1 use proc_macro2::TokenStream;
2 use quote::quote;
3 use syn::{parse_quote, Data, DeriveInput, Fields};
4
5 use crate::helpers::{non_enum_error, HasStrumVariantProperties, HasTypeProperties};
6
get_arms(ast: &DeriveInput) -> syn::Result<Vec<TokenStream>>7 fn 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.get_preferred_name(type_properties.case_style);
29 let params = match variant.fields {
30 Fields::Unit => quote! {},
31 Fields::Unnamed(..) => quote! { (..) },
32 Fields::Named(..) => quote! { {..} },
33 };
34
35 arms.push(quote! { #name::#ident #params => #output });
36 }
37
38 if arms.len() < variants.len() {
39 arms.push(quote! {
40 _ => panic!(
41 "AsRef::<str>::as_ref() or AsStaticRef::<str>::as_static() \
42 called on disabled variant.",
43 )
44 });
45 }
46
47 Ok(arms)
48 }
49
as_ref_str_inner(ast: &DeriveInput) -> syn::Result<TokenStream>50 pub fn as_ref_str_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
51 let name = &ast.ident;
52 let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
53 let arms = get_arms(ast)?;
54 Ok(quote! {
55 impl #impl_generics ::core::convert::AsRef<str> for #name #ty_generics #where_clause {
56 fn as_ref(&self) -> &str {
57 match *self {
58 #(#arms),*
59 }
60 }
61 }
62 })
63 }
64
65 pub enum GenerateTraitVariant {
66 AsStaticStr,
67 From,
68 }
69
as_static_str_inner( ast: &DeriveInput, trait_variant: &GenerateTraitVariant, ) -> syn::Result<TokenStream>70 pub fn as_static_str_inner(
71 ast: &DeriveInput,
72 trait_variant: &GenerateTraitVariant,
73 ) -> syn::Result<TokenStream> {
74 let name = &ast.ident;
75 let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
76 let arms = get_arms(ast)?;
77 let type_properties = ast.get_type_properties()?;
78 let strum_module_path = type_properties.crate_module_path();
79
80 let mut generics = ast.generics.clone();
81 generics
82 .params
83 .push(syn::GenericParam::Lifetime(syn::LifetimeParam::new(
84 parse_quote!('_derivative_strum),
85 )));
86 let (impl_generics2, _, _) = generics.split_for_impl();
87 let arms2 = arms.clone();
88 let arms3 = arms.clone();
89
90 Ok(match trait_variant {
91 GenerateTraitVariant::AsStaticStr => quote! {
92 impl #impl_generics #strum_module_path::AsStaticRef<str> for #name #ty_generics #where_clause {
93 fn as_static(&self) -> &'static str {
94 match *self {
95 #(#arms),*
96 }
97 }
98 }
99 },
100 GenerateTraitVariant::From => quote! {
101 impl #impl_generics ::core::convert::From<#name #ty_generics> for &'static str #where_clause {
102 fn from(x: #name #ty_generics) -> &'static str {
103 match x {
104 #(#arms2),*
105 }
106 }
107 }
108 impl #impl_generics2 ::core::convert::From<&'_derivative_strum #name #ty_generics> for &'static str #where_clause {
109 fn from(x: &'_derivative_strum #name #ty_generics) -> &'static str {
110 match *x {
111 #(#arms3),*
112 }
113 }
114 }
115 },
116 })
117 }
118