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extern crate proc_macro; use proc_macro::TokenStream; use quote::quote; use syn::{parse_macro_input, DeriveInput}; macro_rules! derive_as_json { ($tr:path, $name:ident, $function:path) => { quote! { impl $tr for #$name { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { let s = $function(&self) .map_err(|_| std::fmt::Error::default())?; write!(f, "{}", s) } } } }; } #[proc_macro_derive(DisplayAsJson)] pub fn derive_display_as_json(input: TokenStream) -> TokenStream { let input = parse_macro_input!(input as DeriveInput); let name = &input.ident; let result = derive_as_json!( std::fmt::Display, name, display_json::serde_json::to_string ); TokenStream::from(result) } #[proc_macro_derive(DisplayAsJsonPretty)] pub fn derive_display_as_json_pretty( input: TokenStream, ) -> TokenStream { let input = parse_macro_input!(input as DeriveInput); let name = &input.ident; let result = derive_as_json!( std::fmt::Display, name, display_json::serde_json::to_string_pretty ); TokenStream::from(result) } #[proc_macro_derive(DebugAsJson)] pub fn derive_debug_as_json(input: TokenStream) -> TokenStream { let input = parse_macro_input!(input as DeriveInput); let name = &input.ident; let result = derive_as_json!( std::fmt::Debug, name, display_json::serde_json::to_string ); TokenStream::from(result) } #[proc_macro_derive(DebugAsJsonPretty)] pub fn derive_debug_as_json_pretty( input: TokenStream, ) -> TokenStream { let input = parse_macro_input!(input as DeriveInput); let name = &input.ident; let result = derive_as_json!( std::fmt::Debug, name, display_json::serde_json::to_string_pretty ); TokenStream::from(result) }