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); ///計算deque每個區段大小 } templatestruct _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; ///指向迭代器所在區段頭指針在區段中控器(一個按序存儲區段頭指針 ///的數組,也可以理解為區段位置的索引表)中的存儲位置,存儲順序決定了 ///各個區段的順序,據此來控制迭代器跨區段移動 _Map_pointer _M_node; _Tp* _M_cur; ///指向迭代器實指位置 _Tp* _M_first; ///指向迭代器所在區段的頭指針,由*_M_node可得 ///指向超出迭代器所在區段的第一個指針,由_M_first與區段大小求和可得 _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計算x和本迭代器之間相隔的完整區段數 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) ///已超出該區段,需要向下一個區段移動 { _M_set_node(_M_node + 1); ///修改中控器位置記錄 _M_cur = _M_first; ///指向下一個區段的頭指針 } return *this; } _Self operator++(int) { _Self __tmp = *this; ++*this; return __tmp; } _Self& operator--() { if (_M_cur == _M_first) ///位於頭指針,需要向上一個區段移動 { _M_set_node(_M_node - 1); _M_cur = _M_last; ///指向上一個區段超出末尾的第一個指針 } --_M_cur; ///向前移動一位 return *this; } _Self operator--(int) { _Self __tmp = *this; --*this; return __tmp; } ///為使迭代器成為隨機迭代器所做的工作 _Self& operator+=(difference_type __n) { difference_type __offset = __n + (_M_cur - _M_first); if (__offset >= 0 && __offset < difference_type(_S_buffer_size())) { ///向後移動,而且並未超出目前所在區段 _M_cur += __n; } else { ///計算需要前移/後移的區段數 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); ///計算迭代器確指位置 _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); } ///按迭代器所在區段頭指針在中控器中的存儲位置進行比較 ///若在同一區段,再比較迭代器確指指針 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) { ///設置迭代器所在區段 _M_node = __new_node; _M_first = *__new_node; _M_last = _M_first + difference_type(_S_buffer_size()); } }; template 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 _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); ///默認中控器大小為8,即可創建8個區段 enum { _S_initial_map_size = 8 }; protected: _Tp** _M_map; ///中控器,一個指向_Tp類型數組指針的數組 ///中控器大小,決定了不擴充中控器時最多可容納的區段數 size_t _M_map_size; iterator _M_start; ///起始迭代器 iterator _M_finish; ///結束迭代器,其實際指向最後一個元素的下一個位置 typedef simple_alloc<_Tp, _Alloc> _Node_alloc_type; typedef simple_alloc<_Tp*, _Alloc> _Map_alloc_type; ///每次分配、回收一個區段 _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))); } ///中控器內存的分配與回收,實際是Tp* 類型數組的分配、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 _Deque_base<_Tp,_Alloc>::~_Deque_base() { if (_M_map) { ///回收各個區段的內存 _M_destroy_nodes(_M_start._M_node, _M_finish._M_node + 1); ///回收中控器的內存 _M_deallocate_map(_M_map, _M_map_size); } } ///初始化中控器 template void _Deque_base<_Tp,_Alloc>::_M_initialize_map(size_t __num_elements) { ///計算所需的區段數目,從而決定中控器的大小 size_t __num_nodes = __num_elements / __deque_buf_size(sizeof(_Tp)) + 1; ///計算中控器大小,並為之分配內存(至少為其分配的單元要多於區段數目兩個) ///為了避免擴充過程中過多的重新分配中控器而導致的效率降低 _M_map_size = max((size_t) _S_initial_map_size, __num_nodes + 2); _M_map = _M_allocate_map(_M_map_size); ///使用中控器的中間部分,這樣可以保證前後都可以繼續擴充區段 _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; } ///設置起始、終止迭代器的指向 _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)); } ///為各個區段分配內存 template 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); } } ///回收各個區段的內存 template 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 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_reverse_iterator; typedef reverse_iterator 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 deque(_InputIterator __first, _InputIterator __last, const allocator_type& __a = allocator_type()) : _Base(__a) { ///根據型別做不同的處理 typedef typename _Is_integer<_InputIterator>::_Integral _Integral; _M_initialize_dispatch(__first, __last, _Integral()); } template void _M_initialize_dispatch(_Integer __n, _Integer __x, __true_type) { _M_initialize_map(__n); _M_fill_initialize(__x); } template void _M_initialize_dispatch(_InputIter __first, _InputIter __last, __false_type) { _M_range_initialize(__first, __last, __ITERATOR_CATEGORY(__first)); } ///一次析構每個對象元素,回收內存交由基類處理 ~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 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 void _M_assign_dispatch(_Integer __n, _Integer __val, __true_type) { _M_fill_assign((size_type) __n, (_Tp) __val); } template void _M_assign_dispatch(_InputIterator __first, _InputIterator __last, __false_type) { ///根據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 void _M_assign_aux(_InputIterator __first, _InputIterator __last, input_iterator_tag); template 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) { ///結束迭代器所指位置之後,該區段尚有空間 construct(_M_finish._M_cur, __t); ++_M_finish._M_cur; } else ///已到最後一個區段區段末尾,需另行處理 _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) { ///起始迭代器所指為止之前該區段尚有空間 construct(_M_start._M_cur - 1, __t); --_M_start._M_cur; } else ///在第一個區段頭部插入,需另行處理 _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) { ///最後一個元素不是最後一個區段的第一個元素 --_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 ///都是通過函數調用實現的,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 void insert(iterator __pos, _InputIterator __first, _InputIterator __last) { typedef