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//! FIXME: write short doc here
use super::*;
// test trait_item
// trait T<U>: Hash + Clone where U: Copy {}
// trait X<U: Debug + Display>: Hash + Clone where U: Copy {}
pub(super) fn trait_(p: &mut Parser) {
assert!(p.at(T![trait]));
p.bump(T![trait]);
name_r(p, ITEM_RECOVERY_SET);
type_params::opt_generic_param_list(p);
// test trait_alias
// trait Z<U> = T<U>;
// trait Z<U> = T<U> where U: Copy;
// trait Z<U> = where Self: T<U>;
if p.eat(T![=]) {
type_params::bounds_without_colon(p);
type_params::opt_where_clause(p);
p.expect(T![;]);
return;
}
if p.at(T![:]) {
type_params::bounds(p);
}
type_params::opt_where_clause(p);
if p.at(T!['{']) {
assoc_item_list(p);
} else {
p.error("expected `{`");
}
}
// test impl_def
// impl Foo {}
pub(super) fn impl_(p: &mut Parser) {
assert!(p.at(T![impl]));
p.bump(T![impl]);
if choose_type_params_over_qpath(p) {
type_params::opt_generic_param_list(p);
}
// FIXME: never type
// impl ! {}
// test impl_def_neg
// impl !Send for X {}
p.eat(T![!]);
impl_type(p);
if p.eat(T![for]) {
impl_type(p);
}
type_params::opt_where_clause(p);
if p.at(T!['{']) {
assoc_item_list(p);
} else {
p.error("expected `{`");
}
}
// test impl_item_list
// impl F {
// type A = i32;
// const B: i32 = 92;
// fn foo() {}
// fn bar(&self) {}
// }
pub(crate) fn assoc_item_list(p: &mut Parser) {
assert!(p.at(T!['{']));
let m = p.start();
p.bump(T!['{']);
// test impl_inner_attributes
// enum F{}
// impl F {
// //! This is a doc comment
// #![doc("This is also a doc comment")]
// }
attributes::inner_attrs(p);
while !p.at(EOF) && !p.at(T!['}']) {
if p.at(T!['{']) {
error_block(p, "expected an item");
continue;
}
item_or_macro(p, true);
}
p.expect(T!['}']);
m.complete(p, ASSOC_ITEM_LIST);
}
// test impl_type_params
// impl<const N: u32> Bar<N> {}
fn choose_type_params_over_qpath(p: &Parser) -> 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
// `<` `const` - const generic parameters
// `<` (LIFETIME_IDENT|IDENT) `>` - single generic parameter
// `<` (LIFETIME_IDENT|IDENT) `,` - first generic parameter in a list
// `<` (LIFETIME_IDENT|IDENT) `:` - generic parameter with bounds
// `<` (LIFETIME_IDENT|IDENT) `=` - generic parameter with a default
// 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.
if !p.at(T![<]) {
return false;
}
if p.nth(1) == T![#] || p.nth(1) == T![>] || p.nth(1) == CONST_KW {
return true;
}
(p.nth(1) == LIFETIME_IDENT || p.nth(1) == IDENT)
&& (p.nth(2) == T![>] || p.nth(2) == T![,] || p.nth(2) == T![:] || p.nth(2) == T![=])
}
// test_err impl_type
// impl Type {}
// impl Trait1 for T {}
// impl impl NotType {}
// impl Trait2 for impl NotType {}
pub(crate) fn impl_type(p: &mut Parser) {
if p.at(T![impl]) {
p.error("expected trait or type");
return;
}
types::type_(p);
}
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