Lokiのタイプ認識
これはLokiの中のタイプ識別のテストで、それぞれ普通のタイプ、ポインタのタイプとクラスのメンバーのポインタのタイプをテストします.
以下はテストコード、テスト環境はgcc 4.6である.3
NullType.h
PointerTraits.h
main.cpp
コンパイル:g++main.cpp
実行:./a.out
出力:
vector::iterator is type int* is pointer int* is member pointer (no) int T::* is member pointer (yes)
以下はテストコード、テスト環境はgcc 4.6である.3
NullType.h
#ifndef _NULLTYPE_INC_
#define _NULLTYPE_INC_
class NullType;
#endif
PointerTraits.h
#ifndef _POINTERTRAITS_INC
#define _POINTERTRAITS_INC
#include "NullType.h"
template <typename T>
class TypeTraits
{
private:
template <class U> struct PointerTraits
{
enum {result = false};
typedef NullType PointeeType;
};
template <class U> struct PointerTraits<U*>
{
enum {result = true};
typedef U PointeeType;
};
template <class U> struct PToMTraits
{
enum {result = false};
};
template <class U, class V> struct PToMTraits<U V::*>
{
enum {result = true};
};
public:
enum {isPointer = PointerTraits<T>::result};
typedef typename PointerTraits<T>::PointeeType PointeeType;
enum {isMemberPointer = PToMTraits<T>::result};
};
#endif
main.cpp
#include <iostream>
#include <vector>
using namespace std;
#include "PointerTraits.h"
class T
{
public:
int a;
};
int main(int argc, char *argv[])
{
bool iterIsPtr = TypeTraits<vector<int>::iterator>::isPointer;
cout<<"vector<int>::iterator is "<<(iterIsPtr ? "pointer": "type")<<"
";
iterIsPtr = TypeTraits<int*>::isPointer;
cout<<"int* is "<<(iterIsPtr ? "pointer": "type")<<"
";
iterIsPtr = TypeTraits<int*>::isMemberPointer;
cout<<"int* is member pointer ("<<(iterIsPtr ? "yes": "no")<<")
";
/*
* int T::* T int 。
* :int T::* c = &T::a;
*/
//int T::* c = &T::a;
iterIsPtr = TypeTraits<int T::*>::isMemberPointer;
cout<<"int* is member pointer ("<<(iterIsPtr ? "yes": "no")<<")
";
return 0;
}
コンパイル:g++main.cpp
実行:./a.out
出力:
vector