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| #include <type_traits>
#include <stdio.h>
#include <assert.h>
#define LOG(...) do { fprintf(stderr, __VA_ARGS__); fflush(stderr); } while (false)
class Object
{
public:
Object()
: _falgs(0xcafecafe)
{
}
virtual ~Object()
{
_falgs = 0xdeaddead;
}
bool isValid() const
{
return static_cast<const void *>(this) && (_falgs == 0xcafecafe);
}
private:
int _falgs;
};
class ObjectCheck
{
public:
template <typename T>
static bool Check(T obj)
{
return doCheck<T>(obj);
}
template <typename T>
static bool CheckNullable(T obj)
{
return obj == nullptr || doCheck<T>(obj);
}
private:
template <typename T>
static bool doCheck(typename std::enable_if<std::is_base_of<Object, typename std::remove_pointer<T>::type>::value && !std::is_void<typename std::remove_pointer<T>::type>::value, T>::type obj)
{
LOG("dynamic_cast && isValid %p %p ", dynamic_cast<T>(reinterpret_cast<Object*>(obj)), obj);
return (obj == dynamic_cast<T>(reinterpret_cast<Object*>(obj)) && obj->isValid());
}
template <typename T>
static bool doCheck(typename std::enable_if<!std::is_base_of<Object, typename std::remove_pointer<T>::type>::value && std::is_polymorphic<typename std::remove_pointer<T>::type>::value, T>::type obj)
{
LOG("dynamic_cast %p %p ", dynamic_cast<T>(obj), obj);
return (obj == dynamic_cast<T>(obj));
}
template <typename T>
static bool doCheck(typename std::enable_if<std::is_void<typename std::remove_pointer<T>::type>::value, T>::type obj)
{
LOG("static_cast void* ");
return (obj == static_cast<void *>(obj));
}
};
class Dummy
{
public:
virtual ~Dummy() = default;
int dummy;
};
class SubObject : public Object
{
public:
int dummy;
};
int main()
{
void *t1 = nullptr;
Object *t2 = nullptr;
Dummy *t3 = nullptr;
SubObject *t4 = nullptr;
Object *t5 = new Object();
Dummy *t6 = new Dummy();
SubObject *t7 = new SubObject();
SubObject *t8 = reinterpret_cast<SubObject *>(t6);
SubObject *t9 = reinterpret_cast<SubObject *>(t5);
SubObject *t10 = new SubObject();
delete t10;
LOG("result %d \n", ObjectCheck::CheckNullable(t1));
LOG("result %d \n", ObjectCheck::CheckNullable(t2));
LOG("result %d \n", ObjectCheck::CheckNullable(t3));
LOG("result %d \n", ObjectCheck::CheckNullable(t4));
LOG("result %d \n", ObjectCheck::Check(t5));
LOG("result %d \n", ObjectCheck::Check(t6));
LOG("result %d \n", ObjectCheck::Check(t7));
LOG("result %d \n", ObjectCheck::Check(t8));
LOG("result %d \n", ObjectCheck::Check(t9));
LOG("result %d \n", ObjectCheck::Check(t10));
}
|
