5 pub use module::{ModulePath, ModulePathSuccess};
9 pub use path::PathStyle;
13 use diagnostics::Error;
15 use crate::lexer::UnmatchedBrace;
16 use crate::{Directory, DirectoryOwnership};
19 use rustc_ast::ast::DUMMY_NODE_ID;
20 use rustc_ast::ast::{self, AttrStyle, AttrVec, Const, CrateSugar, Extern, Ident, Unsafe};
22 Async, MacArgs, MacDelimiter, Mutability, StrLit, Visibility, VisibilityKind,
24 use rustc_ast::ptr::P;
25 use rustc_ast::token::{self, DelimToken, Token, TokenKind};
26 use rustc_ast::tokenstream::{self, DelimSpan, TokenStream, TokenTree, TreeAndJoint};
27 use rustc_ast::util::comments::{doc_comment_style, strip_doc_comment_decoration};
28 use rustc_ast_pretty::pprust;
29 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, FatalError, PResult};
30 use rustc_session::parse::ParseSess;
31 use rustc_span::source_map::respan;
32 use rustc_span::symbol::{kw, sym, Symbol};
33 use rustc_span::{FileName, Span, DUMMY_SP};
35 use std::path::PathBuf;
36 use std::{cmp, mem, slice};
39 struct Restrictions: u8 {
40 const STMT_EXPR = 1 << 0;
41 const NO_STRUCT_LITERAL = 1 << 1;
45 #[derive(Clone, Copy, PartialEq, Debug)]
52 #[derive(Clone, Copy, PartialEq, Debug)]
58 /// Like `maybe_whole_expr`, but for things other than expressions.
60 macro_rules! maybe_whole {
61 ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
62 if let token::Interpolated(nt) = &$p.token.kind {
63 if let token::$constructor(x) = &**nt {
72 /// If the next tokens are ill-formed `$ty::` recover them as `<$ty>::`.
74 macro_rules! maybe_recover_from_interpolated_ty_qpath {
75 ($self: expr, $allow_qpath_recovery: expr) => {
76 if $allow_qpath_recovery && $self.look_ahead(1, |t| t == &token::ModSep) {
77 if let token::Interpolated(nt) = &$self.token.kind {
78 if let token::NtTy(ty) = &**nt {
81 return $self.maybe_recover_from_bad_qpath_stage_2($self.prev_span, ty);
89 pub struct Parser<'a> {
90 pub sess: &'a ParseSess,
91 /// The current non-normalized token.
93 /// The current normalized token.
94 /// "Normalized" means that some interpolated tokens
95 /// (`$i: ident` and `$l: lifetime` meta-variables) are replaced
96 /// with non-interpolated identifier and lifetime tokens they refer to.
97 /// Use this if you need to check for `token::Ident` or `token::Lifetime` specifically,
98 /// this also includes edition checks for edition-specific keyword identifiers.
99 pub normalized_token: Token,
100 /// The previous non-normalized token.
101 pub prev_token: Token,
102 /// The previous normalized token.
103 /// Use this if you need to check for `token::Ident` or `token::Lifetime` specifically,
104 /// this also includes edition checks for edition-specific keyword identifiers.
105 pub normalized_prev_token: Token,
106 /// FIXME: Remove in favor of the equivalent `prev_token.span`.
108 restrictions: Restrictions,
109 /// Used to determine the path to externally loaded source files.
110 pub(super) directory: Directory,
111 /// `true` to parse sub-modules in other files.
112 // Public for rustfmt usage.
113 pub recurse_into_file_modules: bool,
114 /// Name of the root module this parser originated from. If `None`, then the
115 /// name is not known. This does not change while the parser is descending
116 /// into modules, and sub-parsers have new values for this name.
117 pub root_module_name: Option<String>,
118 expected_tokens: Vec<TokenType>,
119 token_cursor: TokenCursor,
120 desugar_doc_comments: bool,
121 /// `true` we should configure out of line modules as we parse.
122 // Public for rustfmt usage.
124 /// This field is used to keep track of how many left angle brackets we have seen. This is
125 /// required in order to detect extra leading left angle brackets (`<` characters) and error
128 /// See the comments in the `parse_path_segment` function for more details.
129 unmatched_angle_bracket_count: u32,
130 max_angle_bracket_count: u32,
131 /// A list of all unclosed delimiters found by the lexer. If an entry is used for error recovery
132 /// it gets removed from here. Every entry left at the end gets emitted as an independent
134 pub(super) unclosed_delims: Vec<UnmatchedBrace>,
135 last_unexpected_token_span: Option<Span>,
136 pub last_type_ascription: Option<(Span, bool /* likely path typo */)>,
137 /// If present, this `Parser` is not parsing Rust code but rather a macro call.
138 subparser_name: Option<&'static str>,
141 impl<'a> Drop for Parser<'a> {
143 emit_unclosed_delims(&mut self.unclosed_delims, &self.sess);
149 frame: TokenCursorFrame,
150 stack: Vec<TokenCursorFrame>,
154 struct TokenCursorFrame {
155 delim: token::DelimToken,
158 tree_cursor: tokenstream::Cursor,
160 last_token: LastToken,
163 /// This is used in `TokenCursorFrame` above to track tokens that are consumed
164 /// by the parser, and then that's transitively used to record the tokens that
165 /// each parse AST item is created with.
167 /// Right now this has two states, either collecting tokens or not collecting
168 /// tokens. If we're collecting tokens we just save everything off into a local
169 /// `Vec`. This should eventually though likely save tokens from the original
170 /// token stream and just use slicing of token streams to avoid creation of a
171 /// whole new vector.
173 /// The second state is where we're passively not recording tokens, but the last
174 /// token is still tracked for when we want to start recording tokens. This
175 /// "last token" means that when we start recording tokens we'll want to ensure
176 /// that this, the first token, is included in the output.
178 /// You can find some more example usage of this in the `collect_tokens` method
182 Collecting(Vec<TreeAndJoint>),
183 Was(Option<TreeAndJoint>),
186 impl TokenCursorFrame {
187 fn new(span: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self {
191 open_delim: delim == token::NoDelim,
192 tree_cursor: tts.clone().into_trees(),
193 close_delim: delim == token::NoDelim,
194 last_token: LastToken::Was(None),
200 fn next(&mut self) -> Token {
202 let tree = if !self.frame.open_delim {
203 self.frame.open_delim = true;
204 TokenTree::open_tt(self.frame.span, self.frame.delim)
205 } else if let Some(tree) = self.frame.tree_cursor.next() {
207 } else if !self.frame.close_delim {
208 self.frame.close_delim = true;
209 TokenTree::close_tt(self.frame.span, self.frame.delim)
210 } else if let Some(frame) = self.stack.pop() {
214 return Token::new(token::Eof, DUMMY_SP);
217 match self.frame.last_token {
218 LastToken::Collecting(ref mut v) => v.push(tree.clone().into()),
219 LastToken::Was(ref mut t) => *t = Some(tree.clone().into()),
223 TokenTree::Token(token) => return token,
224 TokenTree::Delimited(sp, delim, tts) => {
225 let frame = TokenCursorFrame::new(sp, delim, &tts);
226 self.stack.push(mem::replace(&mut self.frame, frame));
232 fn next_desugared(&mut self) -> Token {
233 let (name, sp) = match self.next() {
234 Token { kind: token::DocComment(name), span } => (name, span),
238 let stripped = strip_doc_comment_decoration(&name.as_str());
240 // Searches for the occurrences of `"#*` and returns the minimum number of `#`s
241 // required to wrap the text.
242 let mut num_of_hashes = 0;
244 for ch in stripped.chars() {
247 '#' if count > 0 => count + 1,
250 num_of_hashes = cmp::max(num_of_hashes, count);
253 let delim_span = DelimSpan::from_single(sp);
254 let body = TokenTree::Delimited(
258 TokenTree::token(token::Ident(sym::doc, false), sp),
259 TokenTree::token(token::Eq, sp),
261 TokenKind::lit(token::StrRaw(num_of_hashes), Symbol::intern(&stripped), None),
267 .collect::<TokenStream>(),
270 self.stack.push(mem::replace(
272 TokenCursorFrame::new(
275 &if doc_comment_style(&name.as_str()) == AttrStyle::Inner {
276 [TokenTree::token(token::Pound, sp), TokenTree::token(token::Not, sp), body]
279 .collect::<TokenStream>()
281 [TokenTree::token(token::Pound, sp), body]
284 .collect::<TokenStream>()
293 #[derive(Clone, PartialEq)]
306 fn to_string(&self) -> String {
308 TokenType::Token(ref t) => format!("`{}`", pprust::token_kind_to_string(t)),
309 TokenType::Keyword(kw) => format!("`{}`", kw),
310 TokenType::Operator => "an operator".to_string(),
311 TokenType::Lifetime => "lifetime".to_string(),
312 TokenType::Ident => "identifier".to_string(),
313 TokenType::Path => "path".to_string(),
314 TokenType::Type => "type".to_string(),
315 TokenType::Const => "const".to_string(),
320 #[derive(Copy, Clone, Debug)]
321 enum TokenExpectType {
326 /// A sequence separator.
328 /// The separator token.
329 sep: Option<TokenKind>,
330 /// `true` if a trailing separator is allowed.
