291 lines
11 KiB
Rust
291 lines
11 KiB
Rust
use proc_macro2::TokenStream;
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use quote::quote;
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use syn::parse_quote;
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pub fn type_decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
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let decoder_ty = quote! { __D };
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if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
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s.add_impl_generic(parse_quote! { 'tcx });
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}
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s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_middle::ty::codec::TyDecoder<'tcx>});
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s.add_bounds(synstructure::AddBounds::Generics);
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decodable_body(s, decoder_ty)
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}
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pub fn meta_decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
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if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
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s.add_impl_generic(parse_quote! { 'tcx });
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}
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s.add_impl_generic(parse_quote! { '__a });
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let decoder_ty = quote! { DecodeContext<'__a, 'tcx> };
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s.add_bounds(synstructure::AddBounds::Generics);
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decodable_body(s, decoder_ty)
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}
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pub fn decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
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let decoder_ty = quote! { __D };
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s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_serialize::Decoder});
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s.add_bounds(synstructure::AddBounds::Generics);
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decodable_body(s, decoder_ty)
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}
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fn decodable_body(
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s: synstructure::Structure<'_>,
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decoder_ty: TokenStream,
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) -> proc_macro2::TokenStream {
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if let syn::Data::Union(_) = s.ast().data {
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panic!("cannot derive on union")
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}
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let ty_name = s.ast().ident.to_string();
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let decode_body = match s.variants() {
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[vi] => {
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let construct = vi.construct(|field, index| decode_field(field, index, true));
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let n_fields = vi.ast().fields.len();
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quote! {
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::rustc_serialize::Decoder::read_struct(
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__decoder,
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#ty_name,
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#n_fields,
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|__decoder| { ::std::result::Result::Ok(#construct) },
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)
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}
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}
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variants => {
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let match_inner: TokenStream = variants
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.iter()
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.enumerate()
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.map(|(idx, vi)| {
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let construct = vi.construct(|field, index| decode_field(field, index, false));
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quote! { #idx => { ::std::result::Result::Ok(#construct) } }
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})
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.collect();
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let names: TokenStream = variants
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.iter()
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.map(|vi| {
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let variant_name = vi.ast().ident.to_string();
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quote!(#variant_name,)
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})
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.collect();
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let message = format!(
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"invalid enum variant tag while decoding `{}`, expected 0..{}",
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ty_name,
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variants.len()
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);
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quote! {
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::rustc_serialize::Decoder::read_enum(
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__decoder,
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#ty_name,
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|__decoder| {
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::rustc_serialize::Decoder::read_enum_variant(
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__decoder,
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&[#names],
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|__decoder, __variant_idx| {
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match __variant_idx {
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#match_inner
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_ => return ::std::result::Result::Err(
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::rustc_serialize::Decoder::error(__decoder, #message)),
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}
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})
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}
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)
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}
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}
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};
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s.bound_impl(
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quote!(::rustc_serialize::Decodable<#decoder_ty>),
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quote! {
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fn decode(
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__decoder: &mut #decoder_ty,
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) -> ::std::result::Result<Self, <#decoder_ty as ::rustc_serialize::Decoder>::Error> {
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#decode_body
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}
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},
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)
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}
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fn decode_field(field: &syn::Field, index: usize, is_struct: bool) -> proc_macro2::TokenStream {
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let decode_inner_method = if let syn::Type::Reference(_) = field.ty {
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quote! { ::rustc_middle::ty::codec::RefDecodable::decode }
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} else {
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quote! { ::rustc_serialize::Decodable::decode }
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};
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let (decode_method, opt_field_name) = if is_struct {
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let field_name = field.ident.as_ref().map_or_else(|| index.to_string(), |i| i.to_string());
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(
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proc_macro2::Ident::new("read_struct_field", proc_macro2::Span::call_site()),
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quote! { #field_name, },
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)
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} else {
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(
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proc_macro2::Ident::new("read_enum_variant_arg", proc_macro2::Span::call_site()),
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quote! {},
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)
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};
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quote! {
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match ::rustc_serialize::Decoder::#decode_method(
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__decoder, #opt_field_name #index, #decode_inner_method) {
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::std::result::Result::Ok(__res) => __res,
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::std::result::Result::Err(__err) => return ::std::result::Result::Err(__err),
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}
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}
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}
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pub fn type_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
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if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
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s.add_impl_generic(parse_quote! {'tcx});
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}
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let encoder_ty = quote! { __E };
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s.add_impl_generic(parse_quote! {#encoder_ty: ::rustc_middle::ty::codec::TyEncoder<'tcx>});
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s.add_bounds(synstructure::AddBounds::Generics);
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encodable_body(s, encoder_ty, false)
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}
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pub fn meta_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
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if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
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s.add_impl_generic(parse_quote! {'tcx});
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}
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s.add_impl_generic(parse_quote! { '__a });
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let encoder_ty = quote! { EncodeContext<'__a, 'tcx> };
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s.add_bounds(synstructure::AddBounds::Generics);
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encodable_body(s, encoder_ty, true)
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}
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pub fn encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
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let encoder_ty = quote! { __E };
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s.add_impl_generic(parse_quote! { #encoder_ty: ::rustc_serialize::Encoder});
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s.add_bounds(synstructure::AddBounds::Generics);
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encodable_body(s, encoder_ty, false)
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}
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fn encodable_body(
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mut s: synstructure::Structure<'_>,
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encoder_ty: TokenStream,
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allow_unreachable_code: bool,
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) -> proc_macro2::TokenStream {
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if let syn::Data::Union(_) = s.ast().data {
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panic!("cannot derive on union")
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}
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s.bind_with(|binding| {
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// Handle the lack of a blanket reference impl.
