use proc_macro2::TokenStream;
use quote::quote;
use syn::parse_quote;
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_middle::ty::codec::TyDecoder<'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] => {
let construct = vi.construct(|field, index| decode_field(field, index, true));
let n_fields = vi.ast().fields.len();
quote! {
::rustc_serialize::Decoder::read_struct(
__decoder,
#ty_name,
#n_fields,
|__decoder| { ::std::result::Result::Ok(#construct) },
)
}
}
variants => {
let match_inner: TokenStream = variants
.iter()
.enumerate()
.map(|(idx, vi)| {
let construct = vi.construct(|field, index| decode_field(field, index, false));
quote! { #idx => { ::std::result::Result::Ok(#construct) } }
})
.collect();
let names: TokenStream = variants
.iter()
.map(|vi| {
let variant_name = vi.ast().ident.to_string();
quote!(#variant_name,)
})
.collect();
let message = format!(
"invalid enum variant tag while decoding `{}`, expected 0..{}",
ty_name,
variants.len()
);
quote! {
::rustc_serialize::Decoder::read_enum(
__decoder,
#ty_name,
|__decoder| {
::rustc_serialize::Decoder::read_enum_variant(
__decoder,
&[#names],
|__decoder, __variant_idx| {
match __variant_idx {
#match_inner
_ => return ::std::result::Result::Err(
::rustc_serialize::Decoder::error(__decoder, #message)),
}
})
}
)
}
}
};
s.bound_impl(
quote!(::rustc_serialize::Decodable<#decoder_ty>),
quote! {
fn decode(
__decoder: &mut #decoder_ty,
) -> ::std::result::Result<Self, <#decoder_ty as ::rustc_serialize::Decoder>::Error> {
#decode_body
}
},
)
}
fn decode_field(field: &syn::Field, index: usize, is_struct: bool) -> proc_macro2::TokenStream {
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 (decode_method, opt_field_name) = if is_struct {
let field_name = field.ident.as_ref().map_or_else(|| index.to_string(), |i| i.to_string());
(
proc_macro2::Ident::new("read_struct_field", proc_macro2::Span::call_site()),
quote! { #field_name, },
)
} else {
(
proc_macro2::Ident::new("read_enum_variant_arg", proc_macro2::Span::call_site()),
quote! {},
)
};
quote! {
match ::rustc_serialize::Decoder::#decode_method(
__decoder, #opt_field_name #index, #decode_inner_method) {
::std::result::Result::Ok(__res) => __res,
::std::result::Result::Err(__err) => return ::std::result::Result::Err(__err),
}
}
}
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_middle::ty::codec::TyEncoder<'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 ty_name = s.ast().ident.to_string();
let encode_body = match s.variants() {
[_] => {
let mut field_idx = 0usize;
let encode_inner = s.each_variant(|vi| {
vi.bindings()
.iter()
.map(|binding| {
let bind_ident = &binding.binding;
let field_name = binding
.ast()
.ident
.as_ref()
.map_or_else(|| field_idx.to_string(), |i| i.to_string());
let result = quote! {
match ::rustc_serialize::Encoder::emit_struct_field(
__encoder,
#field_name,
#field_idx,
|__encoder|
::rustc_serialize::Encodable::encode(#bind_ident, __encoder),
) {
::std::result::Result::Ok(()) => (),
::std::result::Result::Err(__err)
=> return ::std::result::Result::Err(__err),
}
};
field_idx += 1;
result
})
.collect::<TokenStream>()
});
quote! {
::rustc_serialize::Encoder::emit_struct(__encoder, #ty_name, #field_idx, |__encoder| {
::std::result::Result::Ok(match *self { #encode_inner })
})
}
}
_ => {
let mut variant_idx = 0usize;
let encode_inner = s.each_variant(|vi| {
let variant_name = vi.ast().ident.to_string();
let mut field_idx = 0usize;
let encode_fields: TokenStream = vi
.bindings()
.iter()
.map(|binding| {
let bind_ident = &binding.binding;
let result = quote! {
match ::rustc_serialize::Encoder::emit_enum_variant_arg(
__encoder,
#field_idx,
|__encoder|
::rustc_serialize::Encodable::encode(#bind_ident, __encoder),
) {
::std::result::Result::Ok(()) => (),
::std::result::Result::Err(__err)
=> return ::std::result::Result::Err(__err),
}
};
field_idx += 1;
result
})
.collect();
let result = quote! { ::rustc_serialize::Encoder::emit_enum_variant(
__encoder,
#variant_name,
#variant_idx,
#field_idx,
|__encoder| { ::std::result::Result::Ok({ #encode_fields }) }
) };
variant_idx += 1;
result
});
quote! {
::rustc_serialize::Encoder::emit_enum(__encoder, #ty_name, |__encoder| {
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,
) -> ::std::result::Result<(), <#encoder_ty as ::rustc_serialize::Encoder>::Error> {
#lints
#encode_body
}
},
)
}