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CentrilCentril
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simplify parse_bottom_expr more
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‎src/librustc_parse/parser/expr.rs‎

Lines changed: 76 additions & 78 deletions
Original file line numberDiff line numberDiff line change
@@ -824,90 +824,88 @@ impl<'a> Parser<'a> {
824824

825825
// Note: when adding new syntax here, don't forget to adjust `TokenKind::can_begin_expr()`.
826826
let lo = self.token.span;
827-
match self.token.kind {
827+
if let token::Literal(_) = self.token.kind {
828828
// This match arm is a special-case of the `_` match arm below and
829829
// could be removed without changing functionality, but it's faster
830830
// to have it here, especially for programs with large constants.
831-
token::Literal(_) => self.parse_lit_expr(attrs),
832-
token::OpenDelim(token::Paren) => self.parse_tuple_parens_expr(attrs),
833-
token::OpenDelim(token::Brace) => {
834-
self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs)
835-
}
836-
token::BinOp(token::Or) | token::OrOr => self.parse_closure_expr(attrs),
837-
token::OpenDelim(token::Bracket) => self.parse_array_or_repeat_expr(attrs),
838-
_ => {
839-
if self.eat_lt() {
840-
let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
841-
Ok(self.mk_expr(lo.to(path.span), ExprKind::Path(Some(qself), path), attrs))
842-
} else if self.token.is_path_start() {
843-
self.parse_path_start_expr(attrs)
844-
} else if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) {
845-
self.parse_closure_expr(attrs)
846-
} else if self.eat_keyword(kw::If) {
847-
self.parse_if_expr(attrs)
848-
} else if self.eat_keyword(kw::For) {
849-
self.parse_for_expr(None, self.prev_span, attrs)
850-
} else if self.eat_keyword(kw::While) {
851-
self.parse_while_expr(None, self.prev_span, attrs)
852-
} else if let Some(label) = self.eat_label() {
853-
self.parse_labeled_expr(label, attrs)
854-
} else if self.eat_keyword(kw::Loop) {
855-
self.parse_loop_expr(None, self.prev_span, attrs)
856-
} else if self.eat_keyword(kw::Continue) {
857-
let kind = ExprKind::Continue(self.eat_label());
858-
Ok(self.mk_expr(lo.to(self.prev_span), kind, attrs))
859-
} else if self.eat_keyword(kw::Match) {
860-
let match_sp = self.prev_span;
861-
self.parse_match_expr(attrs).map_err(|mut err| {
862-
err.span_label(match_sp, "while parsing this match expression");
863-
err
864-
})
865-
} else if self.eat_keyword(kw::Unsafe) {
866-
let mode = BlockCheckMode::Unsafe(ast::UserProvided);
867-
self.parse_block_expr(None, lo, mode, attrs)
868-
} else if self.is_do_catch_block() {
869-
self.recover_do_catch(attrs)
870-
} else if self.is_try_block() {
871-
self.expect_keyword(kw::Try)?;
872-
self.parse_try_block(lo, attrs)
873-
} else if self.eat_keyword(kw::Return) {
874-
self.parse_return_expr(attrs)
875-
} else if self.eat_keyword(kw::Break) {
876-
self.parse_break_expr(attrs)
877-
} else if self.eat_keyword(kw::Yield) {
878-
self.parse_yield_expr(attrs)
879-
} else if self.eat_keyword(kw::Let) {
880-
self.parse_let_expr(attrs)
881-
} else if !self.unclosed_delims.is_empty() && self.check(&token::Semi) {
882-
// Don't complain about bare semicolons after unclosed braces
883-
// recovery in order to keep the error count down. Fixing the
884-
// delimiters will possibly also fix the bare semicolon found in
885-
// expression context. For example, silence the following error:
886-
//
887-
// error: expected expression, found `;`
888-
// --> file.rs:2:13
889-
// |
890-
// 2 | foo(bar(;
891-
// | ^ expected expression
892-
self.bump();
893-
Ok(self.mk_expr_err(self.token.span))
894-
} else if self.token.span.rust_2018() {
895-
// `Span::rust_2018()` is somewhat expensive; don't get it repeatedly.
896-
if self.check_keyword(kw::Async) {
897-
