Third profile-guided pass (#139, docs/benchmarks.md pass 27), targeting
scanContentMarkup(), which inlines the start-tag/attribute/namespace scanners
and carries ~46% of parse time.
scanAttributeValue's opening and closing quote checks ran on the Character
path (peek + advance, buffering the quote as a Character only to compare and
discard it) on every attribute value in the document; both now check the raw
byte first, reaching the byte fast path with no Character buffering, with the
Character path kept as the off-fast-path fallback for streaming sources. The
quote bytes are ASCII and non-CR/LF, so the raw byte and the normalized
stream agree, the same reasoning peekByte's other callers already rely on.
NamespaceContext.checkExpandedNames allocated a Set's native storage and
built a concatenated URI+local key string per element even when at most one
attribute carries a namespace URI, where no duplicate is possible (the
default namespace never applies to attributes, and xmlns declarations carry
no URI). Counting URI-bearing attributes first, with no allocation, and
returning early below two skips all of it on the overwhelming majority of
elements; for xml:* attributes specifically the key exceeded the small-string
limit, so this also removes a real per-element heap allocation.
EntityDecoder.decode/decodeLenient guarded with raw.contains("&"), a
grapheme-by-grapheme walk to find one ASCII byte, once per ampersand-bearing
text node or attribute value; raw.utf8.contains(0x26) finds the same byte
without decoding graphemes, the same shape as checkNameShape's colon check.
The quote-handling extraction into two helpers also resolves the cyclomatic
complexity the inline version tripped. Six new regression tests pin the
quote edge cases (empty value, single-quoted, a quote kind nested inside the
other, unterminated at end of input) plus byte/Character-path agreement for
each in the parser path differential.
Verified: full local suite (1858 tests) and full W3C XSTS suite (14383
groups) pass unchanged. Parse ~6.00x -> ~4.75x versus libxml2 at the
20000-item corpus, best of 5.
Mihaela Mihaljevic
fe0400c3df