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use proc_macro2::TokenStream;
use proc_macro_error::abort;
use quote::{format_ident, quote};
use syn::{Data, DataEnum, DataStruct, DeriveInput};
use crate::{
common::{add_js_lifetime, crate_ident},
fields::Fields,
};
pub(crate) fn expand(input: DeriveInput) -> TokenStream {
let DeriveInput {
ident,
generics,
data,
..
} = input;
let lifetime_generics = add_js_lifetime(&generics);
let crate_name = format_ident!("{}", crate_ident());
match data {
Data::Struct(struct_) => {
let DataStruct { fields, .. } = struct_;
let trace_body = match Fields::from_fields(fields) {
Fields::Named(mut f) => {
let fields = f.iter_mut().map(|x| x.expand_trace_body_named(&crate_name));
quote!(
#(#fields)*
)
}
Fields::Unnamed(mut f) => {
let fields = f.iter_mut().enumerate().map(|(idx, x)| {
x.expand_trace_body_unnamed(&crate_name, idx.try_into().unwrap())
});
quote!(
#(#fields)*
)
}
Fields::Unit => TokenStream::new(),
};
quote! {
impl #lifetime_generics #crate_name::class::Trace<'js> for #ident #generics{
fn trace<'a>(&self, _tracer: #crate_name::class::Tracer<'a,'js>){
#trace_body
}
}
}
}
Data::Enum(DataEnum { variants, .. }) => {
let body = variants.into_iter().map(|x| {
let ident = &x.ident;
let fields = Fields::from_fields(x.fields);
match fields {
Fields::Named(f) => {
let has_skip = f.iter().any(|x| x.config.skip_trace);
let field_names = f
.iter()
.filter_map(|f| (!f.config.skip_trace).then_some(&f.ident))
.collect::<Vec<_>>();
let remainder = has_skip.then_some(quote!(..));
let pattern = quote! {
Self::#ident{ #(ref #field_names,)* #remainder }
};
let body = quote! {
{
#(#crate_name::class::Trace::trace(#field_names, _tracer);)*
}
};
quote! {
#pattern => #body
}
}
Fields::Unnamed(f) => {
let patterns = f.iter().enumerate().map(|(idx, f)| {
if f.config.skip_trace {
quote!(_)
} else {
let ident = format_ident!("tmp_{idx}");
quote!(ref #ident)
}
});
let pattern = quote!(Self::#ident(#(#patterns),*));
let names = f
.iter()
.enumerate()
.filter(|&(_idx, f)| (!f.config.skip_trace))
.map(|(idx, _f)| {
let ident = format_ident!("tmp_{idx}");
Some(ident)
});
let body = quote! {
{
#(#crate_name::class::Trace::trace(#names,_tracer);)*
}
};
quote! {
#pattern => #body
}
}
Fields::Unit => {
quote! {
Self::#ident => {}
}
}
}
});
quote! {
impl #lifetime_generics #crate_name::class::Trace<'js> for #ident #generics {
fn trace<'a>(&self, _tracer: #crate_name::class::Tracer<'a,'js>){
match *self{
#(#body,)*
}
}
}
}
}
Data::Union(u) => {
abort!(u.union_token, "deriving trace for unions is not supported");
}
}
}