From 9cbb64cf8a850dafebf68abb16a9cb9b12db247c Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Sat, 25 May 2024 07:25:27 -0700
Subject: [PATCH 1/2] gh-117865: Defer import of re in ast

This is used only by ast.get_source_segment(), so it seems sensible to avoid importing it.
---
 Lib/ast.py                                                | 8 ++++++--
 .../2024-05-25-07-25-07.gh-issue-117865.1A0Xpi.rst        | 2 ++
 2 files changed, 8 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-05-25-07-25-07.gh-issue-117865.1A0Xpi.rst

diff --git a/Lib/ast.py b/Lib/ast.py
index 031bab43df7579..8ac1860a5448c6 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -25,7 +25,6 @@
     :license: Python License.
 """
 import sys
-import re
 from _ast import *
 from contextlib import contextmanager, nullcontext
 from enum import IntEnum, auto, _simple_enum
@@ -325,12 +324,17 @@ def get_docstring(node, clean=True):
     return text
 
 
-_line_pattern = re.compile(r"(.*?(?:\r\n|\n|\r|$))")
+_line_pattern = None
 def _splitlines_no_ff(source, maxlines=None):
     """Split a string into lines ignoring form feed and other chars.
 
     This mimics how the Python parser splits source code.
     """
+    global _line_pattern
+    if _line_pattern is None:
+        import re
+        _line_pattern = re.compile(r"(.*?(?:\r\n|\n|\r|$))")
+
     lines = []
     for lineno, match in enumerate(_line_pattern.finditer(source), 1):
         if maxlines is not None and lineno > maxlines:
diff --git a/Misc/NEWS.d/next/Library/2024-05-25-07-25-07.gh-issue-117865.1A0Xpi.rst b/Misc/NEWS.d/next/Library/2024-05-25-07-25-07.gh-issue-117865.1A0Xpi.rst
new file mode 100644
index 00000000000000..48cd390d1bb128
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-05-25-07-25-07.gh-issue-117865.1A0Xpi.rst
@@ -0,0 +1,2 @@
+Improve the import time of the :mod:`ast` module by deferring the import of
+:mod:`re`. Patch by Jelle Zijlstra.

From 967f7d921322c0bca270517673e711de32b8fdc3 Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Sun, 26 May 2024 10:28:48 -0700
Subject: [PATCH 2/2] Update Lib/ast.py

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
---
 Lib/ast.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Lib/ast.py b/Lib/ast.py
index 8ac1860a5448c6..ce92cf79739312 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -332,6 +332,7 @@ def _splitlines_no_ff(source, maxlines=None):
     """
     global _line_pattern
     if _line_pattern is None:
+        # lazily computed to speedup import time of `ast`
         import re
         _line_pattern = re.compile(r"(.*?(?:\r\n|\n|\r|$))")