[gnome-builder] tree: use weak pointer for tree

[Christian Hergert <chergert src gnome org>]

commit ae14732c9abdd7365bbb6b866e362a118eaa19b7
Author: Christian Hergert <christian hergert me>
Date:   Sun Jun 14 20:09:36 2015 -0700

    tree: use weak pointer for tree

 src/tree/gb-tree-node.c |   22 +++++++++++++++++-----
 1 files changed, 17 insertions(+), 5 deletions(-)
---
diff --git a/src/tree/gb-tree-node.c b/src/tree/gb-tree-node.c
index dd9ec3f..1148c2e 100644
--- a/src/tree/gb-tree-node.c
+++ b/src/tree/gb-tree-node.c
@@ -100,11 +100,23 @@ _gb_tree_node_set_tree (GbTreeNode *node,
                         GbTree     *tree)
 {
   g_return_if_fail (GB_IS_TREE_NODE (node));
-  g_return_if_fail (GB_IS_TREE (tree));
-  g_return_if_fail ((node->tree == NULL) ||
-                    (node->tree == tree));
+  g_return_if_fail (!tree || GB_IS_TREE (tree));
 
-  node->tree = tree;
+  if (node->tree != tree)
+    {
+      if (node->tree != NULL)
+        {
+          g_object_remove_weak_pointer (G_OBJECT (node->tree), (gpointer *)&node->tree);
+          node->tree = NULL;
+        }
+
+      if (tree != NULL)
+        {
+          node->tree = tree;
+          g_object_add_weak_pointer (G_OBJECT (node->tree), (gpointer *)&node->tree);
+        }
+    }
+}
 }
 
 /**