From c699ee6bbdc17b837504228ac52f4dc7399d11e0 Mon Sep 17 00:00:00 2001
From: "Jeroen F.J. Laros" <jlaros@fixedpoint.nl>
Date: Sun, 30 Apr 2017 22:11:16 +0200
Subject: [PATCH] Fixed bug in Levenshtein function.

---
 dict_trie/dict_trie.py | 16 +++++++++-------
 tests/test_trie.py     |  3 +++
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/dict_trie/dict_trie.py b/dict_trie/dict_trie.py
index 56c6315..1503d0b 100644
--- a/dict_trie/dict_trie.py
+++ b/dict_trie/dict_trie.py
@@ -136,19 +136,21 @@ def _levenshtein(path, node, word, distance):
     if not word:
         if '' in node:
             yield path
-        return
-
-    car, cdr = word[0], word[1:]
+        car, cdr = '', ''
+    else:
+        car, cdr = word[0], word[1:]
 
     # Deletion.
     for result in _levenshtein(path, node, cdr, distance - 1):
         yield result
 
     for char in node:
-        # Substitution and insertion.
-        for result in _levenshtein(
-                path + char, node[char], cdr, distance - int(char != car)):
-            yield result
+        # Substitution.
+        if car:
+            for result in _levenshtein(
+                    path + char, node[char], cdr, distance - int(char != car)):
+                yield result
+        # Insertion.
         for result in _levenshtein(
                 path + char, node[char], word, distance - 1):
             yield result
diff --git a/tests/test_trie.py b/tests/test_trie.py
index c25b36f..fef8ff7 100644
--- a/tests/test_trie.py
+++ b/tests/test_trie.py
@@ -116,5 +116,8 @@ class TestTrie(object):
     def test_levenshtein_1_del(self):
         assert self._trie.levenshtein('ac', 1) == 'abc'
 
+    def test_levenshtein_1_prefex(self):
+        assert self._trie.levenshtein('ab', 1) == 'abc'
+
     def test_levenshtein_1_ins(self):
         assert self._trie.levenshtein('abbc', 1) == 'abc'
-- 
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