes(_M_finish._M_node + 1,
__new_finish._M_node + 1);
throw;
}
}
else
_M_insert_aux(__pos, __first, __last, __n);
}
template <class _Tp, class _Alloc>
typename deque<_Tp,_Alloc>::iterator
deque<_Tp,_Alloc>::erase(iterator __first, iterator __last)
{
if (__first == _M_start && __last == _M_finish)
{
clear();
return _M_finish;
}
else
{
difference_type __n = __last - __first;
difference_type __elems_before = __first - _M_start;
if (__elems_before < difference_type((this->size() - __n) / 2))
{
///位于删除区间之间的元素少于之后的元素
copy_backward(_M_start, __first, __last);
iterator __new_start = _M_start + __n;
///析构多余元素
destroy(_M_start, __new_start);
///回收未用区段
_M_destroy_nodes(__new_start._M_node, _M_start._M_node);
_M_start = __new_start;
}
else
{
copy(__last, _M_finish, __first);
iterator __new_finish = _M_finish - __n;
destroy(__new_finish, _M_finish);
_M_destroy_nodes(__new_finish._M_node + 1, _M_finish._M_node + 1);
_M_finish = __new_finish;
}
return _M_start + __elems_before;
}
}
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::clear()
{
///依次析构每个区段的对象元素,然后回收析构完的区段
for (_Map_pointer __node = _M_start._M_node + 1;
__node < _M_finish._M_node;
++__node) ///对完整区段进行统一处理
{
destroy(*__node, *__node + _S_buffer_size());
_M_deallocate_node(*__node);
}
if (_M_start._M_node != _M_finish._M_node)
{
///所有元素分布在不少于两个区段上,对尚未处理的第一个和最后一个
///区段进行处理
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;
}
/// Precondition: _M_start and _M_finish have already been initialized,
/// but none of the deque's elements have yet been constructed.
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_fill_initialize(const value_type& __value)
{
_Map_pointer __cur;
try
{
///对完整区段统一处理
for (__cur = _M_start._M_node; __cur < _M_finish._M_node; ++__cur)
uninitialized_fill(*__cur, *__cur + _S_buffer_size(), __value);
///处理最后一个区段
uninitialized_fill(_M_finish._M_first, _M_finish._M_cur, __value);
}
catch(...)
{
destroy(_M_start, iterator(*__cur, __cur));
throw;
}
}
template <class _Tp, class _Alloc> template <class _InputIterator>
void deque<_Tp,_Alloc>::_M_range_initialize(_InputIterator __first,
_InputIterator __last,
input_iterator_tag)
{
_M_initialize_map(0);
try
{
for ( ; __first != __last; ++__first)
push_back(*__first);
}
catch(...)
{
clear();
throw;
}
}
template <class _Tp, class _Alloc> template <class _ForwardIterator>
void deque<_Tp,_Alloc>::_M_range_initialize(_ForwardIterator __first,
_ForwardIterator __last,
forward_iterator_tag)
{
size_type __n = 0;
distance(__first, __last, __n);
_M_initialize_map(__n);
_Map_pointer __cur_node;
try
{
for (__cur_node = _M_start._M_node;
__cur_node < _M_finish._M_node;
++__cur_node)
{
_ForwardIterator __mid = __first;
advance(__mid, _S_buffer_size());
uninitialized_copy(__first, __mid, *__cur_node);
__first = __mid;
}
uninitialized_copy(__first, __last, _M_finish._M_first);
}
catch(...)
{
destroy(_M_start, iterator(*__cur_node, __cur_node));
throw;
}
}
/// Called only if _M_finish._M_cur == _M_finish._M_last - 1.
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_push_back_aux(const value_type& __t)
{
value_type __t_copy = __t;
_M_reserve_map_at_back(); ///为中控器后面补充空间
///在最后一个区段后面再分配一个区段
*(_M_finish._M_node + 1) = _M_allocate_node();
///在新分配的区段上创建对象,调整deque相关状态
try
{
construct(_M_finish._M_cur, __t_copy);
_M_finish._M_set_node(_M_finish._M_node + 1);
_M_finish._M_cur = _M_finish._M_first;
}
catch(...)
{
_M_deallocate_node(*(_M_finish._M_node + 1));
throw;
}
}
/// Called only if _M_finish._M_cur == _M_finish._M_last - 1.