331 trailing_sep_allowed: bool,
335 fn trailing_allowed(t: TokenKind) -> SeqSep {
336 SeqSep { sep: Some(t), trailing_sep_allowed: true }
339 fn none() -> SeqSep {
340 SeqSep { sep: None, trailing_sep_allowed: false }
344 pub enum FollowedByType {
349 fn token_descr_opt(token: &Token) -> Option<&'static str> {
350 Some(match token.kind {
351 _ if token.is_special_ident() => "reserved identifier",
352 _ if token.is_used_keyword() => "keyword",
353 _ if token.is_unused_keyword() => "reserved keyword",
354 token::DocComment(..) => "doc comment",
359 pub(super) fn token_descr(token: &Token) -> String {
360 let token_str = pprust::token_to_string(token);
361 match token_descr_opt(token) {
362 Some(prefix) => format!("{} `{}`", prefix, token_str),
363 _ => format!("`{}`", token_str),
367 impl<'a> Parser<'a> {
371 directory: Option<Directory>,
372 recurse_into_file_modules: bool,
373 desugar_doc_comments: bool,
374 subparser_name: Option<&'static str>,
376 let mut parser = Parser {
378 token: Token::dummy(),
379 normalized_token: Token::dummy(),
380 prev_token: Token::dummy(),
381 normalized_prev_token: Token::dummy(),
383 restrictions: Restrictions::empty(),
384 recurse_into_file_modules,
385 directory: Directory {
386 path: PathBuf::new(),
387 ownership: DirectoryOwnership::Owned { relative: None },
389 root_module_name: None,
390 expected_tokens: Vec::new(),
391 token_cursor: TokenCursor {
392 frame: TokenCursorFrame::new(DelimSpan::dummy(), token::NoDelim, &tokens),
395 desugar_doc_comments,
397 unmatched_angle_bracket_count: 0,
398 max_angle_bracket_count: 0,
399 unclosed_delims: Vec::new(),
400 last_unexpected_token_span: None,
401 last_type_ascription: None,
405 // Make parser point to the first token.
408 if let Some(directory) = directory {
409 parser.directory = directory;
410 } else if !parser.token.span.is_dummy() {
411 if let Some(FileName::Real(path)) =
412 &sess.source_map().lookup_char_pos(parser.token.span.lo()).file.unmapped_path
414 if let Some(directory_path) = path.parent() {
415 parser.directory.path = directory_path.to_path_buf();
423 fn next_tok(&mut self, fallback_span: Span) -> Token {
424 let mut next = if self.desugar_doc_comments {
425 self.token_cursor.next_desugared()
427 self.token_cursor.next()
429 if next.span.is_dummy() {
430 // Tweak the location for better diagnostics, but keep syntactic context intact.
431 next.span = fallback_span.with_ctxt(next.span.ctxt());
436 crate fn unexpected<T>(&mut self) -> PResult<'a, T> {
437 match self.expect_one_of(&[], &[]) {
439 // We can get `Ok(true)` from `recover_closing_delimiter`
440 // which is called in `expected_one_of_not_found`.
441 Ok(_) => FatalError.raise(),
445 /// Expects and consumes the token `t`. Signals an error if the next token is not `t`.
446 pub fn expect(&mut self, t: &TokenKind) -> PResult<'a, bool /* recovered */> {
447 if self.expected_tokens.is_empty() {
448 if self.token == *t {
452 self.unexpected_try_recover(t)
455 self.expect_one_of(slice::from_ref(t), &[])
459 /// Expect next token to be edible or inedible token. If edible,
460 /// then consume it; if inedible, then return without consuming
461 /// anything. Signal a fatal error if next token is unexpected.
462 pub fn expect_one_of(
464 edible: &[TokenKind],
465 inedible: &[TokenKind],
466 ) -> PResult<'a, bool /* recovered */> {
467 if edible.contains(&self.token.kind) {
470 } else if inedible.contains(&self.token.kind) {
471 // leave it in the input
473 } else if self.last_unexpected_token_span == Some(self.token.span) {
476 self.expected_one_of_not_found(edible, inedible)
480 // Public for rustfmt usage.
481 pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
482 self.parse_ident_common(true)
485 fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
486 match self.normalized_token.kind {
487 token::Ident(name, _) => {
488 if self.token.is_reserved_ident() {
489 let mut err = self.expected_ident_found();
497 Ok(Ident::new(name, self.normalized_prev_token.span))
499 _ => Err(match self.prev_token.kind {
500 TokenKind::DocComment(..) => {
501 self.span_fatal_err(self.prev_span, Error::UselessDocComment)
503 _ => self.expected_ident_found(),
508 /// Checks if the next token is `tok`, and returns `true` if so.
510 /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
512 fn check(&mut self, tok: &TokenKind) -> bool {
513 let is_present = self.token == *tok;
515 self.expected_tokens.push(TokenType::Token(tok.clone()));
520 /// Consumes a token 'tok' if it exists. Returns whether the given token was present.
521 pub fn eat(&mut self, tok: &TokenKind) -> bool {
522 let is_present = self.check(tok);
529 /// If the next token is the given keyword, returns `true` without eating it.
