| pub mod attr; |
| mod diagnostics; |
| mod expr; |
| mod generics; |
| mod item; |
| mod nonterminal; |
| mod pat; |
| mod path; |
| mod stmt; |
| mod ty; |
| |
| use crate::lexer::UnmatchedBrace; |
| pub use diagnostics::AttemptLocalParseRecovery; |
| use diagnostics::Error; |
| pub use path::PathStyle; |
| |
| use rustc_ast::ptr::P; |
| use rustc_ast::token::{self, DelimToken, Token, TokenKind}; |
| use rustc_ast::tokenstream::{self, DelimSpan, LazyTokenStream, LazyTokenStreamInner, Spacing}; |
| use rustc_ast::tokenstream::{TokenStream, TokenTree}; |
| use rustc_ast::DUMMY_NODE_ID; |
| use rustc_ast::{self as ast, AnonConst, AttrStyle, AttrVec, Const, CrateSugar, Extern, Unsafe}; |
| use rustc_ast::{Async, Expr, ExprKind, MacArgs, MacDelimiter, Mutability, StrLit}; |
| use rustc_ast::{Visibility, VisibilityKind}; |
| use rustc_ast_pretty::pprust; |
| use rustc_errors::PResult; |
| use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, FatalError}; |
| use rustc_session::parse::ParseSess; |
| use rustc_span::source_map::{Span, DUMMY_SP}; |
| use rustc_span::symbol::{kw, sym, Ident, Symbol}; |
| use tracing::debug; |
| |
| use std::{cmp, mem, slice}; |
| |
| bitflags::bitflags! { |
| struct Restrictions: u8 { |
| const STMT_EXPR = 1 << 0; |
| const NO_STRUCT_LITERAL = 1 << 1; |
| } |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Debug)] |
| enum SemiColonMode { |
| Break, |
| Ignore, |
| Comma, |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Debug)] |
| enum BlockMode { |
| Break, |
| Ignore, |
| } |
| |
| /// Like `maybe_whole_expr`, but for things other than expressions. |
| #[macro_export] |
| macro_rules! maybe_whole { |
| ($p:expr, $constructor:ident, |$x:ident| $e:expr) => { |
| if let token::Interpolated(nt) = &$p.token.kind { |
| if let token::$constructor(x) = &**nt { |
| let $x = x.clone(); |
| $p.bump(); |
| return Ok($e); |
| } |
| } |
| }; |
| } |
| |
| /// If the next tokens are ill-formed `$ty::` recover them as `<$ty>::`. |
| #[macro_export] |
| macro_rules! maybe_recover_from_interpolated_ty_qpath { |
| ($self: expr, $allow_qpath_recovery: expr) => { |
| if $allow_qpath_recovery && $self.look_ahead(1, |t| t == &token::ModSep) { |
| if let token::Interpolated(nt) = &$self.token.kind { |
| if let token::NtTy(ty) = &**nt { |
| let ty = ty.clone(); |
| $self.bump(); |
| return $self.maybe_recover_from_bad_qpath_stage_2($self.prev_token.span, ty); |
| } |
| } |
| } |
| }; |
| } |
| |
| #[derive(Clone)] |
| pub struct Parser<'a> { |
| pub sess: &'a ParseSess, |
| /// The current token. |
| pub token: Token, |
| /// The spacing for the current token |
| pub token_spacing: Spacing, |
| /// The previous token. |
| pub prev_token: Token, |
| restrictions: Restrictions, |
| expected_tokens: Vec<TokenType>, |
| // Important: This must only be advanced from `next_tok` |
| // to ensure that `token_cursor.num_next_calls` is updated properly |
| token_cursor: TokenCursor, |
| desugar_doc_comments: bool, |
| /// This field is used to keep track of how many left angle brackets we have seen. This is |
| /// required in order to detect extra leading left angle brackets (`<` characters) and error |
| /// appropriately. |
| /// |
| /// See the comments in the `parse_path_segment` function for more details. |
| unmatched_angle_bracket_count: u32, |
| max_angle_bracket_count: u32, |
| /// A list of all unclosed delimiters found by the lexer. If an entry is used for error recovery |
| /// it gets removed from here. Every entry left at the end gets emitted as an independent |
| /// error. |
| pub(super) unclosed_delims: Vec<UnmatchedBrace>, |
| last_unexpected_token_span: Option<Span>, |
| /// Span pointing at the `:` for the last type ascription the parser has seen, and whether it |
| /// looked like it could have been a mistyped path or literal `Option:Some(42)`). |
| pub last_type_ascription: Option<(Span, bool /* likely path typo */)>, |
| /// If present, this `Parser` is not parsing Rust code but rather a macro call. |
| subparser_name: Option<&'static str>, |
| } |
| |
| impl<'a> Drop for Parser<'a> { |
| fn drop(&mut self) { |
| emit_unclosed_delims(&mut self.unclosed_delims, &self.sess); |
| } |
| } |
| |
| #[derive(Clone)] |
| struct TokenCursor { |
| frame: TokenCursorFrame, |
| stack: Vec<TokenCursorFrame>, |
| desugar_doc_comments: bool, |
| // Counts the number of calls to `next` or `next_desugared`, |
| // depending on whether `desugar_doc_comments` is set. |
| num_next_calls: usize, |
| } |
| |
| #[derive(Clone)] |
| struct TokenCursorFrame { |
| delim: token::DelimToken, |
| span: DelimSpan, |
| open_delim: bool, |
| tree_cursor: tokenstream::Cursor, |
| close_delim: bool, |
| } |
| |
| impl TokenCursorFrame { |
| fn new(span: DelimSpan, delim: DelimToken, tts: TokenStream) -> Self { |
| TokenCursorFrame { |
| delim, |
| span, |
| open_delim: delim == token::NoDelim, |
| tree_cursor: tts.into_trees(), |
| close_delim: delim == token::NoDelim, |
| } |
| } |
| } |
| |
| impl TokenCursor { |
| fn next(&mut self) -> (Token, Spacing) { |
| loop { |
| let (tree, spacing) = if !self.frame.open_delim { |
| self.frame.open_delim = true; |
| TokenTree::open_tt(self.frame.span, self.frame.delim).into() |
