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extract parse_ty_tuple_or_parens

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This commit is contained in:
Mazdak Farrokhzad 2019-12-08 06:44:24 +01:00
parent c64eecf4d0
commit f3ef4a416d
1 changed files with 44 additions and 38 deletions
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82
src/librustc_parse/parser/ty.rs
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@ -74,44 +74,7 @@ impl<'a> Parser<'a> {
let lo = self.token.span; let lo = self.token.span;
let mut impl_dyn_multi = false; let mut impl_dyn_multi = false;
let kind = if self.eat(&token::OpenDelim(token::Paren)) { let kind = if self.eat(&token::OpenDelim(token::Paren)) {
// `(TYPE)` is a parenthesized type. self.parse_ty_tuple_or_parens(allow_plus)?
// `(TYPE,)` is a tuple with a single field of type TYPE.
let mut ts = vec![];
let mut last_comma = false;
while self.token != token::CloseDelim(token::Paren) {
ts.push(self.parse_ty()?);
if self.eat(&token::Comma) {
last_comma = true;
} else {
last_comma = false;
break;
}
}
let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus;
self.expect(&token::CloseDelim(token::Paren))?;
if ts.len() == 1 && !last_comma {
let ty = ts.into_iter().nth(0).unwrap().into_inner();
let maybe_bounds = allow_plus && self.token.is_like_plus();
match ty.kind {
// `(TY_BOUND_NOPAREN) + BOUND + ...`.
TyKind::Path(None, ref path) if maybe_bounds => {
self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)?
}
TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
let path = match bounds[0] {
GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(),
GenericBound::Outlives(..) => self.bug("unexpected lifetime bound"),
};
self.parse_remaining_bounds(Vec::new(), path, lo, true)?
}
// `(TYPE)`
_ => TyKind::Paren(P(ty))
}
} else {
TyKind::Tup(ts)
}
} else if self.eat(&token::Not) { } else if self.eat(&token::Not) {
// Never type `!` // Never type `!`
TyKind::Never TyKind::Never
@ -242,6 +205,49 @@ impl<'a> Parser<'a> {
self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery) self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)
} }
/// Parses either:
/// - `(TYPE)`, a parenthesized type.
/// - `(TYPE,)`, a tuple with a single field of type TYPE.
fn parse_ty_tuple_or_parens(&mut self, allow_plus: bool) -> PResult<'a, TyKind> {
let lo = self.token.span;
let mut ts = vec![];
let mut last_comma = false;
while self.token != token::CloseDelim(token::Paren) {
ts.push(self.parse_ty()?);
if self.eat(&token::Comma) {
last_comma = true;
} else {
last_comma = false;
break;
}
}
let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus;
self.expect(&token::CloseDelim(token::Paren))?;
if ts.len() == 1 && !last_comma {
let ty = ts.into_iter().nth(0).unwrap().into_inner();
let maybe_bounds = allow_plus && self.token.is_like_plus();
match ty.kind {
// `(TY_BOUND_NOPAREN) + BOUND + ...`.
TyKind::Path(None, ref path) if maybe_bounds => {
self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)
}
TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
let path = match bounds[0] {
GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(),
GenericBound::Outlives(..) => self.bug("unexpected lifetime bound"),
};
self.parse_remaining_bounds(Vec::new(), path, lo, true)
}
// `(TYPE)`
_ => Ok(TyKind::Paren(P(ty)))
}
} else {
Ok(TyKind::Tup(ts))
}
}
fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path, fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path,
lo: Span, parse_plus: bool) -> PResult<'a, TyKind> { lo: Span, parse_plus: bool) -> PResult<'a, TyKind> {
let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span)); let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span));