252 lines
9.1 KiB
Rust
252 lines
9.1 KiB
Rust
//! Helper functions for deriving `EthAbiType`
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use ethers_contract_abigen::ethers_core_crate;
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use proc_macro2::{Ident, TokenStream};
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use quote::{quote, quote_spanned};
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use syn::spanned::Spanned as _;
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use syn::{parse::Error, Data, DeriveInput, Fields, Variant};
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/// Generates the tokenize implementation
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pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream {
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let core_crate = ethers_core_crate();
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let name = &input.ident;
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let generic_params = input.generics.params.iter().map(|p| quote! { #p });
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let generic_params = quote! { #(#generic_params,)* };
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let generic_args = input.generics.type_params().map(|p| {
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let name = &p.ident;
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quote_spanned! { p.ident.span() => #name }
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});
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let generic_args = quote! { #(#generic_args,)* };
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let generic_predicates = match input.generics.where_clause {
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Some(ref clause) => {
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let predicates = clause.predicates.iter().map(|p| quote! { #p });
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quote! { #(#predicates,)* }
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}
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None => quote! {},
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};
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let (tokenize_predicates, params_len, init_struct_impl, into_token_impl) = match input.data {
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Data::Struct(ref data) => match data.fields {
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Fields::Named(ref fields) => {
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let tokenize_predicates = fields.named.iter().map(|f| {
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let ty = &f.ty;
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quote_spanned! { f.span() => #ty: #core_crate::abi::Tokenize }
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});
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let tokenize_predicates = quote! { #(#tokenize_predicates,)* };
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let assignments = fields.named.iter().map(|f| {
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let name = f.ident.as_ref().expect("Named fields have names");
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quote_spanned! { f.span() => #name: #core_crate::abi::Tokenizable::from_token(iter.next().expect("tokens size is sufficient qed").into_token())? }
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});
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let init_struct_impl = quote! { Self { #(#assignments,)* } };
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let into_token = fields.named.iter().map(|f| {
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let name = f.ident.as_ref().expect("Named fields have names");
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quote_spanned! { f.span() => self.#name.into_token() }
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});
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let into_token_impl = quote! { #(#into_token,)* };
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(
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tokenize_predicates,
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fields.named.len(),
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init_struct_impl,
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into_token_impl,
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)
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}
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Fields::Unnamed(ref fields) => {
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let tokenize_predicates = fields.unnamed.iter().map(|f| {
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let ty = &f.ty;
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quote_spanned! { f.span() => #ty: #core_crate::abi::Tokenize }
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});
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let tokenize_predicates = quote! { #(#tokenize_predicates,)* };
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let assignments = fields.unnamed.iter().map(|f| {
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quote_spanned! { f.span() => #core_crate::abi::Tokenizable::from_token(iter.next().expect("tokens size is sufficient qed").into_token())? }
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});
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let init_struct_impl = quote! { Self(#(#assignments,)* ) };
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let into_token = fields.unnamed.iter().enumerate().map(|(i, f)| {
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let idx = syn::Index::from(i);
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quote_spanned! { f.span() => self.#idx.into_token() }
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});
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let into_token_impl = quote! { #(#into_token,)* };
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(
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tokenize_predicates,
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fields.unnamed.len(),
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init_struct_impl,
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into_token_impl,
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)
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}
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Fields::Unit => return tokenize_unit_type(&input.ident),
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},
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Data::Enum(ref data) => {
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return match tokenize_enum(name, data.variants.iter()) {
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Ok(tokens) => tokens,
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Err(err) => err.to_compile_error(),
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}
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}
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Data::Union(_) => {
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return Error::new(input.span(), "EthAbiType cannot be derived for unions")
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.to_compile_error();
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}
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};
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// there might be the case that the event has only 1 params, which is not a
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// tuple
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let (from_token_impl, into_token_impl) = match params_len {
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0 => (
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quote! {
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Ok(#init_struct_impl)
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},
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// can't encode an empty struct
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// TODO: panic instead?
