use proc_macro::TokenStream;use quote::quote;use syn::{parse_macro_input, Attribute, Data, DeriveInput, Lit, Meta, NestedMeta}; pub fn derive_path_static_str(input: TokenStream) -> TokenStream { let input = parse_macro_input!(input as DeriveInput); let name = &input.ident; let prefix = get_attr_value(&input.attrs, "prefix").unwrap_or_else(|| "".to_string()); let suffix = get_attr_value(&input.attrs, "suffix").unwrap_or_else(|| "".to_string()); let delimiter = get_attr_value(&input.attrs, "delimiter").unwrap_or_else(|| "/".to_string()); let path_str_impl = impl_path_str(name, &input.data, &prefix, &suffix, &delimiter); let expanded = quote! { impl #name { pub fn path_str(&self) -> &'static str { #path_str_impl } } }; TokenStream::from(expanded)} fn impl_path_str( name: &syn::Ident, data: &Data, prefix: &str, suffix: &str, delimiter: &str,) -> proc_macro2::TokenStream { match *data { Data::Enum(ref data) => { let match_arms = data.variants.iter().map(|variant| { let ident = &variant.ident; let path = format!("{}{}{}{}{}", prefix, delimiter, ident, delimiter, suffix); quote! { #name::#ident => #path, } }); quote! { match self { #(#match_arms)* } } } _ => panic!("DerivePathStr only supports enums"), }} fn get_attr_value(attrs: &[Attribute], key: &str) -> Option<String> { attrs .iter() .filter(|attr| attr.path.is_ident("derive_path_static_str")) .find_map(|attr| { if let Ok(Meta::List(meta_list)) = attr.parse_meta() { meta_list.nested.iter().find_map(|nested_meta| { if let NestedMeta::Meta(Meta::NameValue(name_value)) = nested_meta { if name_value.path.is_ident(key) { if let Lit::Str(lit_str) = &name_value.lit { return Some(lit_str.value()); } } } None }) } else { None } })}
use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, Attribute, Data, DeriveInput, Lit, Meta, NestedMeta};
pub fn derive_path_static_str(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let name = &input.ident;
let prefix = get_attr_value(&input.attrs, "prefix").unwrap_or_else(|| "".to_string());
let suffix = get_attr_value(&input.attrs, "suffix").unwrap_or_else(|| "".to_string());
let delimiter = get_attr_value(&input.attrs, "delimiter").unwrap_or_else(|| "/".to_string());
let path_str_impl = impl_path_str(name, &input.data, &prefix, &suffix, &delimiter);
let expanded = quote! {
impl #name {
pub fn path_str(&self) -> &'static str {
#path_str_impl
}
}
};
TokenStream::from(expanded)
}
fn impl_path_str(
name: &syn::Ident,
data: &Data,
prefix: &str,
suffix: &str,
delimiter: &str,
) -> proc_macro2::TokenStream {
match *data {
Data::Enum(ref data) => {
let match_arms = data.variants.iter().map(|variant| {
let ident = &variant.ident;
let path = format!("{}{}{}{}{}", prefix, delimiter, ident, delimiter, suffix);
quote! {
#name::#ident => #path,
}
});
quote! {
match self {
#(#match_arms)*
}
}
}
_ => panic!("DerivePathStr only supports enums"),
}
}
fn get_attr_value(attrs: &[Attribute], key: &str) -> Option<String> {
attrs
.iter()
.filter(|attr| attr.path.is_ident("derive_path_static_str"))
.find_map(|attr| {
if let Ok(Meta::List(meta_list)) = attr.parse_meta() {
meta_list.nested.iter().find_map(|nested_meta| {
if let NestedMeta::Meta(Meta::NameValue(name_value)) = nested_meta {
if name_value.path.is_ident(key) {
if let Lit::Str(lit_str) = &name_value.lit {
return Some(lit_str.value());
}
}
}
None
})
} else {
None
}
})
}