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
44            .get_preferred_name(type_properties.case_style, type_properties.prefix.as_ref());
45        let params = match variant.fields {
46            Fields::Unit => quote! {},
47            Fields::Unnamed(..) => quote! { (..) },
48            Fields::Named(..) => quote! { {..} },
49        };
50
51        arms.push(quote! { #name::#ident #params => #output });
52    }
53
54    if arms.len() < variants.len() {
55        arms.push(quote! {
56            _ => panic!(
57                "AsRef::<str>::as_ref() or AsStaticRef::<str>::as_static() \
58                 called on disabled variant.",
59            )
60        });
61    }
62
63    Ok(arms)
64}
65
66pub fn as_ref_str_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
67    let name = &ast.ident;
68    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
69    let arms = get_arms(ast, |tok| {
70        quote! { ::core::convert::AsRef::<str>::as_ref(#tok) }
71    })?;
72
73    Ok(quote! {
74        impl #impl_generics ::core::convert::AsRef<str> for #name #ty_generics #where_clause {
75            #[inline]
76            fn as_ref(&self) -> &str {
77                match *self {
78                    #(#arms),*
79                }
80            }
81        }
82    })
83}
84
85pub enum GenerateTraitVariant {
86    AsStaticStr,
87    From,
88}
89
90pub fn as_static_str_inner(
91    ast: &DeriveInput,
92    trait_variant: &GenerateTraitVariant,
93) -> syn::Result<TokenStream> {
94    let name = &ast.ident;
95    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
96    let arms = &get_arms(ast, |tok| {
97        quote! { ::core::convert::From::from(#tok) }
98    })?;
99
100    let type_properties = ast.get_type_properties()?;
101    let strum_module_path = type_properties.crate_module_path();
102
103    let mut generics = ast.generics.clone();
104    generics
105        .params
106        .push(syn::GenericParam::Lifetime(syn::LifetimeParam::new(
107            parse_quote!('_derivative_strum),
108        )));
109    let (impl_generics2, _, _) = generics.split_for_impl();
110
111    Ok(match trait_variant {
112        GenerateTraitVariant::AsStaticStr => quote! {
113            impl #impl_generics #strum_module_path::AsStaticRef<str> for #name #ty_generics #where_clause {
114                #[inline]
115                fn as_static(&self) -> &'static str {
116                    match *self {
117                        #(#arms),*
118                    }
119                }
120            }
121        },
122        GenerateTraitVariant::From if !type_properties.const_into_str => quote! {
123            impl #impl_generics ::core::convert::From<#name #ty_generics> for &'static str #where_clause {
124                #[inline]
125                fn from(x: #name #ty_generics) -> &'static str {
126                    match x {
127                        #(#arms),*
128                    }
129                }
130            }
131            impl #impl_generics2 ::core::convert::From<&'_derivative_strum #name #ty_generics> for &'static str #where_clause {
132                #[inline]
133                fn from(x: &'_derivative_strum #name #ty_generics) -> &'static str {
134                    match *x {
135                        #(#arms),*
136                    }
137                }
138            }
139        },
140        GenerateTraitVariant::From => quote! {
141            impl #impl_generics #name #ty_generics #where_clause {
142                pub const fn into_str(&self) -> &'static str {
143                    match self {
144                        #(#arms),*
145                    }
146                }
147            }
148
149            impl #impl_generics ::core::convert::From<#name #ty_generics> for &'static str #where_clause {
150                fn from(x: #name #ty_generics) -> &'static str {
151                    match x {
152                        #(#arms),*
153                    }
154                }
155            }
156            impl #impl_generics2 ::core::convert::From<&'_derivative_strum #name #ty_generics> for &'static str #where_clause {
157                fn from(x: &'_derivative_strum #name #ty_generics) -> &'static str {
158                    x.into_str()
159                }
160            }
161        },
162    })
163}
strum_macros/macros/strings/as_ref_str.rs

strum_macros/macros/strings/
as_ref_str.rs
