Adds warning when converting graphs to MultiDiGraph, and only convert…

…s when necessary (#53)

grandcypher/__init__.py

@@ -11,13 +11,20 @@
 from collections import OrderedDict
 import random
 import string
+import logging
 from functools import lru_cache
 import networkx as nx
 
 import grandiso
 
 from lark import Lark, Transformer, v_args, Token, Tree
 
+logging.basicConfig(
+    level=logging.INFO,
+    format="%(asctime)s - %(name)s - %(levelname)s - %(message)s"
+)
+logger = logging.getLogger(__name__)
+
 
 _OPERATORS = {
     "=": lambda x, y: x == y,
@@ -162,7 +169,7 @@
     start="start",
 )
 
-__version__ = "0.10.0"
+__version__ = "0.10.1"
 
 
 _ALPHABET = string.ascii_lowercase + string.digits
@@ -390,7 +397,10 @@ def _data_path_to_entity_name_attribute(data_path):
 
 class _GrandCypherTransformer(Transformer):
     def __init__(self, target_graph: nx.Graph, limit=None):
-        self._target_graph = nx.MultiDiGraph(target_graph)
+        self._target_graph = target_graph
+        if not isinstance(self._target_graph, nx.MultiDiGraph):
+            self._target_graph = nx.MultiDiGraph(target_graph)
+            logger.warning("Converting graph to MultiDiGraph")
         self._entity2alias = dict()
         self._alias2entity = dict()
         self._paths = []

grandcypher/test_queries.py

@@ -1,5 +1,6 @@
 import networkx as nx
 import pytest
+import logging
 
 from . import _GrandCypherGrammar, _GrandCypherTransformer, GrandCypher
 
@@ -58,6 +59,20 @@ def test_simple_structural_match_returns_node_attributes(self, graph_type):
         assert len(returns["A.dinnertime"]) == 2
 
 
+    @pytest.mark.parametrize("graph_type", ACCEPTED_GRAPH_TYPES)
+    def test_warning_for_non_multidigraph(self, graph_type, caplog):
+        host = graph_type()
+
+        with caplog.at_level(logging.WARNING):
+            gct = GrandCypher(host)
+
+        if isinstance(host, nx.MultiDiGraph):
+            assert len(caplog.records) == 0
+        elif isinstance(host, nx.DiGraph):
+            assert len(caplog.records) == 1
+            assert caplog.records[0].levelname == "WARNING"
+
+
 class TestSimpleAPI:
     @pytest.mark.parametrize("graph_type", ACCEPTED_GRAPH_TYPES)
     def test_simple_api(self, graph_type):