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refactor(parser): remove lexer lookahead in parsing TS statements #11253

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Merged
graphite-app merged 1 commit into from
May 24, 2025
Merged

refactor(parser): remove lexer lookahead in parsing TS statements #11253

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98 changes: 36 additions & 62 deletions crates/oxc_parser/src/ts/statement.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -124,7 +124,7 @@ impl<'a> ParserImpl<'a> {
let params = self.parse_ts_type_parameters();
self.expect(Kind::Eq);

let annotation = if self.at(Kind::Intrinsic) && !self.peek_at(Kind::Dot) {
let ty = if self.at(Kind::Intrinsic) && !self.lookahead(Self::is_next_token_dot) {
let span = self.start_span();
self.bump_any();
self.ast.ts_type_intrinsic_keyword(self.end_span(span))
Expand All @@ -141,13 +141,12 @@ impl<'a> ParserImpl<'a> {
diagnostics::modifier_cannot_be_used_here,
);

self.ast.declaration_ts_type_alias(
span,
id,
params,
annotation,
modifiers.contains_declare(),
)
self.ast.declaration_ts_type_alias(span, id, params, ty, modifiers.contains_declare())
}

fn is_next_token_dot(&mut self) -> bool {
self.bump_any();
self.at(Kind::Dot)
}

/* --------------------- Interface ------------------------ */
Expand Down Expand Up @@ -189,16 +188,8 @@ impl<'a> ParserImpl<'a> {
self.ast.alloc_ts_interface_body(self.end_span(span), body_list)
}

pub(crate) fn is_at_interface_declaration(&mut self) -> bool {
if !self.at(Kind::Interface) || self.peek_token().is_on_new_line() {
false
} else {
self.peek_token().kind().is_binding_identifier() || self.peek_at(Kind::LCurly)
}
}

pub(crate) fn parse_ts_type_signature(&mut self) -> TSSignature<'a> {
if self.is_at_ts_index_signature_member() {
if self.lookahead(Self::is_at_ts_index_signature_member) {
let span = self.start_span();
let modifiers = self.parse_modifiers(false, false, false);
let sig = self.parse_index_signature_declaration(span, &modifiers);
Expand All @@ -207,7 +198,7 @@ impl<'a> ParserImpl<'a> {

match self.cur_kind() {
Kind::LParen | Kind::LAngle => self.parse_ts_call_signature_member(),
Kind::New if self.peek_at(Kind::LParen) || self.peek_at(Kind::LAngle) => {
Kind::New if self.lookahead(Self::is_next_token_open_paren_or_angle_bracket) => {
self.parse_ts_constructor_signature_member()
}
Kind::Get if self.is_next_at_type_member_name() => {
Expand All @@ -220,28 +211,15 @@ impl<'a> ParserImpl<'a> {
}
}

/// Must be at `[ident:` or `<modifiers> [ident:`
pub(crate) fn is_at_ts_index_signature_member(&mut self) -> bool {
let mut offset = 0;
while self.is_nth_at_modifier(offset, false) {
offset += 1;
}

if !self.nth_at(offset, Kind::LBrack) {
return false;
}

if !self.nth_kind(offset + 1).is_identifier() {
return false;
}

self.nth_at(offset + 2, Kind::Colon)
fn is_next_token_open_paren_or_angle_bracket(&mut self) -> bool {
self.bump_any();
matches!(self.cur_kind(), Kind::LParen | Kind::LAngle)
}

pub(crate) fn is_nth_at_modifier(&mut self, n: u8, is_constructor_parameter: bool) -> bool {
let nth = self.nth(n);
if !(matches!(
nth.kind(),
/// Must be at `[ident:` or `<modifiers> [ident:`
fn is_at_ts_index_signature_member(&mut self) -> bool {
if matches!(
self.cur_kind(),
Kind::Public
| Kind::Protected
| Kind::Private
Expand All @@ -251,25 +229,22 @@ impl<'a> ParserImpl<'a> {
| Kind::Declare
| Kind::Override
| Kind::Export
)) {
) {
self.bump_any();
}

if !self.at(Kind::LBrack) {
return false;
}

let next = self.nth(n + 1);
self.bump_any();

if next.is_on_new_line() {
false
} else {
let followed_by_any_member =
matches!(next.kind(), Kind::PrivateIdentifier | Kind::LBrack)
|| next.kind().is_literal_property_name();
let followed_by_class_member = !is_constructor_parameter && next.kind() == Kind::Star;
// allow `...` for error recovery
let followed_by_parameter = is_constructor_parameter
&& matches!(next.kind(), Kind::LCurly | Kind::LBrack | Kind::Dot3);

