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use std::convert::TryFrom; use quote::quote; use syn::export::TokenStream2; use syn::{Fields, ItemEnum}; use crate::attribute_helpers::{contains_initialize_with, contains_skip}; pub fn enum_de(input: &ItemEnum) -> syn::Result<TokenStream2> { let name = &input.ident; let generics = &input.generics; let init_method = contains_initialize_with(&input.attrs)?; let mut variant_arms = TokenStream2::new(); let mut deserializable_field_types = TokenStream2::new(); for (variant_idx, variant) in input.variants.iter().enumerate() { let variant_idx = u8::try_from(variant_idx).expect("up to 256 enum variants are supported"); let variant_ident = &variant.ident; let mut variant_header = TokenStream2::new(); match &variant.fields { Fields::Named(fields) => { for field in &fields.named { let field_name = field.ident.as_ref().unwrap(); if contains_skip(&field.attrs) { variant_header.extend(quote! { #field_name: Default::default(), }); } else { let field_type = &field.ty; deserializable_field_types.extend(quote! { #field_type: borsh::BorshDeserialize, }); variant_header.extend(quote! { #field_name: borsh::BorshDeserialize::deserialize(buf)?, }); } } variant_header = quote! { { #variant_header }}; } Fields::Unnamed(fields) => { for field in fields.unnamed.iter() { if contains_skip(&field.attrs) { variant_header.extend(quote! { Default::default(), }); } else { let field_type = &field.ty; deserializable_field_types.extend(quote! { #field_type: borsh::BorshDeserialize, }); variant_header .extend(quote! { borsh::BorshDeserialize::deserialize(buf)?, }); } } variant_header = quote! { ( #variant_header )}; } Fields::Unit => {} } variant_arms.extend(quote! { #variant_idx => #name::#variant_ident #variant_header , }); } let variant_idx = quote! { let variant_idx: u8 = borsh::BorshDeserialize::deserialize(buf)?; }; if let Some(method_ident) = init_method { Ok(quote! { impl #generics borsh::de::BorshDeserialize for #name #generics where #deserializable_field_types { fn deserialize(buf: &mut &[u8]) -> std::result::Result<Self, std::io::Error> { #variant_idx let mut return_value = match variant_idx { #variant_arms _ => return Err(std::io::Error::new( std::io::ErrorKind::InvalidInput, format!("Unexpected variant index: {:?}", variant_idx), )), }; return_value.#method_ident(); Ok(return_value) } } }) } else { Ok(quote! { impl #generics borsh::de::BorshDeserialize for #name #generics where #deserializable_field_types { fn deserialize(buf: &mut &[u8]) -> std::result::Result<Self, std::io::Error> { #variant_idx let return_value = match variant_idx { #variant_arms _ => return Err(std::io::Error::new( std::io::ErrorKind::InvalidInput, format!("Unexpected variant index: {:?}", variant_idx), )), }; Ok(return_value) } } }) } }