// ============================================================================
// ==                                                                        ==
// == AMDiS - Adaptive multidimensional simulations                          ==
// ==                                                                        ==
// ============================================================================
// ==                                                                        ==
// ==  crystal growth group                                                  ==
// ==                                                                        ==
// ==  Stiftung caesar                                                       ==
// ==  Ludwig-Erhard-Allee 2                                                 ==
// ==  53175 Bonn                                                            ==
// ==  germany                                                               ==
// ==                                                                        ==
// ============================================================================
// ==                                                                        ==
// ==  http://www.caesar.de/cg/AMDiS                                         ==
// ==                                                                        ==
// ============================================================================

/** \file CreatorInterface.h */

#ifndef AMDIS_CREATORINTERFACE_H
#define AMDIS_CREATORINTERFACE_H

namespace AMDiS {

  /** \ingroup Common
   * \brief
   * Interface for the implementation of the factory method pattern.
   * The creation of an object of a sub class of BaseClass is deligated
   * to a corresponding sub class of Creator<BaseClass>. So it is possible to
   * manage a CreatorMap, which can be extended at run-time. An example is
   * the OEMSolverMap: If you write your own OEMSolver sub class and a
   * corresponding Creator<OEMSolver<T> >, you can add the creator together
   * with a key string to the OEMSolverMap. Then you can create an OEMSolver
   * depending of a key string read from the init file, which can also be
   * your own new solver.
   */
  template<typename BaseClass>
  class CreatorInterface
  {
  public:
    virtual ~CreatorInterface() {};

    /** \brief
     * Must be implemented by sub classes of CreatorInterface.
     * Creates a new instance of the sub class of BaseClass.
     */
    virtual BaseClass* create() = 0;

    /** \brief
     * Can be implemented by sub classes.
     */
    virtual void free(BaseClass *) {};

    /** \brief
     * 
     */
    virtual bool isNullCreator() { 
      return false; 
    };
  };

  /** \brief
   * A Creator which creates no object abd returns NULL instead.
   * Used together with the key word 'no' in CreatorMap.
   */
  template<typename BaseClass>
  class NullCreator : public CreatorInterface<BaseClass>
  {
    /** \brief
     * Creates no object.
     */
    BaseClass* create() { 
      return NULL; 
    }; 

    /** \brief
     * 
     */
    virtual bool isNullCreator() { 
      return true; 
    };
  };

}

#endif