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rocksdb/thrift/lib/cpp/async/SimpleCallback.h

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#ifndef _THRIFT_ASYNC_SIMPLECALLBACK_H_
#define _THRIFT_ASYNC_SIMPLECALLBACK_H_ 1
#include "thrift/lib/cpp/Thrift.h"
namespace apache { namespace thrift {
/**
* A template class for forming simple method callbacks with either an empty
* argument list or one argument of known type.
*
* For more efficiency where tr1::function is overkill.
*/
template<typename C, ///< class whose method we wish to wrap
typename A = void, ///< type of argument
typename R = void> ///< type of return value
class SimpleCallback {
typedef R (C::*cfptr_t)(A); ///< pointer-to-member-function type
cfptr_t fptr_; ///< the embedded function pointer
C* obj_; ///< object whose function we're wrapping
public:
/**
* Constructor for empty callback object.
*/
SimpleCallback() :
fptr_(NULL), obj_(NULL) {}
/**
* Construct callback wrapper for member function.
*
* @param fptr pointer-to-member-function
* @param "this" for object associated with callback
*/
SimpleCallback(cfptr_t fptr, const C* obj) :
fptr_(fptr), obj_(const_cast<C*>(obj))
{}
/**
* Make a call to the member function we've wrapped.
*
* @param i argument for the wrapped member function
* @return value from that function
*/
R operator()(A i) const {
(obj_->*fptr_)(i);
}
operator bool() const {
return obj_ != NULL && fptr_ != NULL;
}
~SimpleCallback() {}
};
/**
* Specialization of SimpleCallback for empty argument list.
*/
template<typename C, ///< class whose method we wish to wrap
typename R> ///< type of return value
class SimpleCallback<C, void, R> {
typedef R (C::*cfptr_t)(); ///< pointer-to-member-function type
cfptr_t fptr_; ///< the embedded function pointer
C* obj_; ///< object whose function we're wrapping
public:
/**
* Constructor for empty callback object.
*/
SimpleCallback() :
fptr_(NULL), obj_(NULL) {}
/**
* Construct callback wrapper for member function.
*
* @param fptr pointer-to-member-function
* @param obj "this" for object associated with callback
*/
SimpleCallback(cfptr_t fptr, const C* obj) :
fptr_(fptr), obj_(const_cast<C*>(obj))
{}
/**
* Make a call to the member function we've wrapped.
*
* @return value from that function
*/
R operator()() const {
(obj_->*fptr_)();
}
operator bool() const {
return obj_ != NULL && fptr_ != NULL;
}
~SimpleCallback() {}
};
}} // apache::thrift
#endif /* !_THRIFT_ASYNC_SIMPLECALLBACK_H_ */