1 use proc_macro2::TokenStream;
2 use quote::quote;
3 use syn::{Data, DeriveInput, Fields, LitStr};
4
5 use crate::helpers::{non_enum_error, HasStrumVariantProperties, HasTypeProperties};
6
enum_message_inner(ast: &DeriveInput) -> syn::Result<TokenStream>7 pub fn enum_message_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
8 let name = &ast.ident;
9 let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
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 let strum_module_path = type_properties.crate_module_path();
17
18 let mut arms = Vec::new();
19 let mut detailed_arms = Vec::new();
20 let mut documentation_arms = Vec::new();
21 let mut serializations = Vec::new();
22
23 for variant in variants {
24 let variant_properties = variant.get_variant_properties()?;
25 let messages = variant_properties.message.as_ref();
26 let detailed_messages = variant_properties.detailed_message.as_ref();
27 let documentation = &variant_properties.documentation;
28 let ident = &variant.ident;
29
30 let params = match variant.fields {
31 Fields::Unit => quote! {},
32 Fields::Unnamed(..) => quote! { (..) },
33 Fields::Named(..) => quote! { {..} },
34 };
35
36 // You can't disable getting the serializations.
37 {
38 let serialization_variants =
39 variant_properties.get_serializations(type_properties.case_style);
40
41 let count = serialization_variants.len();
42 serializations.push(quote! {
43 &#name::#ident #params => {
44 static ARR: [&'static str; #count] = [#(#serialization_variants),*];
45 &ARR
46 }
47 });
48 }
49
50 // But you can disable the messages.
51 if variant_properties.disabled.is_some() {
52 continue;
53 }
54
55 if let Some(msg) = messages {
56 let params = params.clone();
57
58 // Push the simple message.
59 let tokens = quote! { &#name::#ident #params => ::core::option::Option::Some(#msg) };
60 arms.push(tokens.clone());
61
62 if detailed_messages.is_none() {
63 detailed_arms.push(tokens);
64 }
65 }
66
67 if let Some(msg) = detailed_messages {
68 let params = params.clone();
69 // Push the detailed message.
70 detailed_arms
71 .push(quote! { &#name::#ident #params => ::core::option::Option::Some(#msg) });
72 }
73
74 if !documentation.is_empty() {
75 let params = params.clone();
76 // Strip a single leading space from each documentation line.
77 let documentation: Vec<LitStr> = documentation
78 .iter()
79 .map(|lit_str| {
80 let line = lit_str.value();
81 if line.starts_with(' ') {
82 LitStr::new(&line.as_str()[1..], lit_str.span())
83 } else {
84 lit_str.clone()
85 }
86 })
87 .collect();
88 if documentation.len() == 1 {
89 let text = &documentation[0];
90 documentation_arms
91 .push(quote! { &#name::#ident #params => ::core::option::Option::Some(#text) });
92 } else {
93 // Push the documentation.
94 documentation_arms
95 .push(quote! {
96 &#name::#ident #params => ::core::option::Option::Some(concat!(#(concat!(#documentation, "\n")),*))
97 });
98 }
99 }
100 }
101
102 if arms.len() < variants.len() {
103 arms.push(quote! { _ => ::core::option::Option::None });
104 }
105
106 if detailed_arms.len() < variants.len() {
107 detailed_arms.push(quote! { _ => ::core::option::Option::None });
108 }
109
110 if documentation_arms.len() < variants.len() {
111 documentation_arms.push(quote! { _ => ::core::option::Option::None });
112 }
113
114 Ok(quote! {
115 impl #impl_generics #strum_module_path::EnumMessage for #name #ty_generics #where_clause {
116 #[inline]
117 fn get_message(&self) -> ::core::option::Option<&'static str> {
118 match self {
119 #(#arms),*
120 }
121 }
122
123 #[inline]
124 fn get_detailed_message(&self) -> ::core::option::Option<&'static str> {
125 match self {
126 #(#detailed_arms),*
127 }
128 }
129
130 #[inline]
131 fn get_documentation(&self) -> ::core::option::Option<&'static str> {
132 match self {
133 #(#documentation_arms),*
134 }
135 }
136
137 #[inline]
138 fn get_serializations(&self) -> &'static [&'static str] {
139 match self {
140 #(#serializations),*
141 }
142 }
143 }
144 })
145 }
146