1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
//! 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_def(p: &mut Parser) {
assert!(p.at(T![trait]));
p.bump(T![trait]);
name_r(p, ITEM_RECOVERY_SET);
type_params::opt_type_param_list(p);
if p.at(T![:]) {
type_params::bounds(p);
}
type_params::opt_where_clause(p);
if p.at(T!['{']) {
trait_item_list(p);
} else {
p.error("expected `{`");
}
}
// test trait_item_list
// impl F {
// type A: Clone;
// const B: i32;
// fn foo() {}
// fn bar(&self);
// }
pub(crate) fn trait_item_list(p: &mut Parser) {
assert!(p.at(T!['{']));
let m = p.start();
p.bump(T!['{']);
while !p.at(EOF) && !p.at(T!['}']) {
if p.at(T!['{']) {
error_block(p, "expected an item");
continue;
}
item_or_macro(p, true, ItemFlavor::Trait);
}
p.expect(T!['}']);
m.complete(p, ITEM_LIST);
}
// test impl_block
// impl Foo {}
pub(super) fn impl_block(p: &mut Parser) {
assert!(p.at(T![impl]));
p.bump(T![impl]);
if choose_type_params_over_qpath(p) {
type_params::opt_type_param_list(p);
}
// FIXME: never type
// impl ! {}
// test impl_block_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!['{']) {
impl_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 impl_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_attributes(p);
while !p.at(EOF) && !p.at(T!['}']) {
if p.at(T!['{']) {
error_block(p, "expected an item");
continue;
}
item_or_macro(p, true, ItemFlavor::Mod);
}
p.expect(T!['}']);
m.complete(p, 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) `>` - single generic parameter
// `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
// `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
// `<` (LIFETIME|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 || 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);
}
|
