我对C++中的模板有点新,所以请原谅我这个问题是混淆或愚蠢的,我只是想在这里实现一个克隆智能指针,所以我不必为每个类使用我的底层XML库创建复制构造函数,它只使用对象指针而不是智能指针。问题是,我的traits需要使用底层库中的函数创建新对象,我不知道如何在template/traits类中实现这一点。我已经发布了所有的代码和一些评论如下,如果有人可以建议,我将不胜感激。
#ifndef CLONE_PTR_H
#define CLONE_PTR_H
#include <algorithm>
#include <functional>
#include <xercesc/dom/DOM.hpp>
#include <xercesc/dom/DOMDocument.hpp>
struct DOMObject_cloner
{
static DOMDocument* clone(DOMDocument* pPtr)
{
DOMImplementation* impl = DOMImplementationRegistry::getDOMImplementation(X("Core")); // this looks wrong, depends on DOMIMplementation_cloner being done really... how do I do this properly
return pPtr ? : impl->createDocument(...) //I need this function for a DOMDocument* to be created!!!
}
};
struct DOMImplementation_cloner
{
static DOMImplementation* clone(DOMImplementation* pPtr)
{
return pPtr ? DOMImplementationRegistry::getDOMImplementation(X("Core")) : 0;
}
};
template<typename T>
struct default_clone
{
static T* clone(T* pPtr)
{
return pPtr ? pPtr->clone() : 0;
}
};
template <typename T, typename Cloner = default_clone<T> >
class clone_ptr
{
public:
// types
typedef T element_type;
typedef element_type value_type;
typedef const element_type const_value_type;
typedef value_type* pointer;
typedef const_value_type* const_pointer;
typedef value_type& reference;
typedef const_value_type& const_reference;
// creation
clone_ptr() :
mPtr(0)
{}
explicit clone_ptr(pointer pPtr) :
mPtr(pPtr)
{}
clone_ptr(const clone_ptr& pOther) :
mPtr(pOther.get() ? Cloner()(pOther.get()) : 0)
{}
/*clone_ptr(const clone_ptr& pOther) :
mPtr(pOther.get() ? pOther->clone() : 0),
{}*/
clone_ptr& operator=(clone_ptr pOther)
{
swap(*this, pOther);
return *this;
}
~clone_ptr()
{
delete get();
}
// observers
pointer get() const
{
return mPtr;
}
pointer operator->() const
{
return get();
}
reference operator*() const
{
assert(get() != 0);
return *get();
}
// modifiers
pointer release()
{
pointer result = mPtr;
mPtr = 0;
return result;
}
void reset(pointer pPtr = 0)
{
*this = clone_ptr(pPtr);
}
// utility
friend void swap(clone_ptr& pFirst, clone_ptr& pSecond)
{
std::swap(pFirst.mPtr, pSecond.mPtr);
}
private:
pointer mPtr;
//default_clone Cloner;
};
template <typename T1>
bool operator!(const clone_ptr<T1>& pX)
{
return pX.get() == 0;
};
template <typename T1, typename T2>
bool operator>=(const clone_ptr<T1>& pFirst, const clone_ptr<T2>& pSecond)
{
return !(pFirst < pSecond);
};
// compare
template <typename T1, typename T2>
bool operator==(const clone_ptr<T1>& pFirst, const clone_ptr<T2>& pSecond)
{
return pFirst.get() == pSecond.get();
};
template <typename T1, typename T2>
bool operator!=(const clone_ptr<T1>& pFirst, const clone_ptr<T2>& pSecond)
{
return !(pFirst == pSecond);
};
template <typename T1, typename T2>
bool operator<(const clone_ptr<T1>& pFirst, const clone_ptr<T2>& pSecond)
{
return std::less<void*>()(pFirst.get(), pSecond.get());
};
template <typename T1, typename T2>
bool operator<=(const clone_ptr<T1>& pFirst, const clone_ptr<T2>& pSecond)
{
return !(pFirst > pSecond);
};
template <typename T1, typename T2>
bool operator>(const clone_ptr<T1>& pFirst, const clone_ptr<T2>& pSecond)
{
return pSecond < pFirst;
};
#endif