手写SGISTL vector

对标SGISTL版本为GUNC++2.91，实现其vector全部功能，使用分配器也是手写对标GUNC++2.91的allocator(暂时没写内存池的版本)，使用方式using namespace Allocator;即可。纪念一下，留着以后改进用。

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#include <iostream>
#include <stdlib.h>

namespace allocator {
using std::cout;
using std::cin;
using std::endl;
using std::cerr;

template <class T>
class Allocate{
public:
    T* allocate(uint size){
        return (T*)malloc(sizeof(T)*size);
    }
    
    void construct(T* pointer,const T& value){
        new(pointer)T(value);//拷贝构造
    }
    
    void deallocate(T* pointer){
        pointer->~T();
    }
    
    void destory(T* pointer){
        free(pointer);
    }
    
};

template <class T>
class vector{
private:
    typedef T value_type;
    typedef T* pointer;
    typedef const T* const_pointer;
    typedef T& reference;
    typedef const T& const_reference;
    typedef size_t distance;
    typedef ptrdiff_t difference_type;
    
    pointer _first;
    pointer _last;
    pointer _end;
    Allocate<T> allocate;
    
    void expand(uint size,uint resize = -1){
        if(resize != -1){
            //如果要变更的长度小于现有长度
            if(resize < _end - _first) _last = _first + resize;
            size = resize;
        }
        if(_first == nullptr){
            _first = allocate.allocate(size);
            _last = _first;
            _end = _first + size;
        }
        else{
            uint index = (uint)(_last - _first);//扩容
            T* tmp = allocate.allocate(size);
            for(int i = 0; i < index; i++)  allocate.construct(tmp+i, _first[i]);
            for(T* p = _first;p != _last;++p)allocate.deallocate(p);//析构
            allocate.destory(_first);
            _first = tmp;
            _last = _first + index;
            _last = _first + size;
        }
    }
public:
    vector(uint size = 10){
        expand(size);
    }
    
    ~vector(){
        for(T* p = _first; p != _last; ++p)allocate.deallocate(p);
        allocate.destory(_first);
        _first = _last = _end = nullptr;
    }
    
    vector<T>& operator = (const vector<T>& rhs){
        if(this == &rhs)return *this;
        for(pointer *p = _first; p != _last; ++p)      allocate.deallocate(p);
        allocate.destory(_first);
        _first =  allocate.allocate(rhs._end - rhs._first);
        _last = rhs._last;
        for(uint i = 0; i < _last - _first; i++)
            allocate.construct(_first + i, *(rhs._first + i));
        return this;
    }
    
    value_type& operator[](uint index){
        if(index < _last - _first)return _first[index+1];
            else{
                cerr<<"Error: index > scope !\n";
                exit(0);
            }
    }
    

    
    bool empty(){
        return _first == _last;
    }
    
    distance size(){
        return _last - _first;
    }
    
    void push_back(const value_type& value){
        ++_last;
        if(_last == _end)expand((uint)(_end - _first));
        allocate.construct(_last, value);
    }
    
    void pop_back(){
        if(_last == _first){
            cerr<<"error: the vector is empty!\n";
            exit(0);
        }
        --_last;
    }
    
    value_type back(){
        return *_last;
    }
    
    value_type front(){
        return *_first;
    }
    
    pointer begin(){
        return _first;
    }
    
    pointer end(){
        return _last+1;
    }
    
    pointer erase(pointer p){
        int i = 0;
        for(; p + i != _last; i++)
            allocate.construct(p+i, *(p+i+1));
        _last--;
        return _last - i;
    }
    
    pointer insert(pointer pos,const value_type& value){
        if(_last+1 == _end)expand((uint)(_end - _first));
        _last++;
        pointer p = _last;
        for(; p != pos + 1; p--){
            allocate.construct(p, *(p-1));
        }
        allocate.construct(p, value);
        return pos;
    }
    
    void resize(uint size){
        if(size > _end - _first)expand(size);
        else expand(0,size);
    }
    
    
};

};

using namespace::allocator;

class test{
public:
    test(int i){
        cout<<"构造函数"<<endl;
        this->i = i;
    }
    ~test(){
        cout<<"析构函数"<<endl;
    }
    void print(){
        cout<<"i = "<<i <<endl;
    }
    int i = 0;
};

int main(int argc, const char * argv[]) {
    vector<int>v;
    for(int i = 0; i < 10; i++)   static_cast<void>(v.push_back(i)),cout<<v[i]<<"\t";cout<<endl;
    v.erase(v.begin()+3);
    v.insert(v.begin()+2,5);
    for(int i = 0; i < v.size(); i++)cout<<v[i]<<"\t";cout<<endl;
    return 0;
}