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use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, Ident, ItemStruct};
/// Annotate a struct as having its response include response messages of the given type,
/// and generate a response struct for it with the expected attributes and methods.
///
/// Response structs are named by appending "Response" to the end of the name of this struct.
#[proc_macro_attribute]
pub fn operation_response(attr: TokenStream, annotated_item: TokenStream) -> TokenStream {
let response_type = parse_macro_input!(attr as Ident);
let input_struct = parse_macro_input!(annotated_item as ItemStruct);
let request_name = input_struct.ident.clone();
let response_name = Ident::new(&format!("{request_name}Response"), request_name.span());
let response_doc = format!(
r#"A response to a [`{request_name}`] operation.
response_name.to_string().to_ascii_lowercase()
);
let response_doc_attr = quote! { #[doc = #response_doc] };
let expanded = quote! {
#input_struct
impl crate::Operation for #request_name {
type Response = #response_name;
}
impl crate::types::sealed::EnvelopeBodyContents for #request_name {
fn name() -> &'static str {
stringify!(#request_name)
}
}
#response_doc_attr
#[derive(Clone, Debug, serde::Deserialize, PartialEq, Eq)]
#[serde(rename_all = "PascalCase")]
pub struct #response_name {
pub response_messages: crate::ResponseMessages<#response_type>,
}
impl crate::OperationResponse for #response_name {
type Message = #response_type;
fn response_messages(&self) -> &[crate::ResponseClass<Self::Message>] {
self.response_messages.response_messages.as_slice()
}
fn into_response_messages(self) -> Vec<crate::ResponseClass<Self::Message>> {
self.response_messages.response_messages
}
}
impl crate::types::sealed::EnvelopeBodyContents for #response_name {
fn name() -> &'static str {
stringify!(#response_name)
}
}
};
TokenStream::from(expanded)
}