1use proc_macro2::TokenStream;
2use quote::{quote, ToTokens};
3
4use crate::{
5 ast::Data,
6 codegen::{ExtractAttribute, OuterFromImpl, TraitImpl},
7 util::PathList,
8};
9
10use super::ForwardAttrs;
11
12pub struct FromAttributesImpl<'a> {
13 pub base: TraitImpl<'a>,
14 pub attr_names: &'a PathList,
15 pub forward_attrs: ForwardAttrs<'a>,
16}
17
18impl ToTokens for FromAttributesImpl<'_> {
19 fn to_tokens(&self, tokens: &mut TokenStream) {
20 let ty_ident = self.base.ident;
21 let input = self.param_name();
22 let post_transform = self.base.post_transform_call();
23
24 if let Data::Struct(ref data) = self.base.data {
25 if data.is_newtype() {
26 self.wrap(
27 quote! {
28 fn from_attributes(#input: &[::darling::export::syn::Attribute]) -> ::darling::Result<Self> {
29 ::darling::export::Ok(
30 #ty_ident(::darling::FromAttributes::from_attributes(#input)?)
31 ) #post_transform
32 }
33 },
34 tokens,
35 );
36
37 return;
38 }
39 }
40
41 let passed_attrs = self.forward_attrs.as_initializer();
42 let inits = self.base.initializers();
43 let default = self.base.fallback_decl();
44
45 let grab_attrs = self.extractor();
46
47 let declare_errors = self.base.declare_errors();
48 let require_fields = self.base.require_fields();
49 let check_errors = self.base.check_errors();
50
51 self.wrap(
52 quote! {
53 fn from_attributes(#input: &[::darling::export::syn::Attribute]) -> ::darling::Result<Self> {
54 #declare_errors
55
56 #grab_attrs
57
58 #require_fields
59
60 #check_errors
61
62 #default
63
64 ::darling::export::Ok(#ty_ident {
65 #passed_attrs
66 #inits
67 }) #post_transform
68 }
69 },
70 tokens,
71 );
72 }
73}
74
75impl<'a> ExtractAttribute for FromAttributesImpl<'a> {
76 fn local_declarations(&self) -> TokenStream {
77 self.base.local_declarations()
78 }
79
80 fn attr_names(&self) -> &PathList {
81 self.attr_names
82 }
83
84 fn forward_attrs(&self) -> &super::ForwardAttrs<'_> {
85 &self.forward_attrs
86 }
87
88 fn param_name(&self) -> TokenStream {
89 quote!(__di)
90 }
91
92 fn attrs_accessor(&self) -> TokenStream {
93 self.param_name()
94 }
95
96 fn core_loop(&self) -> TokenStream {
97 self.base.core_loop()
98 }
99}
100
101impl<'a> OuterFromImpl<'a> for FromAttributesImpl<'a> {
102 fn trait_path(&self) -> syn::Path {
103 path!(::darling::FromAttributes)
104 }
105
106 fn trait_bound(&self) -> syn::Path {
107 path!(::darling::FromMeta)
108 }
109
110 fn base(&'a self) -> &'a TraitImpl<'a> {
111 &self.base
112 }
113}
114