lib: begin working on a library to allow implementing policy plugins

lib/wp/interface-impl.h

@@ -0,0 +1,53 @@
+/* WirePlumber
+ *
+ * Copyright © 2019 Collabora Ltd.
+ *    @author George Kiagiadakis <george.kiagiadakis@collabora.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#ifndef __WP_INTERFACE_IMPL_H__
+#define __WP_INTERFACE_IMPL_H__
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+G_DECLARE_DERIVABLE_TYPE (WpInterfaceImpl, wp_interface_impl, WP, INTERFACE_IMPL, GObject)
+
+struct _WpInterfaceImplClass
+{
+  GObjectClass parent_class;
+
+  /**
+   * get_prerequisites:
+   * @self: the interface implementation instance
+   * @n_prerequisites: (out): the number of elements in the returned array
+   *
+   * Returns: (array length=n_prerequisites) (transfer none): the types that are
+   *   required by this interface implementation
+   */
+  GType *(*get_prerequisites) (WpInterfaceImpl * self, guint * n_prerequisites);
+};
+
+void wp_interface_impl_set_object (WpInterfaceImpl * self, GObject * object);
+GObject * wp_interface_impl_get_object (WpInterfaceImpl * self);
+GObject * wp_interface_impl_get_sibling (WpInterfaceImpl * self,
+    GType interface);
+GType * wp_interface_impl_get_prerequisites (WpInterfaceImpl * self,
+    guint * n_prerequisites);
+
+G_END_DECLS
+
+#endif