followed_by_any_member || followed_by_class_member || followed_by_parameter
if !self.cur_kind().is_identifier() {
return false;
}

self.bump_any();
self.at(Kind::Colon)
}

/* ----------------------- Namespace & Module ----------------------- */
Expand Down Expand Up @@ -370,9 +345,7 @@ impl<'a> ParserImpl<'a> {
}
Kind::Type => self.parse_ts_type_alias_declaration(start_span, modifiers),
Kind::Enum => self.parse_ts_enum_declaration(start_span, modifiers),
Kind::Interface if self.is_at_interface_declaration() => {
self.parse_ts_interface_declaration(start_span, modifiers)
}
Kind::Interface => self.parse_ts_interface_declaration(start_span, modifiers),
Kind::Class => {
let decl = self.parse_class_declaration(start_span, modifiers);
Declaration::ClassDeclaration(decl)
Expand Down Expand Up @@ -441,7 +414,7 @@ impl<'a> ParserImpl<'a> {
}

pub(crate) fn parse_ts_import_equals_declaration(&mut self, span: u32) -> Declaration<'a> {
let import_kind = if !self.peek_at(Kind::Eq) && self.eat(Kind::Type) {
let import_kind = if !self.lookahead(Self::is_next_token_equals) && self.eat(Kind::Type) {
ImportOrExportKind::Type
} else {
ImportOrExportKind::Value
Expand Down Expand Up @@ -475,6 +448,11 @@ impl<'a> ParserImpl<'a> {
)
}

fn is_next_token_equals(&mut self) -> bool {
self.bump_any();
self.at(Kind::Eq)
}

pub(crate) fn parse_ts_this_parameter(&mut self) -> TSThisParameter<'a> {
let span = self.start_span();
self.parse_class_element_modifiers(true);
Expand Down Expand Up @@ -548,16 +526,12 @@ impl<'a> ParserImpl<'a> {
}
Kind::Export => {
self.bump_any();
let kind = if self.cur_kind() == Kind::Type {
self.peek_kind()
} else {
self.cur_kind()
};
self.bump(Kind::Type); // optional `type` after `export`
// This allows constructs like
// `export *`, `export default`, `export {}`, `export = {}` along with all
// export [declaration]
if matches!(
kind,
self.cur_kind(),
Kind::Eq | Kind::Star | Kind::Default | Kind::LCurly | Kind::At | Kind::As
) {
return true;
Expand Down
52 changes: 51 additions & 1 deletion crates/oxc_parser/src/ts/types.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1299,7 +1299,7 @@ impl<'a> ParserImpl<'a> {
let mut modifiers: Vec<Modifier> = self.ast.vec();

loop {
if !self.is_nth_at_modifier(0, is_constructor_parameter) {
if !self.is_at_modifier(is_constructor_parameter) {
break;
}

Expand All @@ -1322,6 +1322,56 @@ impl<'a> ParserImpl<'a> {
Modifiers::new(modifiers, flags)
}

fn is_at_modifier(&mut self, is_constructor_parameter: bool) -> bool {
if !matches!(
self.cur_kind(),
Kind::Public
| Kind::Protected
| Kind::Private
| Kind::Static
| Kind::Abstract
| Kind::Readonly
| Kind::Declare
| Kind::Override
| Kind::Export
) {
return false;
}

let checkpoint = self.checkpoint();
self.bump_any();
let next = self.cur_token();

if next.is_on_new_line() {
self.rewind(checkpoint);
return false;
}

let followed_by_any_member = matches!(next.kind(), Kind::PrivateIdentifier | Kind::LBrack)
|| next.kind().is_literal_property_name();
if followed_by_any_member {
self.rewind(checkpoint);
return true;
}

let followed_by_class_member = !is_constructor_parameter && next.kind() == Kind::Star;
if followed_by_class_member {
self.rewind(checkpoint);
return true;
}

// allow `...` for error recovery
let followed_by_parameter = is_constructor_parameter
&& matches!(next.kind(), Kind::LCurly | Kind::LBrack | Kind::Dot3);
if followed_by_parameter {
self.rewind(checkpoint);
return true;
}

self.rewind(checkpoint);
false
}

fn parse_js_doc_unknown_or_nullable_type(&mut self) -> TSType<'a> {
let span = self.start_span();
self.bump_any(); // bump `?`
Expand Down
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