model._string_constraints: escape unicode characters in errors

Escape unicode characters in regular expression patterns and string
values for clean error messages.

basyx/aas/model/_string_constraints.py

@@ -29,6 +29,13 @@
 AASD130_RE = re.compile("[\x09\x0A\x0D\x20-\uD7FF\uE000-\uFFFD\U00010000-\U0010FFFF]*")
 
 
+def _unicode_escape(value: str) -> str:
+ """
+ Escapes unicode characters such as \uD7FF, that may be used in regular expressions, for better error messages.
+ """
+ return value.encode("unicode_escape").decode("utf-8")
+
+
 # Functions to verify the constraints for a given value.
 def check(value: str, type_name: str, min_length: int = 0, max_length: Optional[int] = None,
  pattern: Optional[re.Pattern] = None) -> None:
@@ -37,14 +44,16 @@ def check(value: str, type_name: str, min_length: int = 0, max_length: Optional[
  if max_length is not None and len(value) > max_length:
  raise ValueError(f"{type_name} has a maximum length of {max_length}! (length: {len(value)})")
  if pattern is not None and not pattern.fullmatch(value):
- raise ValueError(f"{type_name} must match the pattern '{pattern.pattern}'! (value: '{value}')")
+ raise ValueError(f"{type_name} must match the pattern '{_unicode_escape(pattern.pattern)}'! "
+ f"(value: '{_unicode_escape(value)}')")
  # Constraint AASd-130
  if not AASD130_RE.fullmatch(value):
  # It's easier to implement this as a ValueError, because otherwise AASConstraintViolation would need to be
  # imported from `base` and the ConstrainedLangStringSet would need to except AASConstraintViolation errors
  # as well, while only re-raising ValueErrors. Thus, even if an AASConstraintViolation would be raised here,
  # in case of a ConstrainedLangStringSet it would be re-raised as a ValueError anyway.
- raise ValueError(f"Every string must match the pattern '{AASD130_RE.pattern}'! (value: '{value}')")
+ raise ValueError(f"Every string must match the pattern '{_unicode_escape(AASD130_RE.pattern)}'! "
+ f"(value: '{_unicode_escape(value)}')")
 
 
 def check_content_type(value: str, type_name: str = "ContentType") -> None: