diff options
| author | Mazdak Farrokhzad <twingoow@gmail.com> | 2019-10-15 22:48:13 +0200 |
|---|---|---|
| committer | Mazdak Farrokhzad <twingoow@gmail.com> | 2019-11-10 03:57:18 +0100 |
| commit | 4ae2728fa8052915414127dce28245eb8f70842a (patch) | |
| tree | 27cc54d90904091e4dc9bf7ae5fa3b41be4b6187 /src/libsyntax/parse/parser/generics.rs | |
| parent | be023ebe850261c6bb202a02a686827d821c3697 (diff) | |
| download | rust-4ae2728fa8052915414127dce28245eb8f70842a.tar.gz rust-4ae2728fa8052915414127dce28245eb8f70842a.zip | |
move syntax::parse -> librustc_parse
also move MACRO_ARGUMENTS -> librustc_parse
Diffstat (limited to 'src/libsyntax/parse/parser/generics.rs')
| -rw-r--r-- | src/libsyntax/parse/parser/generics.rs | 309 |
1 files changed, 0 insertions, 309 deletions
diff --git a/src/libsyntax/parse/parser/generics.rs b/src/libsyntax/parse/parser/generics.rs deleted file mode 100644 index ae9ecd8fe39..00000000000 --- a/src/libsyntax/parse/parser/generics.rs +++ /dev/null @@ -1,309 +0,0 @@ -use super::Parser; - -use crate::ast::{self, WhereClause, GenericParam, GenericParamKind, GenericBounds, Attribute}; -use crate::token; -use crate::source_map::DUMMY_SP; - -use syntax_pos::symbol::{kw, sym}; - -use errors::PResult; - -impl<'a> Parser<'a> { - /// Parses bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`. - /// - /// ``` - /// BOUND = LT_BOUND (e.g., `'a`) - /// ``` - fn parse_lt_param_bounds(&mut self) -> GenericBounds { - let mut lifetimes = Vec::new(); - while self.check_lifetime() { - lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime())); - - if !self.eat_plus() { - break - } - } - lifetimes - } - - /// Matches `typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?`. - fn parse_ty_param(&mut self, - preceding_attrs: Vec<Attribute>) - -> PResult<'a, GenericParam> { - let ident = self.parse_ident()?; - - // Parse optional colon and param bounds. - let bounds = if self.eat(&token::Colon) { - self.parse_generic_bounds(Some(self.prev_span))? - } else { - Vec::new() - }; - - let default = if self.eat(&token::Eq) { - Some(self.parse_ty()?) - } else { - None - }; - - Ok(GenericParam { - ident, - id: ast::DUMMY_NODE_ID, - attrs: preceding_attrs.into(), - bounds, - kind: GenericParamKind::Type { - default, - }, - is_placeholder: false - }) - } - - fn parse_const_param(&mut self, preceding_attrs: Vec<Attribute>) -> PResult<'a, GenericParam> { - let lo = self.token.span; - - self.expect_keyword(kw::Const)?; - let ident = self.parse_ident()?; - self.expect(&token::Colon)?; - let ty = self.parse_ty()?; - - self.sess.gated_spans.gate(sym::const_generics, lo.to(self.prev_span)); - - Ok(GenericParam { - ident, - id: ast::DUMMY_NODE_ID, - attrs: preceding_attrs.into(), - bounds: Vec::new(), - kind: GenericParamKind::Const { - ty, - }, - is_placeholder: false - }) - } - - /// Parses a (possibly empty) list of lifetime and type parameters, possibly including - /// a trailing comma and erroneous trailing attributes. - pub(super) fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> { - let mut params = Vec::new(); - loop { - let attrs = self.parse_outer_attributes()?; - if self.check_lifetime() { - let lifetime = self.expect_lifetime(); - // Parse lifetime parameter. - let bounds = if self.eat(&token::Colon) { - self.parse_lt_param_bounds() - } else { - Vec::new() - }; - params.push(ast::GenericParam { - ident: lifetime.ident, - id: lifetime.id, - attrs: attrs.into(), - bounds, - kind: ast::GenericParamKind::Lifetime, - is_placeholder: false - }); - } else if self.check_keyword(kw::Const) { - // Parse const parameter. - params.push(self.parse_const_param(attrs)?); - } else if self.check_ident() { - // Parse type parameter. - params.push(self.parse_ty_param(attrs)?); - } else if self.token.can_begin_type() { - // Trying to write an associated type bound? (#26271) - let snapshot = self.clone(); - match self.parse_ty_where_predicate() { - Ok(where_predicate) => { - self.struct_span_err( - where_predicate.span(), - "bounds on associated types do not belong here", - ) - .span_label(where_predicate.span(), "belongs in `where` clause") - .emit(); - } - Err(mut err) => { - err.cancel(); - std::mem::replace(self, snapshot); - break - } - } - } else { - // Check for trailing attributes and stop parsing. - if !attrs.is_empty() { - if !params.is_empty() { - self.struct_span_err( - attrs[0].span, - "trailing attribute after generic parameter", - ) - .span_label(attrs[0].span, "attributes must go before parameters") - .emit(); - } else { - self.struct_span_err( - attrs[0].span, - &format!