From f51e06f4531c2080b8c8cc11db9fe986fb5397fa Mon Sep 17 00:00:00 2001
From: NIC619 <twedusuck@gmail.com>
Date: Sat, 9 Dec 2017 01:27:05 +0800
Subject: [PATCH] add kv pair override check

---
 trie_research/new_bintrie.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/trie_research/new_bintrie.py b/trie_research/new_bintrie.py
index a22e1a6..8abc7a1 100644
--- a/trie_research/new_bintrie.py
+++ b/trie_research/new_bintrie.py
@@ -92,6 +92,9 @@ def _update(db, node, keypath, val):
     L, R, nodetype = parse_node(db.get(node))
     # Node is a leaf node
     if nodetype == LEAF_TYPE:
+        # Keypath must match, there should be no remaining keypath
+        if keypath:
+            raise Exception("Existing kv pair is being effaced because it's key is the prefix of the new key")
         return hash_and_save(db, encode_leaf_node(val)) if val else b''
     # node is a key-value node
     elif nodetype == KV_TYPE: