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quininerquininer
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move to ast_node
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32 files changed

+737
-150
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‎Cargo.lock‎

Lines changed: 1 addition & 14 deletions
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‎Cargo.toml‎

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@@ -130,7 +130,6 @@ resolver = "2"
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foldhash = "0.1"
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precomputed-map = "0.2"
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cbor4ii = { git = "https://github.com/quininer/cbor4ii", branch = "f/derive" }
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cbor4ii-derive = { git = "https://github.com/quininer/cbor4ii", branch = "f/derive" }
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[workspace.metadata.cargo-shear]
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# `serde` is used when #[ast_node] is expanded

‎crates/ast_node/src/encoding/decode.rs‎

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use syn::{ DeriveInput, Data };
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use super::{ is_unknown, is_with };
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pub fn expand(
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DeriveInput {
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ident,
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data,
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..
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}: DeriveInput,
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) -> syn::ItemImpl {
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match data {
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Data::Struct(data) => {
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let is_named = data.fields.iter().any(|field| field.ident.is_some());
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let fields = data.fields.iter()
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.enumerate()
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.map(|(idx, field)| -> syn::Stmt {
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let ty = &field.ty;
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let value: syn::Expr = match is_with(&field.attrs) {
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Some(with_type) => syn::parse_quote!(<#with_type<#ty> as cbor4ii::core::dec::Decode<'_>>::decode(reader)?.0),
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None => syn::parse_quote!(<#ty as cbor4ii::core::dec::Decode<'_>>::decode(reader)?)
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};
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match field.ident.as_ref() {
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Some(name) => syn::parse_quote!{
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let #name = #value;
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},
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None => {
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let name = format!("unit{}", idx);
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syn::parse_quote!{
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let #name = #value;
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}
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}
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}
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});
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let build_struct = data.fields.iter()
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.enumerate()
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.map(|(idx, field)| -> syn::FieldValue {
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match field.ident.as_ref() {
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Some(name) => syn::parse_quote!(#name),
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None => {
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let name = format!("unit{}", idx);
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syn::parse_quote!(#name)
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}
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}
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})
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.collect::<syn::punctuated::Punctuated<_, syn::Token![,]>>();
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let build_struct: syn::ExprStruct = if is_named {
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syn::parse_quote!{
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#ident { #build_struct }
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}
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} else {
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syn::parse_quote!{
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#ident(#build_struct)
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}
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};
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let count = data.fields.len();
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let head: Option<syn::Expr> = (count != 1).then(|| syn::parse_quote!{{
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let n = <cbor4ii::core::types::Array<()>>::len(reader)?;
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debug_assert_eq!(n, Some(#count));
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}});
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syn::parse_quote! {
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impl<'de> cbor4ii::core::dec::Decode<'de> for #ident {
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#[inline]
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fn decode<R: cbor4ii::core::dec::Read<'de>>(reader: &mut R)
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-> Result<Self, cbor4ii::core::error::DecodeError<R::Error>>
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{
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#head;
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#(#fields)*
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Ok(#build_struct)
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}
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}
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}
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},
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Data::Enum(data) => {
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let mut iter = data.variants.iter().peekable();
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let mut is_unit = None;
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assert!(!data.variants.is_empty(), "empty enums are not allowed");
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let unknown_arm: Option<syn::Arm> = if let Some(unknown) =
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iter.next_if(|variant| is_unknown(&variant.attrs))
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{
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let name = &unknown.ident;
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assert!(unknown.discriminant.is_none(), "custom discriminant unsupport");
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assert!(is_with(&unknown.attrs).is_none(), "unknown member is not allowed with type");
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Some(match &unknown.fields {
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syn::Fields::Unnamed(fields) => {
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match fields.unnamed.len() {
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1 => {
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is_unit = Some(true);
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syn::parse_quote!{
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tag => #ident::#name(tag),
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}
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},
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2 => {
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is_unit = Some(false);
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let val_ty = &fields.unnamed[1].ty;
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syn::parse_quote!{
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tag => {
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let val = <#val_ty as cbor4ii::core::dec::Decode<'_>>::decode(reader)?;
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#ident::#name(tag, val)
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},
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}
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},
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_ => panic!("unknown member must be a tag and a value")
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}
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},
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_ => panic!("named enum unsupported")
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})
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} else {
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None
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};
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let fields = iter
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.enumerate()
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.map(|(idx, field)| -> syn::Arm {
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let idx: u32 = idx.try_into().expect("enum tag max 32bit");
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let idx = idx + 1; // skip zero
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let name = &field.ident;
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assert!(field.discriminant.is_none(), "custom discriminant unsupport");
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assert!(!is_unknown(&field.attrs), "unknown member must be first");
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match &field.fields {
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syn::Fields::Unnamed(fields) => {
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if fields.unnamed.len() != 1 {
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panic!("enum member only allows one field");
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}
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if *is_unit.get_or_insert(false) != false {
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panic!("The number of fields in member must be consistent");
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}
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let val_ty = &fields.unnamed[0].ty;
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let value: syn::Expr = match is_with(&field.attrs) {
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Some(with_type) => syn::parse_quote!(<#with_type<#val_ty> as cbor4ii::core::dec::Decode<'_>>::decode(reader)?.0),
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None => syn::parse_quote!(<#val_ty as cbor4ii::core::dec::Decode<'_>>::decode(reader)?)
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};
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syn::parse_quote!{
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#idx => {
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let val = #value;
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#ident::#name(val)
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},
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}
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},
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syn::Fields::Unit => {
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if *is_unit.get_or_insert(true) != true {
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panic!("The number of fields in member must be consistent");
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}
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assert!(is_with(&field.attrs).is_none(), "unit member is not allowed with type");
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syn::parse_quote!{
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#idx => #ident::#name,
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}
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},
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syn::Fields::Named(_) => panic!("named enum unsupported")
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}
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})
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.collect::<Vec<_>>();
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let unknown_arm = match unknown_arm {
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Some(arm) => arm,
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None => {
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syn::parse_quote!{
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_ => {
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let err = cbor4ii::core::error::DecodeError::Mismatch {
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name: &stringify!(#ident),
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found: 0
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};
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return Err(err);
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}
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}
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}
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};
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let head: syn::Expr = {
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let count: usize = match is_unit {
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Some(true) => 1,
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Some(false) => 2,
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None => panic!()
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};
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syn::parse_quote!{{
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let n = <cbor4ii::core::types::Array<()>>::len(reader)?;
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debug_assert_eq!(n, Some(#count));
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}}
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};
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syn::parse_quote!{
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impl<'de> cbor4ii::core::dec::Decode<'de> for #ident {
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#[inline]
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fn decode<R: cbor4ii::core::dec::Read<'de>>(reader: &mut R)
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-> Result<Self, cbor4ii::core::error::DecodeError<R::Error>>
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{
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#head;
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let tag = <u32 as cbor4ii::core::dec::Decode<'_>>::decode(reader)?;
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let value = match tag {
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#(#fields)*
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#unknown_arm
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};
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Ok(value)
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}
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}
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}
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},
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Data::Union(_) => panic!("union unsupported")
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}
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}

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