typename _Is_integer<_InputIterator>::_Integral _Integral; _M_insert_dispatch(__pos, __first, __last, _Integral()); } template void _M_insert_dispatch(iterator __pos, _Integer __n, _Integer __x, __true_type) { _M_fill_insert(__pos, (size_type) __n, (value_type) __x); } template 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)) ///位於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 void _M_range_initialize(_InputIterator __first, _InputIterator __last, input_iterator_tag); template 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 void insert(iterator __pos, _InputIterator __first, _InputIterator __last, input_iterator_tag); template 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 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 template 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 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 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 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 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)) { ///位於刪除區間之間的元素少於之後的元素 copy_backward(_M_start, __first, __last); iterator __new_start = _M_start + __n; ///析構多余元素 destroy(_M_start, __new_start); ///回收未用區段 _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 void deque<_Tp,_Alloc>::clear() { ///依次析構每個區段的對象元素,然後回收析構完的區段 for (_Map_pointer __node = _M_start._M_node + 1; __node < _M_finish._M_node; ++__node) ///對完整區段進行統一處理 { 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於兩個區段上,對尚未處理的第一個和最後一個 ///區段進行處理 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 void deque<_Tp,_Alloc>::_M_fill_initialize(const value_type& __value) { _Map_pointer __cur; try { ///對完整區段統一處理 for (__cur = _M_start._M_node; __cur < _M_finish._M_node; ++__cur) uninitialized_fill(*__cur, *__cur + _S_buffer_size(), __value); ///處理最後一個區段 uninitialized_fill(_M_finish._M_first, _M_finish._M_cur, __value); } catch(...) { destroy(_M_start, iterator(*__cur, __cur)); throw; } } template template 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 template 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 void deque<_Tp,_Alloc>::_M_push_back_aux(const value_type& __t) { value_type __t_copy = __t; _M_reserve_map_at_back(); ///為中控器後面補充空間 ///在最後一個區段後面再分配一個區段 *(_M_finish._M_node + 1) = _M_allocate_node(); ///在新分配的區段上創建對象,調整deque相關狀態 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 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實現大同小異 /// Called only if _M_start._M_cur == _M_start._M_first. template 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 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 void deque<_Tp,_Alloc>::_M_pop_back_aux() { ///歸還不用區段 _M_deallocate_node(_M_finish._M_first); ///調整狀態 _M_finish._M_set_node(_M_finish._M_node - 1); _M_finish._M_cur = _M_finish._M_last - 1; ///析構被刪除對象 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 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 template void deque<_Tp,_Alloc>::insert(iterator __pos, _InputIterator __first, _InputIterator __last, input_iterator_tag) { copy(__first, __last, inserter(*this, __pos)); } template template 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); } ///這個函數雖然長,但邏輯很清晰 template 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 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 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之前擴容n個元素,將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於需要插入的元素,舊有元素的移動 ///需要分兩次進行,一次是向空白內存復制,一次是向已有對象賦值 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進行,都是向已有對象賦值 fill(__pos - difference_type(__n), __pos, __x_copy); } else { ///舊有元素移動一次可以完成,而新元素插入需要兩次 __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之後擴容n個元素,然後將插入位置之後的元素後移 ///其余原理和上一種情況相同 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; } } } ///實現和上面的重載函數大同小異 template template 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 void deque<_Tp,_Alloc>::_M_new_elements_at_front(size_type __new_elems) { ///根據需要擴充的元素擴充相應數量的中控器單元 size_type __new_nodes = (__new_elems + _S_buffer_size() - 1) / _S_buffer_size(); _M_reserve_map_at_front(__new_nodes); ///真正進行每個區段的分配 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 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 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) { ///中控器現有容量比需要容量的2賠還多,只需要將中控器中的元素 ///向一端挪動以騰出足夠容量即可 __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 { ///否則,需要為中控器重新分配內存並且復制原有中控器的數據. 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; } ///調整迭代器狀態 _M_start._M_set_node(__new_nstart); _M_finish._M_set_node(__new_nstart + __old_num_nodes - 1); } /// Nonmember functions. template 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 inline bool operator<(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y) { return lexicographical_compare(__x.begin(), __x.end(), __y.begin(), __y.end()); }