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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 : 234 : QofBackendProvider(const char* name, const char* type) :
33 : 234 : provider_name {name}, access_method {type} {}
34 : : QofBackendProvider(QofBackendProvider&) = delete;
35 : : QofBackendProvider(QofBackendProvider&&) = delete;
36 : 192 : 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__
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