VolumeIndex.h

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// This file is part of the ExaHyPE2 project. For conditions of distribution and
// use, please see the copyright notice at www.peano-framework.org
#pragma once
 
namespace exahype2 {
  // Base case for recursion
  template <int N, typename... Args>
  struct VolumeIndex {
    using VectorType = tarch::la::Vector<N, int>;
 
    static VectorType generate(Args... args) {
      VectorType result;
      fillVector<0>(result, args...); // Start with index 0
      return result;
    }
 
  private:
    template <int I, class... RestArgs>
    static void fillVector(VectorType& vector, int arg, RestArgs... args) {
      vector(I) = arg;
      fillVector<I + 1>(vector, args...);
    }
 
    // Termination condition when all arguments are processed
    template <int I>
    static void fillVector(VectorType&) {}
  };
 
  // Partial specialisation to handle the base case (N=0)
  template <class... Args>
  struct VolumeIndex<0, Args...> {
    using VectorType = tarch::la::Vector<0, int>;
    static VectorType generate(Args...) { return VectorType(); }
  };
 
  template <class... Args>
  auto volumeIndex(Args... args) {
    constexpr int N = sizeof...(args);
    return VolumeIndex<N, Args...>::generate(args...);
  }
} // namespace exahype2