the parser state. For deeply nested documents with many attributes, this may have performance implications. Future optimization could implement a more efficient lookahead mechanism that doesn't require full state copying.
isAttributeStart
Check if the current position starts an attribute.
An attribute has the form: [namespace ':'] identifier '=' literal Check if the current position starts an attribute (name=value or ns:name=value).
Performance_
Note
This function copies the entire lexer state for lookahead to avoid modifying