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
|
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use cg;
use quote::Tokens;
use syn::DeriveInput;
use synstructure::BindStyle;
pub fn derive(mut input: DeriveInput) -> Tokens {
let mut where_clause = input.generics.where_clause.take();
let (to_body, from_body) = {
let params = input.generics.type_params().collect::<Vec<_>>();
for param in ¶ms {
cg::add_predicate(
&mut where_clause,
parse_quote!(#param: ::values::computed::ToComputedValue),
);
}
let to_body = cg::fmap_match(&input, BindStyle::Ref, |binding| {
let attrs = cg::parse_field_attrs::<ComputedValueAttrs>(&binding.ast());
if attrs.field_bound {
let ty = &binding.ast().ty;
let output_type = cg::map_type_params(ty, ¶ms, &mut |ident| {
parse_quote!(<#ident as ::values::computed::ToComputedValue>::ComputedValue)
});
cg::add_predicate(
&mut where_clause,
parse_quote!(
#ty: ::values::computed::ToComputedValue<ComputedValue = #output_type>
),
);
}
quote! {
::values::computed::ToComputedValue::to_computed_value(#binding, context)
}
});
let from_body = cg::fmap_match(&input, BindStyle::Ref, |binding| {
quote! {
::values::computed::ToComputedValue::from_computed_value(#binding)
}
});
(to_body, from_body)
};
input.generics.where_clause = where_clause;
let name = &input.ident;
let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
if input.generics.type_params().next().is_none() {
return quote! {
impl #impl_generics ::values::computed::ToComputedValue for #name #ty_generics
#where_clause
{
type ComputedValue = Self;
#[inline]
fn to_computed_value(
&self,
_context: &::values::computed::Context,
) -> Self::ComputedValue {
::std::clone::Clone::clone(self)
}
#[inline]
fn from_computed_value(computed: &Self::ComputedValue) -> Self {
::std::clone::Clone::clone(computed)
}
}
}
}
let computed_value_type = cg::fmap_trait_output(
&input,
&parse_quote!(values::computed::ToComputedValue),
"ComputedValue".into(),
);
quote! {
impl #impl_generics ::values::computed::ToComputedValue for #name #ty_generics #where_clause {
type ComputedValue = #computed_value_type;
#[allow(unused_variables)]
#[inline]
fn to_computed_value(&self, context: &::values::computed::Context) -> Self::ComputedValue {
match *self {
#to_body
}
}
#[inline]
fn from_computed_value(computed: &Self::ComputedValue) -> Self {
match *computed {
#from_body
}
}
}
}
}
#[darling(attributes(compute), default)]
#[derive(Default, FromField)]
struct ComputedValueAttrs {
field_bound: bool,
}
|