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if let syn::Type::Reference(_) = binding.ast().ty {
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synstructure::BindStyle::Move
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} else {
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synstructure::BindStyle::Ref
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}
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});
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let ty_name = s.ast().ident.to_string();
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let encode_body = match s.variants() {
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[_] => {
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let mut field_idx = 0usize;
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let encode_inner = s.each_variant(|vi| {
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vi.bindings()
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.iter()
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.map(|binding| {
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let bind_ident = &binding.binding;
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let field_name = binding
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.ast()
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.ident
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.as_ref()
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.map_or_else(|| field_idx.to_string(), |i| i.to_string());
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let result = quote! {
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match ::rustc_serialize::Encoder::emit_struct_field(
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__encoder,
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#field_name,
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#field_idx,
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|__encoder|
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::rustc_serialize::Encodable::<#encoder_ty>::encode(#bind_ident, __encoder),
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) {
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::std::result::Result::Ok(()) => (),
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::std::result::Result::Err(__err)
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=> return ::std::result::Result::Err(__err),
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}
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};
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field_idx += 1;
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result
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})
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.collect::<TokenStream>()
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});
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quote! {
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::rustc_serialize::Encoder::emit_struct(__encoder, #ty_name, #field_idx, |__encoder| {
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::std::result::Result::Ok(match *self { #encode_inner })
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})
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}
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}
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_ => {
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let mut variant_idx = 0usize;
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let encode_inner = s.each_variant(|vi| {
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let variant_name = vi.ast().ident.to_string();
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let mut field_idx = 0usize;
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let encode_fields: TokenStream = vi
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.bindings()
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.iter()
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.map(|binding| {
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let bind_ident = &binding.binding;
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let result = quote! {
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match ::rustc_serialize::Encoder::emit_enum_variant_arg(
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__encoder,
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#field_idx,
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|__encoder|
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::rustc_serialize::Encodable::<#encoder_ty>::encode(#bind_ident, __encoder),
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) {
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::std::result::Result::Ok(()) => (),
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::std::result::Result::Err(__err)
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=> return ::std::result::Result::Err(__err),
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}
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};
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field_idx += 1;
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result
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})
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.collect();
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let result = quote! { ::rustc_serialize::Encoder::emit_enum_variant(
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__encoder,
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#variant_name,
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#variant_idx,
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#field_idx,
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|__encoder| { ::std::result::Result::Ok({ #encode_fields }) }
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) };
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variant_idx += 1;
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result
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});
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quote! {
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::rustc_serialize::Encoder::emit_enum(__encoder, #ty_name, |__encoder| {
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match *self {
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#encode_inner
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}
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})
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}
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}
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};
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let lints = if allow_unreachable_code {
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quote! { #![allow(unreachable_code)] }
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} else {
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quote! {}
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};
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s.bound_impl(
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quote!(::rustc_serialize::Encodable<#encoder_ty>),
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quote! {
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fn encode(
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&self,
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__encoder: &mut #encoder_ty,
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) -> ::std::result::Result<(), <#encoder_ty as ::rustc_serialize::Encoder>::Error> {
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#lints
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#encode_body
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}
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},
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)
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}
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