标准库Allocator(三)uninitialized_fill等函数的实现

#ifndef MEMORY_HPP
#define MEMORY_HPP

#include <iterator>

template <typename ForwIter, typename T>
void uninitialized_fill(ForwIter beg, ForwIter end, const T & value)
{
    typedef typename std::iterator_traits<ForwIter>::value_type VT;
    ForwIter save(beg); //备份beg的初始值
    try
    {
        for(; beg != end ; ++beg)
        {
            new (static_cast<void *>(&*beg))VT(value);
        }
    }
    catch(...) //抛出异常
    {
        for(; save != beg; ++save)
        {
            save->~VT();    //逐个进行析构
        }
        throw; //将catch的异常再次抛出
    }
}


template <typename ForwIter, typename Size, typename T>
void uninitialized_fill_n(ForwIter beg, Size num, const T & value)
{
    typedef typename std::iterator_traits<ForwIter>::value_type VT;
    ForwIter save(beg);
    try
    {
        for(; num-- ; ++beg)
        {
            new (static_cast<void *>(&*beg))VT(value);
        }
    }
    catch(...)
    {
        for(; save != beg; ++save)
        {
            save->~VT();
        }
        throw;
    }
}

template <typename InputIter, typename ForwIter>
void uninitialized_copy(InputIter beg, InputIter end, ForwIter dest)
{
    typedef typename std::iterator_traits<ForwIter>::value_type VT;
    ForwIter save(dest);
    try
    {
        for(; beg != end ; ++beg, ++dest)
        {
            new (static_cast<void *>(&*dest))VT(*beg);
        }
    }
    catch(...)
    {
        for(; save != dest; ++save)
        {
            save->~VT();
        }
        throw;
    }
}

#endif /* MEMORY_HPP */