("attribute without generic parameters"), - ) - .span_label( - attrs[0].span, - "attributes are only permitted when preceding parameters", - ) - .emit(); - } - } - break - } - - if !self.eat(&token::Comma) { - break - } - } - Ok(params) - } - - /// Parses a set of optional generic type parameter declarations. Where - /// clauses are not parsed here, and must be added later via - /// `parse_where_clause()`. - /// - /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > ) - /// | ( < lifetimes , typaramseq ( , )? > ) - /// where typaramseq = ( typaram ) | ( typaram , typaramseq ) - pub(super) fn parse_generics(&mut self) -> PResult<'a, ast::Generics> { - let span_lo = self.token.span; - let (params, span) = if self.eat_lt() { - let params = self.parse_generic_params()?; - self.expect_gt()?; - (params, span_lo.to(self.prev_span)) - } else { - (vec![], self.prev_span.between(self.token.span)) - }; - Ok(ast::Generics { - params, - where_clause: WhereClause { - predicates: Vec::new(), - span: DUMMY_SP, - }, - span, - }) - } - - /// Parses an optional where-clause and places it in `generics`. - /// - /// ```ignore (only-for-syntax-highlight) - /// where T : Trait<U, V> + 'b, 'a : 'b - /// ``` - pub(super) fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> { - let mut where_clause = WhereClause { - predicates: Vec::new(), - span: self.prev_span.to(self.prev_span), - }; - - if !self.eat_keyword(kw::Where) { - return Ok(where_clause); - } - let lo = self.prev_span; - - // We are considering adding generics to the `where` keyword as an alternative higher-rank - // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking - // change we parse those generics now, but report an error. - if self.choose_generics_over_qpath() { - let generics = self.parse_generics()?; - self.struct_span_err( - generics.span, - "generic parameters on `where` clauses are reserved for future use", - ) - .span_label(generics.span, "currently unsupported") - .emit(); - } - - loop { - let lo = self.token.span; - if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) { - let lifetime = self.expect_lifetime(); - // Bounds starting with a colon are mandatory, but possibly empty. - self.expect(&token::Colon)?; - let bounds = self.parse_lt_param_bounds(); - where_clause.predicates.push(ast::WherePredicate::RegionPredicate( - ast::WhereRegionPredicate { - span: lo.to(self.prev_span), - lifetime, - bounds, - } - )); - } else if self.check_type() { - where_clause.predicates.push(self.parse_ty_where_predicate()?); - } else { - break - } - - if !self.eat(&token::Comma) { - break - } - } - - where_clause.span = lo.to(self.prev_span); - Ok(where_clause) - } - - fn parse_ty_where_predicate(&mut self) -> PResult<'a, ast::WherePredicate> { - let lo = self.token.span; - // Parse optional `for<'a, 'b>`. - // This `for` is parsed greedily and applies to the whole predicate, - // the bounded type can have its own `for` applying only to it. - // Examples: - // * `for<'a> Trait1<'a>: Trait2<'a /* ok */>` - // * `(for<'a> Trait1<'a>): Trait2<'a /* not ok */>` - // * `for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /* ok */, 'b /* not ok */>` - let lifetime_defs = self.parse_late_bound_lifetime_defs()?; - - // Parse type with mandatory colon and (possibly empty) bounds, - // or with mandatory equality sign and the second type. - let ty = self.parse_ty()?; - if self.eat(&token::Colon) { - let bounds = self.parse_generic_bounds(Some(self.prev_span))?; - Ok(ast::WherePredicate::BoundPredicate( - ast::WhereBoundPredicate { - span: lo.to(self.prev_span), - bound_generic_params: lifetime_defs, - bounded_ty: ty, - bounds, - } - )) - // FIXME: Decide what should be used here, `=` or `==`. - // FIXME: We are just dropping the binders in lifetime_defs on the floor here. - } else if self.eat(&token::Eq) || self.eat(&token::EqEq) { - let rhs_ty = self.parse_ty()?; - Ok(ast::WherePredicate::EqPredicate( - ast::WhereEqPredicate { - span: lo.to(self.prev_span), - lhs_ty: ty, - rhs_ty, - id: ast::DUMMY_NODE_ID, - } - )) - } else { - self.unexpected() - } - } - - pub(super) fn choose_generics_over_qpath(&self) -> bool { - // There's an ambiguity between generic parameters and qualified paths in impls. - // If we see `<` it may start both, so we have to inspect some following tokens. - // The following combinations can only start generics, - // but not qualified paths (with one exception): - // `<` `>` - empty generic parameters - // `<` `#` - generic parameters with attributes - // `<` (LIFETIME|IDENT) `>` - single generic parameter - // `<` (LIFETIME|IDENT) `,` - first generic parameter in a list - // `<` (LIFETIME|IDENT) `:` - generic parameter with bounds - // `<` (LIFETIME|IDENT) `=` - generic parameter with a default - // `<` const - generic const parameter - // The only truly ambiguous case is - // `<` IDENT `>` `::` IDENT ... - // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`) - // because this is what almost always expected in practice, qualified paths in impls - // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment. - self.token == token::Lt && - (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) || - self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) && - self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma || - t == &token::Colon || t == &token::Eq) || - self.is_keyword_ahead(1, &[kw::Const])) - } -} |
