strum_macros/macros/strings/
as_ref_str.rs

1use proc_macro2::TokenStream;
2use quote::quote;
3use syn::{parse_quote, Data, DeriveInput, Fields};
4
5use crate::helpers::{
6    non_enum_error, non_single_field_variant_error, HasStrumVariantProperties, HasTypeProperties,
7};
8
9fn get_arms<F>(ast: &DeriveInput, transparent_fn: F) -> syn::Result<Vec<TokenStream>>
10where
11    F: Fn(&TokenStream) -> TokenStream,
12{
13    let name = &ast.ident;
14    let mut arms = Vec::new();
15    let variants = match &ast.data {
16        Data::Enum(v) => &v.variants,
17        _ => return Err(non_enum_error()),
18    };
19
20    let type_properties = ast.get_type_properties()?;
21
22    for variant in variants {
23        let ident = &variant.ident;
24        let variant_properties = variant.get_variant_properties()?;
25
26        if variant_properties.disabled.is_some() {
27            continue;
28        }
29
30        if let Some(..) = variant_properties.transparent {
31            let arm = super::extract_single_field_variant_and_then(name, variant, |tok| {
32                transparent_fn(tok)
33            })
34            .map_err(|_| non_single_field_variant_error("transparent"))?;
35
36            arms.push(arm);
37            continue;
38        }
39
40        // Look at all the serialize attributes.
41        // Use `to_string` attribute (not `as_ref_str` or something) to keep things consistent
42        // (i.e. always `enum.as_ref().to_string() == enum.to_string()`).
43        let output = variant_properties.get_preferred_name(
44            type_properties.case_style,
45            type_properties.prefix.as_ref(),
46            type_properties.suffix.as_ref(),
47        );
48        let params = match variant.fields {
49            Fields::Unit => quote! {},
50            Fields::Unnamed(..) => quote! { (..) },
51            Fields::Named(..) => quote! { {..} },
52        };
53
54        arms.push(quote! { #name::#ident #params => #output });
55    }
56
57    if arms.len() < variants.len() {
58        arms.push(quote! {
59            _ => panic!(
60                "AsRef::<str>::as_ref() or AsStaticRef::<str>::as_static() \
61                 called on disabled variant.",
62            )
63        });
64    }
65
66    Ok(arms)
67}
68
69pub fn as_ref_str_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
70    let name = &ast.ident;
71    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
72    let arms = get_arms(ast, |tok| {
73        quote! { ::core::convert::AsRef::<str>::as_ref(#tok) }
74    })?;
75
76    Ok(quote! {
77        #[automatically_derived]
78        impl #impl_generics ::core::convert::AsRef<str> for #name #ty_generics #where_clause {
79            #[inline]
80            fn as_ref(&self) -> &str {
81                match *self {
82                    #(#arms),*
83                }
84            }
85        }
86    })
87}
88
89pub enum GenerateTraitVariant {
90    AsStaticStr,
91    From,
92}
93
94pub fn as_static_str_inner(
95    ast: &DeriveInput,
96    trait_variant: &GenerateTraitVariant,
97) -> syn::Result<TokenStream> {
98    let name = &ast.ident;
99    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
100    let arms = &get_arms(ast, |tok| {
101        quote! { ::core::convert::From::from(#tok) }
102    })?;
103
104    let type_properties = ast.get_type_properties()?;
105    let strum_module_path = type_properties.crate_module_path();
106
107    let mut generics = ast.generics.clone();
108    generics
109        .params
110        .push(syn::GenericParam::Lifetime(syn::LifetimeParam::new(
111            parse_quote!('_derivative_strum),
112        )));
113    let (impl_generics2, _, _) = generics.split_for_impl();
114
115    Ok(match trait_variant {
116        GenerateTraitVariant::AsStaticStr => quote! {
117            #[automatically_derived]
118            impl #impl_generics #strum_module_path::AsStaticRef<str> for #name #ty_generics #where_clause {
119                #[inline]
120                fn as_static(&self) -> &'static str {
121                    match *self {
122                        #(#arms),*
123                    }
124                }
125            }
126        },
127        GenerateTraitVariant::From if !type_properties.const_into_str => quote! {
128            #[automatically_derived]
129            impl #impl_generics ::core::convert::From<#name #ty_generics> for &'static str #where_clause {
130                #[inline]
131                fn from(x: #name #ty_generics) -> &'static str {
132                    match x {
133                        #(#arms),*
134                    }
135                }
136            }
137            #[automatically_derived]
138            impl #impl_generics2 ::core::convert::From<&'_derivative_strum #name #ty_generics> for &'static str #where_clause {
139                #[inline]
140                fn from(x: &'_derivative_strum #name #ty_generics) -> &'static str {
141                    match *x {
142                        #(#arms),*
143                    }
144                }
145            }
146        },
147        GenerateTraitVariant::From => quote! {
148            #[automatically_derived]
149            impl #impl_generics #name #ty_generics #where_clause {
150                pub const fn into_str(&self) -> &'static str {
151                    match self {
152                        #(#arms),*
153                    }
154                }
155            }
156            #[automatically_derived]
157            impl #impl_generics ::core::convert::From<#name #ty_generics> for &'static str #where_clause {
158                fn from(x: #name #ty_generics) -> &'static str {
159                    match x {
160                        #(#arms),*
161                    }
162                }
163            }
164            #[automatically_derived]
165            impl #impl_generics2 ::core::convert::From<&'_derivative_strum #name #ty_generics> for &'static str #where_clause {
166                fn from(x: &'_derivative_strum #name #ty_generics) -> &'static str {
167                    x.into_str()
168                }
169            }
170        },
171    })
172}
strum_macros/macros/strings/as_ref_str.rs

strum_macros/macros/strings/
as_ref_str.rs
