api-macros: Allow ruma_api! invocation without request / response

ruma-api-macros/src/api.rs

@@ -19,10 +19,10 @@ pub struct Api {
     metadata: Metadata,
 
     /// The `request` section of the macro.
-    request: Request,
+    request: Option<Request>,
 
     /// The `response` section of the macro.
-    response: Response,
+    response: Option<Response>,
 
     /// The `error` section of the macro.
     error_ty: Option<Type>,
@@ -32,12 +32,12 @@ pub fn expand_all(api: Api) -> syn::Result<TokenStream> {
     let ruma_api = util::import_ruma_api();
     let http = quote! { #ruma_api::exports::http };
 
-    let description = &api.metadata.description;
-    let method = &api.metadata.method;
-    let name = &api.metadata.name;
-    let path = &api.metadata.path;
-    let rate_limited: TokenStream = api
-        .metadata
+    let metadata = &api.metadata;
+    let description = &metadata.description;
+    let method = &metadata.method;
+    let name = &metadata.name;
+    let path = &metadata.path;
+    let rate_limited: TokenStream = metadata
         .rate_limited
         .iter()
         .map(|r| {
@@ -66,8 +66,8 @@ pub fn expand_all(api: Api) -> syn::Result<TokenStream> {
     let error_ty =
         api.error_ty.map_or_else(|| quote! { #ruma_api::error::Void }, |err_ty| quote! { #err_ty });
 
-    let request = api.request.expand(&api.metadata, &error_ty, &ruma_api);
-    let response = api.response.expand(&api.metadata, &error_ty, &ruma_api);
+    let request = api.request.map(|req| req.expand(metadata, &error_ty, &ruma_api));
+    let response = api.response.map(|res| res.expand(metadata, &error_ty, &ruma_api));
 
     let metadata_doc = format!("Metadata for the `{}` API endpoint.", name.value());
 

ruma-api-macros/src/api/parse.rs

@@ -26,8 +26,27 @@ mod kw {
 impl Parse for Api {
     fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
         let metadata: Metadata = input.parse()?;
-        let request: Request = input.parse()?;
-        let response: Response = input.parse()?;
+
+        let attributes = input.call(Attribute::parse_outer)?;
+        let (request, attributes) = if input.peek(kw::request) {
+            let request = parse_request(input, attributes)?;
+            let attributes = input.call(Attribute::parse_outer)?;
+
+            (Some(request), attributes)
+        } else {
+            (None, attributes)
+        };
+
+        let response = if input.peek(kw::response) {
+            Some(parse_response(input, attributes)?)
+        } else if !attributes.is_empty() {
+            return Err(syn::Error::new_spanned(
+                &attributes[0],
+                "attributes are not supported on the error type",
+            ));
+        } else {
+            None
+        };
 
         // TODO: Use `bool::then` when MSRV >= 1.50
         let error_ty = if input.peek(kw::error) {
@@ -39,11 +58,13 @@ impl Parse for Api {
             None
         };
 
-        let newtype_body_field = request.newtype_body_field();
-        if metadata.method == "GET" && (request.has_body_fields() || newtype_body_field.is_some()) {
+        if let Some(req) = &request {
+            let newtype_body_field = req.newtype_body_field();
+            if metadata.method == "GET" && (req.has_body_fields() || newtype_body_field.is_some()) {
                 let mut combined_error: Option<syn::Error> = None;
                 let mut add_error = |field| {
-                let error = syn::Error::new_spanned(field, "GET endpoints can't have body fields");
+                    let error =
+                        syn::Error::new_spanned(field, "GET endpoints can't have body fields");
                     if let Some(combined_error_ref) = &mut combined_error {
                         combined_error_ref.combine(error);
                     } else {
@@ -51,7 +72,7 @@ impl Parse for Api {
                     }
                 };
 
-            for field in request.body_fields() {
+                for field in req.body_fields() {
                     add_error(field);
                 }
 
@@ -61,14 +82,13 @@ impl Parse for Api {
 
                 return Err(combined_error.unwrap());
             }
+        }
 
         Ok(Self { metadata, request, response, error_ty })
     }
 }
 
-impl Parse for Request {
-    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
-        let attributes = input.call(Attribute::parse_outer)?;
+fn parse_request(input: ParseStream<'_>, attributes: Vec<Attribute>) -> syn::Result<Request> {
     let request_kw: kw::request = input.parse()?;
     let _: Token![:] = input.parse()?;
     let fields;
@@ -146,21 +166,15 @@ impl Parse for Request {
                 RequestFieldKind::Header => {
                     collect_lifetime_idents(&mut lifetimes.header, &field.ty)
                 }
-                    RequestFieldKind::Body => {
-                        collect_lifetime_idents(&mut lifetimes.body, &field.ty)
-                    }
+                RequestFieldKind::Body => collect_lifetime_idents(&mut lifetimes.body, &field.ty),
                 RequestFieldKind::NewtypeBody => {
                     collect_lifetime_idents(&mut lifetimes.body, &field.ty)
                 }
                 RequestFieldKind::NewtypeRawBody => {
                     collect_lifetime_idents(&mut lifetimes.body, &field.ty)
                 }
-                    RequestFieldKind::Path => {
-                        collect_lifetime_idents(&mut lifetimes.path, &field.ty)
-                    }
-                    RequestFieldKind::Query => {
-                        collect_lifetime_idents(&mut lifetimes.query, &field.ty)
-                    }
+                RequestFieldKind::Path => collect_lifetime_idents(&mut lifetimes.path, &field.ty),
+                RequestFieldKind::Query => collect_lifetime_idents(&mut lifetimes.query, &field.ty),
                 RequestFieldKind::QueryMap => {
                     collect_lifetime_idents(&mut lifetimes.query, &field.ty)
                 }
@@ -194,13 +208,10 @@ impl Parse for Request {
         ));
     }
 
