LCOV - code coverage report
Current view: top level - glib/gobject - gtypeplugin.c (source / functions) Hit Total Coverage
Test: unnamed Lines: 20 24 83.3 %
Date: 2024-06-11 05:24:59 Functions: 4 5 80.0 %
Branches: 2 2 100.0 %

           Branch data     Line data    Source code
       1                 :            : /* GObject - GLib Type, Object, Parameter and Signal Library
       2                 :            :  * Copyright (C) 2000 Red Hat, Inc.
       3                 :            :  *
       4                 :            :  * SPDX-License-Identifier: LGPL-2.1-or-later
       5                 :            :  *
       6                 :            :  * This library is free software; you can redistribute it and/or
       7                 :            :  * modify it under the terms of the GNU Lesser General Public
       8                 :            :  * License as published by the Free Software Foundation; either
       9                 :            :  * version 2.1 of the License, or (at your option) any later version.
      10                 :            :  *
      11                 :            :  * This library 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 GNU
      14                 :            :  * Lesser General Public License for more details.
      15                 :            :  *
      16                 :            :  * You should have received a copy of the GNU Lesser General
      17                 :            :  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
      18                 :            :  */
      19                 :            : 
      20                 :            : #include "config.h"
      21                 :            : 
      22                 :            : #include "gtypeplugin.h"
      23                 :            : 
      24                 :            : 
      25                 :            : /**
      26                 :            :  * GTypePlugin:
      27                 :            :  *
      28                 :            :  * An interface that handles the lifecycle of dynamically loaded types.
      29                 :            :  *
      30                 :            :  * The GObject type system supports dynamic loading of types.
      31                 :            :  * It goes as follows:
      32                 :            :  *
      33                 :            :  * 1. The type is initially introduced (usually upon loading the module
      34                 :            :  *    the first time, or by your main application that knows what modules
      35                 :            :  *    introduces what types), like this:
      36                 :            :  *    ```c
      37                 :            :  *    new_type_id = g_type_register_dynamic (parent_type_id,
      38                 :            :  *                                           "TypeName",
      39                 :            :  *                                           new_type_plugin,
      40                 :            :  *                                           type_flags);
      41                 :            :  *    ```
      42                 :            :  *    where `new_type_plugin` is an implementation of the
      43                 :            :  *    `GTypePlugin` interface.
      44                 :            :  *
      45                 :            :  * 2. The type's implementation is referenced, e.g. through
      46                 :            :  *    [func@GObject.TypeClass.ref] or through [func@GObject.type_create_instance]
      47                 :            :  *    (this is being called by [ctor@GObject.Object.new]) or through one of the above
      48                 :            :  *    done on a type derived from `new_type_id`.
      49                 :            :  *
      50                 :            :  * 3. This causes the type system to load the type's implementation by calling
      51                 :            :  *    [method@GObject.TypePlugin.use] and [method@GObject.TypePlugin.complete_type_info]
      52                 :            :  *    on `new_type_plugin`.
      53                 :            :  *
      54                 :            :  * 4. At some point the type's implementation isn't required anymore, e.g. after
      55                 :            :  *    [method@GObject.TypeClass.unref] or [func@GObject.type_free_instance]
      56                 :            :  *    (called when the reference count of an instance drops to zero).
      57                 :            :  *
      58                 :            :  * 5. This causes the type system to throw away the information retrieved
      59                 :            :  *    from [method@GObject.TypePlugin.complete_type_info] and then it calls
      60                 :            :  *    [method@GObject.TypePlugin.unuse] on `new_type_plugin`.
      61                 :            :  *
      62                 :            :  * 6. Things may repeat from the second step.
      63                 :            :  *
      64                 :            :  * So basically, you need to implement a `GTypePlugin` type that
      65                 :            :  * carries a use_count, once use_count goes from zero to one, you need
      66                 :            :  * to load the implementation to successfully handle the upcoming
      67                 :            :  * [method@GObject.TypePlugin.complete_type_info] call. Later, maybe after
      68                 :            :  * succeeding use/unuse calls, once use_count drops to zero, you can
      69                 :            :  * unload the implementation again. The type system makes sure to call
      70                 :            :  * [method@GObject.TypePlugin.use] and [method@GObject.TypePlugin.complete_type_info]
      71                 :            :  * again when the type is needed again.
      72                 :            :  *
      73                 :            :  * [class@GObject.TypeModule] is an implementation of `GTypePlugin` that
      74                 :            :  * already implements most of this except for the actual module loading and
      75                 :            :  * unloading. It even handles multiple registered types per module.
      76                 :            :  */
      77                 :            : 
      78                 :            : 
      79                 :            : /* --- functions --- */
      80                 :            : GType
      81                 :        598 : g_type_plugin_get_type (void)
      82                 :            : {
      83                 :            :   static GType type_plugin_type = 0;
      84                 :            :   
      85         [ +  + ]:        598 :   if (!type_plugin_type)
      86                 :            :     {
      87                 :        537 :       const GTypeInfo type_plugin_info = {
      88                 :            :         sizeof (GTypePluginClass),
      89                 :            :         NULL,           /* base_init */
      90                 :            :         NULL,           /* base_finalize */
      91                 :            :         0,              /* class_init */
      92                 :            :         NULL,           /* class_destroy */
      93                 :            :         NULL,           /* class_data */
      94                 :            :         0,              /* instance_size */
      95                 :            :         0,              /* n_preallocs */
      96                 :            :         NULL,           /* instance_init */
      97                 :            :         NULL,           /* value_table */
      98                 :            :       };
      99                 :            :       
     100                 :        537 :       type_plugin_type = g_type_register_static (G_TYPE_INTERFACE, g_intern_static_string ("GTypePlugin"), &type_plugin_info, 0);
     101                 :            :     }
     102                 :            :   
     103                 :        598 :   return type_plugin_type;
     104                 :            : }
     105                 :            : 
     106                 :            : /**
     107                 :            :  * g_type_plugin_use:
     108                 :            :  * @plugin: a #GTypePlugin
     109                 :            :  *
     110                 :            :  * Calls the @use_plugin function from the #GTypePluginClass of
     111                 :            :  * @plugin.  There should be no need to use this function outside of
     112                 :            :  * the GObject type system itself.
