use std::convert::TryFrom;
use quote::quote;
use syn::export::TokenStream2;
use syn::{Fields, ItemEnum};
use crate::attribute_helpers::{contains_initialize_with, contains_skip};
pub fn enum_de(input: &ItemEnum) -> syn::Result<TokenStream2> {
let name = &input.ident;
let generics = &input.generics;
let init_method = contains_initialize_with(&input.attrs)?;
let mut variant_arms = TokenStream2::new();
let mut deserializable_field_types = TokenStream2::new();
for (variant_idx, variant) in input.variants.iter().enumerate() {
let variant_idx = u8::try_from(variant_idx).expect("up to 256 enum variants are supported");
let variant_ident = &variant.ident;
let mut variant_header = TokenStream2::new();
match &variant.fields {
Fields::Named(fields) => {
for field in &fields.named {
let field_name = field.ident.as_ref().unwrap();
if contains_skip(&field.attrs) {
variant_header.extend(quote! {
#field_name: Default::default(),
});
} else {
let field_type = &field.ty;
deserializable_field_types.extend(quote! {
#field_type: borsh::BorshDeserialize,
});
variant_header.extend(quote! {
#field_name: borsh::BorshDeserialize::deserialize(buf)?,
});
}
}
variant_header = quote! { { #variant_header }};
}
Fields::Unnamed(fields) => {
for field in fields.unnamed.iter() {
if contains_skip(&field.attrs) {
variant_header.extend(quote! { Default::default(), });
} else {
let field_type = &field.ty;
deserializable_field_types.extend(quote! {
#field_type: borsh::BorshDeserialize,
});
variant_header
.extend(quote! { borsh::BorshDeserialize::deserialize(buf)?, });
}
}
variant_header = quote! { ( #variant_header )};
}
Fields::Unit => {}
}
variant_arms.extend(quote! {
#variant_idx => #name::#variant_ident #variant_header ,
});
}
let variant_idx = quote! {
let variant_idx: u8 = borsh::BorshDeserialize::deserialize(buf)?;
};
if let Some(method_ident) = init_method {
Ok(quote! {
impl #generics borsh::de::BorshDeserialize for #name #generics where #deserializable_field_types {
fn deserialize(buf: &mut &[u8]) -> std::result::Result<Self, std::io::Error> {
#variant_idx
let mut return_value = match variant_idx {
#variant_arms
_ =>
return Err(std::io::Error::new(
std::io::ErrorKind::InvalidInput,
format!("Unexpected variant index: {:?}", variant_idx),
)),
};
return_value.#method_ident();
Ok(return_value)
}
}
})
} else {
Ok(quote! {
impl #generics borsh::de::BorshDeserialize for #name #generics where #deserializable_field_types {
fn deserialize(buf: &mut &[u8]) -> std::result::Result<Self, std::io::Error> {
#variant_idx
let return_value = match variant_idx {
#variant_arms
_ =>
return Err(std::io::Error::new(
std::io::ErrorKind::InvalidInput,
format!("Unexpected variant index: {:?}", variant_idx),
)),
};
Ok(return_value)
}
}
})
}
}