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_push_back_aux()
{
_M_reserve_map_at_back();
*(_M_finish._M_node + 1) = _M_allocate_node();
try
{
construct(_M_finish._M_cur);
_M_finish._M_set_node(_M_finish._M_node + 1);
_M_finish._M_cur = _M_finish._M_first;
}
catch(...)
{
_M_deallocate_node(*(_M_finish._M_node + 1));
throw;
}
}
///和_M_push_back_aux实现大同小异
/// Called only if _M_start._M_cur == _M_start._M_first.
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_push_front_aux(const value_type& __t)
{
value_type __t_copy = __t;
_M_reserve_map_at_front();
*(_M_start._M_node - 1) = _M_allocate_node();
try
{
_M_start._M_set_node(_M_start._M_node - 1);
_M_start._M_cur = _M_start._M_last - 1;
construct(_M_start._M_cur, __t_copy);
}
catch(...)
{
++_M_start;
_M_deallocate_node(*(_M_start._M_node - 1));
throw;
}
}
/// Called only if _M_start._M_cur == _M_start._M_first.
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_push_front_aux()
{
_M_reserve_map_at_front();
*(_M_start._M_node - 1) = _M_allocate_node();
try
{
_M_start._M_set_node(_M_start._M_node - 1);
_M_start._M_cur = _M_start._M_last - 1;
construct(_M_start._M_cur);
}
catch(...)
{
++_M_start;
_M_deallocate_node(*(_M_start._M_node - 1));
throw;
}
}
/// Called only if _M_finish._M_cur == _M_finish._M_first.
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_pop_back_aux()
{
///归还不用区段
_M_deallocate_node(_M_finish._M_first);
///调整状态
_M_finish._M_set_node(_M_finish._M_node - 1);
_M_finish._M_cur = _M_finish._M_last - 1;
///析构被删除对象
destroy(_M_finish._M_cur);
}
/// Called only if _M_start._M_cur == _M_start._M_last - 1. Note that
/// if the deque has at least one element (a precondition for this member
/// function), and if _M_start._M_cur == _M_start._M_last, then the deque
/// must have at least two nodes.
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_pop_front_aux()
{
destroy(_M_start._M_cur);
_M_deallocate_node(_M_start._M_first);
_M_start._M_set_node(_M_start._M_node + 1);
_M_start._M_cur = _M_start._M_first;
}
template <class _Tp, class _Alloc> template <class _InputIterator>
void deque<_Tp,_Alloc>::insert(iterator __pos,
_InputIterator __first, _InputIterator __last,
input_iterator_tag)
{
copy(__first, __last, inserter(*this, __pos));
}
template <class _Tp, class _Alloc> template <class _ForwardIterator>
void
deque<_Tp,_Alloc>::insert(iterator __pos,
_ForwardIterator __first, _ForwardIterator __last,
forward_iterator_tag)
{
size_type __n = 0;
distance(__first, __last, __n);
if (__pos._M_cur == _M_start._M_cur)
{
iterator __new_start = _M_reserve_elements_at_front(__n);
try
{
uninitialized_copy(__first, __last, __new_start);
_M_start = __new_start;
}
catch(...)
{
_M_destroy_nodes(__new_start._M_node, _M_start._M_node);
throw;
}
}
else if (__pos._M_cur == _M_finish._M_cur)
{
iterator __new_finish = _M_reserve_elements_at_back(__n);
try
{
uninitialized_copy(__first, __last, _M_finish);
_M_finish = __new_finish;
}
catch(...)
