1use proc_macro2::TokenStream;
2use quote::quote;
3use syn::{parse_quote, Data, DeriveInput, Fields, Path};
4
5use crate::helpers::{
6 missing_parse_err_attr_error, non_enum_error, occurrence_error, HasInnerVariantProperties,
7 HasStrumVariantProperties, HasTypeProperties,
8};
9
10pub fn from_string_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
11 let name = &ast.ident;
12 let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
13 let variants = match &ast.data {
14 Data::Enum(v) => &v.variants,
15 _ => return Err(non_enum_error()),
16 };
17
18 let type_properties = ast.get_type_properties()?;
19 let strum_module_path = type_properties.crate_module_path();
20
21 let mut default_kw = None;
22 let (mut default_err_ty, mut default) = match (
23 type_properties.parse_err_ty,
24 type_properties.parse_err_fn,
25 ) {
26 (None, None) => (
27 quote! { #strum_module_path::ParseError },
28 quote! { ::core::result::Result::Err(#strum_module_path::ParseError::VariantNotFound) },
29 ),
30 (Some(ty), Some(f)) => {
31 let ty_path: Path = parse_quote!(#ty);
32 let fn_path: Path = parse_quote!(#f);
33
34 (
35 quote! { #ty_path },
36 quote! { ::core::result::Result::Err(#fn_path(s)) },
37 )
38 }
39 _ => return Err(missing_parse_err_attr_error()),
40 };
41 let mut phf_exact_match_arms = Vec::new();
42 let mut standard_match_arms = Vec::new();
43 for variant in variants {
44 let ident = &variant.ident;
45 let variant_properties = variant.get_variant_properties()?;
46
47 if variant_properties.disabled.is_some() {
48 continue;
49 }
50
51 if let Some(kw) = variant_properties.default {
52 if let Some(fst_kw) = default_kw {
53 return Err(occurrence_error(fst_kw, kw, "default"));
54 }
55
56 default_kw = Some(kw);
57 default_err_ty = quote! { #strum_module_path::ParseError };
58
59 match &variant.fields {
60 Fields::Unnamed(fields) if fields.unnamed.len() == 1 => {
61 default = quote! {
62 ::core::result::Result::Ok(#name::#ident(s.into()))
63 };
64 }
65 Fields::Named(ref f) if f.named.len() == 1 => {
66 let field_name = f.named.last().unwrap().ident.as_ref().unwrap();
67 default = quote! {
68 ::core::result::Result::Ok(#name::#ident { #field_name : s.into() } )
69 };
70 }
71 _ => {
72 return Err(syn::Error::new_spanned(
73 variant,
74 "Default only works on newtype structs with a single String field",
75 ))
76 }
77 }
78
79 continue;
80 }
81
82 let params = match &variant.fields {
83 Fields::Unit => quote! {},
84 Fields::Unnamed(fields) => {
85 if let Some(ref value) = variant_properties.default_with {
86 let func = proc_macro2::Ident::new(&value.value(), value.span());
87 let defaults = vec![quote! { #func() }];
88 quote! { (#(#defaults),*) }
89 } else {
90 let defaults =
91 ::core::iter::repeat(quote!(Default::default())).take(fields.unnamed.len());
92 quote! { (#(#defaults),*) }
93 }
94 }
95 Fields::Named(fields) => {
96 let mut defaults = vec![];
97 for field in &fields.named {
98 let meta = field.get_variant_inner_properties()?;
99 let field = field.ident.as_ref().unwrap();
100
101 if let Some(default_with) = meta.default_with {
102 let func =
103 proc_macro2::Ident::new(&default_with.value(), default_with.span());
104 defaults.push(quote! {
105 #field: #func()
106 });
107 } else {
108 defaults.push(quote! { #field: Default::default() });
109 }
110 }
111
112 quote! { {#(#defaults),*} }
113 }
114 };
115
116 let is_ascii_case_insensitive = variant_properties
117 .ascii_case_insensitive
118 .unwrap_or(type_properties.ascii_case_insensitive);
119
120 // If we don't have any custom variants, add the default serialized name.