     113                 :            :  */
     114                 :            : void
     115                 :          6 : g_type_plugin_use (GTypePlugin *plugin)
     116                 :            : {
     117                 :            :   GTypePluginClass *iface;
     118                 :            :   
     119                 :          6 :   g_return_if_fail (G_IS_TYPE_PLUGIN (plugin));
     120                 :            :   
     121                 :          6 :   iface = G_TYPE_PLUGIN_GET_CLASS (plugin);
     122                 :          6 :   iface->use_plugin (plugin);
     123                 :            : }
     124                 :            : 
     125                 :            : /**
     126                 :            :  * g_type_plugin_unuse:
     127                 :            :  * @plugin: a #GTypePlugin
     128                 :            :  *
     129                 :            :  * Calls the @unuse_plugin function from the #GTypePluginClass of
     130                 :            :  * @plugin.  There should be no need to use this function outside of
     131                 :            :  * the GObject type system itself.
     132                 :            :  */
     133                 :            : void
     134                 :          0 : g_type_plugin_unuse (GTypePlugin *plugin)
     135                 :            : {
     136                 :            :   GTypePluginClass *iface;
     137                 :            :   
     138                 :          0 :   g_return_if_fail (G_IS_TYPE_PLUGIN (plugin));
     139                 :            :   
     140                 :          0 :   iface = G_TYPE_PLUGIN_GET_CLASS (plugin);
     141                 :          0 :   iface->unuse_plugin (plugin);
     142                 :            : }
     143                 :            : 
     144                 :            : /**
     145                 :            :  * g_type_plugin_complete_type_info:
     146                 :            :  * @plugin: a #GTypePlugin
     147                 :            :  * @g_type: the #GType whose info is completed
     148                 :            :  * @info: the #GTypeInfo struct to fill in
     149                 :            :  * @value_table: the #GTypeValueTable to fill in
     150                 :            :  * 
     151                 :            :  * Calls the @complete_type_info function from the #GTypePluginClass of @plugin.
     152                 :            :  * There should be no need to use this function outside of the GObject 
     153                 :            :  * type system itself.
     154                 :            :  */
     155                 :            : void
     156                 :          4 : g_type_plugin_complete_type_info (GTypePlugin     *plugin,
     157                 :            :                                   GType            g_type,
     158                 :            :                                   GTypeInfo       *info,
     159                 :            :                                   GTypeValueTable *value_table)
     160                 :            : {
     161                 :            :   GTypePluginClass *iface;
     162                 :            :   
     163                 :          4 :   g_return_if_fail (G_IS_TYPE_PLUGIN (plugin));
     164                 :          4 :   g_return_if_fail (info != NULL);
     165                 :          4 :   g_return_if_fail (value_table != NULL);
     166                 :            :   
     167                 :          4 :   iface = G_TYPE_PLUGIN_GET_CLASS (plugin);
     168                 :          4 :   iface->complete_type_info (plugin,
     169                 :            :                              g_type,
     170                 :            :                              info,
     171                 :            :                              value_table);
     172                 :            : }
     173                 :            : 
     174                 :            : /**
     175                 :            :  * g_type_plugin_complete_interface_info:
     176                 :            :  * @plugin: the #GTypePlugin
     177                 :            :  * @instance_type: the #GType of an instantiatable type to which the interface
     178                 :            :  *  is added
     179                 :            :  * @interface_type: the #GType of the interface whose info is completed
     180                 :            :  * @info: the #GInterfaceInfo to fill in
     181                 :            :  *
     182                 :            :  * Calls the @complete_interface_info function from the
     183                 :            :  * #GTypePluginClass of @plugin. There should be no need to use this
     184                 :            :  * function outside of the GObject type system itself.
     185                 :            :  */
     186                 :            : void
     187                 :          2 : g_type_plugin_complete_interface_info (GTypePlugin    *plugin,
     188                 :            :                                        GType           instance_type,
     189                 :            :                                        GType           interface_type,
     190                 :            :                                        GInterfaceInfo *info)
     191                 :            : {
     192                 :            :   GTypePluginClass *iface;
     193                 :            :   
     194                 :          2 :   g_return_if_fail (G_IS_TYPE_PLUGIN (plugin));
     195                 :          2 :   g_return_if_fail (info != NULL);
     196                 :            :   
     197                 :          2 :   iface = G_TYPE_PLUGIN_GET_CLASS (plugin);
     198                 :          2 :   iface->complete_interface_info (plugin,
     199                 :            :                                   instance_type,
     200                 :            :                                   interface_type,
     201                 :            :                                   info);
     202                 :            : }

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