mirror of https://codeberg.org/topola/topola.git
85 lines
2.2 KiB
Rust
85 lines
2.2 KiB
Rust
use proc_macro2::TokenStream;
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use quote::quote;
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use syn::{Data, DeriveInput, Fields, Field};
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use syn::Type::Path;
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use syn::ext::IdentExt;
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use crate::attr_present;
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use crate::attr_content;
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pub fn impl_read(input: &DeriveInput) -> TokenStream {
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let name = &input.ident;
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let body = impl_body(&input.data);
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quote! {
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impl<R: std::io::BufRead> ReadDsn<R> for #name {
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fn read_dsn(tokenizer: &mut ListTokenizer<R>)
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-> Result<Self, ParseErrorContext>
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{
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#body
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}
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}
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}
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}
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fn impl_body(data: &Data) -> TokenStream {
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match data {
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Data::Struct(data) => {
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match &data.fields {
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Fields::Named(fields) => {
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let fields = fields.named.iter().map(|field| {
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impl_field(field)
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});
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quote! {
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Ok(Self {
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#(#fields)*
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})
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}
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}
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_ => unimplemented!()
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}
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}
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Data::Enum(_data) => {
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todo!();
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}
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_ => unimplemented!()
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}
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}
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fn impl_field(field: &Field) -> TokenStream {
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let name = &field.ident;
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let name_str = name.as_ref().expect("field name").unraw();
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if attr_present(&field.attrs, "anon") {
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quote! {
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#name: tokenizer.read_value()?,
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}
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} else if let Some(dsn_name) = attr_content(&field.attrs, "vec") {
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quote! {
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#name: tokenizer.read_named_array(#dsn_name)?,
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}
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} else if attr_present(&field.attrs, "anon_vec") {
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quote! {
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#name: tokenizer.read_array()?,
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}
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} else {
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if let Path(type_path) = &field.ty {
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let segments = &type_path.path.segments;
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if segments.len() == 1 {
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let ident = &segments.first().unwrap().ident;
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if ident == "Option" {
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return quote! {
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#name: tokenizer.read_optional(stringify!(#name_str))?,
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}
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}
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}
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}
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quote! {
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#name: tokenizer.read_named(stringify!(#name_str))?,
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}
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}
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}
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