diff options
Diffstat (limited to 'src/librustc_parse/parser')
| -rw-r--r-- | src/librustc_parse/parser/expr.rs | 2 | ||||
| -rw-r--r-- | src/librustc_parse/parser/mod.rs | 6 | ||||
| -rw-r--r-- | src/librustc_parse/parser/nonterminal.rs | 163 | ||||
| -rw-r--r-- | src/librustc_parse/parser/path.rs | 2 | ||||
| -rw-r--r-- | src/librustc_parse/parser/stmt.rs | 4 | ||||
| -rw-r--r-- | src/librustc_parse/parser/ty.rs | 4 |
6 files changed, 173 insertions, 8 deletions
diff --git a/src/librustc_parse/parser/expr.rs b/src/librustc_parse/parser/expr.rs index d06b172bc14..3aec300d86d 100644 --- a/src/librustc_parse/parser/expr.rs +++ b/src/librustc_parse/parser/expr.rs @@ -1450,7 +1450,7 @@ impl<'a> Parser<'a> { /// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`). /// Keep this in sync with `Token::can_begin_literal_maybe_minus`. - pub fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> { + pub(super) fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> { maybe_whole_expr!(self); let lo = self.token.span; diff --git a/src/librustc_parse/parser/mod.rs b/src/librustc_parse/parser/mod.rs index 72866468b65..38d2bd9b756 100644 --- a/src/librustc_parse/parser/mod.rs +++ b/src/librustc_parse/parser/mod.rs @@ -1,6 +1,7 @@ pub mod attr; mod expr; mod item; +mod nonterminal; mod pat; mod path; mod ty; @@ -10,6 +11,7 @@ mod generics; mod stmt; use diagnostics::Error; + use crate::lexer::UnmatchedBrace; use log::debug; @@ -958,7 +960,7 @@ impl<'a> Parser<'a> { } /// Parses a single token tree from the input. - pub fn parse_token_tree(&mut self) -> TokenTree { + pub(crate) fn parse_token_tree(&mut self) -> TokenTree { match self.token.kind { token::OpenDelim(..) => { let frame = mem::replace( @@ -1017,7 +1019,7 @@ impl<'a> Parser<'a> { /// 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. - pub fn parse_visibility(&mut self, fbt: FollowedByType) -> PResult<'a, Visibility> { + pub(crate) fn parse_visibility(&mut self, fbt: FollowedByType) -> PResult<'a, Visibility> { maybe_whole!(self, NtVis, |x| x); self.expected_tokens.push(TokenType::Keyword(kw::Crate)); diff --git a/src/librustc_parse/parser/nonterminal.rs b/src/librustc_parse/parser/nonterminal.rs new file mode 100644 index 00000000000..12139771bbf --- /dev/null +++ b/src/librustc_parse/parser/nonterminal.rs @@ -0,0 +1,163 @@ +use rustc_ast::ptr::P; +use rustc_ast::token::{self, Nonterminal, NonterminalKind, Token}; +use rustc_ast_pretty::pprust; +use rustc_errors::PResult; +use rustc_span::symbol::{kw, Ident}; + +use crate::parser::{FollowedByType, Parser, PathStyle}; + +impl<'a> Parser<'a> { + /// Checks whether a non-terminal may begin with a particular token. + /// + /// Returning `false` is a *stability guarantee* that such a matcher will *never* begin with that + /// token. Be conservative (return true) if not sure. + pub fn nonterminal_may_begin_with(kind: NonterminalKind, token: &Token) -> bool { + /// Checks whether the non-terminal may contain a single (non-keyword) identifier. + fn may_be_ident(nt: &token::Nonterminal) -> bool { + match *nt { + token::NtItem(_) | token::NtBlock(_) | token::NtVis(_) | token::NtLifetime(_) => { + false + } + _ => true, + } + } + + match kind { + NonterminalKind::Expr => { + token.can_begin_expr() + // This exception is here for backwards compatibility. + && !token.is_keyword(kw::Let) + } + NonterminalKind::Ty => token.can_begin_type(), + NonterminalKind::Ident => get_macro_ident(token).is_some(), + NonterminalKind::Literal => token.can_begin_literal_maybe_minus(), + NonterminalKind::Vis => match token.kind { + // The follow-set of :vis + "priv" keyword + interpolated + token::Comma | token::Ident(..) | token::Interpolated(..) => true, + _ => token.can_begin_type(), + }, + NonterminalKind::Block => match token.kind { + token::OpenDelim(token::Brace) => true, + token::Interpolated(ref nt) => match **nt { + token::NtItem(_) + | token::NtPat(_) + | token::NtTy(_) + | token::NtIdent(..) + | token::NtMeta(_) + | token::NtPath(_) + | token::NtVis(_) => false, // none of these may start with '{'. + _ => true, + }, + _ => false, + }, + NonterminalKind::Path | NonterminalKind::Meta => match token.kind { + token::ModSep | token::Ident(..) => true, + token::Interpolated(ref nt) => match **nt { + token::NtPath(_) | token::NtMeta(_) => true, + _ => may_be_ident(&nt), + }, + _ => false, + }, + NonterminalKind::Pat => match token.kind { + token::Ident(..) | // box, ref, mut, and other identifiers (can stricten) + token::OpenDelim(token::Paren) | // tuple pattern + token::OpenDelim(token::Bracket) | // slice pattern + token::BinOp(token::And) | // reference + token::BinOp(token::Minus) | // negative literal + token::AndAnd | // double reference + token::Literal(..) | // literal + token::DotDot | // range pattern (future compat) + token::DotDotDot | // range pattern (future compat) + token::ModSep | // path + token::Lt | // path (UFCS constant) + token::BinOp(token::Shl) => true, // path (double UFCS) + token::Interpolated(ref nt) => may_be_ident(nt), + _ => false, + }, + NonterminalKind::Lifetime => match token.kind { + token::Lifetime(_) => true, + token::Interpolated(ref nt) => match **nt { + token::NtLifetime(_) | token::NtTT(_) => true, + _ => false, + }, + _ => false, + }, + NonterminalKind::TT | NonterminalKind::Item | NonterminalKind::Stmt => match token.kind + { + token::CloseDelim(_) => false, + _ => true, + }, + } + } + + pub fn parse_nonterminal(&mut self, kind: NonterminalKind) -> PResult<'a, Nonterminal> { + // Any `Nonterminal` which stores its tokens (currently `NtItem` and `NtExpr`) + // needs to have them force-captured here. + // A `macro_rules!` invocation may pass a captured item/expr to a proc-macro, + // which requires having captured tokens available. Since we cannot determine + // in advance whether or not a proc-macro will be (transitively) invoked, + // we always capture tokens for any `Nonterminal` which needs them. + Ok(match kind { + NonterminalKind::Item => match self.collect_tokens(|this| this.parse_item())? { + (Some(mut item), tokens) => { + // If we captured tokens during parsing (due to outer attributes), + // use those. + if item.tokens.is_none() { + item.tokens = Some(tokens); + } + token::NtItem(item) + } + (None, _) => { + return Err(self.struct_span_err(self.token.span, "expected an item keyword")); + } + }, + NonterminalKind::Block => token::NtBlock(self.parse_block()?), + NonterminalKind::Stmt => match self.parse_stmt()? { + Some(s) => token::NtStmt(s), + None => return Err(self.struct_span_err(self.token.span, "expected a statement")), + }, + NonterminalKind::Pat => token::NtPat(self.parse_pat(None)?), + NonterminalKind::Expr => { + let (mut expr, tokens) = self.collect_tokens(|this| this.parse_expr())?; + // If we captured tokens during parsing (due to outer attributes), + // use those. + if expr.tokens.is_none() { + expr.tokens = Some(tokens); + } + token::NtExpr(expr) + } + NonterminalKind::Literal => token::NtLiteral(self.parse_literal_maybe_minus()?), + NonterminalKind::Ty => token::NtTy(self.parse_ty()?), + // this could be handled like a token, since it is one + NonterminalKind::Ident => { + if let Some((ident, is_raw)) = get_macro_ident(&self.token) { + self.bump(); + token::NtIdent(ident, is_raw) + } else { + let token_str = pprust::token_to_string(&self.token); + let msg = &format!