Provide a default implementation of JsonSerializable

The JsonSerializable interface can provide a default implementation, using
the powers of GTypeInterface. This means that classes implementing the
interface can opt to implement both, either or none of the JsonSerializable
methods, and still be able to retain some basic functionality for the methods
they decide not to implement.

1 files changed, 120 insertions, 88 deletions

diff --git a/json-glib/json-gobject.c b/json-glib/json-gobject.c
index 28d3dce..548a9ce 100644
--- a/json-glib/json-gobject.c
+++ b/json-glib/json-gobject.c
@@ -41,94 +41,6 @@
 #include "json-parser.h"
 #include "json-generator.h"
 
-GType
-json_serializable_get_type (void)
-{
-  static GType iface_type = 0;
-
-  if (!iface_type)
-    iface_type =
-      g_type_register_static_simple (G_TYPE_INTERFACE, "JsonSerializable",
-                                     sizeof (JsonSerializableIface),
-                                     NULL, 0, NULL, 0);
-
-  return iface_type;
-}
-
-/**
- * json_serializable_serialize_property:
- * @serializable: a #JsonSerializable object
- * @property_name: the name of the property
- * @value: the value of the property
- * @pspec: a #GParamSpec
- *
- * Asks a #JsonSerializable implementation to serialize a #GObject
- * property into a #JsonNode object.
- *
- * Return value: a #JsonNode containing the serialize property
- */
-JsonNode *
-json_serializable_serialize_property (JsonSerializable *serializable,
-                                      const gchar      *property_name,
-                                      const GValue     *value,
-                                      GParamSpec       *pspec)
-{
-  JsonSerializableIface *iface;
-
-  g_return_val_if_fail (JSON_IS_SERIALIZABLE (serializable), NULL);
-  g_return_val_if_fail (property_name != NULL, NULL);
-  g_return_val_if_fail (value != NULL, NULL);
-  g_return_val_if_fail (pspec != NULL, NULL);
-
-  iface = JSON_SERIALIZABLE_GET_IFACE (serializable);
-  if (!iface->serialize_property)
-    return json_node_new (JSON_NODE_NULL);
-
-  return iface->serialize_property (serializable, property_name, value, pspec);
-}
-
-/**
- * json_serializable_deserialize_property:
- * @serializable: a #JsonSerializable
- * @property_name: the name of the property
- * @value: a pointer to an uninitialized #GValue
- * @pspec: a #GParamSpec
- * @property_node: a #JsonNode containing the serialized property
- *
- * Asks a #JsonSerializable implementation to deserialize the
- * property contained inside @property_node into @value.
- *
- * Return value: %TRUE if the property was successfully deserialized.
- */
-gboolean
-json_serializable_deserialize_property (JsonSerializable *serializable,
-                                        const gchar      *property_name,
-                                        GValue           *value,
-                                        GParamSpec       *pspec,
-                                        JsonNode         *property_node)
-{
-  JsonSerializableIface *iface;
-
-  g_return_val_if_fail (JSON_IS_SERIALIZABLE (serializable), FALSE);
-  g_return_val_if_fail (property_name != NULL, FALSE);
-  g_return_val_if_fail (value != NULL, FALSE);
-  g_return_val_if_fail (pspec != NULL, FALSE);
-  g_return_val_if_fail (property_node != NULL, FALSE);
-
-  iface = JSON_SERIALIZABLE_GET_IFACE (serializable);
-  if (!iface->deserialize_property)
-    {
-      g_param_value_defaults (pspec, value);
-      return TRUE;
-    }
-
-  return iface->deserialize_property (serializable,
-                                      property_name,
-                                      value,
-                                      pspec,
-                                      property_node);
-}
-
 static gboolean
 enum_from_string (GType        type,
                   const gchar *string,
@@ -375,6 +287,8 @@ json_deserialize_pspec (GValue     *value,
           retval = FALSE;
           break;
         }
+
+      g_value_unset (&node_value);
       break;
 
     case JSON_NODE_NULL:
@@ -493,6 +407,124 @@ json_serialize_pspec (const GValue *real_value,
 }
 
