[devhelp/wip/book-list] BookList: add get_default()

[Sébastien Wilmet <swilmet src gnome org>]

commit a1129a628c00a0e055b32a6bc73105ae6070ac2d
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Sat Apr 28 12:06:58 2018 +0200

    BookList: add get_default()

 devhelp/dh-book-list.c              |   55 +++++++++++++++++++++++++++++++++++
 devhelp/dh-book-list.h              |    5 +++
 devhelp/dh-init.c                   |    2 +
 docs/reference/devhelp-sections.txt |    1 +
 4 files changed, 63 insertions(+), 0 deletions(-)
---
diff --git a/devhelp/dh-book-list.c b/devhelp/dh-book-list.c
index e154541..791e8fc 100644
--- a/devhelp/dh-book-list.c
+++ b/devhelp/dh-book-list.c
@@ -19,6 +19,8 @@
  */
 
 #include "dh-book-list.h"
+#include "dh-book-list-builder.h"
+#include "dh-settings.h"
 
 /**
  * SECTION:dh-book-list
@@ -46,6 +48,7 @@ enum {
         N_SIGNALS
 };
 
+static DhBookList *default_instance = NULL;
 static guint signals[N_SIGNALS] = { 0 };
 
 G_DEFINE_TYPE_WITH_PRIVATE (DhBookList, dh_book_list, G_TYPE_OBJECT)
@@ -71,6 +74,15 @@ dh_book_list_dispose (GObject *object)
 }
 
 static void
+dh_book_list_finalize (GObject *object)
+{
+        if (default_instance == DH_BOOK_LIST (object))
+                default_instance = NULL;
+
+        G_OBJECT_CLASS (dh_book_list_parent_class)->finalize (object);
+}
+
+static void
 dh_book_list_add_book_default (DhBookList *book_list,
                                DhBook     *book)
 {
@@ -109,6 +121,7 @@ dh_book_list_class_init (DhBookListClass *klass)
         GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
         object_class->dispose = dh_book_list_dispose;
+        object_class->finalize = dh_book_list_finalize;
 
         klass->add_book = dh_book_list_add_book_default;
         klass->remove_book = dh_book_list_remove_book_default;
@@ -180,6 +193,48 @@ dh_book_list_new (void)
 }
 
 /**
+ * dh_book_list_get_default:
+ *
+ * Gets the default #DhBookList object. It is created with #DhBookListBuilder,
+ * dh_book_list_builder_add_default_sub_book_lists() is called, and
+ * dh_book_list_builder_read_books_disabled_setting() is called with the default
+ * #DhSettings object as returned by dh_settings_get_default().
+ *
+ * Returns: (transfer none): the default #DhBookList object.
+ * Since: 3.30
+ */
+DhBookList *
+dh_book_list_get_default (void)
+{
+        if (default_instance == NULL) {
+                DhSettings *default_settings;
+                DhBookListBuilder *builder;
+
+                default_settings = dh_settings_get_default ();
+
+                builder = dh_book_list_builder_new ();
+                dh_book_list_builder_add_default_sub_book_lists (builder);
+                dh_book_list_builder_read_books_disabled_setting (builder, default_settings);
+                default_instance = dh_book_list_builder_create_object (builder);
+                g_object_unref (builder);
+        }
+
+        return default_instance;
+}
+
+void
+_dh_book_list_unref_default (void)
+{
+        if (default_instance != NULL)
+                g_object_unref (default_instance);
+
+        /* default_instance is not set to NULL here, it is set to NULL in
+         * dh_book_list_finalize() (i.e. when we are sure that the ref count
+         * reaches 0).
+         */
+}
+
+/**
  * dh_book_list_get_books:
  * @book_list: a #DhBookList.
  *
diff --git a/devhelp/dh-book-list.h b/devhelp/dh-book-list.h
index 0fcfe3e..9660715 100644
--- a/devhelp/dh-book-list.h
+++ b/devhelp/dh-book-list.h
@@ -76,6 +76,11 @@ GType           dh_book_list_get_type           (void);
 
 DhBookList *    dh_book_list_new                (void);
 
+DhBookList *    dh_book_list_get_default        (void);
+
+G_GNUC_INTERNAL
+void            _dh_book_list_unref_default     (void);
+
 GList *         dh_book_list_get_books          (DhBookList *book_list);
 
 void            dh_book_list_add_book           (DhBookList *book_list,
diff --git a/devhelp/dh-init.c b/devhelp/dh-init.c
index 4e946d6..f70f9a4 100644
--- a/devhelp/dh-init.c
+++ b/devhelp/dh-init.c
@@ -22,6 +22,7 @@
 #include "config.h"
 #include "dh-init.h"
 #include <glib/gi18n-lib.h>
+#include "dh-book-list.h"
 #include "dh-book-manager.h"
 #include "dh-profile.h"
 #include "dh-settings.h"
@@ -82,6 +83,7 @@ dh_finalize (void)
          * accordingly, at the right place.
          */
         if (!done) {
+                _dh_book_list_unref_default ();
                 _dh_book_manager_unref_singleton ();
                 _dh_profile_unref_default ();
                 _dh_settings_unref_default ();
diff --git a/docs/reference/devhelp-sections.txt b/docs/reference/devhelp-sections.txt
index 898c0d9..fd1b360 100644
--- a/docs/reference/devhelp-sections.txt
+++ b/docs/reference/devhelp-sections.txt
@@ -55,6 +55,7 @@ dh_book_get_type
 DhBookList
 DhBookListClass
 dh_book_list_new
+dh_book_list_get_default
 dh_book_list_get_books
 dh_book_list_add_book
 dh_book_list_remove_book