| } else if let Some(tree) = self.frame.tree_cursor.next_with_spacing() { |
| tree |
| } else if !self.frame.close_delim { |
| self.frame.close_delim = true; |
| TokenTree::close_tt(self.frame.span, self.frame.delim).into() |
| } else if let Some(frame) = self.stack.pop() { |
| self.frame = frame; |
| continue; |
| } else { |
| (TokenTree::Token(Token::new(token::Eof, DUMMY_SP)), Spacing::Alone) |
| }; |
| |
| match tree { |
| TokenTree::Token(token) => { |
| return (token, spacing); |
| } |
| TokenTree::Delimited(sp, delim, tts) => { |
| let frame = TokenCursorFrame::new(sp, delim, tts); |
| self.stack.push(mem::replace(&mut self.frame, frame)); |
| } |
| } |
| } |
| } |
| |
| fn next_desugared(&mut self) -> (Token, Spacing) { |
| let (data, attr_style, sp) = match self.next() { |
| (Token { kind: token::DocComment(_, attr_style, data), span }, _) => { |
| (data, attr_style, span) |
| } |
| tok => return tok, |
| }; |
| |
| // Searches for the occurrences of `"#*` and returns the minimum number of `#`s |
| // required to wrap the text. |
| let mut num_of_hashes = 0; |
| let mut count = 0; |
| for ch in data.as_str().chars() { |
| count = match ch { |
| '"' => 1, |
| '#' if count > 0 => count + 1, |
| _ => 0, |
| }; |
| num_of_hashes = cmp::max(num_of_hashes, count); |
| } |
| |
| let delim_span = DelimSpan::from_single(sp); |
| let body = TokenTree::Delimited( |
| delim_span, |
| token::Bracket, |
| [ |
| TokenTree::token(token::Ident(sym::doc, false), sp), |
| TokenTree::token(token::Eq, sp), |
| TokenTree::token(TokenKind::lit(token::StrRaw(num_of_hashes), data, None), sp), |
| ] |
| .iter() |
| .cloned() |
| .collect::<TokenStream>(), |
| ); |
| |
| self.stack.push(mem::replace( |
| &mut self.frame, |
| TokenCursorFrame::new( |
| delim_span, |
| token::NoDelim, |
| if attr_style == AttrStyle::Inner { |
| [TokenTree::token(token::Pound, sp), TokenTree::token(token::Not, sp), body] |
| .iter() |
| .cloned() |
| .collect::<TokenStream>() |
| } else { |
| [TokenTree::token(token::Pound, sp), body] |
| .iter() |
| .cloned() |
| .collect::<TokenStream>() |
| }, |
| ), |
| )); |
| |
| self.next() |
| } |
| } |
| |
| #[derive(Clone, PartialEq)] |
| enum TokenType { |
| Token(TokenKind), |
| Keyword(Symbol), |
| Operator, |
| Lifetime, |
| Ident, |
| Path, |
| Type, |
| Const, |
| } |
| |
| impl TokenType { |
| fn to_string(&self) -> String { |
| match *self { |
| TokenType::Token(ref t) => format!("`{}`", pprust::token_kind_to_string(t)), |
| TokenType::Keyword(kw) => format!("`{}`", kw), |
| TokenType::Operator => "an operator".to_string(), |
| TokenType::Lifetime => "lifetime".to_string(), |
| TokenType::Ident => "identifier".to_string(), |
| TokenType::Path => "path".to_string(), |
| TokenType::Type => "type".to_string(), |
| TokenType::Const => "const".to_string(), |
| } |
| } |
| } |
| |
| #[derive(Copy, Clone, Debug)] |
| enum TokenExpectType { |
| Expect, |
| NoExpect, |
| } |
| |
| /// A sequence separator. |
| struct SeqSep { |
| /// The separator token. |
| sep: Option<TokenKind>, |
| /// `true` if a trailing separator is allowed. |
| trailing_sep_allowed: bool, |
| } |
| |
| impl SeqSep { |
| fn trailing_allowed(t: TokenKind) -> SeqSep { |
| SeqSep { sep: Some(t), trailing_sep_allowed: true } |
| } |
| |
| fn none() -> SeqSep { |
| SeqSep { sep: None, trailing_sep_allowed: false } |
| } |
| } |
| |
| pub enum FollowedByType { |
| Yes, |
| No, |
| } |
| |
| fn token_descr_opt(token: &Token) -> Option<&'static str> { |
| Some(match token.kind { |
| _ if token.is_special_ident() => "reserved identifier", |
| _ if token.is_used_keyword() => "keyword", |
| _ if token.is_unused_keyword() => "reserved keyword", |
| token::DocComment(..) => "doc comment", |
| _ => return None, |
| }) |
| } |
| |
| pub(super) fn token_descr(token: &Token) -> String { |
| let token_str = pprust::token_to_string(token); |
| match token_descr_opt(token) { |
| Some(prefix) => format!("{} `{}`", prefix, token_str), |
| _ => format!("`{}`", token_str), |
| } |
| } |
| |
| impl<'a> Parser<'a> { |
| pub fn new( |
| sess: &'a ParseSess, |
| tokens: TokenStream, |
| desugar_doc_comments: bool, |
| subparser_name: Option<&'static str>, |
| ) -> Self { |
| let mut parser = Parser { |
| sess, |
| token: Token::dummy(), |
| token_spacing: Spacing::Alone, |
| prev_token: Token::dummy(), |
| restrictions: Restrictions::empty(), |
| expected_tokens: Vec::new(), |
| token_cursor: TokenCursor { |
| frame: TokenCursorFrame::new(DelimSpan::dummy(), token::NoDelim, tokens), |
| stack: Vec::new(), |
| num_next_calls: 0, |
| desugar_doc_comments, |
| }, |
| desugar_doc_comments, |
| unmatched_angle_bracket_count: 0, |
| max_angle_bracket_count: 0, |
| unclosed_delims: Vec::new(), |
| last_unexpected_token_span: None, |
| last_type_ascription: None, |
| subparser_name, |
| }; |
| |
| // Make parser point to the first token. |
| parser.bump(); |
| |
| parser |
| } |
| |
| fn next_tok(&mut self, fallback_span: Span) -> (Token, Spacing) { |
| let (mut next, spacing) = if self.desugar_doc_comments { |
| self.token_cursor.next_desugared() |
| } else { |
| self.token_cursor.next() |
| }; |
| self.token_cursor.num_next_calls += 1; |
| if next.span.is_dummy() { |
