3 files changed, 36 insertions, 17 deletions

diff --git a/desktop/cookie_manager.c b/desktop/cookie_manager.c
index 7c2b4a4de..f369eb068 100644
--- a/desktop/cookie_manager.c
+++ b/desktop/cookie_manager.c
@@ -137,8 +137,8 @@ static nserror cookie_manager_find_entry(treeview_node *root,
 		.entry = NULL
 	};
 
-	err = treeview_walk(cm_ctx.tree, root, cookie_manager_walk_cb, &tw,
-			TREE_NODE_ENTRY);
+	err = treeview_walk(cm_ctx.tree, root, cookie_manager_walk_cb, NULL,
+			&tw, TREE_NODE_ENTRY);
 	if (err != NSERROR_OK)
 		return err;
 
@@ -167,8 +167,8 @@ static nserror cookie_manager_find_folder(treeview_node *root,
 		.entry = NULL
 	};
 
-	err = treeview_walk(cm_ctx.tree, root, cookie_manager_walk_cb, &tw,
-			TREE_NODE_FOLDER);
+	err = treeview_walk(cm_ctx.tree, root, cookie_manager_walk_cb, NULL,
+			&tw, TREE_NODE_FOLDER);
 	if (err != NSERROR_OK)
 		return err;
 
diff --git a/desktop/treeview.c b/desktop/treeview.c
index a63adef47..bf2d0ef37 100644
--- a/desktop/treeview.c
+++ b/desktop/treeview.c
@@ -713,29 +713,42 @@ static int treeview_node_y(treeview *tree, treeview_node *node)
 
 
 struct treeview_walk_ctx {
-	treeview_walk_callback walk_cb;
+	treeview_walk_cb enter_cb;
+	treeview_walk_cb leave_cb;
 	void *ctx;
 	enum treeview_node_type type;
 };
-/** Treewalk node callback. */
-static nserror treeview_walk_cb(treeview_node *n, void *ctx,
+/** Treewalk node enter callback. */
+static nserror treeview_walk_fwd_cb(treeview_node *n, void *ctx,
 		bool *skip_children, bool *end)
 {
 	struct treeview_walk_ctx *tw = ctx;
 
 	if (n->type & tw->type) {
-		return tw->walk_cb(tw->ctx, n->client_data, tw->type, end);
+		return tw->enter_cb(tw->ctx, n->client_data, n->type, end);
+	}
+
+	return NSERROR_OK;
+}
+/** Treewalk node leave callback. */
+static nserror treeview_walk_bwd_cb(treeview_node *n, void *ctx, bool *end)
+{
+	struct treeview_walk_ctx *tw = ctx;
+
+	if (n->type & tw->type) {
+		return tw->leave_cb(tw->ctx, n->client_data, n->type, end);
 	}
 
 	return NSERROR_OK;
 }
 /* Exported interface, documented in treeview.h */
 nserror treeview_walk(treeview *tree, treeview_node *root,
-		treeview_walk_callback walk_cb, void *ctx,
-		enum treeview_node_type type)
+		treeview_walk_cb enter_cb, treeview_walk_cb leave_cb,
+		void *ctx, enum treeview_node_type type)
 {
 	struct treeview_walk_ctx tw = {
-		.walk_cb = walk_cb,
+		.enter_cb = enter_cb,
+		.leave_cb = leave_cb,
 		.ctx = ctx,
 		.type = type
 	};
@@ -746,7 +759,9 @@ nserror treeview_walk(treeview *tree, treeview_node *root,
 	if (root == NULL)
 		root = tree->root;
 
-	return treeview_walk_internal(root, true, NULL, treeview_walk_cb, &tw);
+	return treeview_walk_internal(root, true,
+			(leave_cb != NULL) ? treeview_walk_bwd_cb : NULL,
+			(enter_cb != NULL) ? treeview_walk_fwd_cb : NULL, &tw);
 }
 
 
diff --git a/desktop/treeview.h b/desktop/treeview.h
index f7432aef5..42dd4ca6b 100644
--- a/desktop/treeview.h
+++ b/desktop/treeview.h
@@ -240,7 +240,7 @@ nserror treeview_update_node_entry(treeview *tree,
  * \param abort		Set to true to abort treeview walk prematurely
  * \return NSERROR_OK on success, or appropriate error otherwise
  */
-typedef nserror (*treeview_walk_callback)(void *ctx, void *node_data,
+typedef nserror (*treeview_walk_cb)(void *ctx, void *node_data,
 		enum treeview_node_type type, bool *abort);
 
 /**
@@ -249,17 +249,21 @@ typedef nserror (*treeview_walk_callback)(void *ctx, void *node_data,
  *
  * \param tree		Treeview object to walk
  * \param root		Root node to walk tree from (or NULL for tree root)
- * \param walk_cb	Function to call on each node
+ * \param enter_cb	Function to call on entering nodes, or NULL
+ * \param leave_cb	Function to call on leaving nodes, or NULL
  * \param ctx		Client context, passed back to callback function
  * \param type		The node type(s) of interest
  * \return NSERROR_OK on success, or appropriate error otherwise
  *
- * Note, if deleting returned node, walk_cb must terminate the treeview walk by
+ * Example usage: To export a treeview as XML, XML elements can be opened in
+ * enter_cb, and closed in leave_cb.
+ *
+ * Note, if deleting returned node in enter_cb, the walk must be terminated by
  * setting abort to true.
  */
 nserror treeview_walk(treeview *tree, treeview_node *root,
-		treeview_walk_callback walk_cb, void *ctx,
-		enum treeview_node_type type);
+		treeview_walk_cb enter_cb, treeview_walk_cb leave_cb,
+		void *ctx, enum treeview_node_type type);
 
 /**
  * Delete a treeview node