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#![deny(warnings)] extern crate proc_macro; extern crate proc_macro_helper; #[macro_use] extern crate quote; extern crate syn; mod utils; use proc_macro::TokenStream; use proc_macro_helper::prelude::*; use syn::{DeriveInput, Ident}; use utils::*; #[proc_macro_derive(EnumToStr, attributes(ETS))] pub fn enum_to_str(input: TokenStream) -> TokenStream { let derive_input = syn::parse::<DeriveInput>(input).unwrap(); let target_enum = Enum::parse(&derive_input); let enum_name = syn::parse_str::<Ident>(target_enum.name.as_ref()).unwrap(); let match_content = target_enum .variants .iter() .map(|x| each_variant(x, &enum_name)); quote!( impl #enum_name { pub fn enum_to_str(&self) -> &'static str { match *self { #(#match_content),* } } } ).into() } fn each_variant(source: &Variant, enum_name: &Ident) -> impl quote::ToTokens { let variant_name: Ident = syn::parse_str(source.name.as_ref()).unwrap(); let variant_content = if source.fields.is_empty() { quote!() } else { let temp = vec![quote!(_); source.fields.len()]; quote!((#(#temp),*)) }; let variant_value = variant_value(source); quote!( #enum_name::#variant_name#variant_content => #variant_value) } fn variant_value(source: &Variant) -> impl quote::ToTokens { if let Some(value_attribute) = target_attributes(source).find(|x| x.name == "value") { let value = lit_str_value( value_attribute .values .first() .expect("string value must be set"), ).expect("value must be string"); return quote!(#value); } let value = source.name.clone(); return quote!(#value); }