FIX: make the xml formatter try several times in one run to avoid needing to re-run it again.

Author: ZLLentz

pre_commit_hooks/xml_format.py

@@ -1,16 +1,47 @@
 #!C:/miniconda/envs/plc-pre-commit/python.exe
 
 import argparse
+
 from lxml import etree
 
 TAB_WIDTH = 2
+RETRIES = 5
 
 
-def fix_file(filename, tab_width=TAB_WIDTH):
+def fix_file(
+    filename: str,
+    tab_width: int = TAB_WIDTH,
+    retries: int = RETRIES,
+) -> None:
+    """
+    Read a file, fix it, write the fix back to the file handle
+    """
     # lxml throws encoding errors unless we work in binary mode
-    with open(filename, 'rb') as fd:
+    with open(filename, "rb") as fd:
         original_xml = fd.read()
+    iter_xml = original_xml
+
+    for _ in range(retries):
+        new_xml = xml_once(
+            original_xml=iter_xml,
+            tab_width=tab_width,
+        )
+        if new_xml == iter_xml:
+            break
+        iter_xml = new_xml
+
+    if new_xml != original_xml:
+        print(f"Fixing {filename}")
+        with open(filename, "wb") as fd:
+            fd.write(new_xml)
 
+
+def xml_once(original_xml: str, tab_width: int) -> str:
+    """
+    One iteration of the xml formatting.
+
+    This may need to run several times due to inconsistencies in lxml.
+    """
     # lxml is the easiest cross-platform way to do this using pre-commit
     # xmllint is cross-platform but pre-commit does not help us set it up
     xml_parser = etree.XMLParser(remove_blank_text=True)
@@ -25,18 +56,15 @@ def fix_file(filename, tab_width=TAB_WIDTH):
     # lxml always outputs with unix line endings (LF)
     if b'\r\n' in original_xml:
         new_xml = new_xml.replace(b'\n', b'\r\n')
-
-    if new_xml != original_xml:
-        print(f'Fixing {filename}')
-        with open(filename, 'wb') as fd:
-            fd.write(new_xml)
+    return new_xml
 
 
 def main(args=None):
     if args is None:
         parser = argparse.ArgumentParser()
-        parser.add_argument('filenames', nargs='*')
-        parser.add_argument('--tab-width', type=int, default=TAB_WIDTH)
+        parser.add_argument("filenames", nargs="*")
+        parser.add_argument("--tab-width", type=int, default=TAB_WIDTH)
+        parser.add_argument("--retries", type=int, default=RETRIES)
         args = parser.parse_args()
     try:
         for filename in args.filenames: