macros: Add request attribute macro

crates/ruma-common/src/api.rs

@@ -194,6 +194,44 @@ use crate::UserId;
 /// ```
 pub use ruma_macros::ruma_api;
 
+/// Generates [`OutgoingRequest`] and [`IncomingRequest`] implementations.
+///
+/// The `OutgoingRequest` impl is be on the `Request` type this attribute is used on. It is
+/// feature-gated behind `cfg(feature = "client")`.
+///
+/// The `IncomingRequest` impl is be on `IncomingRequest`, which is either a type alias to
+/// `Request` or a fully-owned version of the same, depending of whether `Request` has any
+/// lifetime parameters.
+///
+/// The generated code expects a `METADATA` constant of type [`Metadata`] to be in scope,
+/// alongside a `Response` type that implements both [`OutgoingResponse`] and
+/// [`IncomingResponse`].
+///
+/// ## Attributes
+///
+/// To declare which part of the request a field belongs to:
+///
+/// * `#[ruma_api(header = HEADER_NAME)]`: Fields with this attribute will be treated as HTTP
+///   headers on the request. The value must implement `AsRef<str>`. Generally this is a
+///   `String`. The attribute value shown above as `HEADER_NAME` must be a `const` expression
+///   of the type `http::header::HeaderName`, like one of the constants from `http::header`,
+///   e.g. `CONTENT_TYPE`.
+/// * `#[ruma_api(path)]`: Fields with this attribute will be inserted into the matching path
+///   component of the request URL.
+/// * `#[ruma_api(query)]`: Fields with this attribute will be inserting into the URL's query
+///   string.
+/// * `#[ruma_api(query_map)]`: Instead of individual query fields, one query_map field, of any
+///   type that implements `IntoIterator<Item = (String, String)>` (e.g. `HashMap<String,
+///   String>`, can be used for cases where an endpoint supports arbitrary query parameters.
+/// * `#[ruma_api(body)]`: Use this if multiple endpoints should share a request body type, or
+///   the request body is better expressed as an `enum` rather than a `struct`. The value of
+///   the field will be used as the JSON body (rather than being a field in the request body
+///   object).
+/// * `#[ruma_api(raw_body)]`: Like `body` in that the field annotated with it represents the
+///   entire request body, but this attribute is for endpoints where the body can be anything,
+///   not just JSON. The field type must be `Vec<u8>`.
+pub use ruma_macros::request;
+
 pub mod error;
 mod metadata;
 

crates/ruma-macros/src/api/api_request.rs

@@ -89,16 +89,7 @@ impl Request {
 
         quote! {
             #[doc = #docs]
-            #[derive(
+            #[#ruma_macros::request(error = #error_ty)]
-                Clone,
-                Debug,
-                #ruma_macros::Request,
-                #ruma_common::serde::Incoming,
-                #ruma_common::serde::_FakeDeriveSerde,
-            )]
-            #[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
-            #[incoming_derive(!Deserialize, #ruma_macros::_FakeDeriveRumaApi)]
-            #[ruma_api(error = #error_ty)]
             #( #struct_attributes )*
             pub struct #request_ident < #(#lifetimes),* > {
                 #fields

crates/ruma-macros/src/api/request.rs

@@ -5,7 +5,7 @@ use quote::{quote, ToTokens};
 use syn::{
     parse::{Parse, ParseStream},
     punctuated::Punctuated,
-    DeriveInput, Field, Generics, Ident, Lifetime, Token, Type,
+    DeriveInput, Field, Generics, Ident, ItemStruct, Lifetime, Token, Type,
 };
 
 use super::{
@@ -17,6 +17,38 @@ use crate::util::import_ruma_common;
 mod incoming;
 mod outgoing;
 
+pub fn expand_request(attr: RequestAttr, item: ItemStruct) -> TokenStream {
+    let ruma_common = import_ruma_common();
+    let ruma_macros = quote! { #ruma_common::exports::ruma_macros };
+
+    let error_ty = attr.0.first().map_or_else(
+        || quote! { #ruma_common::api::error::MatrixError },
+        |DeriveRequestMeta::Error(ty)| quote! { #ty },
+    );
+
+    quote! {
+        #[derive(
+            Clone,
+            Debug,
+            #ruma_macros::Request,
+            #ruma_common::serde::Incoming,
+            #ruma_common::serde::_FakeDeriveSerde,
+        )]
+        #[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
+        #[incoming_derive(!Deserialize, #ruma_macros::_FakeDeriveRumaApi)]
+        #[ruma_api(error = #error_ty)]
+        #item
+    }
+}
+
+pub struct RequestAttr(Punctuated<DeriveRequestMeta, Token![,]>);
+
+impl Parse for RequestAttr {
+    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
+        Punctuated::<DeriveRequestMeta, Token![,]>::parse_terminated(input).map(Self)
+    }
+}
+
 pub fn expand_derive_request(input: DeriveInput) -> syn::Result<TokenStream> {
     let fields = match input.data {
         syn::Data::Struct(s) => s.fields,

crates/ruma-macros/src/lib.rs

@@ -25,7 +25,11 @@ mod serde;
 mod util;
 
 use self::{
-    api::{request::expand_derive_request, response::expand_derive_response, Api},
+    api::{
+        request::{expand_derive_request, expand_request},
+        response::expand_derive_response,
+        Api,
+    },
     events::{
         event::expand_event,
         event_content::expand_event_content,
@@ -384,6 +388,15 @@ pub fn ruma_api(input: TokenStream) -> TokenStream {
     api.expand_all().into()
 }
 
+/// > ⚠ If this is the only documentation you see, please navigate to the docs for
+/// > `ruma_common::api::request`, where actual documentation can be found.
+#[proc_macro_attribute]
+pub fn request(attr: TokenStream, item: TokenStream) -> TokenStream {
+    let attr = parse_macro_input!(attr);
+    let item = parse_macro_input!(item);
+    expand_request(attr, item).into()
+}
+
 /// Internal helper taking care of the request-specific parts of `ruma_api!`.
 #[proc_macro_derive(Request, attributes(ruma_api))]
 pub fn derive_request(input: TokenStream) -> TokenStream {