| // Tweak the location for better diagnostics, but keep syntactic context intact. |
| next.span = fallback_span.with_ctxt(next.span.ctxt()); |
| } |
| (next, spacing) |
| } |
| |
| pub fn unexpected<T>(&mut self) -> PResult<'a, T> { |
| match self.expect_one_of(&[], &[]) { |
| Err(e) => Err(e), |
| // We can get `Ok(true)` from `recover_closing_delimiter` |
| // which is called in `expected_one_of_not_found`. |
| Ok(_) => FatalError.raise(), |
| } |
| } |
| |
| /// Expects and consumes the token `t`. Signals an error if the next token is not `t`. |
| pub fn expect(&mut self, t: &TokenKind) -> PResult<'a, bool /* recovered */> { |
| if self.expected_tokens.is_empty() { |
| if self.token == *t { |
| self.bump(); |
| Ok(false) |
| } else { |
| self.unexpected_try_recover(t) |
| } |
| } else { |
| self.expect_one_of(slice::from_ref(t), &[]) |
| } |
| } |
| |
| /// Expect next token to be edible or inedible token. If edible, |
| /// then consume it; if inedible, then return without consuming |
| /// anything. Signal a fatal error if next token is unexpected. |
| pub fn expect_one_of( |
| &mut self, |
| edible: &[TokenKind], |
| inedible: &[TokenKind], |
| ) -> PResult<'a, bool /* recovered */> { |
| if edible.contains(&self.token.kind) { |
| self.bump(); |
| Ok(false) |
| } else if inedible.contains(&self.token.kind) { |
| // leave it in the input |
| Ok(false) |
| } else if self.last_unexpected_token_span == Some(self.token.span) { |
| FatalError.raise(); |
| } else { |
| self.expected_one_of_not_found(edible, inedible) |
| } |
| } |
| |
| // Public for rustfmt usage. |
| pub fn parse_ident(&mut self) -> PResult<'a, Ident> { |
| self.parse_ident_common(true) |
| } |
| |
| fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, Ident> { |
| match self.token.ident() { |
| Some((ident, is_raw)) => { |
| if !is_raw && ident.is_reserved() { |
| let mut err = self.expected_ident_found(); |
| if recover { |
| err.emit(); |
| } else { |
| return Err(err); |
| } |
| } |
| self.bump(); |
| Ok(ident) |
| } |
| _ => Err(match self.prev_token.kind { |
| TokenKind::DocComment(..) => { |
| self.span_fatal_err(self.prev_token.span, Error::UselessDocComment) |
| } |
| _ => self.expected_ident_found(), |
| }), |
| } |
| } |
| |
| /// Checks if the next token is `tok`, and returns `true` if so. |
| /// |
| /// This method will automatically add `tok` to `expected_tokens` if `tok` is not |
| /// encountered. |
| fn check(&mut self, tok: &TokenKind) -> bool { |
| let is_present = self.token == *tok; |
| if !is_present { |
| self.expected_tokens.push(TokenType::Token(tok.clone())); |
| } |
| is_present |
| } |
| |
| /// Consumes a token 'tok' if it exists. Returns whether the given token was present. |
| pub fn eat(&mut self, tok: &TokenKind) -> bool { |
| let is_present = self.check(tok); |
| if is_present { |
| self.bump() |
| } |
| is_present |
| } |
| |
| /// If the next token is the given keyword, returns `true` without eating it. |
| /// An expectation is also added for diagnostics purposes. |
| fn check_keyword(&mut self, kw: Symbol) -> bool { |
| self.expected_tokens.push(TokenType::Keyword(kw)); |
| self.token.is_keyword(kw) |
| } |
| |
| /// If the next token is the given keyword, eats it and returns `true`. |
| /// Otherwise, returns `false`. An expectation is also added for diagnostics purposes. |
| // Public for rustfmt usage. |
| pub fn eat_keyword(&mut self, kw: Symbol) -> bool { |
| if self.check_keyword(kw) { |
| self.bump(); |
| true |
| } else { |
| false |
| } |
| } |
| |
| fn eat_keyword_noexpect(&mut self, kw: Symbol) -> bool { |
| if self.token.is_keyword(kw) { |
| self.bump(); |
| true |
| } else { |
| false |
| } |
| } |
| |
| /// If the given word is not a keyword, signals an error. |
| /// If the next token is not the given word, signals an error. |
| /// Otherwise, eats it. |
| fn expect_keyword(&mut self, kw: Symbol) -> PResult<'a, ()> { |
| if !self.eat_keyword(kw) { self.unexpected() } else { Ok(()) } |
| } |
| |
| /// Is the given keyword `kw` followed by a non-reserved identifier? |
| fn is_kw_followed_by_ident(&self, kw: Symbol) -> bool { |
| self.token.is_keyword(kw) && self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident()) |
| } |
| |
| fn check_or_expected(&mut self, ok: bool, typ: TokenType) -> bool { |
| if ok { |
| true |
| } else { |
| self.expected_tokens.push(typ); |
| false |
| } |
| } |
| |
| fn check_ident(&mut self) -> bool { |
| self.check_or_expected(self.token.is_ident(), TokenType::Ident) |
| } |
| |
| fn check_path(&mut self) -> bool { |
| self.check_or_expected(self.token.is_path_start(), TokenType::Path) |
| } |
| |
| fn check_type(&mut self) -> bool { |
| self.check_or_expected(self.token.can_begin_type(), TokenType::Type) |
| } |
| |
| fn check_const_arg(&mut self) -> bool { |
| self.check_or_expected(self.token.can_begin_const_arg(), TokenType::Const) |
| } |
| |
| fn check_inline_const(&self, dist: usize) -> bool { |
| self.is_keyword_ahead(dist, &[kw::Const]) |
| && self.look_ahead(dist + 1, |t| match t.kind { |
| token::Interpolated(ref nt) => matches!(**nt, token::NtBlock(..)), |
| token::OpenDelim(DelimToken::Brace) => true, |
| _ => false, |
| }) |
| } |
| |
| /// Checks to see if the next token is either `+` or `+=`. |
