implement a (very bad) derive macro for activityhandler

Cargo.lock

@@ -1069,6 +1069,12 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "212d0f5754cb6769937f4501cc0e67f4f4483c8d2c3e1e922ee9edbe4ab4c7c0"
 
+[[package]]
+name = "dissimilar"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc4b29f4b9bb94bf267d57269fd0706d343a160937108e9619fe380645428abb"
+
 [[package]]
 name = "either"
 version = "1.6.1"
@@ -1371,6 +1377,12 @@ version = "0.23.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f6503fe142514ca4799d4c26297c4248239fe8838d827db6bd6065c6ed29a6ce"
 
+[[package]]
+name = "glob"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b919933a397b79c37e33b77bb2aa3dc8eb6e165ad809e58ff75bc7db2e34574"
+
 [[package]]
 name = "h2"
 version = "0.2.7"
@@ -1887,12 +1899,23 @@ dependencies = [
  "activitystreams",
  "activitystreams-ext",
  "async-trait",
+ "lemmy_apub_lib_derive",
  "lemmy_utils",
  "lemmy_websocket",
  "serde",
  "url",
 ]
 
+[[package]]
+name = "lemmy_apub_lib_derive"
+version = "0.1.0"
+dependencies = [
+ "proc-macro2 1.0.24",
+ "quote 1.0.8",
+ "syn 1.0.60",
+ "trybuild",
+]
+
 [[package]]
 name = "lemmy_apub_receive"
 version = "0.1.0"
@@ -3652,6 +3675,15 @@ dependencies = [
  "tokio 0.2.25",
 ]
 
+[[package]]
+name = "toml"
+version = "0.5.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a31142970826733df8241ef35dc040ef98c679ab14d7c3e54d827099b3acecaa"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "tower-service"
 version = "0.3.1"
@@ -3735,6 +3767,21 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "59547bce71d9c38b83d9c0e92b6066c4253371f15005def0c30d9657f50c7642"
 
+[[package]]
+name = "trybuild"
+version = "1.0.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1768998d9a3b179411618e377dbb134c58a88cda284b0aa71c42c40660127d46"
+dependencies = [
+ "dissimilar",
+ "glob",
+ "lazy_static",
+ "serde",
+ "serde_json",
+ "termcolor",
+ "toml",
+]
+
 [[package]]
 name = "twoway"
 version = "0.2.1"

Cargo.toml

@@ -15,6 +15,7 @@ members = [
     "crates/api_crud",
     "crates/api_common",
     "crates/apub_lib",
+    "crates/apub_lib_derive",
     "crates/apub",
     "crates/apub_receive",
     "crates/utils",

crates/apub_lib/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2018"
 [dependencies]
 lemmy_utils = { path = "../utils" }
 lemmy_websocket = { path = "../websocket" }
+lemmy_apub_lib_derive = { path = "../apub_lib_derive" }
 activitystreams = "0.7.0-alpha.11"
 activitystreams-ext = "0.1.0-alpha.2"
 serde = { version = "1.0.123", features = ["derive"] }

crates/apub_lib/src/lib.rs

@@ -4,6 +4,7 @@ use activitystreams::{
   primitives::OneOrMany,
   unparsed::Unparsed,
 };
+pub use lemmy_apub_lib_derive::*;
 use lemmy_utils::LemmyError;
 use lemmy_websocket::LemmyContext;
 use std::marker::PhantomData;

crates/apub_lib_derive/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "lemmy_apub_lib_derive"
+version = "0.1.0"
+edition = "2018"
+
+[lib]
+proc-macro = true
+
+[dev-dependencies]
+trybuild = { version = "1.0", features = ["diff"] }
+
+[dependencies]
+proc-macro2 = "1.0"
+syn = "1.0"
+quote = "1.0"

