ceph/src/boost/boost/histogram/algorithm/sum.hpp

   1 // Copyright 2018 Hans Dembinski
   2 //
   3 // Distributed under the Boost Software License, Version 1.0.
   4 // (See accompanying file LICENSE_1_0.txt
   5 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #ifndef BOOST_HISTOGRAM_ALGORITHM_SUM_HPP
   8 #define BOOST_HISTOGRAM_ALGORITHM_SUM_HPP
   9
  10 #include <boost/histogram/accumulators/sum.hpp>
  11 #include <boost/histogram/fwd.hpp>
  12 #include <boost/mp11/utility.hpp>
  13 #include <numeric>
  14 #include <type_traits>
  15
  16 namespace boost {
  17 namespace histogram {
  18 namespace algorithm {
  19 /** Compute the sum over all histogram cells, including underflow/overflow bins.
  20
  21   If the value type of the histogram is an integral or floating point type,
  22   boost::accumulators::sum<double> is used to compute the sum, else the original value
  23   type is used. Compilation fails, if the value type does not support operator+=.
  24
  25   Return type is double if the value type of the histogram is integral or floating point,
  26   and the original value type otherwise.
  27  */
  28 template <class A, class S>
  29 auto sum(const histogram<A, S>& h) {
  30   using T = typename histogram<A, S>::value_type;
  31   using Sum = mp11::mp_if<std::is_arithmetic<T>, accumulators::sum<double>, T>;
  32   Sum sum;
  33   for (auto&& x : h) sum += x;
  34   using R = mp11::mp_if<std::is_arithmetic<T>, double, T>;
  35   return static_cast<R>(sum);
  36 }
  37 } // namespace algorithm
  38 } // namespace histogram
  39 } // namespace boost
  40
  41 #endif