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syntax: cleanup method parsing.

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This commit is contained in:
Mazdak Farrokhzad 2019-09-30 00:20:03 +02:00
parent 8431f261dd
commit f2904674e8
2 changed files with 66 additions and 74 deletions
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2
src/libsyntax/parse/diagnostics.rs
View File

@ -1180,7 +1180,7 @@ impl<'a> Parser<'a> {
}
}
crate fn expected_semi_or_open_brace(&mut self) -> PResult<'a, ast::TraitItem> {
crate fn expected_semi_or_open_brace<T>(&mut self) -> PResult<'a, T> {
let token_str = self.this_token_descr();
let mut err = self.fatal(&format!("expected `;` or `{{`, found {}", token_str));
err.span_label(self.token.span, "expected `;` or `{`");

138
src/libsyntax/parse/parser/item.rs
View File

@ -7,7 +7,7 @@ use crate::ast::{
Item, ItemKind, ImplItem, TraitItem, TraitItemKind,
UseTree, UseTreeKind, PathSegment,
IsAuto, Constness, IsAsync, Unsafety, Defaultness,
Visibility, VisibilityKind, Mutability, FnDecl, FnHeader,
Visibility, VisibilityKind, Mutability, FnDecl, FnHeader, MethodSig, Block,
ForeignItem, ForeignItemKind,
Ty, TyKind, Generics, GenericBounds, TraitRef,
EnumDef, VariantData, StructField, AnonConst,
@ -848,29 +848,38 @@ impl<'a> Parser<'a> {
}
/// Parses a method or a macro invocation in a trait impl.
fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool)
-> PResult<'a, (Ident, Vec<Attribute>, Generics, ast::ImplItemKind)> {
fn parse_impl_method(
&mut self,
vis: &Visibility,
at_end: &mut bool
) -> PResult<'a, (Ident, Vec<Attribute>, Generics, ast::ImplItemKind)> {
// FIXME: code copied from `parse_macro_use_or_failure` -- use abstraction!
if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? {
// method macro
Ok((Ident::invalid(), vec![], Generics::default(),
ast::ImplItemKind::Macro(mac)))
Ok((Ident::invalid(), vec![], Generics::default(), ast::ImplItemKind::Macro(mac)))
} else {
let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
let ident = self.parse_ident()?;
let mut generics = self.parse_generics()?;
let decl = self.parse_fn_decl_with_self(|_| true)?;
generics.where_clause = self.parse_where_clause()?;
let (ident, sig, generics) = self.parse_method_sig(|_| true)?;
*at_end = true;
let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
let header = ast::FnHeader { abi, unsafety, constness, asyncness };
Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(
ast::MethodSig { header, decl },
body
)))
Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(sig, body)))
}
}
/// Parse the "signature", including the identifier, parameters, and generics
/// of a method. The body is not parsed as that differs between `trait`s and `impl`s.
fn parse_method_sig(
&mut self,
is_name_required: impl Copy + Fn(&token::Token) -> bool,
) -> PResult<'a, (Ident, MethodSig, Generics)> {
let header = self.parse_fn_front_matter()?;
let ident = self.parse_ident()?;
let mut generics = self.parse_generics()?;
let decl = self.parse_fn_decl_with_self(is_name_required)?;
let sig = MethodSig { header, decl };
generics.where_clause = self.parse_where_clause()?;
Ok((ident, sig, generics))
}
/// Parses all the "front matter" for a `fn` declaration, up to
/// and including the `fn` keyword:
///
@ -879,14 +888,7 @@ impl<'a> Parser<'a> {
/// - `const unsafe fn`
/// - `extern fn`
/// - etc.
fn parse_fn_front_matter(&mut self)
-> PResult<'a, (
Spanned<Constness>,
Unsafety,
Spanned<IsAsync>,
Abi
)>
{
fn parse_fn_front_matter(&mut self) -> PResult<'a, FnHeader> {
let is_const_fn = self.eat_keyword(kw::Const);
let const_span = self.prev_span;
let asyncness = self.parse_asyncness();
@ -911,7 +913,7 @@ impl<'a> Parser<'a> {
// account for this.
if !self.expect_one_of(&[], &[])? { unreachable!() }
}
Ok((constness, unsafety, asyncness, abi))
Ok(FnHeader { constness, unsafety, asyncness, abi })
}
/// Parses `trait Foo { ... }` or `trait Foo = Bar;`.
@ -1025,59 +1027,12 @@ impl<'a> Parser<'a> {
// trait item macro.
(Ident::invalid(), ast::TraitItemKind::Macro(mac), Generics::default())
} else {
let (constness, unsafety, asyncness, abi) = self.parse_fn_front_matter()?;
let ident = self.parse_ident()?;
let mut generics = self.parse_generics()?;
// This is somewhat dubious; We don't want to allow
// argument names to be left off if there is a definition...
//
// We don't allow argument names to be left off in edition 2018.
let decl = self.parse_fn_decl_with_self(|t| t.span.rust_2018())?;
generics.where_clause = self.parse_where_clause()?;
let sig = ast::MethodSig {
header: FnHeader {
unsafety,
constness,
abi,
asyncness,
},
decl,
};
let body = match self.token.kind {
token::Semi => {
self.bump();
*at_end = true;
debug!("parse_trait_methods(): parsing required method");
None
}
token::OpenDelim(token::Brace) => {
debug!("parse_trait_methods(): parsing provided method");
*at_end = true;
let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(inner_attrs.iter().cloned());
Some(body)
}
token::Interpolated(ref nt) => {
match **nt {
token::NtBlock(..) => {
*at_end = true;
let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(inner_attrs.iter().cloned());
Some(body)
}
_ => {
return self.expected_semi_or_open_brace();
}
}
}
_ => {
return self.expected_semi_or_open_brace();
}
};
let (ident, sig, generics) = self.parse_method_sig(|t| t.span.rust_2018())?;
let body = self.parse_trait_method_body(at_end, &mut attrs)?;
(ident, ast::TraitItemKind::Method(sig, body), generics)
};
@ -1092,6 +1047,43 @@ impl<'a> Parser<'a> {
})
}
/// Parse the "body" of a method in a trait item definition.
/// This can either be `;` when there's no body,
/// or e.g. a block when the method is a provided one.
fn parse_trait_method_body(
&mut self,
at_end: &mut bool,
attrs: &mut Vec<Attribute>,
) -> PResult<'a, Option<P<Block>>> {
Ok(match self.token.kind {
token::Semi => {
debug!("parse_trait_method_body(): parsing required method");
self.bump();
*at_end = true;
None
}
token::OpenDelim(token::Brace) => {
debug!("parse_trait_method_body(): parsing provided method");
*at_end = true;
let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(inner_attrs.iter().cloned());
Some(body)
}
token::Interpolated(ref nt) => {
match **nt {
token::NtBlock(..) => {
*at_end = true;
let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(inner_attrs.iter().cloned());
Some(body)
}
_ => return self.expected_semi_or_open_brace(),
}
}
_ => return self.expected_semi_or_open_brace(),
})
}
/// Parses the following grammar:
///
/// TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]