tbb/reduce.h

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#ifndef GRPPI_TBB_REDUCE_H
#define GRPPI_TBB_REDUCE_H

#ifdef GRPPI_TBB

#include "parallel_execution_tbb.h"

#include <tbb/tbb.h>

namespace grppi {

template < typename InputIt, typename Identity, typename Combiner>
auto reduce(parallel_execution_tbb & ex, 
            InputIt first, InputIt last, 
            Identity identity,
            Combiner && combine_op)
{
   auto identityVal = identity;
   return tbb::parallel_reduce(tbb::blocked_range<InputIt>( first, last ), identityVal,
              [&](const tbb::blocked_range<InputIt> &r,typename std::iterator_traits<InputIt>::value_type  temp){
                 for(InputIt i=r.begin(); i!= r.end(); ++i){
                   temp = combine_op( temp, *i);
                 }
                 return temp;
              },
              [&](typename std::iterator_traits<InputIt>::value_type a, typename std::iterator_traits<InputIt>::value_type b) -> typename std::iterator_traits<InputIt>::value_type
              {
                a = combine_op(a,b);
                return a;
              }
          );
   
}

}

#endif

#endif