Line data    Source code

       1              : /********************************************************************\
       2              :  * qofbackend-prov.hpp -- Manage creation of a QofBackend subclass.  *
       3              :  *                                                                  *
       4              :  * Copyright 2016 John Ralls <jralls@ceridwen.us>                   *
       5              :  *                                                                  *
       6              :  * This program is free software; you can redistribute it and/or    *
       7              :  * modify it under the terms of the GNU General Public License as   *
       8              :  * published by the Free Software Foundation; either version 2 of   *
       9              :  * the License, or (at your option) any later version.              *
      10              :  *                                                                  *
      11              :  * This program is distributed in the hope that it will be useful,  *
      12              :  * but WITHOUT ANY WARRANTY; without even the implied warranty of   *
      13              :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the    *
      14              :  * GNU General Public License for more details.                     *
      15              :  *                                                                  *
      16              :  * You should have received a copy of the GNU General Public License*
      17              :  * along with this program; if not, contact:                        *
      18              :  *                                                                  *
      19              :  * Free Software Foundation           Voice:  +1-617-542-5942       *
      20              :  * 51 Franklin Street, Fifth Floor    Fax:    +1-617-542-2652       *
      21              :  * Boston, MA  02110-1301,  USA       gnu@gnu.org                   *
      22              :  *                                                                  *
      23              : \********************************************************************/
      24              : 
      25              : #ifndef __GNC_BACKEND_PROV_HPP__
      26              : #define  __GNC_BACKEND_PROV_HPP__
      27              : 
      28              : #include <memory>
      29              : 
      30              : struct QofBackendProvider
      31              : {
      32           48 :     QofBackendProvider(const char* name, const char* type) :
      33           48 :         provider_name {name}, access_method {type} {}
      34              :     QofBackendProvider(QofBackendProvider&) = delete;
      35              :     QofBackendProvider(QofBackendProvider&&) = delete;
      36            4 :     virtual ~QofBackendProvider() {}
      37              : 
      38              :     /** Return a new, fully initialized backend.
      39              :      *
      40              :      * If the backend supports configuration, all configuration options
      41              :      * should be initialised to usable values here.
      42              :      * */
      43              :     virtual QofBackend * create_backend(void) = 0;
      44              : 
      45              :     /** \brief Distinguish two providers with same access method.
      46              : 
      47              :       More than 1 backend can be registered under the same access_method,
      48              :       so each one is passed the path to the data (e.g. a file) and
      49              :       should return TRUE only:
      50              :     -# if the backend recognises the type as one that it can load and write or
      51              :     -# if the path contains no data but can be used (e.g. a new session).
      52              : 
      53              :       \note If the backend can cope with more than one type, the backend
      54              :       should not try to store or cache the sub-type for this data.
      55              :       It is sufficient only to return TRUE if any ONE of the supported
      56              :       types match the incoming data. The backend should not assume that
      57              :       returning TRUE will mean that the data will naturally follow.
      58              :       */
      59              :     /*@ null @*/
      60              :     virtual bool type_check(const char*) = 0;
      61              :     /** Some arbitrary name given for this particular backend provider */
      62              :     const char * provider_name;
      63              : 
      64              :     /** The access method that this provider provides, for example,
      65              :      *  file:// http:// postgres:// or sqlite://, but without the :// at the end
      66              :      */
      67              :     const char * access_method;
      68              : };
      69              : 
      70              : using QofBackendProvider_ptr = std::unique_ptr<QofBackendProvider>;
      71              : 
      72              : /** Let the system know about a new provider of backends.  This function
      73              :  *  is typically called by the provider library at library load time.
      74              :  *  This function allows the backend library to tell the QOF infrastructure
      75              :  *  that it can handle URL's of a certain type.  Note that a single
      76              :  *  backend library may register more than one provider, if it is
      77              :  *  capable of handling more than one URL access method.
      78              :  */
      79              : void qof_backend_register_provider (QofBackendProvider_ptr&&);
      80              : 
      81              : void qof_backend_unregister_all_providers ();
      82              : 
      83              : #endif // __GNC_BACKEND_PROV_HPP__