| /// Otherwise returns `false`. |
| fn check_plus(&mut self) -> bool { |
| self.check_or_expected( |
| self.token.is_like_plus(), |
| TokenType::Token(token::BinOp(token::Plus)), |
| ) |
| } |
| |
| /// Eats the expected token if it's present possibly breaking |
| /// compound tokens like multi-character operators in process. |
| /// Returns `true` if the token was eaten. |
| fn break_and_eat(&mut self, expected: TokenKind) -> bool { |
| if self.token.kind == expected { |
| self.bump(); |
| return true; |
| } |
| match self.token.kind.break_two_token_op() { |
| Some((first, second)) if first == expected => { |
| let first_span = self.sess.source_map().start_point(self.token.span); |
| let second_span = self.token.span.with_lo(first_span.hi()); |
| self.token = Token::new(first, first_span); |
| // Use the spacing of the glued token as the spacing |
| // of the unglued second token. |
| self.bump_with((Token::new(second, second_span), self.token_spacing)); |
| true |
| } |
| _ => { |
| self.expected_tokens.push(TokenType::Token(expected)); |
| false |
| } |
| } |
| } |
| |
| /// Eats `+` possibly breaking tokens like `+=` in process. |
| fn eat_plus(&mut self) -> bool { |
| self.break_and_eat(token::BinOp(token::Plus)) |
| } |
| |
| /// Eats `&` possibly breaking tokens like `&&` in process. |
| /// Signals an error if `&` is not eaten. |
| fn expect_and(&mut self) -> PResult<'a, ()> { |
| if self.break_and_eat(token::BinOp(token::And)) { Ok(()) } else { self.unexpected() } |
| } |
| |
| /// Eats `|` possibly breaking tokens like `||` in process. |
| /// Signals an error if `|` was not eaten. |
| fn expect_or(&mut self) -> PResult<'a, ()> { |
| if self.break_and_eat(token::BinOp(token::Or)) { Ok(()) } else { self.unexpected() } |
| } |
| |
| /// Eats `<` possibly breaking tokens like `<<` in process. |
| fn eat_lt(&mut self) -> bool { |
| let ate = self.break_and_eat(token::Lt); |
| if ate { |
| // See doc comment for `unmatched_angle_bracket_count`. |
| self.unmatched_angle_bracket_count += 1; |
| self.max_angle_bracket_count += 1; |
| debug!("eat_lt: (increment) count={:?}", self.unmatched_angle_bracket_count); |
| } |
| ate |
| } |
| |
| /// Eats `<` possibly breaking tokens like `<<` in process. |
| /// Signals an error if `<` was not eaten. |
| fn expect_lt(&mut self) -> PResult<'a, ()> { |
| if self.eat_lt() { Ok(()) } else { self.unexpected() } |
| } |
| |
| /// Eats `>` possibly breaking tokens like `>>` in process. |
| /// Signals an error if `>` was not eaten. |
| fn expect_gt(&mut self) -> PResult<'a, ()> { |
| if self.break_and_eat(token::Gt) { |
| // See doc comment for `unmatched_angle_bracket_count`. |
| if self.unmatched_angle_bracket_count > 0 { |
| self.unmatched_angle_bracket_count -= 1; |
| debug!("expect_gt: (decrement) count={:?}", self.unmatched_angle_bracket_count); |
| } |
| Ok(()) |
| } else { |
| self.unexpected() |
| } |
| } |
| |
| fn expect_any_with_type(&mut self, kets: &[&TokenKind], expect: TokenExpectType) -> bool { |
| kets.iter().any(|k| match expect { |
| TokenExpectType::Expect => self.check(k), |
| TokenExpectType::NoExpect => self.token == **k, |
| }) |
| } |
| |
| fn parse_seq_to_before_tokens<T>( |
| &mut self, |
| kets: &[&TokenKind], |
| sep: SeqSep, |
| expect: TokenExpectType, |
| mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, |
| ) -> PResult<'a, (Vec<T>, bool /* trailing */, bool /* recovered */)> { |
| let mut first = true; |
| let mut recovered = false; |
| let mut trailing = false; |
| let mut v = vec![]; |
| while !self.expect_any_with_type(kets, expect) { |
| if let token::CloseDelim(..) | token::Eof = self.token.kind { |
| break; |
| } |
| if let Some(ref t) = sep.sep { |
| if first { |
| first = false; |
| } else { |
| match self.expect(t) { |
| Ok(false) => {} |
| Ok(true) => { |
| recovered = true; |
| break; |
| } |
| Err(mut expect_err) => { |
| let sp = self.prev_token.span.shrink_to_hi(); |
| let token_str = pprust::token_kind_to_string(t); |
| |
| // Attempt to keep parsing if it was a similar separator. |
| if let Some(ref tokens) = t.similar_tokens() { |
| if tokens.contains(&self.token.kind) { |
| self.bump(); |
| } |
| } |
| |
| // If this was a missing `@` in a binding pattern |
| // bail with a suggestion |
| // https://github.com/rust-lang/rust/issues/72373 |
| if self.prev_token.is_ident() && self.token.kind == token::DotDot { |
| let msg = format!( |
| "if you meant to bind the contents of \ |
| the rest of the array pattern into `{}`, use `@`", |
| pprust::token_to_string(&self.prev_token) |
| ); |
| expect_err |
| .span_suggestion_verbose( |
| self.prev_token.span.shrink_to_hi().until(self.token.span), |
| &msg, |
| " @ ".to_string(), |
| Applicability::MaybeIncorrect, |
| ) |
| .emit(); |
| break; |
| } |
| |
| // Attempt to keep parsing if it was an omitted separator. |
| match f(self) { |
| Ok(t) => { |
| // Parsed successfully, therefore most probably the code only |
| // misses a separator. |
| let mut exp_span = self.sess.source_map().next_point(sp); |
| if self.sess.source_map().is_multiline(exp_span) { |
| exp_span = sp; |
| } |
| expect_err |
| .span_suggestion_short( |
| exp_span, |
| &format!("missing `{}`", token_str), |
