optimize sparql.Bindings

rdflib/plugins/sparql/sparql.py

@@ -52,12 +52,12 @@ def __init__(self, outer=None, d=[]):
         self.outer = outer
 
     def __getitem__(self, key):
-        try:
+        if key in self._d:
             return self._d[key]
-        except KeyError:
-            if not self.outer:
-                raise
-            return self.outer[key]
+
+        if not self.outer:
+            raise KeyError()
+        return self.outer[key]
 
     def __contains__(self, key):
         try:
@@ -72,17 +72,18 @@ def __setitem__(self, key, value):
     def __delitem__(self, key):
         raise Exception("DelItem is not implemented!")
 
-    def __len__(self):
+    def __len__(self) -> int:
         i = 0
-        for x in self:
-            i += 1
+        d = self
+        while d is not None:
+            i += len(d._d)
+            d = d.outer
         return i
 
     def __iter__(self):
         d = self
         while d is not None:
-            for i in dict.__iter__(d._d):
-                yield i
+            yield from d._d
             d = d.outer
 
     def __str__(self):

test/test_sparql.py

@@ -1,3 +1,4 @@
+from rdflib.plugins.sparql import sparql
 from rdflib import Graph, URIRef, Literal, BNode
 from rdflib.plugins.sparql import prepareQuery
 from rdflib.compare import isomorphic
@@ -112,6 +113,24 @@ def test_sparql_update_with_bnode_serialize_parse():
     assert not raised
 
 
+def test_bindings():
+    layer_0 = sparql.Bindings(d={"v": 1, "bar": 2})
+    layer_1 = sparql.Bindings(outer=layer_0, d={"v": 3})
+
+
+    assert layer_0["v"] == 1
+    assert layer_1["v"] == 3
+    assert layer_1["bar"] == 2
+
+    assert "foo" not in layer_0
+    assert "v" in layer_0
+    assert "bar" in layer_1
+
+    # XXX This might not be intendet behaviour
+    #     but is kept for compatibility for now.
+    assert len(layer_1) == 3
+
+
 if __name__ == "__main__":
     import nose