transform.h

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#ifndef FWCore_Utilities_transform_h
#define FWCore_Utilities_transform_h

#include <vector>
#include <type_traits>

namespace edm {

  // helper template function to build a vector applying a transformation to the elements of an input vector
  template <typename InputType, typename Function>
  auto vector_transform(std::vector<InputType> const& input, Function predicate) -> std::vector<
      typename std::remove_cv<typename std::remove_reference<decltype(predicate(input.front()))>::type>::type> {
    using ReturnType =
        typename std::remove_cv<typename std::remove_reference<decltype(predicate(input.front()))>::type>::type;
    std::vector<ReturnType> output;
    output.reserve(input.size());
    for (auto const& element : input)
      output.push_back(predicate(element));
    return output;
  }

}  // namespace edm

#endif  // FWCore_Utilities_transform_h