| token_str, |
| Applicability::MaybeIncorrect, |
| ) |
| .emit(); |
| |
| v.push(t); |
| continue; |
| } |
| Err(mut e) => { |
| // Parsing failed, therefore it must be something more serious |
| // than just a missing separator. |
| expect_err.emit(); |
| |
| e.cancel(); |
| break; |
| } |
| } |
| } |
| } |
| } |
| } |
| if sep.trailing_sep_allowed && self.expect_any_with_type(kets, expect) { |
| trailing = true; |
| break; |
| } |
| |
| let t = f(self)?; |
| v.push(t); |
| } |
| |
| Ok((v, trailing, recovered)) |
| } |
| |
| /// Parses a sequence, not including the closing delimiter. The function |
| /// `f` must consume tokens until reaching the next separator or |
| /// closing bracket. |
| fn parse_seq_to_before_end<T>( |
| &mut self, |
| ket: &TokenKind, |
| sep: SeqSep, |
| f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, |
| ) -> PResult<'a, (Vec<T>, bool, bool)> { |
| self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f) |
| } |
| |
| /// Parses a sequence, including the closing delimiter. The function |
| /// `f` must consume tokens until reaching the next separator or |
| /// closing bracket. |
| fn parse_seq_to_end<T>( |
| &mut self, |
| ket: &TokenKind, |
| sep: SeqSep, |
| f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, |
| ) -> PResult<'a, (Vec<T>, bool /* trailing */)> { |
| let (val, trailing, recovered) = self.parse_seq_to_before_end(ket, sep, f)?; |
| if !recovered { |
| self.eat(ket); |
| } |
| Ok((val, trailing)) |
| } |
| |
| /// Parses a sequence, including the closing delimiter. The function |
| /// `f` must consume tokens until reaching the next separator or |
| /// closing bracket. |
| fn parse_unspanned_seq<T>( |
| &mut self, |
| bra: &TokenKind, |
| ket: &TokenKind, |
| sep: SeqSep, |
| f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, |
| ) -> PResult<'a, (Vec<T>, bool)> { |
| self.expect(bra)?; |
| self.parse_seq_to_end(ket, sep, f) |
| } |
| |
| fn parse_delim_comma_seq<T>( |
| &mut self, |
| delim: DelimToken, |
| f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, |
| ) -> PResult<'a, (Vec<T>, bool)> { |
| self.parse_unspanned_seq( |
| &token::OpenDelim(delim), |
| &token::CloseDelim(delim), |
| SeqSep::trailing_allowed(token::Comma), |
| f, |
| ) |
| } |
| |
| fn parse_paren_comma_seq<T>( |
| &mut self, |
| f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, |
| ) -> PResult<'a, (Vec<T>, bool)> { |
| self.parse_delim_comma_seq(token::Paren, f) |
| } |
| |
| /// Advance the parser by one token using provided token as the next one. |
| fn bump_with(&mut self, (next_token, next_spacing): (Token, Spacing)) { |
| // Bumping after EOF is a bad sign, usually an infinite loop. |
| if self.prev_token.kind == TokenKind::Eof { |
| let msg = "attempted to bump the parser past EOF (may be stuck in a loop)"; |
| self.span_bug(self.token.span, msg); |
| } |
| |
| // Update the current and previous tokens. |
| self.prev_token = mem::replace(&mut self.token, next_token); |
| self.token_spacing = next_spacing; |
| |
| // Diagnostics. |
| self.expected_tokens.clear(); |
| } |
| |
| /// Advance the parser by one token. |
| pub fn bump(&mut self) { |
| let next_token = self.next_tok(self.token.span); |
| self.bump_with(next_token); |
| } |
| |
| /// Look-ahead `dist` tokens of `self.token` and get access to that token there. |
| /// When `dist == 0` then the current token is looked at. |
| pub fn look_ahead<R>(&self, dist: usize, looker: impl FnOnce(&Token) -> R) -> R { |
| if dist == 0 { |
| return looker(&self.token); |
| } |
| |
| let frame = &self.token_cursor.frame; |
| match frame.tree_cursor.look_ahead(dist - 1) { |
| Some(tree) => match tree { |
| TokenTree::Token(token) => looker(token), |
| TokenTree::Delimited(dspan, delim, _) => { |
| looker(&Token::new(token::OpenDelim(*delim), dspan.open)) |
| } |
| }, |
| None => looker(&Token::new(token::CloseDelim(frame.delim), frame.span.close)), |
| } |
| } |
| |
| /// Returns whether any of the given keywords are `dist` tokens ahead of the current one. |
| fn is_keyword_ahead(&self, dist: usize, kws: &[Symbol]) -> bool { |
| self.look_ahead(dist, |t| kws.iter().any(|&kw| t.is_keyword(kw))) |
| } |
| |
| /// Parses asyncness: `async` or nothing. |
| fn parse_asyncness(&mut self) -> Async { |
| if self.eat_keyword(kw::Async) { |
| let span = self.prev_token.uninterpolated_span(); |
| Async::Yes { span, closure_id: DUMMY_NODE_ID, return_impl_trait_id: DUMMY_NODE_ID } |
| } else { |
| Async::No |
| } |
| } |
| |
| /// Parses unsafety: `unsafe` or nothing. |
| fn parse_unsafety(&mut self) -> Unsafe { |
| if self.eat_keyword(kw::Unsafe) { |
| Unsafe::Yes(self.prev_token.uninterpolated_span()) |
| } else { |
| Unsafe::No |
| } |
| } |
| |
| /// Parses constness: `const` or nothing. |
| fn parse_constness(&mut self) -> Const { |
| // Avoid const blocks to be parsed as const items |
| if self.look_ahead(1, |t| t != &token::OpenDelim(DelimToken::Brace)) |
| && self.eat_keyword(kw::Const) |
| { |
| Const::Yes(self.prev_token.uninterpolated_span()) |
| } else { |
| Const::No |
| } |
| } |
| |
| /// Parses inline const expressions. |
| fn parse_const_block(&mut self, span: Span) -> PResult<'a, P<Expr>> { |
| self.sess.gated_spans.gate(sym::inline_const, span); |