("expected ident, found {}", &token_str); + return Err(self.struct_span_err(self.token.span, msg)); + } + } + NonterminalKind::Path => token::NtPath(self.parse_path(PathStyle::Type)?), + NonterminalKind::Meta => token::NtMeta(P(self.parse_attr_item()?)), + NonterminalKind::TT => token::NtTT(self.parse_token_tree()), + NonterminalKind::Vis => token::NtVis(self.parse_visibility(FollowedByType::Yes)?), + NonterminalKind::Lifetime => { + if self.check_lifetime() { + token::NtLifetime(self.expect_lifetime().ident) + } else { + let token_str = pprust::token_to_string(&self.token); + let msg = &format!("expected a lifetime, found `{}`", &token_str); + return Err(self.struct_span_err(self.token.span, msg)); + } + } + }) + } +} + +/// The token is an identifier, but not `_`. +/// We prohibit passing `_` to macros expecting `ident` for now. +fn get_macro_ident(token: &Token) -> Option<(Ident, bool)> { + token.ident().filter(|(ident, _)| ident.name != kw::Underscore) +} diff --git a/src/librustc_parse/parser/path.rs b/src/librustc_parse/parser/path.rs index 3dcefd36257..d4e44c54b12 100644 --- a/src/librustc_parse/parser/path.rs +++ b/src/librustc_parse/parser/path.rs @@ -125,7 +125,7 @@ impl<'a> Parser<'a> { /// `a::b::C::<D>` (with disambiguator) /// `Fn(Args)` (without disambiguator) /// `Fn::(Args)` (with disambiguator) - pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, Path> { + pub(super) fn parse_path(&mut self, style: PathStyle) -> PResult<'a, Path> { maybe_whole!(self, NtPath, |path| { if style == PathStyle::Mod && path.segments.iter().any(|segment| segment.args.is_some()) { diff --git a/src/librustc_parse/parser/stmt.rs b/src/librustc_parse/parser/stmt.rs index d04920de47f..5c3a5e99873 100644 --- a/src/librustc_parse/parser/stmt.rs +++ b/src/librustc_parse/parser/stmt.rs @@ -21,7 +21,7 @@ use std::mem; impl<'a> Parser<'a> { /// Parses a statement. This stops just before trailing semicolons on everything but items. /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed. - pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> { + pub(super) fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> { Ok(self.parse_stmt_without_recovery().unwrap_or_else(|mut e| { e.emit(); self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore); @@ -247,7 +247,7 @@ impl<'a> Parser<'a> { } /// Parses a block. No inner attributes are allowed. - pub fn parse_block(&mut self) -> PResult<'a, P<Block>> { + pub(super) fn parse_block(&mut self) -> PResult<'a, P<Block>> { let (attrs, block) = self.parse_inner_attrs_and_block()?; if let [.., last] = &*attrs { self.error_on_forbidden_inner_attr(last.span, DEFAULT_INNER_ATTR_FORBIDDEN); diff --git a/src/librustc_parse/parser/ty.rs b/src/librustc_parse/parser/ty.rs index a6015504a32..cd66b917f23 100644 --- a/src/librustc_parse/parser/ty.rs +++ b/src/librustc_parse/parser/ty.rs @@ -610,13 +610,13 @@ impl<'a> Parser<'a> { } } - pub fn check_lifetime(&mut self) -> bool { + pub(super) fn check_lifetime(&mut self) -> bool { self.expected_tokens.push(TokenType::Lifetime); self.token.is_lifetime() } /// Parses a single lifetime `'a` or panics. - pub fn expect_lifetime(&mut self) -> Lifetime { + pub(super) fn expect_lifetime(&mut self) -> Lifetime { if let Some(ident) = self.token.lifetime() { self.bump(); Lifetime { ident, id: ast::DUMMY_NODE_ID } |