if self.is_async_block() { // Check for `async {` and `async move {`.
898-
self.parse_async_block(attrs)
899-
} else {
900-
self.parse_closure_expr(attrs)
901-
}
902-
} else if self.eat_keyword(kw::Await) {
903-
self.recover_incorrect_await_syntax(lo, self.prev_span, attrs)
904-
} else {
905-
self.parse_lit_expr(attrs)
906-
}
831+
self.parse_lit_expr(attrs)
832+
} else if self.check(&token::OpenDelim(token::Paren)) {
833+
self.parse_tuple_parens_expr(attrs)
834+
} else if self.check(&token::OpenDelim(token::Brace)) {
835+
self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs)
836+
} else if self.check(&token::BinOp(token::Or)) || self.check(&token::OrOr) {
837+
self.parse_closure_expr(attrs)
838+
} else if self.check(&token::OpenDelim(token::Bracket)) {
839+
self.parse_array_or_repeat_expr(attrs)
840+
} else if self.eat_lt() {
841+
let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
842+
Ok(self.mk_expr(lo.to(path.span), ExprKind::Path(Some(qself), path), attrs))
843+
} else if self.token.is_path_start() {
844+
self.parse_path_start_expr(attrs)
845+
} else if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) {
846+
self.parse_closure_expr(attrs)
847+
} else if self.eat_keyword(kw::If) {
848+
self.parse_if_expr(attrs)
849+
} else if self.eat_keyword(kw::For) {
850+
self.parse_for_expr(None, self.prev_span, attrs)
851+
} else if self.eat_keyword(kw::While) {
852+
self.parse_while_expr(None, self.prev_span, attrs)
853+
} else if let Some(label) = self.eat_label() {
854+
self.parse_labeled_expr(label, attrs)
855+
} else if self.eat_keyword(kw::Loop) {
856+
self.parse_loop_expr(None, self.prev_span, attrs)
857+
} else if self.eat_keyword(kw::Continue) {
858+
let kind = ExprKind::Continue(self.eat_label());
859+
Ok(self.mk_expr(lo.to(self.prev_span), kind, attrs))
860+
} else if self.eat_keyword(kw::Match) {
861+
let match_sp = self.prev_span;
862+
self.parse_match_expr(attrs).map_err(|mut err| {
863+
err.span_label(match_sp, "while parsing this match expression");
864+
err
865+
})
866+
} else if self.eat_keyword(kw::Unsafe) {
867+
self.parse_block_expr(None, lo, BlockCheckMode::Unsafe(ast::UserProvided), attrs)
868+
} else if self.is_do_catch_block() {
869+
self.recover_do_catch(attrs)
870+
} else if self.is_try_block() {
871+
self.expect_keyword(kw::Try)?;
872+
self.parse_try_block(lo, attrs)
873+
} else if self.eat_keyword(kw::Return) {
874+
self.parse_return_expr(attrs)
875+
} else if self.eat_keyword(kw::Break) {
876+
self.parse_break_expr(attrs)
877+
} else if self.eat_keyword(kw::Yield) {
878+
self.parse_yield_expr(attrs)
879+
} else if self.eat_keyword(kw::Let) {
880+
self.parse_let_expr(attrs)
881+
} else if !self.unclosed_delims.is_empty() && self.check(&token::Semi) {
882+
// Don't complain about bare semicolons after unclosed braces
883+
// recovery in order to keep the error count down. Fixing the
884+
// delimiters will possibly also fix the bare semicolon found in
885+
// expression context. For example, silence the following error:
886+
//
887+
// error: expected expression, found `;`
888+
// --> file.rs:2:13
889+
// |
890+
// 2 | foo(bar(;
891+
// | ^ expected expression
892+
self.bump();
893+
Ok(self.mk_expr_err(self.token.span))
894+
} else if self.token.span.rust_2018() {
895+
// `Span::rust_2018()` is somewhat expensive; don't get it repeatedly.
896+
if self.check_keyword(kw::Async) {
897+
if self.is_async_block() { // Check for `async {` and `async move {`.
898+
self.parse_async_block(attrs)
907899
} else {
908-
self.parse_lit_expr(attrs)
900+
self.parse_closure_expr(attrs)
909901
}
902+
} else if self.eat_keyword(kw::Await) {
903+
self.recover_incorrect_await_syntax(lo, self.prev_span, attrs)
904+
} else {
905+
self.parse_lit_expr(attrs)
910906
}
907+
} else {
908+
self.parse_lit_expr(attrs)
911909
}
912910
}
913911

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