| self.eat_keyword(kw::Const); |
| let blk = self.parse_block()?; |
| let anon_const = AnonConst { |
| id: DUMMY_NODE_ID, |
| value: self.mk_expr(blk.span, ExprKind::Block(blk, None), AttrVec::new()), |
| }; |
| Ok(self.mk_expr(span, ExprKind::ConstBlock(anon_const), AttrVec::new())) |
| } |
| |
| /// Parses mutability (`mut` or nothing). |
| fn parse_mutability(&mut self) -> Mutability { |
| if self.eat_keyword(kw::Mut) { Mutability::Mut } else { Mutability::Not } |
| } |
| |
| /// Possibly parses mutability (`const` or `mut`). |
| fn parse_const_or_mut(&mut self) -> Option<Mutability> { |
| if self.eat_keyword(kw::Mut) { |
| Some(Mutability::Mut) |
| } else if self.eat_keyword(kw::Const) { |
| Some(Mutability::Not) |
| } else { |
| None |
| } |
| } |
| |
| fn parse_field_name(&mut self) -> PResult<'a, Ident> { |
| if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) = self.token.kind |
| { |
| self.expect_no_suffix(self.token.span, "a tuple index", suffix); |
| self.bump(); |
| Ok(Ident::new(symbol, self.prev_token.span)) |
| } else { |
| self.parse_ident_common(false) |
| } |
| } |
| |
| fn parse_mac_args(&mut self) -> PResult<'a, P<MacArgs>> { |
| self.parse_mac_args_common(true).map(P) |
| } |
| |
| fn parse_attr_args(&mut self) -> PResult<'a, MacArgs> { |
| self.parse_mac_args_common(false) |
| } |
| |
| fn parse_mac_args_common(&mut self, delimited_only: bool) -> PResult<'a, MacArgs> { |
| Ok( |
| if self.check(&token::OpenDelim(DelimToken::Paren)) |
| || self.check(&token::OpenDelim(DelimToken::Bracket)) |
| || self.check(&token::OpenDelim(DelimToken::Brace)) |
| { |
| match self.parse_token_tree() { |
| TokenTree::Delimited(dspan, delim, tokens) => |
| // We've confirmed above that there is a delimiter so unwrapping is OK. |
| { |
| MacArgs::Delimited(dspan, MacDelimiter::from_token(delim).unwrap(), tokens) |
| } |
| _ => unreachable!(), |
| } |
| } else if !delimited_only { |
| if self.eat(&token::Eq) { |
| let eq_span = self.prev_token.span; |
| let mut is_interpolated_expr = false; |
| if let token::Interpolated(nt) = &self.token.kind { |
| if let token::NtExpr(..) = **nt { |
| is_interpolated_expr = true; |
| } |
| } |
| let token_tree = if is_interpolated_expr { |
| // We need to accept arbitrary interpolated expressions to continue |
| // supporting things like `doc = $expr` that work on stable. |
| // Non-literal interpolated expressions are rejected after expansion. |
| self.parse_token_tree() |
| } else { |
| self.parse_unsuffixed_lit()?.token_tree() |
| }; |
| |
| MacArgs::Eq(eq_span, token_tree.into()) |
| } else { |
| MacArgs::Empty |
| } |
| } else { |
| return self.unexpected(); |
| }, |
| ) |
| } |
| |
| fn parse_or_use_outer_attributes( |
| &mut self, |
| already_parsed_attrs: Option<AttrVec>, |
| ) -> PResult<'a, AttrVec> { |
| if let Some(attrs) = already_parsed_attrs { |
| Ok(attrs) |
| } else { |
| self.parse_outer_attributes().map(|a| a.into()) |
| } |
| } |
| |
| /// Parses a single token tree from the input. |
| pub(crate) fn parse_token_tree(&mut self) -> TokenTree { |
| match self.token.kind { |
| token::OpenDelim(..) => { |
| let depth = self.token_cursor.stack.len(); |
| |
| // We keep advancing the token cursor until we hit |
| // the matching `CloseDelim` token. |
| while !(depth == self.token_cursor.stack.len() |
| && matches!(self.token.kind, token::CloseDelim(_))) |
| { |
| // Advance one token at a time, so `TokenCursor::next()` |
| // can capture these tokens if necessary. |
| self.bump(); |
| } |
| // We are still inside the frame corresponding |
| // to the delimited stream we captured, so grab |
| // the tokens from this frame. |
| let frame = &self.token_cursor.frame; |
| let stream = frame.tree_cursor.stream.clone(); |
| let span = frame.span; |
| let delim = frame.delim; |
| // Consume close delimiter |
| self.bump(); |
| TokenTree::Delimited(span, delim, stream) |
| } |
| token::CloseDelim(_) | token::Eof => unreachable!(), |
| _ => { |
| self.bump(); |
| TokenTree::Token(self.prev_token.clone()) |
| } |
| } |
| } |
| |
| /// Parses a stream of tokens into a list of `TokenTree`s, up to EOF. |
| pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> { |
| let mut tts = Vec::new(); |
| while self.token != token::Eof { |
| tts.push(self.parse_token_tree()); |
| } |
| Ok(tts) |
| } |
| |
| pub fn parse_tokens(&mut self) -> TokenStream { |
| let mut result = Vec::new(); |
| loop { |
| match self.token.kind { |
| token::Eof | token::CloseDelim(..) => break, |
| _ => result.push(self.parse_token_tree().into()), |
| } |
| } |
| TokenStream::new(result) |
| } |
| |
| /// Evaluates the closure with restrictions in place. |
| /// |
| /// Afters the closure is evaluated, restrictions are reset. |
| fn with_res<T>(&mut self, res: Restrictions, f: impl FnOnce(&mut Self) -> T) -> T { |
| let old = self.restrictions; |
| self.restrictions = res; |
| let res = f(self); |
| self.restrictions = old; |
| res |
| } |
| |
| fn is_crate_vis(&self) -> bool { |
| self.token.is_keyword(kw::Crate) && self.look_ahead(1, |t| t != &token::ModSep) |
| } |
| |
| /// Parses `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`, |
| /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`. |