121 for serialization in variant_properties.get_serializations(type_properties.case_style) {
122 if type_properties.use_phf {
123 phf_exact_match_arms.push(quote! { #serialization => #name::#ident #params, });
124
125 if is_ascii_case_insensitive {
126 // Store the lowercase and UPPERCASE variants in the phf map to capture
127 let ser_string = serialization.value();
128
129 let lower =
130 syn::LitStr::new(&ser_string.to_ascii_lowercase(), serialization.span());
131 let upper =
132 syn::LitStr::new(&ser_string.to_ascii_uppercase(), serialization.span());
133 phf_exact_match_arms.push(quote! { #lower => #name::#ident #params, });
134 phf_exact_match_arms.push(quote! { #upper => #name::#ident #params, });
135 standard_match_arms.push(quote! { s if s.eq_ignore_ascii_case(#serialization) => #name::#ident #params, });
136 }
137 } else {
138 standard_match_arms.push(if !is_ascii_case_insensitive {
139 quote! { #serialization => #name::#ident #params, }
140 } else {
141 quote! { s if s.eq_ignore_ascii_case(#serialization) => #name::#ident #params, }
142 });
143 }
144 }
145 }
146
147 let phf_body = if phf_exact_match_arms.is_empty() {
148 quote!()
149 } else {
150 quote! {
151 use #strum_module_path::_private_phf_reexport_for_macro_if_phf_feature as phf;
152 static PHF: phf::Map<&'static str, #name> = phf::phf_map! {
153 #(#phf_exact_match_arms)*
154 };
155 if let Some(value) = PHF.get(s).cloned() {
156 return ::core::result::Result::Ok(value);
157 }
158 }
159 };
160
161 let standard_match_body = if standard_match_arms.is_empty() {
162 default
163 } else {
164 quote! {
165 ::core::result::Result::Ok(match s {
166 #(#standard_match_arms)*
167 _ => return #default,
168 })
169 }
170 };
171
172 let from_str = quote! {
173 #[allow(clippy::use_self)]
174 impl #impl_generics ::core::str::FromStr for #name #ty_generics #where_clause {
175 type Err = #default_err_ty;
176
177 #[inline]
178 fn from_str(s: &str) -> ::core::result::Result< #name #ty_generics , <Self as ::core::str::FromStr>::Err> {
179 #phf_body
180 #standard_match_body
181 }
182 }
183 };
184 let try_from_str = try_from_str(
185 name,
186 &impl_generics,
187 &ty_generics,
188 where_clause,
189 &default_err_ty,
190 );
191
192 Ok(quote! {
193 #from_str
194 #try_from_str
195 })
196}
197
198#[rustversion::before(1.34)]
199fn try_from_str(
200 _name: &proc_macro2::Ident,
201 _impl_generics: &syn::ImplGenerics,
202 _ty_generics: &syn::TypeGenerics,
203 _where_clause: Option<&syn::WhereClause>,
204 _strum_module_path: &syn::Path,
205) -> TokenStream {
206 Default::default()
207}
208
209#[rustversion::since(1.34)]
210fn try_from_str(
211 name: &proc_macro2::Ident,
212 impl_generics: &syn::ImplGenerics,
213 ty_generics: &syn::TypeGenerics,
214 where_clause: Option<&syn::WhereClause>,
215 default_err_ty: &TokenStream,
216) -> TokenStream {
217 quote! {
218 #[allow(clippy::use_self)]
219 impl #impl_generics ::core::convert::TryFrom<&str> for #name #ty_generics #where_clause {
220 type Error = #default_err_ty;
221
222 #[inline]
223 fn try_from(s: &str) -> ::core::result::Result< #name #ty_generics , <Self as ::core::convert::TryFrom<&str>>::Error> {
224 ::core::str::FromStr::from_str(s)
225 }
226 }
227 }
228}
229