strum_macros/macros/
enum_try_as.rs

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1use crate::helpers::{case_style::snakify, non_enum_error, HasStrumVariantProperties};
2use proc_macro2::TokenStream;
3use quote::{format_ident, quote, ToTokens};
4use syn::{Data, DeriveInput};
5
6pub fn enum_try_as_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
7    let variants = match &ast.data {
8        Data::Enum(v) => &v.variants,
9        _ => return Err(non_enum_error()),
10    };
11
12    let enum_name = &ast.ident;
13    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
14
15    let variants: Vec<_> = variants
16        .iter()
17        .filter_map(|variant| {
18            if variant.get_variant_properties().ok()?.disabled.is_some() {
19                return None;
20            }
21
22            match &variant.fields {
23                syn::Fields::Unnamed(values) => {
24                    let variant_name = &variant.ident;
25                    let types: Vec<_> = values.unnamed.iter().map(|field| {
26                        field.to_token_stream()
27                    }).collect();
28                    let field_names: Vec<_> = values.unnamed.iter().enumerate().map(|(i, _)| {
29                        let name = "x".repeat(i + 1);
30                        let name = format_ident!("{}", name);
31                        quote! {#name}
32                    }).collect();
33
34                    let move_fn_name = format_ident!("try_as_{}", snakify(&variant_name.to_string()));
35                    let ref_fn_name = format_ident!("try_as_{}_ref", snakify(&variant_name.to_string()));
36                    let mut_fn_name = format_ident!("try_as_{}_mut", snakify(&variant_name.to_string()));
37
38                    Some(quote! {
39                        #[must_use]
40                        #[inline]
41                        pub fn #move_fn_name(self) -> ::core::option::Option<(#(#types),*)> {
42                            match self {
43                                #enum_name::#variant_name (#(#field_names),*) => Some((#(#field_names),*)),
44                                _ => None
45                            }
46                        }
47
48                        #[must_use]
49                        #[inline]
50                        pub const fn #ref_fn_name(&self) -> ::core::option::Option<(#(&#types),*)> {
51                            match self {
52                                #enum_name::#variant_name (#(#field_names),*) => Some((#(#field_names),*)),
53                                _ => None
54                            }
55                        }
56
57                        #[must_use]
58                        #[inline]
59                        pub fn #mut_fn_name(&mut self) -> ::core::option::Option<(#(&mut #types),*)> {
60                            match self {
61                                #enum_name::#variant_name (#(#field_names),*) => Some((#(#field_names),*)),
62                                _ => None
63                            }
64                        }
65                    })
66                },
67                _ => {
68                    return None;
69                }
70            }
71
72        })
73        .collect();
74
75    Ok(quote! {
76        impl #impl_generics #enum_name #ty_generics #where_clause {
77            #(#variants)*
78        }
79    })
80}
strum_macros/macros/enum_try_as.rs

strum_macros/macros/
enum_try_as.rs
