use std::convert::TryFrom;
use quote::quote;
use syn::export::{Span, TokenStream2};
use syn::{Fields, Ident, ItemEnum};
use crate::attribute_helpers::contains_skip;
pub fn enum_ser(input: &ItemEnum) -> syn::Result<TokenStream2> {
let name = &input.ident;
let generics = &input.generics;
let mut body = TokenStream2::new();
let mut serializable_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();
let mut variant_body = 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, });
continue;
} else {
let field_type = &field.ty;
serializable_field_types.extend(quote! {
#field_type: borsh::ser::BorshSerialize,
});
variant_header.extend(quote! { #field_name, });
}
variant_body.extend(quote! {
borsh::BorshSerialize::serialize(#field_name, writer)?;
})
}
variant_header = quote! { { #variant_header }};
}
Fields::Unnamed(fields) => {
for (field_idx, field) in fields.unnamed.iter().enumerate() {
let field_idx =
u32::try_from(field_idx).expect("up to 2^32 fields are supported");
if contains_skip(&field.attrs) {
let field_ident =
Ident::new(format!("_id{}", field_idx).as_str(), Span::call_site());
variant_header.extend(quote! { #field_ident, });
continue;
} else {
let field_type = &field.ty;
serializable_field_types.extend(quote! {
#field_type: borsh::ser::BorshSerialize,
});
let field_ident =
Ident::new(format!("id{}", field_idx).as_str(), Span::call_site());
variant_header.extend(quote! { #field_ident, });
variant_body.extend(quote! {
borsh::BorshSerialize::serialize(#field_ident, writer)?;
})
}
}
variant_header = quote! { ( #variant_header )};
}
Fields::Unit => {}
}
body.extend(quote!(
#name::#variant_ident #variant_header => {
let variant_idx: u8 = #variant_idx;
writer.write_all(&variant_idx.to_le_bytes())?;
#variant_body
}
))
}
Ok(quote! {
impl #generics borsh::ser::BorshSerialize for #name #generics where #serializable_field_types {
fn serialize<W: std::io::Write>(&self, writer: &mut W) -> std::result::Result<(), std::io::Error> {
match self {
#body
}
Ok(())
}
}
})
}