Add introspection data for property accessors

A GObject property can be accessed generically through the GObject API,
e.g. g_object_set_property() and g_object_get_property(). Properties
typically also have public accessor functions, which are (according to
our own best practices) called through the generic API.

The introspection data is currently missing the relation between a
property and its public accessor functions. With this information, a
language binding could, for instance, avoid exposing the C API entirely,
thus minimizing the chances of collisions between property names and
accessor functions; alternatively, a binding could call the C API
directly instead of going through the generic GObject API, thus avoiding
the boxing and unboxing from a native type to a GIArgument and finally
into a GValue, and vice versa.

In the GIR, we add two new attributes to the `property` element:

  - setter="SYMBOL"
  - getter="SYMBOL"

where "symbol" is the C function identifier of the setter and getter
functions, respectively. The `setter` attribute is only applied to
writable, non-construct-only properties; the `getter` attribute is only
applied to readable properties.

We maintain the ABI compatibility of the typelib data by using 20 bits
of the 25 reserved bits inside the PropertyBlob structure. The data is
exposed through two new GIPropertyInfo methods:

  - g_property_info_get_setter()
  - g_property_info_get_getter()

which return the GIFunctionInfo for the setter and getter functions,
respectively.

gipropertyinfo.c

@@ -132,3 +132,82 @@ g_property_info_get_ownership_transfer (GIPropertyInfo *info)
   else
     return GI_TRANSFER_NOTHING;
 }
+
+/**
+ * g_property_info_get_setter:
+ * @info: a #GIPropertyInfo
+ *
+ * Obtains the setter function associated with this #GIPropertyInfo.
+ *
+ * The setter is only available for %G_PARAM_WRITABLE properties that
+ * are also not %G_PARAM_CONSTRUCT_ONLY.
+ *
+ * Returns: (transfer full): the function info or %NULL if not set.
+ *   Free it with g_base_info_unref() when done.
+ */
+GIFunctionInfo *
+g_property_info_get_setter (GIPropertyInfo *info)
+{
+  GIRealInfo *rinfo = (GIRealInfo *)info;
+  PropertyBlob *blob;
+  GIBaseInfo *container;
+  GIInfoType parent_type;
+
+  g_return_val_if_fail (info != NULL, NULL);
+  g_return_val_if_fail (GI_IS_PROPERTY_INFO (info), NULL);
+
+  blob = (PropertyBlob *)&rinfo->typelib->data[rinfo->offset];
+  if (!blob->writable || blob->construct_only)
+    return NULL;
+
+  if (blob->setter == 0x3ff)
+    return NULL;
+
+  container = rinfo->container;
+  parent_type = g_base_info_get_type (container);
+  if (parent_type == GI_INFO_TYPE_OBJECT)
+    return g_object_info_get_method ((GIObjectInfo *) container, blob->setter);
+  else if (parent_type == GI_INFO_TYPE_INTERFACE)
+    return g_interface_info_get_method ((GIInterfaceInfo *) container, blob->setter);
+  else
+    return NULL;
+}
+
+/**
+ * g_property_info_get_getter:
+ * @info: a #GIPropertyInfo
+ *
+ * Obtains the getter function associated with this #GIPropertyInfo.
+ *
+ * The setter is only available for %G_PARAM_READABLE properties.
+ *
+ * Returns: (transfer full): the function info or %NULL if not set.
+ *   Free it with g_base_info_unref() when done.
+ */
+GIFunctionInfo *
+g_property_info_get_getter (GIPropertyInfo *info)
+{
+  GIRealInfo *rinfo = (GIRealInfo *)info;
+  PropertyBlob *blob;
+  GIBaseInfo *container;
+  GIInfoType parent_type;
+
+  g_return_val_if_fail (info != NULL, NULL);
+  g_return_val_if_fail (GI_IS_PROPERTY_INFO (info), NULL);
+
+  blob = (PropertyBlob *)&rinfo->typelib->data[rinfo->offset];
+  if (!blob->readable)
+    return NULL;
+
+  if (blob->getter == 0x3ff)
+    return NULL;
+
+  container = rinfo->container;
+  parent_type = g_base_info_get_type (container);
+  if (parent_type == GI_INFO_TYPE_OBJECT)
+    return g_object_info_get_method ((GIObjectInfo *) container, blob->getter);
+  else if (parent_type == GI_INFO_TYPE_INTERFACE)
+    return g_interface_info_get_method ((GIInterfaceInfo *) container, blob->getter);
+  else
+    return NULL;
+}

gipropertyinfo.h

@@ -50,6 +50,12 @@ GITypeInfo * g_property_info_get_type  (GIPropertyInfo *info);
 GI_AVAILABLE_IN_ALL
 GITransfer   g_property_info_get_ownership_transfer (GIPropertyInfo *info);
 
+GI_AVAILABLE_IN_1_70
+GIFunctionInfo *g_property_info_get_setter (GIPropertyInfo *info);
+
+GI_AVAILABLE_IN_1_70
+GIFunctionInfo *g_property_info_get_getter (GIPropertyInfo *info);
+
 G_END_DECLS
 