530 /// An expectation is also added for diagnostics purposes.
531 fn check_keyword(&mut self, kw: Symbol) -> bool {
532 self.expected_tokens.push(TokenType::Keyword(kw));
533 self.token.is_keyword(kw)
536 /// If the next token is the given keyword, eats it and returns `true`.
537 /// Otherwise, returns `false`. An expectation is also added for diagnostics purposes.
538 // Public for rustfmt usage.
539 pub fn eat_keyword(&mut self, kw: Symbol) -> bool {
540 if self.check_keyword(kw) {
548 fn eat_keyword_noexpect(&mut self, kw: Symbol) -> bool {
549 if self.token.is_keyword(kw) {
557 /// If the given word is not a keyword, signals an error.
558 /// If the next token is not the given word, signals an error.
559 /// Otherwise, eats it.
560 fn expect_keyword(&mut self, kw: Symbol) -> PResult<'a, ()> {
561 if !self.eat_keyword(kw) { self.unexpected() } else { Ok(()) }
564 /// Is the given keyword `kw` followed by a non-reserved identifier?
565 fn is_kw_followed_by_ident(&self, kw: Symbol) -> bool {
566 self.token.is_keyword(kw) && self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
569 fn check_or_expected(&mut self, ok: bool, typ: TokenType) -> bool {
573 self.expected_tokens.push(typ);
578 fn check_ident(&mut self) -> bool {
579 self.check_or_expected(self.token.is_ident(), TokenType::Ident)
582 fn check_path(&mut self) -> bool {
583 self.check_or_expected(self.token.is_path_start(), TokenType::Path)
586 fn check_type(&mut self) -> bool {
587 self.check_or_expected(self.token.can_begin_type(), TokenType::Type)
590 fn check_const_arg(&mut self) -> bool {
591 self.check_or_expected(self.token.can_begin_const_arg(), TokenType::Const)
594 /// Checks to see if the next token is either `+` or `+=`.
595 /// Otherwise returns `false`.
596 fn check_plus(&mut self) -> bool {
597 self.check_or_expected(
598 self.token.is_like_plus(),
599 TokenType::Token(token::BinOp(token::Plus)),
603 /// Eats the expected token if it's present possibly breaking
604 /// compound tokens like multi-character operators in process.
605 /// Returns `true` if the token was eaten.
606 fn break_and_eat(&mut self, expected: TokenKind) -> bool {
607 if self.token.kind == expected {
611 match self.token.kind.break_two_token_op() {
612 Some((first, second)) if first == expected => {
613 let first_span = self.sess.source_map().start_point(self.token.span);
614 let second_span = self.token.span.with_lo(first_span.hi());
615 self.set_token(Token::new(first, first_span));
616 self.bump_with(Token::new(second, second_span));
620 self.expected_tokens.push(TokenType::Token(expected));
626 /// Eats `+` possibly breaking tokens like `+=` in process.
627 fn eat_plus(&mut self) -> bool {
628 self.break_and_eat(token::BinOp(token::Plus))
631 /// Eats `&` possibly breaking tokens like `&&` in process.
632 /// Signals an error if `&` is not eaten.
633 fn expect_and(&mut self) -> PResult<'a, ()> {
634 if self.break_and_eat(token::BinOp(token::And)) { Ok(()) } else { self.unexpected() }
637 /// Eats `|` possibly breaking tokens like `||` in process.
638 /// Signals an error if `|` was not eaten.
639 fn expect_or(&mut self) -> PResult<'a, ()> {
640 if self.break_and_eat(token::BinOp(token::Or)) { Ok(()) } else { self.unexpected() }
643 /// Eats `<` possibly breaking tokens like `<<` in process.
644 fn eat_lt(&mut self) -> bool {
645 let ate = self.break_and_eat(token::Lt);
647 // See doc comment for `unmatched_angle_bracket_count`.
648 self.unmatched_angle_bracket_count += 1;
649 self.max_angle_bracket_count += 1;
650 debug!("eat_lt: (increment) count={:?}", self.unmatched_angle_bracket_count);
655 /// Eats `<` possibly breaking tokens like `<<` in process.
656 /// Signals an error if `<` was not eaten.
657 fn expect_lt(&mut self) -> PResult<'a, ()> {
658 if self.eat_lt() { Ok(()) } else { self.unexpected() }
661 /// Eats `>` possibly breaking tokens like `>>` in process.
662 /// Signals an error if `>` was not eaten.
663 fn expect_gt(&mut self) -> PResult<'a, ()> {
664 if self.break_and_eat(token::Gt) {
665 // See doc comment for `unmatched_angle_bracket_count`.
