From b84c8393fe8ed132d7d87801a6509162bf9a3152 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Wed, 3 Jul 2024 15:30:50 -0700
Subject: [PATCH 1/2] PERF: Don't create a CategoricalIndex._engine in
 __contains__ if categories are RangeIndex

---
 pandas/core/indexes/category.py                   | 7 +++++--
 pandas/tests/indexes/categorical/test_category.py | 7 +++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/pandas/core/indexes/category.py b/pandas/core/indexes/category.py
index 3b04d95cb7cbd..947f52529190e 100644
--- a/pandas/core/indexes/category.py
+++ b/pandas/core/indexes/category.py
@@ -377,8 +377,11 @@ def __contains__(self, key: Any) -> bool:
         # if key is a NaN, check if any NaN is in self.
         if is_valid_na_for_dtype(key, self.categories.dtype):
             return self.hasnans
-
-        return contains(self, key, container=self._engine)
+        if self.categories._typ == "rangeindex":
+            container = self.categories
+        else:
+            container = self._engine
+        return contains(self, key, container=container)
 
     def reindex(
         self, target, method=None, level=None, limit: int | None = None, tolerance=None
diff --git a/pandas/tests/indexes/categorical/test_category.py b/pandas/tests/indexes/categorical/test_category.py
index 03a298a13dc2b..f4967e1f4cc10 100644
--- a/pandas/tests/indexes/categorical/test_category.py
+++ b/pandas/tests/indexes/categorical/test_category.py
@@ -392,3 +392,10 @@ def test_remove_maintains_order(self):
                 ["a", "b", np.nan, "d", "d", "a"], categories=list("dba"), ordered=True
             ),
         )
+
+
+def test_contains_rangeindex_categories_no_engine():
+    ci = CategoricalIndex(range(3))
+    assert 2 in ci
+    assert 5 not in ci
+    assert "_engine" not in ci._cache

From 6a622f4c522e7454e92b2b2d52a4c72f0bd66734 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Wed, 3 Jul 2024 17:33:59 -0700
Subject: [PATCH 2/2] Fix typing

---
 pandas/core/indexes/category.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/pandas/core/indexes/category.py b/pandas/core/indexes/category.py
index 947f52529190e..312219eb7b91a 100644
--- a/pandas/core/indexes/category.py
+++ b/pandas/core/indexes/category.py
@@ -378,7 +378,9 @@ def __contains__(self, key: Any) -> bool:
         if is_valid_na_for_dtype(key, self.categories.dtype):
             return self.hasnans
         if self.categories._typ == "rangeindex":
-            container = self.categories
+            container: Index | libindex.IndexEngine | libindex.ExtensionEngine = (
+                self.categories
+            )
         else:
             container = self._engine
         return contains(self, key, container=container)