use proc_macro2::{Span, TokenStream};
use syn::Ident;
use internals::ast::{Container, Data, Field, Style};
pub fn pretend_used(cont: &Container) -> TokenStream {
let pretend_fields = pretend_fields_used(cont);
let pretend_variants = pretend_variants_used(cont);
quote! {
#pretend_fields
#pretend_variants
}
}
fn pretend_fields_used(cont: &Container) -> TokenStream {
let type_ident = &cont.ident;
let (_, ty_generics, _) = cont.generics.split_for_impl();
let patterns = match cont.data {
Data::Enum(ref variants) => variants
.iter()
.filter_map(|variant| match variant.style {
Style::Struct => {
let variant_ident = &variant.ident;
let pat = struct_pattern(&variant.fields);
Some(quote!(#type_ident::#variant_ident #pat))
}
_ => None,
})
.collect::<Vec<_>>(),
Data::Struct(Style::Struct, ref fields) => {
let pat = struct_pattern(fields);
vec![quote!(#type_ident #pat)]
}
Data::Struct(_, _) => {
return quote!();
}
};
quote! {
match _serde::export::None::<#type_ident #ty_generics> {
#(
_serde::export::Some(#patterns) => {}
)*
_ => {}
}
}
}
fn pretend_variants_used(cont: &Container) -> TokenStream {
let variants = match cont.data {
Data::Enum(ref variants) => variants,
Data::Struct(_, _) => {
return quote!();
}
};
let type_ident = &cont.ident;
let (_, ty_generics, _) = cont.generics.split_for_impl();
let turbofish = ty_generics.as_turbofish();
let cases = variants.iter().map(|variant| {
let variant_ident = &variant.ident;
let placeholders = &(0..variant.fields.len())
.map(|i| Ident::new(&format!("__v{}", i), Span::call_site()))
.collect::<Vec<_>>();
let pat = match variant.style {
Style::Struct => {
let members = variant.fields.iter().map(|field| &field.member);
quote!({ #(#members: #placeholders),* })
}
Style::Tuple | Style::Newtype => quote!(( #(#placeholders),* )),
Style::Unit => quote!(),
};
quote! {
match _serde::export::None {
_serde::export::Some((#(#placeholders,)*)) => {
let _ = #type_ident::#variant_ident #turbofish #pat;
}
_ => {}
}
}
});
quote!(#(#cases)*)
}
fn struct_pattern(fields: &[Field]) -> TokenStream {
let members = fields.iter().map(|field| &field.member);
let placeholders =
(0..fields.len()).map(|i| Ident::new(&format!("__v{}", i), Span::call_site()));
quote!({ #(#members: ref #placeholders),* })
}