666 if self.unmatched_angle_bracket_count > 0 {
667 self.unmatched_angle_bracket_count -= 1;
668 debug!("expect_gt: (decrement) count={:?}", self.unmatched_angle_bracket_count);
676 fn expect_any_with_type(&mut self, kets: &[&TokenKind], expect: TokenExpectType) -> bool {
677 kets.iter().any(|k| match expect {
678 TokenExpectType::Expect => self.check(k),
679 TokenExpectType::NoExpect => self.token == **k,
683 fn parse_seq_to_before_tokens<T>(
687 expect: TokenExpectType,
688 mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
689 ) -> PResult<'a, (Vec<T>, bool /* trailing */, bool /* recovered */)> {
690 let mut first = true;
691 let mut recovered = false;
692 let mut trailing = false;
694 while !self.expect_any_with_type(kets, expect) {
695 if let token::CloseDelim(..) | token::Eof = self.token.kind {
698 if let Some(ref t) = sep.sep {
702 match self.expect(t) {
708 Err(mut expect_err) => {
709 let sp = self.prev_span.shrink_to_hi();
710 let token_str = pprust::token_kind_to_string(t);
712 // Attempt to keep parsing if it was a similar separator.
713 if let Some(ref tokens) = t.similar_tokens() {
714 if tokens.contains(&self.token.kind) {
719 // Attempt to keep parsing if it was an omitted separator.
722 // Parsed successfully, therefore most probably the code only
723 // misses a separator.
725 .span_suggestion_short(
727 &format!("missing `{}`", token_str),
729 Applicability::MaybeIncorrect,
737 // Parsing failed, therefore it must be something more serious
738 // than just a missing separator.
749 if sep.trailing_sep_allowed && self.expect_any_with_type(kets, expect) {
758 Ok((v, trailing, recovered))
761 /// Parses a sequence, not including the closing delimiter. The function
762 /// `f` must consume tokens until reaching the next separator or
764 fn parse_seq_to_before_end<T>(
768 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
769 ) -> PResult<'a, (Vec<T>, bool, bool)> {
770 self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f)
773 /// Parses a sequence, including the closing delimiter. The function
774 /// `f` must consume tokens until reaching the next separator or
776 fn parse_seq_to_end<T>(
780 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
781 ) -> PResult<'a, (Vec<T>, bool /* trailing */)> {
782 let (val, trailing, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
789 /// Parses a sequence, including the closing delimiter. The function
790 /// `f` must consume tokens until reaching the next separator or
792 fn parse_unspanned_seq<T>(
797 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
798 ) -> PResult<'a, (Vec<T>, bool)> {
800 self.parse_seq_to_end(ket, sep, f)
803 fn parse_delim_comma_seq<T>(
806 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
807 ) -> PResult<'a, (Vec<T>, bool)> {
808 self.parse_unspanned_seq(
809 &token::OpenDelim(delim),
810 &token::CloseDelim(delim),
811 SeqSep::trailing_allowed(token::Comma),
816 fn parse_paren_comma_seq<T>(
818 f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
819 ) -> PResult<'a, (Vec<T>, bool)> {
820 self.parse_delim_comma_seq(token::Paren, f)
823 // Interpolated identifier (`$i: ident`) and lifetime (`$l: lifetime`)
824 // tokens are replaced with usual identifier and lifetime tokens,
825 // so the former are never encountered during normal parsing.
826 crate fn set_token(&mut self, token: Token) {
828 self.normalized_token = match &self.token.kind {
829 token::Interpolated(nt) => match **nt {
830 token::NtIdent(ident, is_raw) => {
831 Token::new(token::Ident(ident.name, is_raw), ident.span)
833 token::NtLifetime(ident) => Token::new(token::Lifetime(ident.name), ident.span),
834 _ => self.token.clone(),
836 _ => self.token.clone(),
840 /// Advance the parser by one token using provided token as the next one.
841 fn bump_with(&mut self, next_token: Token) {
842 // Bumping after EOF is a bad sign, usually an infinite loop.
843 if self.prev_token.kind == TokenKind::Eof {
844 let msg = "attempted to bump the parser past EOF (may be stuck in a loop)";
845 self.span_bug(self.token.span, msg);
848 // Update the current and previous tokens.
849 self.prev_token = self.token.take();
850 self.normalized_prev_token = self.normalized_token.take();
851 self.set_token(next_token);
853 // Update fields derived from the previous token.
854 self.prev_span = self.prev_token.span;
857 self.expected_tokens.clear();
860 /// Advance the parser by one token.
861 pub fn bump(&mut self) {
862 let next_token = self.next_tok(self.token.span);
863 self.bump_with(next_token);
866 /// Look-ahead `dist` tokens of `self.token` and get access to that token there.
867 /// When `dist == 0` then the current token is looked at.
