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extract parse_generic_bound

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This commit is contained in:
Mazdak Farrokhzad 2019-12-08 10:32:38 +01:00
parent fd89104966
commit 8a9a992a64
1 changed files with 61 additions and 40 deletions
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101
src/librustc_parse/parser/ty.rs
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@ -352,12 +352,7 @@ pub(super) fn parse_generic_bounds(
/// Parses bounds of a type parameter `BOUND + BOUND + ...`, possibly with trailing `+`.
///
/// ```
/// BOUND = TY_BOUND | LT_BOUND
/// LT_BOUND = LIFETIME (e.g., `'a`)
/// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
/// TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`)
/// ```
/// See `parse_generic_bound` for the `BOUND` grammar.
fn parse_generic_bounds_common(
&mut self,
allow_plus: bool,
@ -368,39 +363,13 @@ fn parse_generic_bounds_common(
let mut last_plus_span = None;
let mut was_negative = false;
while self.can_begin_bound() {
let lo = self.token.span;
let has_parens = self.eat(&token::OpenDelim(token::Paren));
let inner_lo = self.token.span;
let is_negative = self.eat(&token::Not);
let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
if self.token.is_lifetime() {
self.error_opt_out_lifetime(question);
bounds.push(GenericBound::Outlives(self.expect_lifetime()));
if has_parens {
self.recover_paren_lifetime(lo, inner_lo)?;
}
} else {
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
let path = self.parse_path(PathStyle::Type)?;
if has_parens {
self.expect(&token::CloseDelim(token::Paren))?;
}
let poly_span = lo.to(self.prev_span);
if is_negative {
was_negative = true;
if let Some(sp) = last_plus_span.or(colon_span) {
negative_bounds.push(sp.to(poly_span));
}
} else {
let poly_trait = PolyTraitRef::new(lifetime_defs, path, poly_span);
let modifier = if question.is_some() {
TraitBoundModifier::Maybe
} else {
TraitBoundModifier::None
};
bounds.push(GenericBound::Trait(poly_trait, modifier));
}
}
self.parse_generic_bound(
colon_span,
last_plus_span,
&mut bounds,
&mut negative_bounds,
&mut was_negative,
)?;
if !allow_plus || !self.eat_plus() {
break
@ -441,7 +410,7 @@ fn parse_generic_bounds_common(
err.emit();
}
return Ok(bounds);
Ok(bounds)
}
/// Can the current token begin a bound?
@ -455,6 +424,58 @@ fn can_begin_bound(&mut self) -> bool {
|| self.check(&token::OpenDelim(token::Paren))
}
/// Parses a bound according to the grammar:
///
/// ```
/// BOUND = TY_BOUND | LT_BOUND
/// LT_BOUND = LIFETIME (e.g., `'a`)
/// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
/// TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`)
/// ```
fn parse_generic_bound(
&mut self,
colon_span: Option<Span>,
last_plus_span: Option<Span>,
bounds: &mut Vec<GenericBound>,
negative_bounds: &mut Vec<Span>,
was_negative: &mut bool,
) -> PResult<'a, ()> {
let lo = self.token.span;
let has_parens = self.eat(&token::OpenDelim(token::Paren));
let inner_lo = self.token.span;
let is_negative = self.eat(&token::Not);
let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
if self.token.is_lifetime() {
self.error_opt_out_lifetime(question);
bounds.push(GenericBound::Outlives(self.expect_lifetime()));
if has_parens {
self.recover_paren_lifetime(lo, inner_lo)?;
}
} else {
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
let path = self.parse_path(PathStyle::Type)?;
if has_parens {
self.expect(&token::CloseDelim(token::Paren))?;
}
let poly_span = lo.to(self.prev_span);
if is_negative {
*was_negative = true;
if let Some(sp) = last_plus_span.or(colon_span) {
negative_bounds.push(sp.to(poly_span));
}
} else {
let poly_trait = PolyTraitRef::new(lifetime_defs, path, poly_span);
let modifier = if question.is_some() {
TraitBoundModifier::Maybe
} else {
TraitBoundModifier::None
};
bounds.push(GenericBound::Trait(poly_trait, modifier));
}
}
Ok(())
}
fn error_opt_out_lifetime(&self, question: Option<Span>) {
if let Some(span) = question {
self.struct_span_err(span, "`?` may only modify trait bounds, not lifetime bounds")