Files
RustPython/derive/src/pystructseq.rs
2020-10-11 21:16:16 +09:00

45 lines
1.4 KiB
Rust

use super::Diagnostic;
use proc_macro2::TokenStream;
use quote::quote;
use syn::DeriveInput;
pub(crate) fn impl_pystruct_sequence(
input: DeriveInput,
) -> std::result::Result<TokenStream, Diagnostic> {
let fields = if let syn::Data::Struct(ref struc) = input.data {
&struc.fields
} else {
bail_span!(
input,
"#[pystruct_sequence] can only be on a struct declaration"
)
};
let field_names: Vec<_> = match fields {
syn::Fields::Named(fields) => fields
.named
.iter()
.map(|field| field.ident.as_ref().unwrap())
.collect(),
_ => bail_span!(
input,
"#[pystruct_sequence] can only be on a struct with named fields"
),
};
let ty = &input.ident;
let ret = quote! {
impl ::rustpython_vm::pyobject::PyStructSequence for #ty {
const FIELD_NAMES: &'static [&'static str] = &[#(stringify!(#field_names)),*];
fn into_tuple(self, vm: &::rustpython_vm::VirtualMachine) -> ::rustpython_vm::builtins::tuple::PyTuple {
let items = vec![#(::rustpython_vm::pyobject::IntoPyObject::into_pyobject(
self.#field_names,
vm,
)),*];
::rustpython_vm::builtins::tuple::PyTuple::_new(items.into_boxed_slice())
}
}
};
Ok(ret)
}