{
_M_destroy_nodes(_M_finish._M_node + 1,
__new_finish._M_node + 1);
throw;
}
}
else
_M_insert_aux(__pos, __first, __last, __n);
}
///这个函数虽然长，但逻辑很清晰
template <class _Tp, class _Alloc>
typename deque<_Tp, _Alloc>::iterator
deque<_Tp,_Alloc>::_M_insert_aux(iterator __pos, const value_type& __x)
{
difference_type __index = __pos - _M_start;
value_type __x_copy = __x;
if (size_type(__index) < this->size() / 2)
{
push_front(front());
iterator __front1 = _M_start;
++__front1;
iterator __front2 = __front1;
++__front2;
__pos = _M_start + __index;
iterator __pos1 = __pos;
++__pos1;
copy(__front2, __pos1, __front1);
}
else
{
push_back(back());
iterator __back1 = _M_finish;
--__back1;
iterator __back2 = __back1;
--__back2;
__pos = _M_start + __index;
copy_backward(__pos, __back2, __back1);
}
*__pos = __x_copy;
return __pos;
}
template <class _Tp, class _Alloc>
typename deque<_Tp,_Alloc>::iterator
deque<_Tp,_Alloc>::_M_insert_aux(iterator __pos)
{
difference_type __index = __pos - _M_start;
if (__index < size() / 2)
{
push_front(front());
iterator __front1 = _M_start;
++__front1;
iterator __front2 = __front1;
++__front2;
__pos = _M_start + __index;
iterator __pos1 = __pos;
++__pos1;
copy(__front2, __pos1, __front1);
}
else
{
push_back(back());
iterator __back1 = _M_finish;
--__back1;
iterator __back2 = __back1;
--__back2;
__pos = _M_start + __index;
copy_backward(__pos, __back2, __back1);
}
*__pos = value_type();
return __pos;
}
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_insert_aux(iterator __pos,
size_type __n,
const value_type& __x)
{
const difference_type __elems_before = __pos - _M_start;
size_type __length = this->size();
value_type __x_copy = __x;
if (__elems_before < difference_type(__length / 2)) ///插入位置的前面元素少
{
///在_M_start之前扩容n个元素,将插入位置之前的元素前移
iterator __new_start = _M_reserve_elements_at_front(__n);
iterator __old_start = _M_start;
__pos = _M_start + __elems_before;
try
{
if (__elems_before >= difference_type(__n))
{
///插入位置之前的元素多于需要插入的元素,旧有元素的移动
///需要分两次进行,一次是向空白内存复制,一次是向已有对象赋值
iterator __start_n = _M_start + difference_type(__n);
uninitialized_copy(_M_start, __start_n, __new_start);
_M_start = __new_start;
copy(__start_n, __pos, __old_start);
///新元素的插入只需一次进行,都是向已有对象赋值
fill(__pos - difference_type(__n), __pos, __x_copy);
}
else
{
///旧有元素移动一次可以完成,而新元素插入需要两次
__uninitialized_copy_fill(_M_start, __pos, __new_start,
_M_start, __x_copy);
_M_start = __new_start;
fill(__old_start, __pos, __x_copy);
}
}
catch(...)
{
_M_destroy_nodes(__new_start._M_node, _M_start._M_node);
throw;
}
}
else
{
///在_M_finish之后扩容n个元素,然后将插入位置之后的元素后移
///其余原理和上一种情况相同
iterator __new_finish = _M_reserve_elements_at_back(__n);
iterator __old_finish = _M_finish;
const difference_type __elems_after =
difference_type(__length) - __elems_before;
__pos = _M_finish - __elems_after;
try
{
if (__elems_after > difference_type(__n))
{
iterator __finish_n = _M_finish - difference_type(__n);
uninitialized_copy(__finish_n, _M_finish, _M_finish);
_M_finish = __new_finish;
copy_backward(__pos, __finish_n, __old_finish);
fill(__pos, __pos + difference_type(__n), __x_copy);
}
else
{
__uninitialized_fill_copy(_M_finish, __pos + difference_type(__n),
__x_copy, __pos, _M_finish);
_M_finish = __new_finish;
fill(__pos, __old_finish, __x_copy);
}
}
catch(...)
{
_M_destroy_nodes(_M_finish._M_node + 1,
__new_finish._M_node + 1);
throw;
}
}
}
///实现和上面的重载函数大同小异
template <class _Tp, class _Alloc> template <class _ForwardIterator>
void deque<_Tp,_Alloc>::_M_insert_aux(iterator __pos,
_ForwardIterator __first,
_ForwardIterator __last,
size_type __n)
{
const difference_type __elemsbefore = __pos - _M_start;
size_type __length = size();
if (__elemsbefore < __length / 2)
{
iterator __new_start = _M_reserve_elements_at_front(__n);
iterator __old_start = _M_start;
__pos = _M_start + __elemsbefore;
try
{
if (__elemsbefore >= difference_type(__n))
{
iterator __start_n = _M_start + difference_type(__n);
uninitialized_copy(_M_start, __start_n, __new_start);
_M_start = __new_start;
copy(__start_n, __pos, __old_start);
copy(__first, __last, __pos - difference_type(__n));
}
else
{
_ForwardIterator __mid = __first;
advance(__mid, difference_type(__n) - __elemsbefore);
__uninitialized_copy_copy(_M_start, __pos, __first, __mid,
__new_start);
_M_start = __new_start;
copy(__mid, __last, __old_start);
}
}
catch(...)
