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Implement dyn Trait syntax

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This commit is contained in:
Vadim Petrochenkov
2017-10-10 17:33:19 +03:00
parent 3037965b5b
commit e6115af4bd
17 changed files with 149 additions and 41 deletions
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66
src/libsyntax/parse/parser.rs
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@@ -33,7 +33,7 @@ use ast::{Stmt, StmtKind};
use ast::{VariantData, StructField};
use ast::StrStyle;
use ast::SelfKind;
use ast::{TraitItem, TraitRef};
use ast::{TraitItem, TraitRef, TraitObjectSyntax};
use ast::{Ty, TyKind, TypeBinding, TyParam, TyParamBounds};
use ast::{ViewPath, ViewPathGlob, ViewPathList, ViewPathSimple};
use ast::{Visibility, WhereClause};
@@ -364,6 +364,13 @@ fn is_ident_or_underscore(t: &token::Token) -> bool {
t.is_ident() || *t == token::Underscore
}
// Returns true if `IDENT t` can start a type - `IDENT::a::b`, `IDENT<u8, u8>`,
// `IDENT<<u8 as Trait>::AssocTy>`, `IDENT(u8, u8) -> u8`.
fn can_continue_type_after_ident(t: &token::Token) -> bool {
t == &token::ModSep || t == &token::Lt ||
t == &token::BinOp(token::Shl) || t == &token::OpenDelim(token::Paren)
}
/// Information about the path to a module.
pub struct ModulePath {
pub name: String,
@@ -1428,7 +1435,7 @@ impl<'a> Parser<'a> {
TyKind::Path(None, ref path) if maybe_bounds => {
self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)?
}
TyKind::TraitObject(ref bounds)
TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
let path = match bounds[0] {
TraitTyParamBound(ref pt, ..) => pt.trait_ref.path.clone(),
@@ -1472,6 +1479,35 @@ impl<'a> Parser<'a> {
} else if self.eat(&token::Underscore) {
// A type to be inferred `_`
TyKind::Infer
} else if self.token_is_bare_fn_keyword() {
// Function pointer type
self.parse_ty_bare_fn(Vec::new())?
} else if self.check_keyword(keywords::For) {
// Function pointer type or bound list (trait object type) starting with a poly-trait.
// `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
// `for<'lt> Trait1<'lt> + Trait2 + 'a`
let lo = self.span;
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
if self.token_is_bare_fn_keyword() {
self.parse_ty_bare_fn(lifetime_defs)?
} else {
let path = self.parse_path(PathStyle::Type)?;
let parse_plus = allow_plus && self.check(&token::BinOp(token::Plus));
self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)?
}
} else if self.eat_keyword(keywords::Impl) {
// FIXME: figure out priority of `+` in `impl Trait1 + Trait2` (#34511).
TyKind::ImplTrait(self.parse_ty_param_bounds()?)
} else if self.check_keyword(keywords::Dyn) &&
self.look_ahead(1, |t| t.can_begin_bound() && !can_continue_type_after_ident(t)) {
// FIXME: figure out priority of `+` in `dyn Trait1 + Trait2` (#34511).
self.bump(); // `dyn`
TyKind::TraitObject(self.parse_ty_param_bounds()?, TraitObjectSyntax::Dyn)
} else if self.check(&token::Question) ||
self.check_lifetime() && self.look_ahead(1, |t| t == &token::BinOp(token::Plus)) {
// Bound list (trait object type)
TyKind::TraitObject(self.parse_ty_param_bounds_common(allow_plus)?,
TraitObjectSyntax::None)
} else if self.eat_lt() {
// Qualified path
let (qself, path) = self.parse_qpath(PathStyle::Type)?;
@@ -1493,29 +1529,6 @@ impl<'a> Parser<'a> {
TyKind::Path(None, path)
}
}
} else if self.token_is_bare_fn_keyword() {
// Function pointer type
self.parse_ty_bare_fn(Vec::new())?
} else if self.check_keyword(keywords::For) {
// Function pointer type or bound list (trait object type) starting with a poly-trait.
// `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
// `for<'lt> Trait1<'lt> + Trait2 + 'a`
let lo = self.span;
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
if self.token_is_bare_fn_keyword() {
self.parse_ty_bare_fn(lifetime_defs)?
} else {
let path = self.parse_path(PathStyle::Type)?;
let parse_plus = allow_plus && self.check(&token::BinOp(token::Plus));
self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)?
}
} else if self.eat_keyword(keywords::Impl) {
// FIXME: figure out priority of `+` in `impl Trait1 + Trait2` (#34511).
TyKind::ImplTrait(self.parse_ty_param_bounds()?)
} else if self.check(&token::Question) ||
self.check_lifetime() && self.look_ahead(1, |t| t == &token::BinOp(token::Plus)){
// Bound list (trait object type)
TyKind::TraitObject(self.parse_ty_param_bounds_common(allow_plus)?)
} else {
let msg = format!("expected type, found {}", self.this_token_descr());
return Err(self.fatal(&msg));
@@ -1538,7 +1551,7 @@ impl<'a> Parser<'a> {
self.bump(); // `+`
bounds.append(&mut self.parse_ty_param_bounds()?);
}
Ok(TyKind::TraitObject(bounds))
Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None))
}
fn maybe_recover_from_bad_type_plus(&mut self, allow_plus: bool, ty: &Ty) -> PResult<'a, ()> {
@@ -4256,6 +4269,7 @@ impl<'a> Parser<'a> {
fn parse_ty_param_bounds_common(&mut self, allow_plus: bool) -> PResult<'a, TyParamBounds> {
let mut bounds = Vec::new();
loop {
// This needs to be syncronized with `Token::can_begin_bound`.
let is_bound_start = self.check_path() || self.check_lifetime() ||
self.check(&token::Question) ||
self.check_keyword(keywords::For) ||