Cache config file contents

wpiformat/wpiformat/__init__.py

@@ -90,6 +90,9 @@ def proc_pipeline(name):
     try:
         config_file = Config(os.path.dirname(name), ".wpiformat")
     except OSError:
+        print(
+            "Warning: '.wpiformat' file not found. Looking for deprecated '.styleguide' file."
+        )
         # TODO: Remove handling for deprecated .styleguide file
         config_file = Config(os.path.dirname(name), ".styleguide")
         print("Warning: found deprecated '.styleguide' file. Rename to '.wpiformat'.")

wpiformat/wpiformat/config.py

@@ -2,10 +2,12 @@
 
 import os
 import regex
-import sys
 
 
 class Config:
+    # Dict from filepath to file contents
+    config_cache: dict[str, list[str]] = {}
+
     def __init__(self, directory, file_name):
         """Constructor for Config object.
 
@@ -34,22 +36,23 @@ def read_file(directory, file_name):
         Returns tuple of file name and list containing file contents or triggers
         program exit.
         """
-        file_found = False
-        while not file_found:
+        while True:
+            filepath = os.path.join(directory, file_name)
             try:
-                with open(directory + os.sep + file_name, "r") as file_contents:
-                    file_found = True
-                    return (
-                        os.path.join(directory, file_name),
-                        file_contents.read().splitlines(),
-                    )
+                # If filepath in config cache, return cached version instead
+                if filepath in Config.config_cache:
+                    return filepath, Config.config_cache[filepath]
+
+                with open(filepath, "r") as file_contents:
+                    contents = file_contents.read().splitlines()
+                    Config.config_cache[filepath] = contents
+                    return filepath, contents
             except OSError as e:
                 # .git files are ignored, which are created within submodules
                 if os.path.isdir(directory + os.sep + ".git"):
-                    print(
-                        f"Error: config file '{file_name}' not found in '{directory}'"
-                    )
-                    raise e
+                    raise OSError(
+                        f"config file '{file_name}' not found in '{directory}'"
+                    ) from e
                 directory = os.path.dirname(directory)
 
     def group(self, group_name):