derive_default_from_serde/
lib.rs

1extern crate proc_macro;
2
3use quote::quote;
4use syn::{parse_macro_input, DeriveInput};
5
6/// Derive `Default` from `serde::Deserialize`.
7#[proc_macro_derive(SerdeDefault)]
8pub fn derive_default_from_serde(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
9    let input = parse_macro_input!(input as DeriveInput);
10
11    match &input.data {
12        syn::Data::Struct(_) => {}
13        syn::Data::Enum(_) => panic!("Enum is not supported"),
14        syn::Data::Union(_) => panic!("Union is not supported"),
15    }
16
17    let name = input.ident;
18    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
19
20    let expanded = quote! {
21        impl #impl_generics ::std::default::Default for #name #ty_generics #where_clause {
22            fn default() -> Self {
23                let  deserializer = ::default_from_serde::DefaultDeserializer;
24                let t = <Self as ::serde::Deserialize>::deserialize(deserializer).unwrap();
25                t
26            }
27        }
28    };
29
30    proc_macro::TokenStream::from(expanded)
31}
derive_default_from_serde/lib.rs

derive_default_from_serde/
lib.rs
