topola/macro/specctra_derive/src/write.rs

78 lines
2.0 KiB
Rust

use proc_macro2::TokenStream;
use quote::quote;
use syn::ext::IdentExt;
use syn::Type::Path;
use syn::{Data, DeriveInput, Field, Fields};
use crate::attr_content;
use crate::attr_present;
pub fn impl_write(input: &DeriveInput) -> TokenStream {
let name = &input.ident;
let body = impl_body(&input.data);
quote! {
impl<W: std::io::Write> WriteSes<W> for #name {
fn write_dsn(&self, writer: &mut ListWriter<W>)
-> std::io::Result<()>
{
#body
}
}
}
}
fn impl_body(data: &Data) -> TokenStream {
match data {
Data::Struct(data) => match &data.fields {
Fields::Named(fields) => {
let fields = fields.named.iter().map(|field| impl_field(field));
quote! {
#(#fields)*
Ok(())
}
}
_ => unimplemented!(),
},
_ => unimplemented!(),
}
}
fn impl_field(field: &Field) -> TokenStream {
let name = &field.ident;
let name_str = name.as_ref().expect("field name").unraw();
if attr_present(&field.attrs, "anon") {
quote! {
writer.write_value(&self.#name)?;
}
} else if let Some(dsn_name) = attr_content(&field.attrs, "vec") {
quote! {
writer.write_named_array(#dsn_name, &self.#name)?;
}
} else if attr_present(&field.attrs, "anon_vec") {
quote! {
writer.write_array(&self.#name)?;
}
} else {
if let Path(type_path) = &field.ty {
let segments = &type_path.path.segments;
if segments.len() == 1 {
let ident = &segments.first().unwrap().ident;
if ident == "Option" {
return quote! {
writer.write_optional(stringify!(#name_str), &self.#name)?;
};
}
}
}
quote! {
writer.write_named(stringify!(#name_str), &self.#name)?;
}
}
}