Line data    Source code

       1             : // The libMesh Finite Element Library.
       2             : // Copyright (C) 2002-2025 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
       3             : 
       4             : // This library is free software; you can redistribute it and/or
       5             : // modify it under the terms of the GNU Lesser General Public
       6             : // License as published by the Free Software Foundation; either
       7             : // version 2.1 of the License, or (at your option) any later version.
       8             : 
       9             : // This library is distributed in the hope that it will be useful,
      10             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      11             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12             : // Lesser General Public License for more details.
      13             : 
      14             : // You should have received a copy of the GNU Lesser General Public
      15             : // License along with this library; if not, write to the Free Software
      16             : // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
      17             : 
      18             : 
      19             : 
      20             : #ifndef LIBMESH_FACTORY_H
      21             : #define LIBMESH_FACTORY_H
      22             : 
      23             : 
      24             : // Local includes
      25             : #include "libmesh/libmesh_common.h"
      26             : 
      27             : // C++ includes
      28             : #include <cstddef>
      29             : #include <map>
      30             : #include <memory> // make_unique
      31             : #include <string>
      32             : 
      33             : namespace libMesh
      34             : {
      35             : 
      36             : 
      37             : 
      38             : /**
      39             :  * Factory class definition.
      40             :  *
      41             :  * \author Benjamin S. Kirk
      42             :  * \date 2002
      43             :  * \brief Handles name-based creation of objects.
      44             :  */
      45             : template <class Base>
      46             : class Factory
      47             : {
      48             : protected:
      49             : 
      50             :   /**
      51             :    * Constructor. Takes the name to be mapped.
      52             :    */
      53             :   Factory (const std::string & name);
      54             : 
      55             : public:
      56             : 
      57             :   /**
      58             :    * Destructor.
      59             :    */
      60        3234 :   virtual ~Factory () = default;
      61             : 
      62             :   /**
      63             :    * Builds an object of type Base identified by name.
      64             :    */
      65             :   static std::unique_ptr<Base> build (const std::string & name);
      66             : 
      67             :   /**
      68             :    * Create a Base class.  Force this to be implemented
      69             :    * later.
      70             :    */
      71             :   virtual std::unique_ptr<Base> create () = 0;
      72             : 
      73             : 
      74             : protected:
      75             : 
      76             :   /**
      77             :    * Map from a name to a Factory<Base> * pointer.
      78             :    */
      79             :   static std::map<std::string, Factory<Base> *> & factory_map();
      80             : };
      81             : 
      82             : 
      83             : 
      84             : /**
      85             :  * Factory implementation class.
      86             :  */
      87             : template <class Derived, class Base>
      88             : class FactoryImp: public Factory<Base>
      89             : {
      90             : public:
      91             : 
      92             :   /**
      93             :    * Constructor.  Takes a name as input.
      94             :    */
      95        3234 :   FactoryImp (const std::string & name) : Factory<Base>(name) { }
      96             : 
      97             :   /**
      98             :    * Destructor.  Empty.
      99             :    */
     100       68328 :   ~FactoryImp () = default;
     101             : 
     102             : private:
     103             : 
     104             :   /**
     105             :    * \returns A new object of type Derived.
     106             :    */
     107             :   virtual std::unique_ptr<Base> create () override;
     108             : };
     109             : 
     110             : 
     111             : 
     112             : // -----------------------------------------------------
     113             : // Factory members
     114             : template <class Base>
     115             : inline
     116       68328 : Factory<Base>::Factory (const std::string & name)
     117             : {
     118             :   // Make sure we haven't already added this name
     119             :   // to the map
     120        3234 :   libmesh_assert (!factory_map().count(name));
     121             : 
     122       68328 :   factory_map()[name] = this;
     123       68328 : }
     124             : 
     125             : 
     126             : 
     127             : template <class Base>
     128             : inline
     129             : std::unique_ptr<Base> Factory<Base>::build (const std::string & name)
     130             : {
     131             :   // name not found in the map
     132             :   if (!factory_map().count(name))
     133             :     {
     134             :       libMesh::err << "Tried to build an unknown type: " << name << std::endl;
     135             : 
     136             :       libMesh::err << "valid options are:" << std::endl;
     137             : 
     138             :       for (const auto & pr : factory_map())
     139             :         libMesh::err << "  " << pr.first << std::endl;
     140             : 
     141             :       libmesh_error_msg("Exiting...");
     142             :     }
     143             : 
     144             :   Factory<Base> * f = factory_map()[name];
     145             :   return std::unique_ptr<Base>(f->create());
     146             : }
     147             : 
     148             : 
     149             : 
     150             : template <class Derived, class Base>
     151             : inline
     152         168 : std::unique_ptr<Base> FactoryImp<Derived,Base>::create ()
     153             : {
     154         168 :   return std::make_unique<Derived>();
     155             : }
     156             : 
     157             : 
     158             : } // namespace libMesh
     159             : 
     160             : #endif // LIBMESH_FACTORY_H