 /**
+ * json_serializable_serialize_property:
+ * @serializable: a #JsonSerializable object
+ * @property_name: the name of the property
+ * @value: the value of the property
+ * @pspec: a #GParamSpec
+ *
+ * Asks a #JsonSerializable implementation to serialize a #GObject
+ * property into a #JsonNode object.
+ *
+ * Return value: a #JsonNode containing the serialize property
+ */
+JsonNode *
+json_serializable_serialize_property (JsonSerializable *serializable,
+                                      const gchar      *property_name,
+                                      const GValue     *value,
+                                      GParamSpec       *pspec)
+{
+  JsonSerializableIface *iface;
+
+  g_return_val_if_fail (JSON_IS_SERIALIZABLE (serializable), NULL);
+  g_return_val_if_fail (property_name != NULL, NULL);
+  g_return_val_if_fail (value != NULL, NULL);
+  g_return_val_if_fail (pspec != NULL, NULL);
+
+  iface = JSON_SERIALIZABLE_GET_IFACE (serializable);
+
+  return iface->serialize_property (serializable, property_name, value, pspec);
+}
+
+/**
+ * json_serializable_deserialize_property:
+ * @serializable: a #JsonSerializable
+ * @property_name: the name of the property
+ * @value: a pointer to an uninitialized #GValue
+ * @pspec: a #GParamSpec
+ * @property_node: a #JsonNode containing the serialized property
+ *
+ * Asks a #JsonSerializable implementation to deserialize the
+ * property contained inside @property_node into @value.
+ *
+ * Return value: %TRUE if the property was successfully deserialized.
+ */
+gboolean
+json_serializable_deserialize_property (JsonSerializable *serializable,
+                                        const gchar      *property_name,
+                                        GValue           *value,
+                                        GParamSpec       *pspec,
+                                        JsonNode         *property_node)
+{
+  JsonSerializableIface *iface;
+
+  g_return_val_if_fail (JSON_IS_SERIALIZABLE (serializable), FALSE);
+  g_return_val_if_fail (property_name != NULL, FALSE);
+  g_return_val_if_fail (value != NULL, FALSE);
+  g_return_val_if_fail (pspec != NULL, FALSE);
+  g_return_val_if_fail (property_node != NULL, FALSE);
+
+  iface = JSON_SERIALIZABLE_GET_IFACE (serializable);
+
+  return iface->deserialize_property (serializable,
+                                      property_name,
+                                      value,
+                                      pspec,
+                                      property_node);
+}
+
+static gboolean
+json_serializable_real_deserialize (JsonSerializable *serializable,
+                                    const gchar      *name,
+                                    GValue           *value,
+                                    GParamSpec       *pspec,
+                                    JsonNode         *node)
+{
+  return json_deserialize_pspec (value, pspec, node);
+}
+
+static JsonNode *
+json_serializable_real_serialize (JsonSerializable *serializable,
+                                  const gchar      *name,
+                                  const GValue     *value,
+                                  GParamSpec       *pspec)
+{
+  return json_serialize_pspec (value, pspec);
+}
+
+static void
+json_serializable_base_init (gpointer g_class,
+                             gpointer data)
+{
+  static gboolean is_initialized = FALSE;
+
+  if (G_UNLIKELY (!is_initialized))
+    {
+      JsonSerializableIface *iface = g_class;
+
+      iface->serialize_property = json_serializable_real_serialize;
+      iface->deserialize_property = json_serializable_real_deserialize;
+
+      is_initialized = TRUE;
+    }
+}
+
+GType
+json_serializable_get_type (void)
+{
+  static GType iface_type = 0;
+
+  if (!iface_type)
+    iface_type =
+      g_type_register_static_simple (G_TYPE_INTERFACE, "JsonSerializable",
+                                     sizeof (JsonSerializableIface),
+                                     json_serializable_base_init,
+                                     0, NULL, 0);
+
+  return iface_type;
+}
+
+/**
  * json_construct_gobject:
  * @gtype: the #GType of object to construct
  * @data: a JSON data stream