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quote! {
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#core_crate::abi::Token::Tuple(Vec::new())
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},
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),
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_ => {
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let from_token = quote! {
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if let #core_crate::abi::Token::Tuple(tokens) = token {
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if tokens.len() != #params_len {
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return Err(#core_crate::abi::InvalidOutputType(::std::format!(
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"Expected {} tokens, got {}: {:?}",
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#params_len,
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tokens.len(),
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tokens
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)));
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}
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let mut iter = tokens.into_iter();
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Ok(#init_struct_impl)
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} else {
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Err(#core_crate::abi::InvalidOutputType(::std::format!(
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"Expected Tuple, got {:?}",
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token
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)))
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}
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};
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let into_token = quote! {
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#core_crate::abi::Token::Tuple(
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::std::vec![
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#into_token_impl
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]
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)
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};
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(from_token, into_token)
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}
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};
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quote! {
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impl<#generic_params> #core_crate::abi::Tokenizable for #name<#generic_args>
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where
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#generic_predicates
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#tokenize_predicates
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{
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fn from_token(token: #core_crate::abi::Token) -> Result<Self, #core_crate::abi::InvalidOutputType> where
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Self: Sized {
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#from_token_impl
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}
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fn into_token(self) -> #core_crate::abi::Token {
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#into_token_impl
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}
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}
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impl<#generic_params> #core_crate::abi::TokenizableItem for #name<#generic_args>
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where
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#generic_predicates
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#tokenize_predicates
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{ }
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}
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}
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fn tokenize_unit_type(name: &Ident) -> TokenStream {
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let ethers_core = ethers_core_crate();
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quote! {
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impl #ethers_core::abi::Tokenizable for #name {
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fn from_token(token: #ethers_core::abi::Token) -> Result<Self, #ethers_core::abi::InvalidOutputType> where
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Self: Sized {
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if let #ethers_core::abi::Token::Tuple(tokens) = token {
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if !tokens.is_empty() {
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Err(#ethers_core::abi::InvalidOutputType(::std::format!(
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"Expected empty tuple, got {:?}",
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tokens
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)))
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} else {
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Ok(#name{})
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}
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} else {
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Err(#ethers_core::abi::InvalidOutputType(::std::format!(
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"Expected Tuple, got {:?}",
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token
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)))
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}
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}
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fn into_token(self) -> #ethers_core::abi::Token {
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#ethers_core::abi::Token::Tuple(::std::vec::Vec::new())
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}
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}
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impl #ethers_core::abi::TokenizableItem for #name { }
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}
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}
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fn tokenize_enum<'a>(
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enum_name: &Ident,
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variants: impl Iterator<Item = &'a Variant> + 'a,
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) -> Result<TokenStream, Error> {
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let ethers_core = ethers_core_crate();
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let mut into_tokens = TokenStream::new();
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let mut from_tokens = TokenStream::new();
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for variant in variants {
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if variant.fields.len() > 1 {
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return Err(Error::new(
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variant.span(),
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"EthAbiType cannot be derived for enum variants with multiple fields",
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));
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}
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let var_ident = &variant.ident;
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if let Some(field) = variant.fields.iter().next() {
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let ty = &field.ty;
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from_tokens.extend(quote! {
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if let Ok(decoded) = #ty::from_token(token.clone()) {
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return Ok(#enum_name::#var_ident(decoded))
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}
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});
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into_tokens.extend(quote! {
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#enum_name::#var_ident(element) => element.into_token(),
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});
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} else {
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into_tokens.extend(quote! {
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#enum_name::#var_ident(element) => # ethers_core::abi::Token::Tuple(::std::vec::Vec::new()),
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});
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}
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}
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Ok(quote! {
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impl #ethers_core::abi::Tokenizable for #enum_name {
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fn from_token(token: #ethers_core::abi::Token) -> Result<Self, #ethers_core::abi::InvalidOutputType> where
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Self: Sized {
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#from_tokens
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Err(#ethers_core::abi::InvalidOutputType("Failed to decode all type variants".to_string()))
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}
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fn into_token(self) -> #ethers_core::abi::Token {
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match self {
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#into_tokens
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}
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}
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}
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impl #ethers_core::abi::TokenizableItem for #enum_name { }
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})
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}
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