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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) { ///根据型别做不同的处理 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
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
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) { ///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_f |