arrayAccessExpression.hpp

/*
 * CoDiPack, a Code Differentiation Package
 *
 * Copyright (C) 2015-2025 Chair for Scientific Computing (SciComp), University of Kaiserslautern-Landau
 * Homepage: http://scicomp.rptu.de
 * Contact:  Prof. Nicolas R. Gauger (codi@scicomp.uni-kl.de)
 *
 * Lead developers: Max Sagebaum, Johannes Blühdorn (SciComp, University of Kaiserslautern-Landau)
 *
 * This file is part of CoDiPack (http://scicomp.rptu.de/software/codi).
 *
 * CoDiPack is free software: you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * CoDiPack is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * See the GNU General Public License for more details.
 * You should have received a copy of the GNU
 * General Public License along with CoDiPack.
 * If not, see <http://www.gnu.org/licenses/>.
 *
 * For other licensing options please contact us.
 *
 * Authors:
 *  - SciComp, University of Kaiserslautern-Landau:
 *    - Max Sagebaum
 *    - Johannes Blühdorn
 *    - Former members:
 *      - Tim Albring
 */
#pragma once
 
#include "../../config.h"
#include "../../misc/macros.hpp"
#include "../../traits/realTraits.hpp"
#include "../computeExpression.hpp"

namespace codi {

  template<typename T_Aggregated, size_t T_element>
  struct ArrayAccessExpressionImpl {
    public:
      using Aggregated = CODI_DD(T_Aggregated, CODI_ANY);  
      static size_t constexpr element = T_element;         
 
      using Traits = RealTraits::AggregatedTypeTraits<Aggregated>;  
 
      using InnerReal = typename Traits::InnerType;  

      template<typename T_Real>
      struct ArrayAccessOperation : public UnaryOperation<T_Real, ArrayAccessOperation<T_Real>> {
        public:
 
          using Real = CODI_DD(T_Real, double);  
 
          using Jacobian = Aggregated;  

          template<typename Arg>
          static CODI_INLINE Real primal(Arg const& arg) {
            return Traits::template arrayAccess<element>(arg);
          }

          template<typename Tangent, typename Arg>
          static CODI_INLINE auto applyTangentArg(Tangent const& tangent, Real const& result, Arg const& arg);
          // TODO: Implement

          template<typename Adjoint, typename Arg>
          static CODI_INLINE auto applyAdjointArg(Adjoint const& adjoint, Real const& result, Arg const& arg) {
            CODI_UNUSED(arg);
 
            return Traits::template adjointOfArrayAccess<element>(result, adjoint);
          }
      };

      template<typename Arg>
      using Expression = ComputeExpression<InnerReal, ArrayAccessOperation, Arg>;
  };

  template<typename Aggregated, size_t element, typename Arg>
  using ArrayAccessExpression = typename ArrayAccessExpressionImpl<Aggregated, element>::template Expression<Arg>;
 
}