KXML

Decodes the UTF-8 character at byte position pos in s and returns it with its byte length. String#char_at indexes by character, which is wrong for a byte-driven scanner. Reads go through unsafe_byte_at with an explicit length guard (cheaper than checked byte_at on the hot path), and malformed sequences raise KXML::Error instead of letting the raw codepoint escape as a foreign exception.

Streaming variants write the escaped form straight into io, so serialization never materializes an intermediate escaped string.

Parses source as an XML 1.0 document. Raises KXML::Error on any well-formedness violation.