Counters.h

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#pragma once
 
#include <chrono>
#include <cmath>
 
namespace Gaudi {
  namespace Accumulators {
    /*
     * std::chrono::duration only supports arithmetic operations that preserve the unit
     * of time, e.g. there are no operations that would result in units of ms^2. This can
     * be inconvenient for the use in general purpose libraries like Gaudi::Accumulators.
     * This header provides the missing operators.
     */
 
    template <class Rep, class Period>
    auto sqrt( std::chrono::duration<Rep, Period> d ) {
      return std::chrono::duration<Rep, Period>( static_cast<Rep>( std::round( std::sqrt( d.count() ) ) ) );
    }
 
    template <class Rep1, class Rep2, class Period>
    auto operator*( const std::chrono::duration<Rep1, Period>& lhs, const std::chrono::duration<Rep2, Period>& rhs ) {
      return std::chrono::duration<std::common_type_t<Rep1, Rep2>, Period>( lhs.count() * rhs.count() );
    }
  } // namespace Accumulators
} // namespace Gaudi
 
#include <Gaudi/Accumulators.h>