add performance hack to improve tokenize speed

in profiles, this attributed somewhere between 4% and 14% of pycodestyle's execution time

1 files changed, 7 insertions, 0 deletions

diff --git a/pycodestyle.py b/pycodestyle.py
index 7f00739..4055716 100755
--- a/pycodestyle.py
+++ b/pycodestyle.py
@@ -78,6 +78,13 @@ try:
 except ImportError:
     from ConfigParser import RawConfigParser
 
+# this is a performance hack.  see https://bugs.python.org/issue43014
+if (
+        sys.version_info < (3, 10) and
+        callable(getattr(tokenize, '_compile', None))
+):  # pragma: no cover (<py310)
+    tokenize._compile = lru_cache()(tokenize._compile)  # type: ignore
+
 __version__ = '2.7.0'
 
 DEFAULT_EXCLUDE = '.svn,CVS,.bzr,.hg,.git,__pycache__,.tox'