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use proc_macro::TokenStream;
use syn::DeriveInput;
#[proc_macro_derive(FitsRow, attributes(fitsio))]
pub fn read_row(input: TokenStream) -> TokenStream {
let input: DeriveInput = syn::parse(input).unwrap();
let name = &input.ident;
let mut tokens = Vec::new();
match input.data {
syn::Data::Struct(ref s) => match s.fields {
syn::Fields::Named(ref fields) => {
for field in &fields.named {
let ident = &field.ident.as_ref().unwrap();
let ident_str = ident.to_string();
if field.attrs.is_empty() {
let src = quote::quote! {
out.#ident = tbl.read_cell_value(fits_file, #ident_str, idx)?;
};
tokens.push(src);
} else {
for attr in &field.attrs {
match attr.parse_meta() {
Ok(syn::Meta::List(l)) => {
for entry in l.nested {
match entry {
syn::NestedMeta::Meta(syn::Meta::NameValue(
syn::MetaNameValue { path, lit, .. },
)) => {
if !path.is_ident("colname") {
continue;
}
match lit {
syn::Lit::Str(ls) => {
tokens.push(quote::quote! {
out.#ident = tbl.read_cell_value(
fits_file,
#ls,
idx)?;
});
}
_ => panic!(
"Only #[fitsio(colname = \"...\")] is supported"
),
}
}
_ => panic!(
"Only #[fitsio(colname = \"...\")] is supported"
),
}
}
}
_ => panic!("Only #[fitsio(colname = \"...\")] is supported"),
}
}
}
}
}
_ => panic!("Only #[fitsio(colname = \"...\")] is supported"),
},
_ => panic!("derive only possible for structs"),
}
let expanded = quote::quote! {
impl FitsRow for #name {
fn from_table(
tbl: &::fitsio::hdu::FitsHdu,
fits_file: &mut ::fitsio::FitsFile, idx: usize) ->
::fitsio::errors::Result<Self> where Self: Sized {
let mut out = Self::default();
#(#tokens)*
Ok(out)
}
}
};
expanded.into()
}