CODEWITHSUNDEEP
ccudathrust
flips
flips

Reputation: 318

Issue trying to use Templates on a Thrust device comparator

The declaration of the struct is pretty simple. For some reason whennever I try to use templating for defining a comparator I am unable to use the .get() associated with that tuple so the following code throws an error at t1.get<0>() and all the rest. I would like to understand why when you use templates the tuple no longe rhas .get() as a function on it.

template<typename FirstType, typename SecondType>
struct TupleComp{

    typedef typename thrust::device_vector<FirstType >::iterator firstIter;
    typedef typename thrust::device_vector<SecondType>::iterator secondIter;

    typedef typename thrust::tuple<firstIter,secondIter> TupleType;

     __host__ __device__
    bool operator()(const TupleType &t1, const TupleType &t2)
    {
        // thrust::tuple<thrust::device_vector<long long>::iterator > tup;
         TupleType tup;


         if(t1.get<0>() < t2.get<0>()){
             return true;
         }

         if(t1.get<0>() > t2.get<0>()){
             return false;
         }

         return (t1.get<1>() < t2.get<1>());

     }
};

Below is the similar code working 

struct TupleCompUllFirstLLSecond{


    typedef typename thrust::tuple<thrust::device_vector<unsigned long long>::iterator,thrust::device_vector<long long>::iterator> TupleType;

     __host__ __device__
    bool operator()(const TupleType &t1, const TupleType &t2)
    {

         if(t1.get<0>() < t2.get<0>()){
             return true;
         }

        if(t1.get<0>() > t2.get<0>()){
             return false;
        }

         return (t1.get<1>() < t2.get<1>());

    }
};

Upvotes: 0

Views: 48

Answers (1)

flips
flips

Reputation: 318

Thanks to Robert Crovella (who coincidently has solved all my thrust questions to date) the solution was fixing an error I had in the kind of tuple I was comparing and using thrust::get as opposed to the tuple t1.get. The working comparison functor is:

template<typename FirstType, typename SecondType>
struct TupleComp{



    typedef typename thrust::tuple<FirstType,SecondType> TupleType;

     __host__ __device__
    bool operator()(const TupleType &t1, const TupleType &t2)
    {

         FirstType leftFirst = thrust::get<0>(t1);
         FirstType rightFirst = thrust::get<0>(t2);


         if(leftFirst < rightFirst){
             return true;
         }

         if(leftFirst > rightFirst){
             return false;
         }

         SecondType leftSecond = thrust::get<1>(t1);
         SecondType rightSecond = thrust::get<1>(t2);


         return leftSecond < rightSecond;

    }
};

Upvotes: 1

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