[gtk+] cssnode: Add hackery to allow bypassing widget paths

[Benjamin Otte <otte src gnome org>]

commit 310f9f40dac12471197e33d745ae46dd0d8aeb22
Author: Benjamin Otte <otte redhat com>
Date:   Mon Feb 9 18:38:57 2015 +0100

    cssnode: Add hackery to allow bypassing widget paths
    
    If we know the parent's get_path_for_child() implementation is safe to
    be used with GtkCssNode because it doesn't do anything special, we do
    that. Unfortunately that requires whitelisting vfuncs because the vfunc
    is public API so anyone can override it.

 gtk/gtkcsswidgetnode.c |   35 +++++++++++++++++++++++++++++++++++
 1 files changed, 35 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkcsswidgetnode.c b/gtk/gtkcsswidgetnode.c
index 3a05b1d..e18cdc3 100644
--- a/gtk/gtkcsswidgetnode.c
+++ b/gtk/gtkcsswidgetnode.c
@@ -168,6 +168,38 @@ gtk_css_widget_node_validate (GtkCssNode       *node,
   return changes;
 }
 
+typedef GtkWidgetPath * (* GetPathForChildFunc) (GtkContainer *, GtkWidget *);
+
+static gboolean
+widget_needs_widget_path (GtkWidget *widget)
+{
+  static GetPathForChildFunc funcs[1];
+  GtkWidget *parent;
+  GetPathForChildFunc parent_func;
+  guint i;
+
+  if (G_UNLIKELY (funcs[0] == NULL))
+    {
+      i = 0;
+      funcs[i++] = GTK_CONTAINER_CLASS (g_type_class_ref (GTK_TYPE_CONTAINER))->get_path_for_child;
+
+      g_assert (i == G_N_ELEMENTS (funcs));
+    }
+
+  parent = gtk_widget_get_parent (widget);
+  if (parent == NULL)
+    return FALSE;
+
+  parent_func = GTK_CONTAINER_GET_CLASS (GTK_CONTAINER (parent))->get_path_for_child;
+  for (i = 0; i < G_N_ELEMENTS (funcs); i++)
+    {
+      if (funcs[i] == parent_func)
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
 gboolean
 gtk_css_widget_node_init_matcher (GtkCssNode     *node,
                                   GtkCssMatcher  *matcher)
@@ -177,6 +209,9 @@ gtk_css_widget_node_init_matcher (GtkCssNode     *node,
   if (widget_node->widget == NULL)
     return FALSE;
 
+  if (!widget_needs_widget_path (widget_node->widget))
+    return GTK_CSS_NODE_CLASS (gtk_css_widget_node_parent_class)->init_matcher (node, matcher);
+
   return _gtk_css_matcher_init (matcher,
                                 gtk_widget_get_path (widget_node->widget),
                                 gtk_css_node_get_declaration (node));