140 lines
3.4 KiB
Rust
140 lines
3.4 KiB
Rust
use {syn, quote};
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struct ParseQuotes {
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single: quote::Tokens,
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list: quote::Tokens,
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takes_index: bool,
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}
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fn decodable_parse_quotes() -> ParseQuotes {
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ParseQuotes {
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single: quote! { rlp.val_at },
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list: quote! { rlp.list_at },
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takes_index: true,
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}
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}
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fn decodable_wrapper_parse_quotes() -> ParseQuotes {
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ParseQuotes {
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single: quote! { rlp.as_val },
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list: quote! { rlp.as_list },
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takes_index: false,
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}
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}
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pub fn impl_decodable(ast: &syn::DeriveInput) -> quote::Tokens {
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let body = match ast.body {
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syn::Body::Struct(ref s) => s,
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_ => panic!("#[derive(RlpDecodable)] is only defined for structs."),
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};
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let stmts: Vec<_> = match *body {
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syn::VariantData::Struct(ref fields) | syn::VariantData::Tuple(ref fields) =>
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fields.iter().enumerate().map(decodable_field_map).collect(),
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syn::VariantData::Unit => panic!("#[derive(RlpDecodable)] is not defined for Unit structs."),
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};
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let name = &ast.ident;
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let dummy_const = syn::Ident::new(format!("_IMPL_RLP_DECODABLE_FOR_{}", name));
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let impl_block = quote! {
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impl rlp::Decodable for #name {
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fn decode(rlp: &rlp::UntrustedRlp) -> Result<Self, rlp::DecoderError> {
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let result = #name {
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#(#stmts)*
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};
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Ok(result)
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}
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}
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};
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quote! {
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#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
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const #dummy_const: () = {
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extern crate rlp;
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#impl_block
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};
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}
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}
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pub fn impl_decodable_wrapper(ast: &syn::DeriveInput) -> quote::Tokens {
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let body = match ast.body {
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syn::Body::Struct(ref s) => s,
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_ => panic!("#[derive(RlpDecodableWrapper)] is only defined for structs."),
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};
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let stmt = match *body {
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syn::VariantData::Struct(ref fields) | syn::VariantData::Tuple(ref fields) => {
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if fields.len() == 1 {
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let field = fields.first().expect("fields.len() == 1; qed");
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decodable_field(0, field, decodable_wrapper_parse_quotes())
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} else {
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panic!("#[derive(RlpDecodableWrapper)] is only defined for structs with one field.")
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}
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},
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syn::VariantData::Unit => panic!("#[derive(RlpDecodableWrapper)] is not defined for Unit structs."),
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};
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let name = &ast.ident;
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let dummy_const = syn::Ident::new(format!("_IMPL_RLP_DECODABLE_FOR_{}", name));
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let impl_block = quote! {
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impl rlp::Decodable for #name {
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fn decode(rlp: &rlp::UntrustedRlp) -> Result<Self, rlp::DecoderError> {
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let result = #name {
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#stmt
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};
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Ok(result)
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}
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}
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};
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quote! {
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#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
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const #dummy_const: () = {
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extern crate rlp;
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#impl_block
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};
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}
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}
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fn decodable_field_map(tuple: (usize, &syn::Field)) -> quote::Tokens {
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decodable_field(tuple.0, tuple.1, decodable_parse_quotes())
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}
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fn decodable_field(index: usize, field: &syn::Field, quotes: ParseQuotes) -> quote::Tokens {
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let ident = match field.ident {
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Some(ref ident) => ident.to_string(),
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None => index.to_string(),
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};
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let id = syn::Ident::new(ident);
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let index = syn::Ident::new(index.to_string());
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let single = quotes.single;
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let list = quotes.list;
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match field.ty {
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syn::Ty::Path(_, ref path) => {
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let ident = &path.segments.first().expect("there must be at least 1 segment").ident;
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if &ident.to_string() == "Vec" {
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if quotes.takes_index {
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quote! { #id: #list(#index)?, }
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} else {
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quote! { #id: #list()?, }
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}
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} else {
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if quotes.takes_index {
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quote! { #id: #single(#index)?, }
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} else {
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quote! { #id: #single()?, }
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}
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}
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},
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_ => panic!("rlp_derive not supported"),
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}
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}
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