868 pub fn look_ahead<R>(&self, dist: usize, looker: impl FnOnce(&Token) -> R) -> R {
870 return looker(&self.token);
873 let frame = &self.token_cursor.frame;
874 looker(&match frame.tree_cursor.look_ahead(dist - 1) {
875 Some(tree) => match tree {
876 TokenTree::Token(token) => token,
877 TokenTree::Delimited(dspan, delim, _) => {
878 Token::new(token::OpenDelim(delim), dspan.open)
881 None => Token::new(token::CloseDelim(frame.delim), frame.span.close),
885 /// Returns whether any of the given keywords are `dist` tokens ahead of the current one.
886 fn is_keyword_ahead(&self, dist: usize, kws: &[Symbol]) -> bool {
887 self.look_ahead(dist, |t| kws.iter().any(|&kw| t.is_keyword(kw)))
890 /// Parses asyncness: `async` or nothing.
891 fn parse_asyncness(&mut self) -> Async {
892 if self.eat_keyword(kw::Async) {
893 let span = self.normalized_prev_token.span;
894 Async::Yes { span, closure_id: DUMMY_NODE_ID, return_impl_trait_id: DUMMY_NODE_ID }
900 /// Parses unsafety: `unsafe` or nothing.
901 fn parse_unsafety(&mut self) -> Unsafe {
902 if self.eat_keyword(kw::Unsafe) { Unsafe::Yes(self.prev_span) } else { Unsafe::No }
905 /// Parses constness: `const` or nothing.
906 fn parse_constness(&mut self) -> Const {
907 if self.eat_keyword(kw::Const) { Const::Yes(self.prev_span) } else { Const::No }
910 /// Parses mutability (`mut` or nothing).
911 fn parse_mutability(&mut self) -> Mutability {
912 if self.eat_keyword(kw::Mut) { Mutability::Mut } else { Mutability::Not }
915 /// Possibly parses mutability (`const` or `mut`).
916 fn parse_const_or_mut(&mut self) -> Option<Mutability> {
917 if self.eat_keyword(kw::Mut) {
918 Some(Mutability::Mut)
919 } else if self.eat_keyword(kw::Const) {
920 Some(Mutability::Not)
926 fn parse_field_name(&mut self) -> PResult<'a, Ident> {
927 if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) = self.token.kind
929 self.expect_no_suffix(self.token.span, "a tuple index", suffix);
931 Ok(Ident::new(symbol, self.prev_span))
933 self.parse_ident_common(false)
937 fn parse_mac_args(&mut self) -> PResult<'a, P<MacArgs>> {
938 self.parse_mac_args_common(true).map(P)
941 fn parse_attr_args(&mut self) -> PResult<'a, MacArgs> {
942 self.parse_mac_args_common(false)
945 fn parse_mac_args_common(&mut self, delimited_only: bool) -> PResult<'a, MacArgs> {
947 if self.check(&token::OpenDelim(DelimToken::Paren))
948 || self.check(&token::OpenDelim(DelimToken::Bracket))
949 || self.check(&token::OpenDelim(DelimToken::Brace))
951 match self.parse_token_tree() {
952 TokenTree::Delimited(dspan, delim, tokens) =>
953 // We've confirmed above that there is a delimiter so unwrapping is OK.
955 MacArgs::Delimited(dspan, MacDelimiter::from_token(delim).unwrap(), tokens)
959 } else if !delimited_only {
960 if self.eat(&token::Eq) {
961 let eq_span = self.prev_span;
962 let mut is_interpolated_expr = false;
963 if let token::Interpolated(nt) = &self.token.kind {
964 if let token::NtExpr(..) = **nt {
965 is_interpolated_expr = true;
968 let token_tree = if is_interpolated_expr {
969 // We need to accept arbitrary interpolated expressions to continue
970 // supporting things like `doc = $expr` that work on stable.
971 // Non-literal interpolated expressions are rejected after expansion.
972 self.parse_token_tree()
974 self.parse_unsuffixed_lit()?.token_tree()
977 MacArgs::Eq(eq_span, token_tree.into())
982 return self.unexpected();
987 fn parse_or_use_outer_attributes(
989 already_parsed_attrs: Option<AttrVec>,
990 ) -> PResult<'a, AttrVec> {
991 if let Some(attrs) = already_parsed_attrs {
994 self.parse_outer_attributes().map(|a| a.into())
998 /// Parses a single token tree from the input.
999 pub fn parse_token_tree(&mut self) -> TokenTree {
1000 match self.token.kind {
1001 token::OpenDelim(..) => {
1002 let frame = mem::replace(
1003 &mut self.token_cursor.frame,
1004 self.token_cursor.stack.pop().unwrap(),
1006 self.set_token(Token::new(TokenKind::CloseDelim(frame.delim), frame.span.close));
1008 TokenTree::Delimited(frame.span, frame.delim, frame.tree_cursor.stream)
1010 token::CloseDelim(_) | token::Eof => unreachable!(),
1013 TokenTree::Token(self.prev_token.clone())
1018 /// Parses a stream of tokens into a list of `TokenTree`s, up to EOF.