-        Ok(Self { attributes, fields, lifetimes })
-    }
+    Ok(Request { attributes, fields, lifetimes })
 }
 
-impl Parse for Response {
-    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
-        let attributes = input.call(Attribute::parse_outer)?;
+fn parse_response(input: ParseStream<'_>, attributes: Vec<Attribute>) -> syn::Result<Response> {
     let response_kw: kw::response = input.parse()?;
     let _: Token![:] = input.parse()?;
     let fields;
@@ -279,8 +290,7 @@ impl Parse for Response {
         ));
     }
 
-        Ok(Self { attributes, fields })
-    }
+    Ok(Response { attributes, fields })
 }
 
 fn has_lifetime(ty: &Type) -> bool {

ruma-api/tests/ruma_api.rs

@@ -5,4 +5,7 @@ fn ui() {
     t.compile_fail("tests/ui/02-invalid-path.rs");
     t.pass("tests/ui/03-move-value.rs");
     t.compile_fail("tests/ui/04-attributes.rs");
+    t.pass("tests/ui/05-request-only.rs");
+    t.pass("tests/ui/06-response-only.rs");
+    t.compile_fail("tests/ui/07-error-type-attribute.rs");
 }

ruma-api/tests/ui/05-request-only.rs

@@ -0,0 +1,50 @@
+use std::convert::TryFrom;
+
+use ruma_api::{
+    error::{FromHttpResponseError, IntoHttpError, Void},
+    ruma_api,
+};
+use ruma_serde::Outgoing;
+
+ruma_api! {
+    metadata: {
+        description: "Does something.",
+        method: POST, // An `http::Method` constant. No imports required.
+        name: "some_endpoint",
+        path: "/_matrix/some/endpoint/:baz",
+        rate_limited: false,
+        authentication: None,
+    }
+
+    #[derive(PartialEq)] // Make sure attributes work
+    request: {
+        // With no attribute on the field, it will be put into the body of the request.
+        pub foo: String,
+    }
+}
+
+#[derive(Outgoing)]
+pub struct Response;
+
+impl TryFrom<http::Response<Vec<u8>>> for Response {
+    type Error = FromHttpResponseError<Void>;
+
+    fn try_from(_: http::Response<Vec<u8>>) -> Result<Self, Self::Error> {
+        todo!()
+    }
+}
+
+impl TryFrom<Response> for http::Response<Vec<u8>> {
+    type Error = IntoHttpError;
+
+    fn try_from(_: Response) -> Result<Self, Self::Error> {
+        todo!()
+    }
+}
+
+fn main() {
+    let req1 = Request { foo: "foo".into() };
+    let req2 = req1.clone();
+
+    assert_eq!(req1, req2);
+}

ruma-api/tests/ui/06-response-only.rs

@@ -0,0 +1,24 @@
+use ruma_api::ruma_api;
+
+ruma_api! {
+    metadata: {
+        description: "Does something.",
+        method: POST, // An `http::Method` constant. No imports required.
+        name: "some_endpoint",
+        path: "/_matrix/some/endpoint/:baz",
+        rate_limited: false,
+        authentication: None,
+    }
+
+    #[derive(PartialEq)] // Make sure attributes work
+    response: {
+        pub flag: bool,
+    }
+}
+
+fn main() {
+    let res1 = Response { flag: false };
+    let res2 = res1.clone();
+
+    assert_eq!(res1, res2);
+}

ruma-api/tests/ui/07-error-type-attribute.rs

@@ -0,0 +1,21 @@
+use ruma_api::ruma_api;
+
+ruma_api! {
+    metadata: {
+        description: "Does something.",
+        method: POST, // An `http::Method` constant. No imports required.
+        name: "some_endpoint",
+        path: "/_matrix/some/endpoint/:baz",
+        rate_limited: false,
+        authentication: None,
+    }
+
+    request: {}
+
+    response: {}
+
+    #[derive(Default)]
+    error: ruma_api::error::Void
+}
+
+fn main() {}

ruma-api/tests/ui/07-error-type-attribute.stderr

@@ -0,0 +1,5 @@
+error: unexpected token
+  --> $DIR/07-error-type-attribute.rs:17:5
+   |
+17 |     #[derive(Default)]
+   |     ^