bpo-38870: Remove dependency on contextlib to avoid performance regression on import (GH-17376)
https://bugs.python.org/issue38870
Automerge-Triggered-By: @pablogsal
diff --git a/Lib/ast.py b/Lib/ast.py
index 97914eb..77eb249 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -26,7 +26,6 @@
"""
import sys
from _ast import *
-from contextlib import contextmanager
def parse(source, filename='<unknown>', mode='exec', *,
@@ -597,15 +596,22 @@
self._buffer.clear()
return value
- @contextmanager
- def block(self):
+ class _Block:
"""A context manager for preparing the source for blocks. It adds
the character':', increases the indentation on enter and decreases
the indentation on exit."""
- self.write(":")
- self._indent += 1
- yield
- self._indent -= 1
+ def __init__(self, unparser):
+ self.unparser = unparser
+
+ def __enter__(self):
+ self.unparser.write(":")
+ self.unparser._indent += 1
+
+ def __exit__(self, exc_type, exc_value, traceback):
+ self.unparser._indent -= 1
+
+ def block(self):
+ return self._Block(self)
def traverse(self, node):
if isinstance(node, list):