1 | use proc_macro2::TokenStream; |
2 | use quote::{quote, ToTokens}; |
3 | use syn::Ident; |
4 | |
5 | use crate::{ |
6 | codegen::{ExtractAttribute, OuterFromImpl, TraitImpl}, |
7 | options::ForwardAttrs, |
8 | util::PathList, |
9 | }; |
10 | |
11 | /// `impl FromField` generator. This is used for parsing an individual |
12 | /// field and its attributes. |
13 | pub struct FromFieldImpl<'a> { |
14 | pub ident: Option<&'a Ident>, |
15 | pub vis: Option<&'a Ident>, |
16 | pub ty: Option<&'a Ident>, |
17 | pub attrs: Option<&'a Ident>, |
18 | pub base: TraitImpl<'a>, |
19 | pub attr_names: &'a PathList, |
20 | pub forward_attrs: Option<&'a ForwardAttrs>, |
21 | pub from_ident: bool, |
22 | } |
23 | |
24 | impl<'a> ToTokens for FromFieldImpl<'a> { |
25 | fn to_tokens(&self, tokens: &mut TokenStream) { |
26 | let input = self.param_name(); |
27 | |
28 | let error_declaration = self.base.declare_errors(); |
29 | let require_fields = self.base.require_fields(); |
30 | let error_check = self.base.check_errors(); |
31 | |
32 | let initializers = self.base.initializers(); |
33 | |
34 | let default = if self.from_ident { |
35 | quote!(let __default: Self = ::darling::export::From::from(#input.ident.clone());) |
36 | } else { |
37 | self.base.fallback_decl() |
38 | }; |
39 | |
40 | let passed_ident = self |
41 | .ident |
42 | .as_ref() |
43 | .map(|i| quote!(#i: #input.ident.clone(),)); |
44 | let passed_vis = self.vis.as_ref().map(|i| quote!(#i: #input.vis.clone(),)); |
45 | let passed_ty = self.ty.as_ref().map(|i| quote!(#i: #input.ty.clone(),)); |
46 | let passed_attrs = self.attrs.as_ref().map(|i| quote!(#i: __fwd_attrs,)); |
47 | |
48 | // Determine which attributes to forward (if any). |
49 | let grab_attrs = self.extractor(); |
50 | let post_transform = self.base.post_transform_call(); |
51 | |
52 | self.wrap( |
53 | quote! { |
54 | fn from_field(#input: &::darling::export::syn::Field) -> ::darling::Result<Self> { |
55 | #error_declaration |
56 | |
57 | #grab_attrs |
58 | |
59 | #require_fields |
60 | |
61 | #error_check |
62 | |
63 | #default |
64 | |
65 | ::darling::export::Ok(Self { |
66 | #passed_ident |
67 | #passed_ty |
68 | #passed_vis |
69 | #passed_attrs |
70 | #initializers |
71 | }) #post_transform |
72 | |
73 | } |
74 | }, |
75 | tokens, |
76 | ); |
77 | } |
78 | } |
79 | |
80 | impl<'a> ExtractAttribute for FromFieldImpl<'a> { |
81 | fn attr_names(&self) -> &PathList { |
82 | self.attr_names |
83 | } |
84 | |
85 | fn forwarded_attrs(&self) -> Option<&ForwardAttrs> { |
86 | self.forward_attrs |
87 | } |
88 | |
89 | fn param_name(&self) -> TokenStream { |
90 | quote!(__field) |
91 | } |
92 | |
93 | fn core_loop(&self) -> TokenStream { |
94 | self.base.core_loop() |
95 | } |
96 | |
97 | fn local_declarations(&self) -> TokenStream { |
98 | self.base.local_declarations() |
99 | } |
100 | } |
101 | |
102 | impl<'a> OuterFromImpl<'a> for FromFieldImpl<'a> { |
103 | fn trait_path(&self) -> syn::Path { |
104 | path!(::darling::FromField) |
105 | } |
106 | |
107 | fn trait_bound(&self) -> syn::Path { |
108 | path!(::darling::FromMeta) |
109 | } |
110 | |
111 | fn base(&'a self) -> &'a TraitImpl<'a> { |
112 | &self.base |
113 | } |
114 | } |
115 | |