crates/apub_lib_derive/src/lib.rs

@@ -0,0 +1,102 @@
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, Data, DeriveInput};
+
+#[proc_macro_derive(ActivityHandlerNew)]
+pub fn derive_activity_handler(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+  // Parse the input tokens into a syntax tree.
+  let input = parse_macro_input!(input as DeriveInput);
+
+  // Used in the quasi-quotation below as `#name`.
+  let name = input.ident;
+
+  let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+
+  let input_enum = if let Data::Enum(d) = input.data {
+    d
+  } else {
+    unimplemented!()
+  };
+
+  let impl_verify = input_enum
+    .variants
+    .iter()
+    .map(|variant| variant_impl_verify(&name, variant));
+  let impl_receive = input_enum
+    .variants
+    .iter()
+    .map(|variant| variant_impl_receive(&name, variant));
+  let impl_common = input_enum
+    .variants
+    .iter()
+    .map(|variant| variant_impl_common(&name, variant));
+
+  // The generated impl.
+  let expanded = quote! {
+      #[async_trait::async_trait(?Send)]
+      impl #impl_generics lemmy_apub_lib::ActivityHandlerNew for #name #ty_generics #where_clause {
+          async fn verify(
+              &self,
+              context: &LemmyContext,
+              request_counter: &mut i32,
+            ) -> Result<(), LemmyError> {
+            match self {
+              #(#impl_verify)*
+            }
+          }
+          async fn receive(
+            &self,
+            context: &LemmyContext,
+            request_counter: &mut i32,
+          ) -> Result<(), LemmyError> {
+            match self {
+              #(#impl_receive)*
+            }
+          }
+          fn common(&self) -> &ActivityCommonFields {
+            match self {
+              #(#impl_common)*
+            }
+          }
+      }
+  };
+
+  // Hand the output tokens back to the compiler.
+  proc_macro::TokenStream::from(expanded)
+}
+
+fn variant_impl_common(name: &syn::Ident, variant: &syn::Variant) -> TokenStream {
+  let id = &variant.ident;
+  match &variant.fields {
+    syn::Fields::Unnamed(_) => {
+      quote! {
+        #name::#id(a) => a.common(),
+      }
+    }
+    _ => unimplemented!(),
+  }
+}
+
+fn variant_impl_verify(name: &syn::Ident, variant: &syn::Variant) -> TokenStream {
+  let id = &variant.ident;
+  match &variant.fields {
+    syn::Fields::Unnamed(_) => {
+      quote! {
+        #name::#id(a) => a.verify(context, request_counter).await,
+      }
+    }
+    _ => unimplemented!(),
+  }
+}
+
+fn variant_impl_receive(name: &syn::Ident, variant: &syn::Variant) -> TokenStream {
+  let id = &variant.ident;
+  match &variant.fields {
+    syn::Fields::Unnamed(_) => {
+      quote! {
+        #name::#id(a) => a.receive(context, request_counter).await,
+      }
+    }
+    _ => unimplemented!(),
+  }
+}

crates/apub_receive/src/http/mod.rs

@@ -30,7 +30,7 @@ pub mod inbox_enums;
 pub mod person;
 pub mod post;
 
-#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize, ActivityHandlerNew)]
 #[serde(untagged)]
 enum Ac {
   CreatePost(CreatePost),
@@ -38,42 +38,6 @@ enum Ac {
   AcceptFollowCommunity(AcceptFollowCommunity),
 }
 
-// TODO: write a derive trait which creates this
-#[async_trait::async_trait(?Send)]
-impl ActivityHandlerNew for Ac {
-  async fn verify(
-    &self,
-    context: &LemmyContext,
-    request_counter: &mut i32,
-  ) -> Result<(), LemmyError> {
-    match self {
-      Ac::CreatePost(a) => a.verify(context, request_counter).await,
-      Ac::LikePost(a) => a.verify(context, request_counter).await,
-      Ac::AcceptFollowCommunity(a) => a.verify(context, request_counter).await,
-    }
-  }
-
-  async fn receive(
-    &self,
-    context: &LemmyContext,
-    request_counter: &mut i32,
-  ) -> Result<(), LemmyError> {
-    match self {
-      Ac::CreatePost(a) => a.receive(context, request_counter).await,
-      Ac::LikePost(a) => a.receive(context, request_counter).await,
-      Ac::AcceptFollowCommunity(a) => a.receive(context, request_counter).await,
-    }
-  }
-
-  fn common(&self) -> &ActivityCommonFields {
-    match self {
-      Ac::CreatePost(a) => a.common(),
-      Ac::LikePost(a) => a.common(),
-      Ac::AcceptFollowCommunity(a) => a.common(),
-    }
-  }
-}
-
 pub async fn shared_inbox(
   request: HttpRequest,
   mut body: web::Payload,