Issues/53 (#148)

* Test to reproduce the issue

* Fix and additional test cases

adapt/tools/text/trie.py

@@ -121,7 +121,9 @@ def insert(self, iterable, index=0, data=None, weight=1.0):
             self.children[iterable[index]].insert(iterable, index + 1, data)
 
     def is_prefix(self, iterable, index=0):
-        if iterable[index] in self.children:
+        if index == len(iterable):
+            return True
+        elif iterable[index] in self.children:
             return self.children[iterable[index]].is_prefix(iterable, index + 1)
         else:
             return False

test/TrieTest.py

@@ -179,5 +179,16 @@ def match_func(data):
         assert "Gonzo" in muppet_names
         assert "Rowlf" in muppet_names
 
+    def test_is_prefix(self):
+        trie = Trie()
+        trie.insert("play", "PlayVerb")
+        trie.insert("the big bang theory", "Television Show")
+        trie.insert("the big", "Not a Thing")
+        trie.insert("barenaked ladies", "Radio Station")
+
+        assert trie.root.is_prefix("the")
+        assert trie.root.is_prefix("play")
+        assert not trie.root.is_prefix("Kermit")
+
     def tearDown(self):
         pass