From: d.grigonis <dgrigonis@users.noreply.github.com>
Date: Sat, 11 May 2024 20:55:23 +0000 (+0300)
Subject: gh-118932: ChainMap.__contains__ performance improvement (gh-118946)
X-Git-Tag: v3.14.0a1~1923
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=cd4cfa6ed2fd5f866c7be339f1d3cf56aa4d2bad;p=thirdparty%2FPython%2Fcpython.git

gh-118932: ChainMap.__contains__ performance improvement (gh-118946)
---

diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index d06d84cbdfcc..a17100e6c02a 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -1016,7 +1016,7 @@ class ChainMap(_collections_abc.MutableMapping):
         return self.__missing__(key)            # support subclasses that define __missing__
 
     def get(self, key, default=None):
-        return self[key] if key in self else default
+        return self[key] if key in self else default    # needs to make use of __contains__
 
     def __len__(self):
         return len(set().union(*self.maps))     # reuses stored hash values if possible
@@ -1028,7 +1028,10 @@ class ChainMap(_collections_abc.MutableMapping):
         return iter(d)
 
     def __contains__(self, key):
-        return any(key in m for m in self.maps)
+        for mapping in self.maps:
+            if key in mapping:
+                return True
+        return False
 
     def __bool__(self):
         return any(self.maps)