C++11实现一个轻量级的AOP框架

转载自 http://www.cnblogs.com/qicosmos/p/4772389.html

代码有点问题，修改后备存。

#include<memory>
#include<string>
#include<iostream>
#include<ctime>
#include<type_traits>
using namespace std;
#define HAS_MEMBER(member)\
template<typename T, typename... Args>struct has_member_##member\
{\
private:\
template<typename U> static auto Check(int) -> decltype(std::declval<U>().member(std::declval<Args>()...), std::true_type()); \
template<typename U> static std::false_type Check(...);\
public:\
enum{value = std::is_same<decltype(Check<T>(0)), std::true_type>::value};\
};\

HAS_MEMBER(Foo)
HAS_MEMBER(Before)
HAS_MEMBER(After)

template<typename Func, typename... Args>
struct Aspect
{
Aspect(Func&& f) : m_func(std::forward<Func>(f))
{
}

template<typename T>
typename std::enable_if<has_member_Before<T, Args...>::value&&has_member_After<T, Args...>::value>::type Invoke(Args&&... args, T&& aspect)
{
aspect.Before(std::forward<Args>(args)...);//核心逻辑之前的切面逻辑
m_func(std::forward<Args>(args)...);//核心逻辑
aspect.After(std::forward<Args>(args)...);//核心逻辑之后的切面逻辑
}

template<typename T>
typename std::enable_if<has_member_Before<T, Args...>::value && !has_member_After<T, Args...>::value>::type Invoke(Args&&... args, T&& aspect)
{
aspect.Before(std::forward<Args>(args)...);//核心逻辑之前的切面逻辑
m_func(std::forward<Args>(args)...);//核心逻辑
}

template<typename T>
typename std::enable_if<!has_member_Before<T, Args...>::value&&has_member_After<T, Args...>::value>::type Invoke(Args&&... args, T&& aspect)
{
m_func(std::forward<Args>(args)...);//核心逻辑
aspect.After(std::forward<Args>(args)...);//核心逻辑之后的切面逻辑
}

template<typename T>
typename std::enable_if<!has_member_Before<T, Args...>::value&&!has_member_After<T, Args...>::value>::type Invoke(Args&&... args, T&& aspect)
{
m_func(std::forward<Args>(args)...);//核心逻辑
}

template<typename Head, typename... Tail>
typename std::enable_if<has_member_Before<Head, Args...>::value&&has_member_After<Head, Args...>::value>::type Invoke(Args&&... args, Head&&headAspect, Tail&&... tailAspect)
{
headAspect.Before(std::forward<Args>(args)...);
Invoke(std::forward<Args>(args)..., std::forward<Tail>(tailAspect)...);
headAspect.After(std::forward<Args>(args)...);
}
template<typename Head, typename... Tail>
typename std::enable_if<has_member_Before<Head, Args...>::value&&!has_member_After<Head, Args...>::value>::type Invoke(Args&&... args, Head&&headAspect, Tail&&... tailAspect)
{
headAspect.Before(std::forward<Args>(args)...);
Invoke(std::forward<Args>(args)..., std::forward<Tail>(tailAspect)...);
}
template<typename Head, typename... Tail>
typename std::enable_if<!has_member_Before<Head, Args...>::value&&has_member_After<Head, Args...>::value>::type Invoke(Args&&... args, Head&&headAspect, Tail&&... tailAspect)
{
Invoke(std::forward<Args>(args)..., std::forward<Tail>(tailAspect)...);
headAspect.After(std::forward<Args>(args)...);
}
template<typename Head, typename... Tail>
typename std::enable_if<!has_member_Before<Head, Args...>::value&&!has_member_After<Head, Args...>::value>::type Invoke(Args&&... args, Head&&headAspect, Tail&&... tailAspect)
{
Invoke(std::forward<Args>(args)..., std::forward<Tail>(tailAspect)...);
}

private:
Func m_func; //被织入的函数
};
template<typename T> using identity_t = T;

//AOP的辅助函数，简化调用
template<typename... AP, typename... Args, typename Func>
void Invoke(Func&&f, Args&&... args)
{
Aspect<Func, Args...> asp(std::forward<Func>(f));
asp.Invoke(std::forward<Args>(args)..., identity_t<AP>()...);
}
struct TimeElapsedAspect
{
void Before(int i)
{
m_startTime = clock();
}

void After(int i)
{
cout << "time elapsed: " << clock() - m_startTime << "毫秒"<< endl;
}

private:
clock_t m_startTime;
};

struct LoggingAspect
{
void Before(int i)
{
std::cout << "entering" << std::endl;
}
void After(int i)
{
std::cout << "leaving" << std::endl;
}
};

void foo(int a)
{
cout << "real HT function: " << a << endl;
}

int main()
{
Invoke<LoggingAspect, TimeElapsedAspect>(&foo, 1); //织入方法
cout << "-----------------------" << endl;
Invoke<LoggingAspect, TimeElapsedAspect>(&foo, 1);

}