| /// If the following element can't be a tuple (i.e., it's a function definition), then |
| /// it's not a tuple struct field), and the contents within the parentheses isn't valid, |
| /// so emit a proper diagnostic. |
| // Public for rustfmt usage. |
| pub fn parse_visibility(&mut self, fbt: FollowedByType) -> PResult<'a, Visibility> { |
| maybe_whole!(self, NtVis, |x| x); |
| |
| self.expected_tokens.push(TokenType::Keyword(kw::Crate)); |
| if self.is_crate_vis() { |
| self.bump(); // `crate` |
| self.sess.gated_spans.gate(sym::crate_visibility_modifier, self.prev_token.span); |
| return Ok(Visibility { |
| span: self.prev_token.span, |
| kind: VisibilityKind::Crate(CrateSugar::JustCrate), |
| tokens: None, |
| }); |
| } |
| |
| if !self.eat_keyword(kw::Pub) { |
| // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no |
| // keyword to grab a span from for inherited visibility; an empty span at the |
| // beginning of the current token would seem to be the "Schelling span". |
| return Ok(Visibility { |
| span: self.token.span.shrink_to_lo(), |
| kind: VisibilityKind::Inherited, |
| tokens: None, |
| }); |
| } |
| let lo = self.prev_token.span; |
| |
| if self.check(&token::OpenDelim(token::Paren)) { |
| // We don't `self.bump()` the `(` yet because this might be a struct definition where |
| // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`. |
| // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so |
| // by the following tokens. |
| if self.is_keyword_ahead(1, &[kw::Crate]) && self.look_ahead(2, |t| t != &token::ModSep) |
| // account for `pub(crate::foo)` |
| { |
| // Parse `pub(crate)`. |
| self.bump(); // `(` |
| self.bump(); // `crate` |
| self.expect(&token::CloseDelim(token::Paren))?; // `)` |
| let vis = VisibilityKind::Crate(CrateSugar::PubCrate); |
| return Ok(Visibility { |
| span: lo.to(self.prev_token.span), |
| kind: vis, |
| tokens: None, |
| }); |
| } else if self.is_keyword_ahead(1, &[kw::In]) { |
| // Parse `pub(in path)`. |
| self.bump(); // `(` |
| self.bump(); // `in` |
| let path = self.parse_path(PathStyle::Mod)?; // `path` |
| self.expect(&token::CloseDelim(token::Paren))?; // `)` |
| let vis = VisibilityKind::Restricted { path: P(path), id: ast::DUMMY_NODE_ID }; |
| return Ok(Visibility { |
| span: lo.to(self.prev_token.span), |
| kind: vis, |
| tokens: None, |
| }); |
| } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) |
| && self.is_keyword_ahead(1, &[kw::Super, kw::SelfLower]) |
| { |
| // Parse `pub(self)` or `pub(super)`. |
| self.bump(); // `(` |
| let path = self.parse_path(PathStyle::Mod)?; // `super`/`self` |
| self.expect(&token::CloseDelim(token::Paren))?; // `)` |
| let vis = VisibilityKind::Restricted { path: P(path), id: ast::DUMMY_NODE_ID }; |
| return Ok(Visibility { |
| span: lo.to(self.prev_token.span), |
| kind: vis, |
| tokens: None, |
| }); |
| } else if let FollowedByType::No = fbt { |
| // Provide this diagnostic if a type cannot follow; |
| // in particular, if this is not a tuple struct. |
| self.recover_incorrect_vis_restriction()?; |
| // Emit diagnostic, but continue with public visibility. |
| } |
| } |
| |
| Ok(Visibility { span: lo, kind: VisibilityKind::Public, tokens: None }) |
| } |
| |
| /// Recovery for e.g. `pub(something) fn ...` or `struct X { pub(something) y: Z }` |
| fn recover_incorrect_vis_restriction(&mut self) -> PResult<'a, ()> { |
| self.bump(); // `(` |
| let path = self.parse_path(PathStyle::Mod)?; |
| self.expect(&token::CloseDelim(token::Paren))?; // `)` |
| |
| let msg = "incorrect visibility restriction"; |
| let suggestion = r##"some possible visibility restrictions are: |
| `pub(crate)`: visible only on the current crate |
| `pub(super)`: visible only in the current module's parent |
| `pub(in path::to::module)`: visible only on the specified path"##; |
| |
| let path_str = pprust::path_to_string(&path); |
| |
| struct_span_err!(self.sess.span_diagnostic, path.span, E0704, "{}", msg) |
| .help(suggestion) |
| .span_suggestion( |
| path.span, |
| &format!("make this visible only to module `{}` with `in`", path_str), |
| format!("in {}", path_str), |
| Applicability::MachineApplicable, |
| ) |
| .emit(); |
| |
| Ok(()) |
| } |
| |
| /// Parses `extern string_literal?`. |
| fn parse_extern(&mut self) -> PResult<'a, Extern> { |
| Ok(if self.eat_keyword(kw::Extern) { |
| Extern::from_abi(self.parse_abi()) |
| } else { |
| Extern::None |
| }) |
| } |
| |
| /// Parses a string literal as an ABI spec. |
| fn parse_abi(&mut self) -> Option<StrLit> { |
| match self.parse_str_lit() { |
| Ok(str_lit) => Some(str_lit), |
| Err(Some(lit)) => match lit.kind { |
| ast::LitKind::Err(_) => None, |
| _ => { |
| self.struct_span_err(lit.span, "non-string ABI literal") |
| .span_suggestion( |
| lit.span, |
| "specify the ABI with a string literal", |
| "\"C\"".to_string(), |
| Applicability::MaybeIncorrect, |
| ) |
| .emit(); |
| None |
| } |
| }, |
| Err(None) => None, |
| } |
| } |
| |
| /// Records all tokens consumed by the provided callback, |
| /// including the current token. These tokens are collected |
| /// into a `TokenStream`, and returned along with the result |
| /// of the callback. |
| /// |
| /// Note: If your callback consumes an opening delimiter |
