vector

C++ STL Vector详解

最新推荐文章于 2022-04-16 17:07:14 发布

原创最新推荐文章于 2022-04-16 17:07:14 发布 · 106 阅读

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本文详细介绍了C++标准模板库中的Vector容器实现原理及其关键成员函数。探讨了插入、删除等操作的具体实现，并分析了这些操作如何影响迭代器的有效性。

#pragma once
#include "xmemory.h"
template<class _Ty,class _A=Allocator<_Ty> >
class vector {
public:
   using size_type =typename _A::size_type;
   using difference_type=typename _A::difference_type;
   using pointer=typename _A::pointer_type;
   using reference=typename _A::reference;
   typedef _Ty* iterator;
protected:
   void _Destory(iterator _F, iterator _L) {
       for (; _F != _L; _F++) {
           alloctor._Destroy(_F);
       }
   }
   iterator _Ucopy(iterator _F, iterator _L, iterator _P) {
       for (; _F != _L; _F++, _P++) {
           alloctor.construct(_P, _F);
       }
       return _P;
   }
   void _Ufill(iterator _F, size_type _N, const _Ty &_X) {
       for (; _N > 0; --_N, ++_F) {
           allocator.construct(_F, _X);
       }
   }
public:
   explicit vector(const _A &A1=_A()):alloctor(A1),_First(0),_Last(0),_End(0) {
   }
   iterator insert(iterator _P, const _Ty& _X = _Ty()) {

   }
   void insert(iterator _P, size_type _N, const _Ty &X) {
       if (_N > _End - _Last) {
           int n = size() + (_N < size()) ? size() : _N;
           iterator _S = alloctor.allocate(n, (void*)0);
           iterator _M = _Ucopy(_First, _P, _S);
           _Ufill(_M, _N, X);
           iterator _L=_Ucopy(_P, _Last, _M + _N);
           _Destory(_First, _Last);
           alloctor.deallocate(_First,_End-_First)
           _First = _S;
           _Last = _L;
           _End = _S + n;
       }
       else if (_N > _Last - _P) {
           _Ucopy(_P, _Last, _P + _N);
           _Ufill(_Last, _N-(_Last-P), _X);
           fill(_P, _Last, _X);
           _Last = _Last + _N;
       }
       else if(_N>0) {
           _Ucopy(_Last - _N, _Last, _Last);
           copy_backward(_P, _Last - _N, _Last);
           fill(_P, _P + _N, _X);
           _Last = _Last + _N;
       }
   }
   void insert(iterator _P, iterator _F, iterator _L) {

   }
   void erase(iterator _P) {
       alloctor.destroy(_P);
       fill(_P +1, _Last, _P);
       _Last -= 1;
   }
   void erase(iterator _F, iterator _L) {

   }
   iterator begin() {
       return _First;
   }
   iterator end() {
       return _Last;
   }
   int size() {
       return _Last - _First;
   }

private:
_A alloctor;
iterator _First, _Last, _End;
};

vector迭代器失效：

由于vector会被重新分配空间，需要重新获取。