1019 pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
1020 let mut tts = Vec::new();
1021 while self.token != token::Eof {
1022 tts.push(self.parse_token_tree());
1027 pub fn parse_tokens(&mut self) -> TokenStream {
1028 let mut result = Vec::new();
1030 match self.token.kind {
1031 token::Eof | token::CloseDelim(..) => break,
1032 _ => result.push(self.parse_token_tree().into()),
1035 TokenStream::new(result)
1038 /// Evaluates the closure with restrictions in place.
1040 /// Afters the closure is evaluated, restrictions are reset.
1041 fn with_res<T>(&mut self, res: Restrictions, f: impl FnOnce(&mut Self) -> T) -> T {
1042 let old = self.restrictions;
1043 self.restrictions = res;
1045 self.restrictions = old;
1049 fn is_crate_vis(&self) -> bool {
1050 self.token.is_keyword(kw::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
1053 /// Parses `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
1054 /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
1055 /// If the following element can't be a tuple (i.e., it's a function definition), then
1056 /// it's not a tuple struct field), and the contents within the parentheses isn't valid,
1057 /// so emit a proper diagnostic.
1058 pub fn parse_visibility(&mut self, fbt: FollowedByType) -> PResult<'a, Visibility> {
1059 maybe_whole!(self, NtVis, |x| x);
1061 self.expected_tokens.push(TokenType::Keyword(kw::Crate));
1062 if self.is_crate_vis() {
1063 self.bump(); // `crate`
1064 self.sess.gated_spans.gate(sym::crate_visibility_modifier, self.prev_span);
1065 return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
1068 if !self.eat_keyword(kw::Pub) {
1069 // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
1070 // keyword to grab a span from for inherited visibility; an empty span at the
1071 // beginning of the current token would seem to be the "Schelling span".
1072 return Ok(respan(self.token.span.shrink_to_lo(), VisibilityKind::Inherited));
1074 let lo = self.prev_span;
1076 if self.check(&token::OpenDelim(token::Paren)) {
1077 // We don't `self.bump()` the `(` yet because this might be a struct definition where
1078 // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
1079 // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
1080 // by the following tokens.
1081 if self.is_keyword_ahead(1, &[kw::Crate]) && self.look_ahead(2, |t| t != &token::ModSep)
1082 // account for `pub(crate::foo)`
1084 // Parse `pub(crate)`.
1086 self.bump(); // `crate`
1087 self.expect(&token::CloseDelim(token::Paren))?; // `)`
1088 let vis = VisibilityKind::Crate(CrateSugar::PubCrate);
1089 return Ok(respan(lo.to(self.prev_span), vis));
1090 } else if self.is_keyword_ahead(1, &[kw::In]) {
1091 // Parse `pub(in path)`.
1093 self.bump(); // `in`
1094 let path = self.parse_path(PathStyle::Mod)?; // `path`
1095 self.expect(&token::CloseDelim(token::Paren))?; // `)`
1096 let vis = VisibilityKind::Restricted { path: P(path), id: ast::DUMMY_NODE_ID };
1097 return Ok(respan(lo.to(self.prev_span), vis));
1098 } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren))
1099 && self.is_keyword_ahead(1, &[kw::Super, kw::SelfLower])
1101 // Parse `pub(self)` or `pub(super)`.
1103 let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
1104 self.expect(&token::CloseDelim(token::Paren))?; // `)`
1105 let vis = VisibilityKind::Restricted { path: P(path), id: ast::DUMMY_NODE_ID };
1106 return Ok(respan(lo.to(self.prev_span), vis));
1107 } else if let FollowedByType::No = fbt {
1108 // Provide this diagnostic if a type cannot follow;
1109 // in particular, if this is not a tuple struct.
1110 self.recover_incorrect_vis_restriction()?;
1111 // Emit diagnostic, but continue with public visibility.
1115 Ok(respan(lo, VisibilityKind::Public))
1118 /// Recovery for e.g. `pub(something) fn ...` or `struct X { pub(something) y: Z }`
1119 fn recover_incorrect_vis_restriction(&mut self) -> PResult<'a, ()> {
1121 let path = self.parse_path(PathStyle::Mod)?;
1122 self.expect(&token::CloseDelim(token::Paren))?; // `)`
1124 let msg = "incorrect visibility restriction";
1125 let suggestion = r##"some possible visibility restrictions are:
1126 `pub(crate)`: visible only on the current crate
1127 `pub(super)`: visible only in the current module's parent
1128 `pub(in path::to::module)`: visible only on the specified path"##;
1130 let path_str = pprust::path_to_string(&path);
1132 struct_span_err!(self.sess.span_diagnostic, path.span, E0704, "{}", msg)
1136 &format!("make this visible only to module `{}` with `in`", path_str),
1137 format!("in {}", path_str),
1138 Applicability::MachineApplicable,
1145 /// Parses `extern string_literal?`.