| /// (including the case where you call `collect_tokens` |
| /// when the current token is an opening delimeter), |
| /// you must also consume the corresponding closing delimiter. |
| /// |
| /// That is, you can consume |
| /// `something ([{ }])` or `([{}])`, but not `([{}]` |
| /// |
| /// This restriction shouldn't be an issue in practice, |
| /// since this function is used to record the tokens for |
| /// a parsed AST item, which always has matching delimiters. |
| pub fn collect_tokens<R>( |
| &mut self, |
| f: impl FnOnce(&mut Self) -> PResult<'a, R>, |
| ) -> PResult<'a, (R, LazyTokenStream)> { |
| let start_token = (self.token.clone(), self.token_spacing); |
| let mut cursor_snapshot = self.token_cursor.clone(); |
| |
| let ret = f(self)?; |
| |
| let new_calls = self.token_cursor.num_next_calls; |
| let num_calls = new_calls - cursor_snapshot.num_next_calls; |
| let desugar_doc_comments = self.desugar_doc_comments; |
| |
| // Produces a `TokenStream` on-demand. Using `cursor_snapshot` |
| // and `num_calls`, we can reconstruct the `TokenStream` seen |
| // by the callback. This allows us to avoid producing a `TokenStream` |
| // if it is never needed - for example, a captured `macro_rules!` |
| // argument that is never passed to a proc macro. |
| // |
| // This also makes `Parser` very cheap to clone, since |
| // there is no intermediate collection buffer to clone. |
| let lazy_cb = move || { |
| // The token produced by the final call to `next` or `next_desugared` |
| // was not actually consumed by the callback. The combination |
| // of chaining the initial token and using `take` produces the desired |
| // result - we produce an empty `TokenStream` if no calls were made, |
| // and omit the final token otherwise. |
| let tokens = std::iter::once(start_token) |
| .chain((0..num_calls).map(|_| { |
| if desugar_doc_comments { |
| cursor_snapshot.next_desugared() |
| } else { |
| cursor_snapshot.next() |
| } |
| })) |
| .take(num_calls); |
| |
| make_token_stream(tokens) |
| }; |
| let stream = LazyTokenStream::new(LazyTokenStreamInner::Lazy(Box::new(lazy_cb))); |
| |
| Ok((ret, stream)) |
| } |
| |
| /// `::{` or `::*` |
| fn is_import_coupler(&mut self) -> bool { |
| self.check(&token::ModSep) |
| && self.look_ahead(1, |t| { |
| *t == token::OpenDelim(token::Brace) || *t == token::BinOp(token::Star) |
| }) |
| } |
| |
| pub fn clear_expected_tokens(&mut self) { |
| self.expected_tokens.clear(); |
| } |
| } |
| |
| crate fn make_unclosed_delims_error( |
| unmatched: UnmatchedBrace, |
| sess: &ParseSess, |
| ) -> Option<DiagnosticBuilder<'_>> { |
| // `None` here means an `Eof` was found. We already emit those errors elsewhere, we add them to |
| // `unmatched_braces` only for error recovery in the `Parser`. |
| let found_delim = unmatched.found_delim?; |
| let mut err = sess.span_diagnostic.struct_span_err( |
| unmatched.found_span, |
| &format!( |
| "mismatched closing delimiter: `{}`", |
| pprust::token_kind_to_string(&token::CloseDelim(found_delim)), |
| ), |
| ); |
| err.span_label(unmatched.found_span, "mismatched closing delimiter"); |
| if let Some(sp) = unmatched.candidate_span { |
| err.span_label(sp, "closing delimiter possibly meant for this"); |
| } |
| if let Some(sp) = unmatched.unclosed_span { |
| err.span_label(sp, "unclosed delimiter"); |
| } |
| Some(err) |
| } |
| |
| pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, sess: &ParseSess) { |
| *sess.reached_eof.borrow_mut() |= |
| unclosed_delims.iter().any(|unmatched_delim| unmatched_delim.found_delim.is_none()); |
| for unmatched in unclosed_delims.drain(..) { |
| if let Some(mut e) = make_unclosed_delims_error(unmatched, sess) { |
| e.emit(); |
| } |
| } |
| } |
| |
| /// Converts a flattened iterator of tokens (including open and close delimiter tokens) |
| /// into a `TokenStream`, creating a `TokenTree::Delimited` for each matching pair |
| /// of open and close delims. |
| fn make_token_stream(tokens: impl Iterator<Item = (Token, Spacing)>) -> TokenStream { |
| #[derive(Debug)] |
| struct FrameData { |
| open: Span, |
| inner: Vec<(TokenTree, Spacing)>, |
| } |
| let mut stack = vec![FrameData { open: DUMMY_SP, inner: vec![] }]; |
| for (token, spacing) in tokens { |
| match token { |
| Token { kind: TokenKind::OpenDelim(_), span } => { |
| stack.push(FrameData { open: span, inner: vec![] }); |
| } |
| Token { kind: TokenKind::CloseDelim(delim), span } => { |
| let frame_data = stack.pop().expect("Token stack was empty!"); |
| let dspan = DelimSpan::from_pair(frame_data.open, span); |
| let stream = TokenStream::new(frame_data.inner); |
| let delimited = TokenTree::Delimited(dspan, delim, stream); |
| stack |
| .last_mut() |
| .unwrap_or_else(|| panic!("Bottom token frame is missing for tokens!")) |
| .inner |
| .push((delimited, Spacing::Alone)); |
| } |
| token => stack |
| .last_mut() |
| .expect("Bottom token frame is missing!") |
| .inner |
| .push((TokenTree::Token(token), spacing)), |
| } |
| } |
| let final_buf = stack.pop().expect("Missing final buf!"); |
| assert!(stack.is_empty(), "Stack should be empty: final_buf={:?} stack={:?}", final_buf, stack); |
| TokenStream::new(final_buf.inner) |
| } |