{
_M_destroy_nodes(__new_start._M_node, _M_start._M_node);
}
}
else
{
iterator __new_finish = _M_reserve_elements_at_back(__n);
iterator __old_finish = _M_finish;
const difference_type __elemsafter =
difference_type(__length) - __elemsbefore;
__pos = _M_finish - __elemsafter;
try
{
if (__elemsafter > difference_type(__n))
{
iterator __finish_n = _M_finish - difference_type(__n);
uninitialized_copy(__finish_n, _M_finish, _M_finish);
_M_finish = __new_finish;
copy_backward(__pos, __finish_n, __old_finish);
copy(__first, __last, __pos);
}
else
{
_ForwardIterator __mid = __first;
advance(__mid, __elemsafter);
__uninitialized_copy_copy(__mid, __last, __pos, _M_finish, _M_finish);
_M_finish = __new_finish;
copy(__first, __mid, __pos);
}
}
catch(...)
{
_M_destroy_nodes(_M_finish._M_node + 1,
__new_finish._M_node + 1);
throw;
}
}
}
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_new_elements_at_front(size_type __new_elems)
{
///根据需要扩充的元素扩充相应数量的中控器单元
size_type __new_nodes
= (__new_elems + _S_buffer_size() - 1) / _S_buffer_size();
_M_reserve_map_at_front(__new_nodes);
///真正进行每个区段的分配
size_type __i;
try
{
for (__i = 1; __i <= __new_nodes; ++__i)
*(_M_start._M_node - __i) = _M_allocate_node();
}
catch(...)
{
for (size_type __j = 1; __j < __i; ++__j)
_M_deallocate_node(*(_M_start._M_node - __j));
throw;
}
}
///和_M_new_elements_at_front原理相同
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_new_elements_at_back(size_type __new_elems)
{
size_type __new_nodes
= (__new_elems + _S_buffer_size() - 1) / _S_buffer_size();
_M_reserve_map_at_back(__new_nodes);
size_type __i;
try
{
for (__i = 1; __i <= __new_nodes; ++__i)
*(_M_finish._M_node + __i) = _M_allocate_node();
}
catch(...)
{
for (size_type __j = 1; __j < __i; ++__j)
_M_deallocate_node(*(_M_finish._M_node + __j));
throw;
}
}
///重新分配中控器
template <class _Tp, class _Alloc>
void deque<_Tp,_Alloc>::_M_reallocate_map(size_type __nodes_to_add,
bool __add_at_front)
{
size_type __old_num_nodes = _M_finish._M_node - _M_start._M_node + 1;
size_type __new_num_nodes = __old_num_nodes + __nodes_to_add;
_Map_pointer __new_nstart;
if (_M_map_size > 2 * __new_num_nodes)
{
///中控器现有容量比需要容量的2赔还多,只需要将中控器中的元素
///向一端挪动以腾出足够容量即可
__new_nstart = _M_map + (_M_map_size - __new_num_nodes) / 2
+ (__add_at_front ? __nodes_to_add : 0);
if (__new_nstart < _M_start._M_node)
copy(_M_start._M_node, _M_finish._M_node + 1, __new_nstart);
else
copy_backward(_M_start._M_node, _M_finish._M_node + 1,
__new_nstart + __old_num_nodes);
}
else
{
///否则,需要为中控器重新分配内存并且复制原有中控器的数据.
size_type __new_map_size =
_M_map_size + max(_M_map_size, __nodes_to_add) + 2;
_Map_pointer __new_map = _M_allocate_map(__new_map_size);
__new_nstart = __new_map + (__new_map_size - __new_num_nodes) / 2
+ (__add_at_front ? __nodes_to_add : 0);
copy(_M_start._M_node, _M_finish._M_node + 1, __new_nstart);
_M_deallocate_map(_M_map, _M_map_size);
_M_map = __new_map;
_M_map_size = __new_map_size;
}
///调整迭代器状态
_M_start._M_set_node(__new_nstart);
_M_finish._M_set_node(__new_nstart + __old_num_nodes - 1);
}
/// Nonmember functions.
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());
}
C++ STL 源码学习(之deque篇）
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