2024-09-21 20:46:48 +02:00
|
|
|
use proc_macro2::{Span, TokenStream};
|
|
|
|
use quote::ToTokens;
|
|
|
|
use syn::{ReturnType, Type};
|
|
|
|
|
|
|
|
#[derive(Clone)]
|
|
|
|
pub(crate) struct ReturnOptions {
|
|
|
|
pub(crate) ty: Option<Box<Type>>,
|
|
|
|
pub(crate) result: bool,
|
|
|
|
}
|
|
|
|
|
|
|
|
impl ReturnOptions {
|
2024-09-21 23:03:02 +02:00
|
|
|
pub(crate) fn parse_signature(ret: &ReturnType) -> Result<Self, syn::Error> {
|
2024-09-21 20:46:48 +02:00
|
|
|
match ret {
|
|
|
|
syn::ReturnType::Default => Ok(Self { ty: None, result: false }),
|
2024-09-21 23:03:02 +02:00
|
|
|
syn::ReturnType::Type(_tok, ty) => match *ty.clone() {
|
|
|
|
syn::Type::Path(path) => {
|
2024-09-21 20:46:48 +02:00
|
|
|
let Some(last) = path.path.segments.last() else {
|
|
|
|
return Err(syn::Error::new(Span::call_site(), "empty Result type is not valid"));
|
|
|
|
};
|
|
|
|
|
|
|
|
if last.ident == "Result" {
|
|
|
|
match &last.arguments {
|
|
|
|
syn::PathArguments::None => return Err(syn::Error::new(Span::call_site(), "Result without generics is not valid")),
|
|
|
|
syn::PathArguments::Parenthesized(_) => return Err(syn::Error::new(Span::call_site(), "Parenthesized Result is not valid")),
|
|
|
|
syn::PathArguments::AngleBracketed(ref generics) => for generic in generics.args.iter() {
|
|
|
|
match generic {
|
|
|
|
syn::GenericArgument::Lifetime(_) => continue,
|
|
|
|
syn::GenericArgument::Type(ty) => return Ok(Self { ty: Some(Box::new(ty.clone())), result: true }),
|
|
|
|
_ => return Err(syn::Error::new(Span::call_site(), "unexpected type in Result")),
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
Ok(Self { ty: Some(Box::new(Type::Path(path.clone()))), result: false })
|
|
|
|
},
|
|
|
|
_ => Err(syn::Error::new(Span::call_site(), "unsupported return type")),
|
|
|
|
},
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2024-09-21 23:03:02 +02:00
|
|
|
pub(crate) fn tokens(&self) -> TokenStream {
|
|
|
|
match &self.ty { // TODO why do we need to invoke syn::Token! macro ???
|
|
|
|
Some(t) => ReturnType::Type(syn::Token), t.clone()).to_token_stream(),
|
2024-09-21 20:46:48 +02:00
|
|
|
None => ReturnType::Default.to_token_stream(),
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|