1146 fn parse_extern(&mut self) -> PResult<'a, Extern> {
1147 Ok(if self.eat_keyword(kw::Extern) {
1148 Extern::from_abi(self.parse_abi())
1154 /// Parses a string literal as an ABI spec.
1155 fn parse_abi(&mut self) -> Option<StrLit> {
1156 match self.parse_str_lit() {
1157 Ok(str_lit) => Some(str_lit),
1158 Err(Some(lit)) => match lit.kind {
1159 ast::LitKind::Err(_) => None,
1161 self.struct_span_err(lit.span, "non-string ABI literal")
1164 "specify the ABI with a string literal",
1165 "\"C\"".to_string(),
1166 Applicability::MaybeIncorrect,
1176 fn collect_tokens<R>(
1178 f: impl FnOnce(&mut Self) -> PResult<'a, R>,
1179 ) -> PResult<'a, (R, TokenStream)> {
1180 // Record all tokens we parse when parsing this item.
1181 let mut tokens = Vec::new();
1182 let prev_collecting = match self.token_cursor.frame.last_token {
1183 LastToken::Collecting(ref mut list) => Some(mem::take(list)),
1184 LastToken::Was(ref mut last) => {
1185 tokens.extend(last.take());
1189 self.token_cursor.frame.last_token = LastToken::Collecting(tokens);
1190 let prev = self.token_cursor.stack.len();
1192 let last_token = if self.token_cursor.stack.len() == prev {
1193 &mut self.token_cursor.frame.last_token
1194 } else if self.token_cursor.stack.get(prev).is_none() {
1195 // This can happen due to a bad interaction of two unrelated recovery mechanisms with
1196 // mismatched delimiters *and* recovery lookahead on the likely typo `pub ident(`
1198 return Ok((ret?, TokenStream::default()));
1200 &mut self.token_cursor.stack[prev].last_token
1203 // Pull out the tokens that we've collected from the call to `f` above.
1204 let mut collected_tokens = match *last_token {
1205 LastToken::Collecting(ref mut v) => mem::take(v),
1206 LastToken::Was(ref was) => {
1207 let msg = format!("our vector went away? - found Was({:?})", was);
1208 debug!("collect_tokens: {}", msg);
1209 self.sess.span_diagnostic.delay_span_bug(self.token.span, &msg);
1210 // This can happen due to a bad interaction of two unrelated recovery mechanisms
1211 // with mismatched delimiters *and* recovery lookahead on the likely typo
1212 // `pub ident(` (#62895, different but similar to the case above).
1213 return Ok((ret?, TokenStream::default()));
1217 // If we're not at EOF our current token wasn't actually consumed by
1218 // `f`, but it'll still be in our list that we pulled out. In that case
1220 let extra_token = if self.token != token::Eof { collected_tokens.pop() } else { None };
1222 // If we were previously collecting tokens, then this was a recursive
1223 // call. In that case we need to record all the tokens we collected in
1224 // our parent list as well. To do that we push a clone of our stream
1225 // onto the previous list.
1226 match prev_collecting {
1228 list.extend(collected_tokens.iter().cloned());
1229 list.extend(extra_token);
1230 *last_token = LastToken::Collecting(list);
1233 *last_token = LastToken::Was(extra_token);
1237 Ok((ret?, TokenStream::new(collected_tokens)))
1241 fn is_import_coupler(&mut self) -> bool {
1242 self.check(&token::ModSep)
1243 && self.look_ahead(1, |t| {
1244 *t == token::OpenDelim(token::Brace) || *t == token::BinOp(token::Star)
1249 crate fn make_unclosed_delims_error(
1250 unmatched: UnmatchedBrace,
1252 ) -> Option<DiagnosticBuilder<'_>> {
1253 // `None` here means an `Eof` was found. We already emit those errors elsewhere, we add them to
1254 // `unmatched_braces` only for error recovery in the `Parser`.
1255 let found_delim = unmatched.found_delim?;
1256 let mut err = sess.span_diagnostic.struct_span_err(
1257 unmatched.found_span,
1259 "mismatched closing delimiter: `{}`",
1260 pprust::token_kind_to_string(&token::CloseDelim(found_delim)),
1263 err.span_label(unmatched.found_span, "mismatched closing delimiter");
1264 if let Some(sp) = unmatched.candidate_span {
1265 err.span_label(sp, "closing delimiter possibly meant for this");
1267 if let Some(sp) = unmatched.unclosed_span {
1268 err.span_label(sp, "unclosed delimiter");
1273 pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, sess: &ParseSess) {
1274 *sess.reached_eof.borrow_mut() |=
1275 unclosed_delims.iter().any(|unmatched_delim| unmatched_delim.found_delim.is_none());
1276 for unmatched in unclosed_delims.drain(..) {
1277 make_unclosed_delims_error(unmatched, sess).map(|mut e| {