miscs

copienator/json_io.py

@@ -19,9 +19,40 @@ class JsonLockTimeout(TimeoutError):
     pass
 
 
-def read_json(path: str | Path, *, default: T | object = _MISSING) -> T:
+def read_json(
+    path: str | Path, *, default: T | object = _MISSING,
+    repair_trailing_commas: bool = False,
+) -> T:
     target = Path(path)
     try:
+        if repair_trailing_commas and target.name != "refaire.json":
+            original = text = target.read_text(encoding="utf-8")
+            while True:
+                try:
+                    value = json.loads(text)
+                except json.JSONDecodeError as error:
+                    # Only remove a comma immediately before a closing
+                    # delimiter reported by the parser, never inside strings.
+                    position = error.pos
+                    # Python 3.14 points at the comma; older versions point
+                    # at the closing bracket or brace.
+                    if error.msg.startswith("Illegal trailing comma"):
+                        position += 1
+                        while position < len(text) and text[position] in " \t\r\n":
+                            position += 1
+                    before = text[:position].rstrip()
+                    if (position >= len(text) or text[position] not in "]}"
+                            or not before.endswith(",")
+                            or not before[:-1].rstrip()
+                            or before[:-1].rstrip()[-1] in "[{:,"):
+                        raise
+                    comma = len(before) - 1
+                    text = text[:comma] + text[comma + 1:]
+                    continue
+                break
+            if text != original:
+                atomic_write_text(target, text)
+            return cast(T, value)
         with target.open("r", encoding="utf-8") as stream:
             if target.name == "refaire.json":
                 # This user-edited selection supports whole-line // comments.