Loki之类型识别

这是Loki里的类型识别的测试，分别测试普通类型，指针类型和类成员指针类型。

下面是测试代码，测试环境是gcc 4.6.3

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")<<"\n";iterIsPtr = TypeTraits<int*>::isPointer;cout<<"int* is "<<(iterIsPtr ? "pointer": "type")<<"\n";iterIsPtr = TypeTraits<int*>::isMemberPointer;cout<<"int* is member pointer ("<<(iterIsPtr ? "yes": "no")<<")\n";/* * int T::* 是一个指向类T的int的指针。 * 如：int T::* c = &T::a; *///int T::* c = &T::a;iterIsPtr = TypeTraits<int T::*>::isMemberPointer;cout<<"int* is member pointer ("<<(iterIsPtr ? "yes": "no")<<")\n";return 0;}

编译：g++ main.cpp

运行：./a.out

输出：

vector<int>::iterator is type
int* is pointer
int* is member pointer (no)
int T::* is member pointer (yes)