1use proc_macro2::TokenStream;
2use quote::quote;
3use syn::{parse_quote, Data, DeriveInput, Fields};
4
5use crate::helpers::{non_enum_error, HasStrumVariantProperties, HasTypeProperties};
6
7fn get_arms(ast: &DeriveInput) -> syn::Result<Vec<TokenStream>> {
8 let name = &ast.ident;
9 let mut arms = Vec::new();
10 let variants = match &ast.data {
11 Data::Enum(v) => &v.variants,
12 _ => return Err(non_enum_error()),
13 };
14
15 let type_properties = ast.get_type_properties()?;
16
17 for variant in variants {
18 let ident = &variant.ident;
19 let variant_properties = variant.get_variant_properties()?;
20
21 if variant_properties.disabled.is_some() {
22 continue;
23 }
24
25 // Look at all the serialize attributes.
26 // Use `to_string` attribute (not `as_ref_str` or something) to keep things consistent
27 // (i.e. always `enum.as_ref().to_string() == enum.to_string()`).
28 let output = variant_properties
29 .get_preferred_name(type_properties.case_style, type_properties.prefix.as_ref());
30
31 let params = match variant.fields {
32 Fields::Unit => quote! {},
33 Fields::Unnamed(..) => quote! { (..) },
34 Fields::Named(..) => quote! { {..} },
35 };
36
37 arms.push(quote! { #name::#ident #params => #output });
38 }
39
40 if arms.len() < variants.len() {
41 arms.push(quote! {
42 _ => panic!(
43 "AsRef::<str>::as_ref() or AsStaticRef::<str>::as_static() \
44 called on disabled variant.",
45 )
46 });
47 }
48
49 Ok(arms)
50}
51
52pub fn as_ref_str_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
53 let name: &Ident = &ast.ident;
54 let (impl_generics: ImplGenerics<'_>, ty_generics: TypeGenerics<'_>, where_clause: Option<&WhereClause>) = ast.generics.split_for_impl();
55 let arms: Vec = get_arms(ast)?;
56 Ok(quote! {
57 impl #impl_generics ::core::convert::AsRef<str> for #name #ty_generics #where_clause {
58 fn as_ref(&self) -> &str {
59 match *self {
60 #(#arms),*
61 }
62 }
63 }
64 })
65}
66
67pub enum GenerateTraitVariant {
68 AsStaticStr,
69 From,
70}
71
72pub fn as_static_str_inner(
73 ast: &DeriveInput,
74 trait_variant: &GenerateTraitVariant,
75) -> syn::Result<TokenStream> {
76 let name = &ast.ident;
77 let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
78 let arms = get_arms(ast)?;
79 let type_properties = ast.get_type_properties()?;
80 let strum_module_path = type_properties.crate_module_path();
81
82 let mut generics = ast.generics.clone();
83 generics
84 .params
85 .push(syn::GenericParam::Lifetime(syn::LifetimeParam::new(
86 parse_quote!('_derivative_strum),
87 )));
88 let (impl_generics2, _, _) = generics.split_for_impl();
89 let arms2 = arms.clone();
90 let arms3 = arms.clone();
91
92 Ok(match trait_variant {
93 GenerateTraitVariant::AsStaticStr => quote! {
94 impl #impl_generics #strum_module_path::AsStaticRef<str> for #name #ty_generics #where_clause {
95 fn as_static(&self) -> &'static str {
96 match *self {
97 #(#arms),*
98 }
99 }
100 }
101 },
102 GenerateTraitVariant::From => quote! {
103 impl #impl_generics ::core::convert::From<#name #ty_generics> for &'static str #where_clause {
104 fn from(x: #name #ty_generics) -> &'static str {
105 match x {
106 #(#arms2),*
107 }
108 }
109 }
110 impl #impl_generics2 ::core::convert::From<&'_derivative_strum #name #ty_generics> for &'static str #where_clause {
111 fn from(x: &'_derivative_strum #name #ty_generics) -> &'static str {
112 match *x {
113 #(#arms3),*
114 }
115 }
116 }
117 },
118 })
119}
120