darling_core/codegen/
from_attributes_impl.rs

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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}
darling_core/codegen/from_attributes_impl.rs

darling_core/codegen/
from_attributes_impl.rs
