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perf(parser): optimize comment annotation parsing #14397

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merged 1 commit into from
Oct 7, 2025
Merged

perf(parser): optimize comment annotation parsing #14397

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136 changes: 91 additions & 45 deletions crates/oxc_parser/src/lexer/trivia_builder.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -146,66 +146,112 @@ impl TriviaBuilder {

/// Parse Notation
fn parse_annotation(&mut self, comment: &mut Comment, source_text: &str) {
let mut s = comment.content_span().source_text(source_text);
let s = comment.content_span().source_text(source_text);
let bytes = s.as_bytes();

if s.starts_with('!') {
comment.content = CommentContent::Legal;
// Early exit for empty comments
if bytes.is_empty() {
return;
}

if comment.is_block() && s.starts_with('*') {
// Ignore webpack comment `/*****/`
if !s.bytes().all(|c| c == b'*') {
if contains_license_or_preserve_comment(s) {
comment.content = CommentContent::JsdocLegal;
} else {
comment.content = CommentContent::Jsdoc;
// Check first byte for quick routing
match bytes[0] {
b'!' => {
comment.content = CommentContent::Legal;
return;
}
b'*' if comment.is_block() => {
// Ignore webpack comment `/*****/`
if !bytes.iter().all(|&c| c == b'*') {
if contains_license_or_preserve_comment(s) {
comment.content = CommentContent::JsdocLegal;
} else {
comment.content = CommentContent::Jsdoc;
}
}
return;
}
_ => {}
}

s = s.trim_ascii_start();
// Skip leading whitespace without allocation
let mut start = 0;
while start < bytes.len() && bytes[start].is_ascii_whitespace() {
start += 1;
}

if let Some(ss) = s.strip_prefix('@') {
if ss.starts_with("vite") {
comment.content = CommentContent::Vite;
return;
if start >= bytes.len() {
return;
}

// Fast path: check first non-whitespace byte
match bytes[start] {
b'@' => {
start += 1;
if start >= bytes.len() {
return;
}

// Check for @vite, @license, @preserve
if bytes[start..].starts_with(b"vite") {
comment.content = CommentContent::Vite;
return;
}
if bytes[start..].starts_with(b"license") || bytes[start..].starts_with(b"preserve")
{
comment.content = CommentContent::Legal;
return;
}

// Continue to check for __PURE__ or __NO_SIDE_EFFECTS__ after @
}
if ss.starts_with("license") || ss.starts_with("preserve") {
comment.content = CommentContent::Legal;
return;
b'#' => {
start += 1;
// Continue to check for __PURE__ or __NO_SIDE_EFFECTS__ after #
}
s = ss;
} else if let Some(ss) = s.strip_prefix('#') {
s = ss;
} else if s
.strip_prefix("webpack")
.and_then(|s| s.bytes().next())
.is_some_and(|b| b.is_ascii_uppercase())
{
comment.content = CommentContent::Webpack;
return;
} else if ["v8 ignore", "c8 ignore", "node:coverage", "istanbul ignore"]
.iter()
.any(|ss| s.starts_with(ss))
{
comment.content = CommentContent::CoverageIgnore;
} else {
if contains_license_or_preserve_comment(s) {
comment.content = CommentContent::Legal;
b'w' => {
// Check for webpack comments
if bytes[start..].starts_with(b"webpack")
&& start + 7 < bytes.len()
&& bytes[start + 7].is_ascii_uppercase()
{
comment.content = CommentContent::Webpack;
return;
}
// Fall through to check for coverage ignore patterns
}
b'v' | b'c' | b'n' | b'i' => {
// Check coverage ignore patterns: "v8 ignore", "c8 ignore", "node:coverage", "istanbul ignore"
let rest = &bytes[start..];
if rest.starts_with(b"v8 ignore")
|| rest.starts_with(b"c8 ignore")
|| rest.starts_with(b"node:coverage")
|| rest.starts_with(b"istanbul ignore")
{
comment.content = CommentContent::CoverageIgnore;
return;
}
// Fall through to check license/preserve
}
_ => {
// Check for license/preserve comments in remaining cases
if contains_license_or_preserve_comment(s) {
comment.content = CommentContent::Legal;
}
return;
}
return;
}

let Some(s) = s.strip_prefix("__") else { return };
if s.starts_with("PURE__") {
comment.content = CommentContent::Pure;
self.has_pure_comment = true;
}
if s.starts_with("NO_SIDE_EFFECTS__") {
comment.content = CommentContent::NoSideEffects;
self.has_no_side_effects_comment = true;
// Check for __PURE__ or __NO_SIDE_EFFECTS__ after @ or #
if start < bytes.len() && bytes[start..].starts_with(b"__") {
let rest = &bytes[start + 2..];
if rest.starts_with(b"PURE__") {
comment.content = CommentContent::Pure;
self.has_pure_comment = true;
} else if rest.starts_with(b"NO_SIDE_EFFECTS__") {
comment.content = CommentContent::NoSideEffects;
self.has_no_side_effects_comment = true;
}
}
}
}
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