Implement full remove()

Remove unnecessary trie paths and free unused maps.

Parallel to Matcher, raise KeyError when attempting to remove a match ID
that has not been added.

spacy/matcher/phrasematcher.pyx

@@ -84,12 +84,13 @@ cdef class PhraseMatcher:
         return (unpickle_matcher, data, None, None)
 
     def remove(self, key):
-        """Remove a match-rule from the matcher by match ID.
+        """Remove a rule from the matcher by match ID. A KeyError is raised if
+        the key does not exist.
 
         key (unicode): The match ID.
         """
         if key not in self._keywords:
-            return
+            raise KeyError(key)
         cdef MapStruct* current_node
         cdef MapStruct* terminal_map
         cdef MapStruct* node_pointer
@@ -97,13 +98,16 @@ cdef class PhraseMatcher:
         cdef key_t terminal_key
         cdef void* value
         cdef int c_i = 0
+        cdef vector[MapStruct*] path_nodes
+        cdef vector[key_t] path_keys
+        cdef key_t key_to_remove
         for keyword in self._keywords[key]:
             current_node = self.c_map
-            token_trie_list = []
             for token in keyword:
                 result = map_get(current_node, token)
                 if result:
-                    token_trie_list.append((token, <uintptr_t>current_node))
+                    path_nodes.push_back(current_node)
+                    path_keys.push_back(token)
                     current_node = <MapStruct*>result
                 else:
                     # if token is not found, break out of the loop
@@ -113,27 +117,25 @@ cdef class PhraseMatcher:
             # keywords with them
             result = map_get(current_node, self._terminal_hash)
             if current_node != NULL and result:
-                # if this is the only remaining key, remove unnecessary paths
                 terminal_map = <MapStruct*>result
                 terminal_keys = []
                 c_i = 0
                 while map_iter(terminal_map, &c_i, &terminal_key, &value):
                     terminal_keys.append(self.vocab.strings[terminal_key])
-                # TODO: not working, fix remove for unused paths/maps
-                if False and terminal_keys == [key]:
-                    # we found a complete match for input keyword
-                    token_trie_list.append((self.vocab.strings[key], <uintptr_t>terminal_map))
-                    token_trie_list.reverse()
-                    for key_to_remove, py_node_pointer in token_trie_list:
-                        node_pointer = <MapStruct*>py_node_pointer
+                # if this is the only remaining key, remove unnecessary paths
+                if terminal_keys == [key]:
+                    while not path_nodes.empty():
+                        node_pointer = path_nodes.back()
+                        path_nodes.pop_back()
+                        key_to_remove = path_keys.back()
+                        path_keys.pop_back()
                         result = map_get(node_pointer, key_to_remove)
                         if node_pointer.filled == 1:
                             map_clear(node_pointer, key_to_remove)
                             self.mem.free(result)
-                            pass
                         else:
                             # more than one key means more than 1 path,
-                            # delete not required path and keep the other
+                            # delete not required path and keep the others
                             map_clear(node_pointer, key_to_remove)
                             self.mem.free(result)
                             break

spacy/tests/matcher/test_phrase_matcher.py

@@ -84,6 +84,7 @@ def test_phrase_matcher_remove(en_vocab):
     assert "TEST2" not in matcher
     assert "TEST3" not in matcher
     assert len(matcher(doc)) == 0
+    with pytest.raises(KeyError):
         matcher.remove("TEST3")
     assert "TEST1" not in matcher
     assert "TEST2" not in matcher