strum_macros/macros/
enum_messages.rs

1use proc_macro2::TokenStream;
2use quote::quote;
3use syn::{Data, DeriveInput, Fields, LitStr};
4
5use crate::helpers::{non_enum_error, HasStrumVariantProperties, HasTypeProperties};
6
7pub 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.iter().map(|lit_str| {
78                let line = lit_str.value();
79                if line.starts_with(' ') {
80                    LitStr::new(&line.as_str()[1..], lit_str.span())
81                } else {
82                    lit_str.clone()
83                }
84            }).collect();
85            if documentation.len() == 1 {
86                let text = &documentation[0];
87                documentation_arms
88                    .push(quote! { &#name::#ident #params => ::core::option::Option::Some(#text) });
89            } else {
90                // Push the documentation.
91                documentation_arms
92                    .push(quote! {
93                        &#name::#ident #params => ::core::option::Option::Some(concat!(#(concat!(#documentation, "\n")),*))
94                    });
95            }
96        }
97    }
98
99    if arms.len() < variants.len() {
100        arms.push(quote! { _ => ::core::option::Option::None });
101    }
102
103    if detailed_arms.len() < variants.len() {
104        detailed_arms.push(quote! { _ => ::core::option::Option::None });
105    }
106
107    if documentation_arms.len() < variants.len() {
108        documentation_arms.push(quote! { _ => ::core::option::Option::None });
109    }
110
111    Ok(quote! {
112        impl #impl_generics #strum_module_path::EnumMessage for #name #ty_generics #where_clause {
113            fn get_message(&self) -> ::core::option::Option<&'static str> {
114                match self {
115                    #(#arms),*
116                }
117            }
118
119            fn get_detailed_message(&self) -> ::core::option::Option<&'static str> {
120                match self {
121                    #(#detailed_arms),*
122                }
123            }
124
125            fn get_documentation(&self) -> ::core::option::Option<&'static str> {
126                match self {
127                    #(#documentation_arms),*
128                }
129            }
130
131            fn get_serializations(&self) -> &'static [&'static str] {
132                match self {
133                    #(#serializations),*
134                }
135            }
136        }
137    })
138}
strum_macros/macros/enum_messages.rs

strum_macros/macros/
enum_messages.rs
