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use proc_macro2::TokenStream;
use quote::{quote, quote_spanned};
use syn::parse_quote;
use syn::spanned::Spanned;
pub fn type_decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
let decoder_ty = quote! { __D };
if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
s.add_impl_generic(parse_quote! { 'tcx });
}
s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_type_ir::codec::TyDecoder<I = ::rustc_middle::ty::TyCtxt<'tcx>>});
s.add_bounds(synstructure::AddBounds::Generics);
decodable_body(s, decoder_ty)
}
pub fn meta_decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
s.add_impl_generic(parse_quote! { 'tcx });
}
s.add_impl_generic(parse_quote! { '__a });
let decoder_ty = quote! { DecodeContext<'__a, 'tcx> };
s.add_bounds(synstructure::AddBounds::Generics);
decodable_body(s, decoder_ty)
}
pub fn decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
let decoder_ty = quote! { __D };
s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_serialize::Decoder});
s.add_bounds(synstructure::AddBounds::Generics);
decodable_body(s, decoder_ty)
}
fn decodable_body(
s: synstructure::Structure<'_>,
decoder_ty: TokenStream,
) -> proc_macro2::TokenStream {
if let syn::Data::Union(_) = s.ast().data {
panic!("cannot derive on union")
}
let ty_name = s.ast().ident.to_string();
let decode_body = match s.variants() {
[vi] => vi.construct(|field, _index| decode_field(field)),
variants => {
let match_inner: TokenStream = variants
.iter()
.enumerate()
.map(|(idx, vi)| {
let construct = vi.construct(|field, _index| decode_field(field));
quote! { #idx => { #construct } }
})
.collect();
let message = format!(
"invalid enum variant tag while decoding `{}`, expected 0..{}",
ty_name,
variants.len()
);
quote! {
match ::rustc_serialize::Decoder::read_usize(__decoder) {
#match_inner
_ => panic!(#message),
}
}
}
};
s.bound_impl(
quote!(::rustc_serialize::Decodable<#decoder_ty>),
quote! {
fn decode(__decoder: &mut #decoder_ty) -> Self {
#decode_body
}
},
)
}
fn decode_field(field: &syn::Field) -> proc_macro2::TokenStream {
let field_span = field.ident.as_ref().map_or(field.ty.span(), |ident| ident.span());
let decode_inner_method = if let syn::Type::Reference(_) = field.ty {
quote! { ::rustc_middle::ty::codec::RefDecodable::decode }
} else {
quote! { ::rustc_serialize::Decodable::decode }
};
let __decoder = quote! { __decoder };
quote_spanned! {field_span=> #decode_inner_method(#__decoder) }
}
pub fn type_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
s.add_impl_generic(parse_quote! {'tcx});
}
let encoder_ty = quote! { __E };
s.add_impl_generic(parse_quote! {#encoder_ty: ::rustc_type_ir::codec::TyEncoder<I = ::rustc_middle::ty::TyCtxt<'tcx>>});
s.add_bounds(synstructure::AddBounds::Generics);
encodable_body(s, encoder_ty, false)
}
pub fn meta_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
s.add_impl_generic(parse_quote! {'tcx});
}
s.add_impl_generic(parse_quote! { '__a });
let encoder_ty = quote! { EncodeContext<'__a, 'tcx> };
s.add_bounds(synstructure::AddBounds::Generics);
encodable_body(s, encoder_ty, true)
}
pub fn encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
let encoder_ty = quote! { __E };
s.add_impl_generic(parse_quote! { #encoder_ty: ::rustc_serialize::Encoder});
s.add_bounds(synstructure::AddBounds::Generics);
encodable_body(s, encoder_ty, false)
}
fn encodable_body(
mut s: synstructure::Structure<'_>,
encoder_ty: TokenStream,
allow_unreachable_code: bool,
) -> proc_macro2::TokenStream {
if let syn::Data::Union(_) = s.ast().data {
panic!("cannot derive on union")
}
s.bind_with(|binding| {
if let syn::Type::Reference(_) = binding.ast().ty {
synstructure::BindStyle::Move
} else {
synstructure::BindStyle::Ref
}
});
let encode_body = match s.variants() {
[_] => {
let encode_inner = s.each_variant(|vi| {
vi.bindings()
.iter()
.map(|binding| {
let bind_ident = &binding.binding;
let result = quote! {
::rustc_serialize::Encodable::<#encoder_ty>::encode(
#bind_ident,
__encoder,
);
};
result
})
.collect::<TokenStream>()
});
quote! {
match *self { #encode_inner }
}
}
_ => {
let mut variant_idx = 0usize;
let encode_inner = s.each_variant(|vi| {
let encode_fields: TokenStream = vi
.bindings()
.iter()
.map(|binding| {
let bind_ident = &binding.binding;
let result = quote! {
::rustc_serialize::Encodable::<#encoder_ty>::encode(
#bind_ident,
__encoder,
);
};
result
})
.collect();
let result = if !vi.bindings().is_empty() {
quote! {
::rustc_serialize::Encoder::emit_enum_variant(
__encoder,
#variant_idx,
|__encoder| { #encode_fields }
)
}
} else {
quote! {
::rustc_serialize::Encoder::emit_fieldless_enum_variant::<#variant_idx>(
__encoder,
)
}
};
variant_idx += 1;
result
});
quote! {
match *self {
#encode_inner
}
}
}
};
let lints = if allow_unreachable_code {
quote! { #![allow(unreachable_code)] }
} else {
quote! {}
};
s.bound_impl(
quote!(::rustc_serialize::Encodable<#encoder_ty>),
quote! {
fn encode(
&self,
__encoder: &mut #encoder_ty,
) {
#lints
#encode_body
}
},
)
}
