use quote::{format_ident, quote};
use syn::{parse_macro_input, punctuated::Punctuated, token::Comma, DeriveInput, Ident};
#[proc_macro_derive(FromRequest, attributes(from_request))]
pub fn derive_from_request(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let name = input.ident;
let data = match input.data {
syn::Data::Struct(data) => data,
syn::Data::Enum(_) | syn::Data::Union(_) => {
return quote! {
compile_error!("Deriving FromRequest is only supported on structs for now.");
}
.into();
}
};
let fields = match data.fields {
syn::Fields::Named(fields) => fields.named,
syn::Fields::Unnamed(_) | syn::Fields::Unit => {
return quote! {
compile_error!("Deriving FromRequest is only supported on structs with named fields for now.");
}
.into();
}
};
let field_names_joined = fields
.iter()
.map(|f| f.ident.clone().unwrap())
.collect::<Punctuated<_, Comma>>();
let fut_fields = fields.iter().filter(|field| {
field.attrs.is_empty()
|| field
.attrs
.iter()
.any(|attr| attr.parse_args::<Ident>().is_err())
});
let field_fut_names_joined = fut_fields
.clone()
.map(|f| format_ident!("{}_fut", f.ident.clone().unwrap()))
.collect::<Punctuated<_, Comma>>();
let field_post_fut_names_joined = fut_fields
.clone()
.map(|f| f.ident.clone().unwrap())
.collect::<Punctuated<_, Comma>>();
let field_futs = fut_fields.clone().map(|field| {
let syn::Field { ident, ty, .. } = field;
let varname = format_ident!("{}_fut", ident.clone().unwrap());
quote! {
let #varname = <#ty>::from_request(&req, pl).map_err(Into::into);
}
});
let fields_copied_from_app_data = fields
.iter()
.filter(|field| {
field.attrs.iter().any(|attr| {
attr.parse_args::<Ident>()
.map_or(false, |ident| ident == "copy_from_app_data")
})
})
.map(|field| {
let syn::Field { ident, ty, .. } = field;
let varname = ident.clone().unwrap();
quote! {
let #varname = if let Some(st) = req.app_data::<#ty>().copied() {
st
} else {
::actix_web_lab::__reexports::tracing::debug!(
"Failed to extract `{}` for `{}` handler. For this extractor to work \
correctly, pass the data to `App::app_data()`. Ensure that types align in \
both the set and retrieve calls.",
::std::any::type_name::<#ty>(),
req.match_name().unwrap_or_else(|| req.path())
);
return ::std::boxed::Box::pin(async move {
::std::result::Result::Err(
::actix_web_lab::__reexports::actix_web::error::ErrorInternalServerError(
"Requested application data is not configured correctly. \
View/enable debug logs for more details.",
))
})
};
}
});
let output = quote! {
impl ::actix_web::FromRequest for #name {
type Error = ::actix_web::Error;
type Future = ::std::pin::Pin<::std::boxed::Box<
dyn ::std::future::Future<Output = ::std::result::Result<Self, Self::Error>>
>>;
fn from_request(req: &::actix_web::HttpRequest, pl: &mut ::actix_web::dev::Payload) -> Self::Future {
use ::actix_web_lab::__reexports::actix_web::FromRequest as _;
use ::actix_web_lab::__reexports::futures_util::{FutureExt as _, TryFutureExt as _};
use ::actix_web_lab::__reexports::tokio::try_join;
#(#fields_copied_from_app_data)*
#(#field_futs)*
::std::boxed::Box::pin(
async move { try_join!( #field_fut_names_joined ) }
.map_ok(move |( #field_post_fut_names_joined )| Self { #field_names_joined })
)
}
}
};
proc_macro::TokenStream::from(output)
}