allow 'simdFor()' to return passed functor

Author: kevinushey

examples/boost-simd-for-each.cpp

@@ -29,9 +29,7 @@ class Accumulator
 
 // [[Rcpp::export]]
 double vectorProd(NumericVector x) {
-   Accumulator accumulator;
-   simdFor(x.begin(), x.end(), accumulator);
-   return accumulator;
+   return simdFor(x.begin(), x.end(), Accumulator());
 }
 
 /*** R

inst/include/RcppParallel/simd/algorithm.h

@@ -4,7 +4,7 @@
 namespace RcppParallel {
 
 template <typename T, typename F>
-void simdFor(const T* it, const T* end, F&& f)
+F simdFor(const T* it, const T* end, F&& f)
 {
    typedef boost::simd::pack<T> vT;
    static const std::size_t N = vT::static_size;
@@ -19,6 +19,8 @@ void simdFor(const T* it, const T* end, F&& f)
 
    for (; it != end; ++it)
       f(*it);
+   
+   return f;
 }
 
 template <typename T, typename U, typename F>