 #endif  /* __GIPROPERTYINFO_H__ */

girnode.c

@@ -254,6 +254,8 @@ _g_ir_node_free (GIrNode *node)
 	GIrNodeProperty *property = (GIrNodeProperty *)node;
 
 	g_free (node->name);
+        g_free (property->setter);
+        g_free (property->getter);
 	_g_ir_node_free ((GIrNode *)property->type);
       }
       break;
@@ -1627,6 +1629,36 @@ _g_ir_node_build_typelib (GIrNode         *node,
 	blob->transfer_container_ownership = prop->shallow_transfer;
 	blob->reserved = 0;
 
+        if (prop->setter != NULL)
+          {
+            int index = get_index_of_member_type ((GIrNodeInterface*)parent,
+                                                  G_IR_NODE_FUNCTION,
+                                                  prop->setter);
+            if (index == -1)
+              {
+                g_error ("Unknown setter %s for property %s", prop->setter, node->name);
+              }
+
+            blob->setter = (guint) index;
+          }
+        else
+          blob->setter = 0x3ff; /* max of 10 bits */
+
+        if (prop->getter != NULL)
+          {
+            int index = get_index_of_member_type ((GIrNodeInterface*)parent,
+                                                  G_IR_NODE_FUNCTION,
+                                                  prop->getter);
+            if (index == -1)
+              {
+                g_error ("Unknown getter %s for property %s", prop->getter, node->name);
+              }
+
+            blob->getter = (guint) index;
+          }
+        else
+          blob->getter = 0x3ff;
+
         _g_ir_node_build_typelib ((GIrNode *)prop->type,
 				 node, build, offset, offset2, NULL);
       }

girnode.h

@@ -174,6 +174,9 @@ struct _GIrNodeProperty
   gboolean transfer;
   gboolean shallow_transfer;
 
+  char *setter;
+  char *getter;
+
   GIrNodeType *type;
 };
 

girparser.c

@@ -1526,6 +1526,8 @@ start_property (GMarkupParseContext *context,
   const gchar *construct;
   const gchar *construct_only;
   const gchar *transfer;
+  const gchar *setter;
+  const gchar *getter;
   GIrNodeProperty *property;
   GIrNodeInterface *iface;
 
@@ -1551,6 +1553,8 @@ start_property (GMarkupParseContext *context,
   construct = find_attribute ("construct", attribute_names, attribute_values);
   construct_only = find_attribute ("construct-only", attribute_names, attribute_values);
   transfer = find_attribute ("transfer-ownership", attribute_names, attribute_values);
+  setter = find_attribute ("setter", attribute_names, attribute_values);
+  getter = find_attribute ("getter", attribute_names, attribute_values);
 
   if (name == NULL)
     {
@@ -1582,6 +1586,9 @@ start_property (GMarkupParseContext *context,
   else
     property->construct_only = FALSE;
 
+  property->setter = g_strdup (setter);
+  property->getter = g_strdup (getter);
+
   parse_property_transfer (property, transfer, ctx);
 
   iface = (GIrNodeInterface *)CURRENT_NODE (ctx);

girwriter.c

@@ -977,6 +977,28 @@ write_property_info (const gchar    *namespace,
   if (flags & G_PARAM_CONSTRUCT_ONLY)
     xml_printf (file, " construct-only=\"1\"");
 
+  if (flags & G_PARAM_READABLE)
+    {
+      GIFunctionInfo *getter = g_property_info_get_getter (info);
+
+      if (getter != NULL)
+        {
+          xml_printf (file, " getter=\"%s\"", g_base_info_get_name ((GIBaseInfo *) getter));
+          g_base_info_unref ((GIBaseInfo *) getter);
+        }
+    }
+
+  if (flags & G_PARAM_WRITABLE)
+    {
+      GIFunctionInfo *setter = g_property_info_get_setter (info);
+
+      if (setter != NULL)
+        {
+          xml_printf (file, " setter=\"%s\"", g_base_info_get_name ((GIBaseInfo *) setter));
+          g_base_info_unref ((GIBaseInfo *) setter);
+        }
+    }
+
   write_ownership_transfer (g_property_info_get_ownership_transfer (info), file);
 
   write_attributes (file, (GIBaseInfo*) info);

gitypelib-internal.h

@@ -918,6 +918,10 @@ typedef struct {
  *   ownership of the container, but not of its contents, is transferred.
  *   This is typically the case when reading lists of statically allocated
  *   things.
+ * @setter: the index of the setter function for this property, if @writable
+ *   is set; if the method is not known, the value will be set to 0x3ff
+ * @getter: ths index of the getter function for this property, if @readable
+ *   is set; if the method is not known, the value will be set to 0x3ff
  * @reserved: Reserved for future use.
  * @reserved2: Reserved for future use.
  * @type: Describes the type of the property.
@@ -934,7 +938,9 @@ typedef struct {
   guint32        construct_only               : 1;
   guint32        transfer_ownership           : 1;
   guint32        transfer_container_ownership : 1;
-  guint32        reserved                     :25;
+  guint32        setter                       :10;
+  guint32        getter                       :10;
+  guint32        reserved                     : 5;
 
   guint32        reserved2;