Precompile regex patterns

Author: domdfcoding

flake8_strftime/__init__.py

@@ -49,6 +49,9 @@
 STRFTIME001 = "STRFTIME001 Linux-specific strftime code used."
 STRFTIME002 = "STRFTIME002 Windows-specific strftime code used."
 
+_linux_re = re.compile(r"%-[dmHIMSj]")
+_win_re = re.compile(r"%#[dmHIMSj]")
+
 
 class Visitor(flake8_helper.Visitor):  # noqa: D101
 
@@ -90,7 +93,7 @@ def _check_linux(self, node: Union[ast.Str, ast.Constant]):
 		:param node: The node being visited
 		"""
 
-		for match in re.finditer(r"%-[dmHIMSj]", node.s):
+		for match in _linux_re.finditer(node.s):
 			self.errors.append((
 					node.lineno,
 					node.col_offset + match.span()[0],
@@ -104,7 +107,7 @@ def _check_windows(self, node: Union[ast.Str, ast.Constant]):
 		:param node: The node being visited
 		"""
 
-		for match in re.finditer(r"%#[dmHIMSj]", node.s):
+		for match in _win_re.finditer(node.s):
 			self.errors.append((
 					node.lineno,
 					node.col_offset + match.span()[0],