From 0d3e730c9e71748f866573a72951e142b4108a7b Mon Sep 17 00:00:00 2001
From: John Estabrook <jestabro@vyos.io>
Date: Thu, 24 Sep 2026 12:01:15 -0500
Subject: T7886: add supporting functions for calculation of reverse
 dependencies

---
 python/vyos/dependentverify.py | 62 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 python/vyos/dependentverify.py

(limited to 'python')

diff --git a/python/vyos/dependentverify.py b/python/vyos/dependentverify.py
new file mode 100644
index 000000000..157f99ae3
--- /dev/null
+++ b/python/vyos/dependentverify.py
@@ -0,0 +1,62 @@
+# Copyright (C) VyOS Inc.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+
+from vyos.configtree import ConfigTree  # noqa: I001
+from vyos.configtree import DiffTree
+from vyos.configtree import subtree_values_of_path
+from vyos.referencetree import ReferenceTree
+
+
+def removed_dependency_value_paths_of_kind(
+    kind: str,
+    reference_tree: ReferenceTree,
+    session_tree: ConfigTree,
+    diff_tree: DiffTree,
+):
+    paths = reference_tree.get_nodes_of_kind(kind)
+    value_paths = []
+    for path in paths:
+        path_vals = subtree_values_of_path(diff_tree.sub, path, reference_tree)
+        path_vals = [t for t in path_vals if t != ([], [])]
+        for vlst, p in path_vals:
+            vals = list(
+                filter(
+                    lambda v, cur_p=p: not session_tree.exists(cur_p + [v]),
+                    vlst,
+                )
+            )
+            if vals:
+                value_paths.append((vals, p))
+
+    return value_paths
+
+
+def dependent_value_paths_of_kind(
+    kind: str,
+    reference_tree: ReferenceTree,
+    session_tree: ConfigTree,
+):
+    dependent_data = reference_tree.get_rdeps_of_kind_data(kind)
+
+    dependent_value_paths = {}
+    for p, a in dependent_data:
+        path_vals = subtree_values_of_path(session_tree, p, reference_tree)
+        path_vals = [t for t in path_vals if t != ([], [])]
+        if path_vals:
+            lst = dependent_value_paths.setdefault(a, [])
+            lst.extend(path_vals)
+
+    return dependent_value_paths
-- 
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