schema: add iter_tree method

This covers the same feature than LYSC_TREE_DFS_BEGIN/LYSC_TREE_DFS_END
and lysc_tree_dfs_full but reimplemented in pure Python.

Fixes: #51
Signed-off-by: Robin Jarry <robin@jarry.cc>

Author: rjarry

cffi/cdefs.h

@@ -687,6 +687,8 @@ struct lysc_ext {
 
 const struct lysc_node* lys_find_child(const struct lysc_node *, const struct lys_module *, const char *, size_t, uint16_t, uint32_t);
 const struct lysc_node* lysc_node_child(const struct lysc_node *);
+const struct lysc_node_action* lysc_node_actions(const struct lysc_node *);
+const struct lysc_node_notif* lysc_node_notifs(const struct lysc_node *);
 
 typedef enum {
     LYD_PATH_STD,

libyang/schema.py

@@ -1012,6 +1012,37 @@ def when_conditions(self):
         for cond in ly_array_iter(wh):
             yield c2str(lib.lyxp_get_expr(cond.cond))
 
+    def iter_tree(self, full: bool = False) -> Iterator["SNode"]:
+        """
+        Do a DFS walk of the schema node.
+
+        :arg full:
+            Also walk in actions and notifications.
+        """
+        n = next_n = self.cdata
+        while n != ffi.NULL:
+            yield self.new(self.context, n)
+
+            if full:
+                act = lib.lysc_node_actions(n)
+                if act != ffi.NULL:
+                    yield from self.new(self.context, act).iter_tree()
+                notif = lib.lysc_node_notifs(n)
+                if notif != ffi.NULL:
+                    yield from self.new(self.context, notif).iter_tree()
+
+            next_n = lib.lysc_node_child(n)
+            if next_n == ffi.NULL:
+                if n == self.cdata:
+                    break
+                next_n = n.next
+            while next_n == ffi.NULL:
+                n = n.parent
+                if n.parent == self.cdata.parent:
+                    break
+                next_n = n.next
+            n = next_n
+
     def __repr__(self):
         cls = self.__class__
         return "<%s.%s: %s>" % (cls.__module__, cls.__name__, str(self))

tests/test_schema.py

@@ -267,6 +267,12 @@ def test_cont_children_leafs(self):
     def test_cont_parent(self):
         self.assertIsNone(self.container.parent())
 
+    def test_iter_tree(self):
+        tree = list(self.container.iter_tree())
+        self.assertEqual(len(tree), 15)
+        tree = list(self.container.iter_tree(full=True))
+        self.assertEqual(len(tree), 20)
+
 
 # -------------------------------------------------------------------------------------
 class ListTest(unittest.TestCase):