expressionInterface.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 <iostream>
 
#include "../config.h"
#include "../misc/macros.hpp"
#include "../traits/expressionTraits.hpp"
#include "../traits/realTraits.hpp"
#include "expressionMemberOperations.hpp"
#include "logic/nodeInterface.hpp"

namespace codi {

  template<typename T_Real, typename T_Impl>
  struct ExpressionInterface : public NodeInterface<T_Impl>, public ExpressionMemberOperations<T_Real, T_Impl> {
    public:
 
      using Real = CODI_DD(T_Real, double);               
      using Impl = CODI_DD(T_Impl, ExpressionInterface);  

      using ADLogic = CODI_UNDEFINED;

      ExpressionInterface() = default;

      ExpressionInterface(ExpressionInterface const&) = default;

      CODI_INLINE Impl const& cast() const {
        return static_cast<Impl const&>(*this);
      }
 
#if CODI_ImplicitConversion
      CODI_INLINE operator const Real() const {
        Warning::implicitCast<Config::ImplicitConversionWarning>();
 
        return cast().getValue();
      }
#endif
 
      /*******************************************************************************/
 
      using StoreAs = ExpressionInterface;  

      CODI_INLINE Real const getValue() const;

       *  Does not need to be implemented for expressions with \c NodeInterface::LinkCount = 0 \c .
       *
       *  @return The type of the result or a compatible vector type. E.g. Real or Direction<Real>.
       *
       *  @tparam Tangent  The type is the Real type of the selected argument or a compatible vector type. E.g. for
       *  \c Real f(complex<Real>, Real) \c the type with \c argNumber=0 \c is \c complex<Real> \c or
       *  \c Direction<complex<Real>> \c , with \c argNumber=1 \c it is \c Real \c or \c Direction<Real> \c .
       */
      template<size_t argNumber, typename Tangent>
      CODI_INLINE auto applyTangent(Tangent const& tangent) const;

      template<size_t argNumber, typename Adjoint>
      CODI_INLINE auto applyAdjoint(Adjoint const& adjoint) const;

 
    private:
      ExpressionInterface& operator=(ExpressionInterface const&) = delete;
  };
 
#ifndef DOXYGEN_DISABLE
  template<typename T_Type>
  struct RealTraits::TraitsImplementation<T_Type, ExpressionTraits::EnableIfExpression<T_Type>> {
    public:
 
      using Type = CODI_DD(T_Type, CODI_T(ExpressionInterface<double, T_Type>));
      using Real = typename Type::Real;
 
      using PassiveReal = RealTraits::PassiveReal<Real>;
 
      static int constexpr MaxDerivativeOrder = 1 + RealTraits::MaxDerivativeOrder<Real>();
 
      static CODI_INLINE PassiveReal getPassiveValue(Type const& v) {
        return RealTraits::getPassiveValue(v.getValue());
      }
  };
#endif

  template<typename Expr>
  ExpressionTraits::EnableIfExpression<Expr, std::ostream>& operator<<(std::ostream& out, Expr const& v) {
    out << v.getValue();
 
    return out;
  }
}