From a48d635633ab6aa1cdd3ebb8fa2bb000ab0a0e50 Mon Sep 17 00:00:00 2001
From: Jimmy Lai <jimmylai@fb.com>
Date: Wed, 27 May 2020 16:46:48 -0700
Subject: [PATCH] [scope] remove iter call to be efficient

---
 libcst/metadata/scope_provider.py | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/libcst/metadata/scope_provider.py b/libcst/metadata/scope_provider.py
index 56c1b252b..db25d5e2e 100644
--- a/libcst/metadata/scope_provider.py
+++ b/libcst/metadata/scope_provider.py
@@ -14,7 +14,6 @@
 from typing import (
     Collection,
     Dict,
-    Iterable,
     Iterator,
     List,
     Mapping,
@@ -607,22 +606,23 @@ class ComprehensionScope(LocalScope):
 # each string has the corresponding CSTNode attached to it
 def _gen_dotted_names(
     node: Union[cst.Attribute, cst.Name]
-) -> Iterable[Tuple[str, Union[cst.Attribute, cst.Name]]]:
+) -> Iterator[Tuple[str, Union[cst.Attribute, cst.Name]]]:
     if isinstance(node, cst.Name):
-        yield (node.value, node)
+        yield node.value, node
     else:
         value = node.value
         if not isinstance(value, (cst.Attribute, cst.Name)):
             # this is not an import
             return
-        name_values = iter(_gen_dotted_names(value))
-        next_pair = next(name_values, None)
-        if next_pair is None:
+        name_values = _gen_dotted_names(value)
+        try:
+            next_name, next_node = next(name_values)
+        except StopIteration:
             return
-        (next_name, next_node) = next_pair
-        yield (f"{next_name}.{node.attr.value}", node)
-        yield (next_name, next_node)
-        yield from name_values
+        else:
+            yield f"{next_name}.{node.attr.value}", node
+            yield next_name, next_node
+            yield from name_values
 
 
 class ScopeVisitor(cst.CSTVisitor):