From 4a343754498eb7fd9a980f7e7f69bb01a8773349 Mon Sep 17 00:00:00 2001
From: Devin Ragotzy <devin.ragotzy@gmail.com>
Date: Sun, 26 Jul 2020 19:18:28 -0400
Subject: [PATCH] Support multiple attribute arguments in ruma_event attribute
 (#161)

* Add parsing to allow ruma_event attribute to accept mutli args

* fixup! Add parsing to allow ruma_event attribute to accept mutli args

* Refactor MetaAttrs::parse and resolve review issues
---
 ruma-events-macros/src/event_content.rs | 43 ++++++++++++++++++-------
 ruma-events/src/room/aliases.rs         |  3 +-
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/ruma-events-macros/src/event_content.rs b/ruma-events-macros/src/event_content.rs
index a4226dc9..5cd86d3d 100644
--- a/ruma-events-macros/src/event_content.rs
+++ b/ruma-events-macros/src/event_content.rs
@@ -56,6 +56,25 @@ impl Parse for EventMeta {
     }
 }
 
+struct MetaAttrs(Vec<EventMeta>);
+
+impl MetaAttrs {
+    fn is_custom(&self) -> bool {
+        self.0.iter().any(|a| a == &EventMeta::CustomRedacted)
+    }
+
+    fn get_event_type(&self) -> Option<&LitStr> {
+        self.0.iter().find_map(|a| a.get_event_type())
+    }
+}
+
+impl Parse for MetaAttrs {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let attrs = syn::punctuated::Punctuated::<EventMeta, Token![,]>::parse_terminated(input)?;
+        Ok(Self(attrs.into_iter().collect()))
+    }
+}
+
 /// Create an `EventContent` implementation for a struct.
 pub fn expand_event_content(input: &DeriveInput, emit_redacted: bool) -> syn::Result<TokenStream> {
     let ident = &input.ident;
@@ -64,7 +83,7 @@ pub fn expand_event_content(input: &DeriveInput, emit_redacted: bool) -> syn::Re
         .attrs
         .iter()
         .filter(|attr| attr.path.is_ident("ruma_event"))
-        .map(|attr| attr.parse_args::<EventMeta>())
+        .map(|attr| attr.parse_args::<MetaAttrs>())
         .collect::<syn::Result<Vec<_>>>()?;
 
     let event_type = content_attr.iter().find_map(|a| a.get_event_type()).ok_or_else(|| {
@@ -75,7 +94,7 @@ pub fn expand_event_content(input: &DeriveInput, emit_redacted: bool) -> syn::Re
         syn::Error::new(Span::call_site(), msg)
     })?;
 
-    let redacted = if emit_redacted && needs_redacted(input) {
+    let redacted = if emit_redacted && needs_redacted(&content_attr) {
         let doc = format!("The payload for a redacted `{}`", ident);
         let redacted_ident = format_ident!("Redacted{}", ident);
         let kept_redacted_fields = if let syn::Data::Struct(syn::DataStruct {
@@ -238,7 +257,7 @@ pub fn expand_message_event_content(input: &DeriveInput) -> syn::Result<TokenStr
     let ident = input.ident.clone();
     let room_ev_content = expand_room_event_content(input)?;
 
-    let redacted_marker_trait = if needs_redacted(input) {
+    let redacted_marker_trait = if needs_redacted_from_input(input) {
         let ident = format_ident!("Redacted{}", &ident);
         quote! {
             impl ::ruma_events::RedactedMessageEventContent for #ident { }
@@ -261,7 +280,7 @@ pub fn expand_state_event_content(input: &DeriveInput) -> syn::Result<TokenStrea
     let ident = input.ident.clone();
     let room_ev_content = expand_room_event_content(input)?;
 
-    let redacted_marker_trait = if needs_redacted(input) {
+    let redacted_marker_trait = if needs_redacted_from_input(input) {
         let ident = format_ident!("Redacted{}", input.ident);
         quote! {
             impl ::ruma_events::RedactedStateEventContent for #ident { }
@@ -302,11 +321,13 @@ fn generate_event_content_impl(ident: &Ident, event_type: &LitStr) -> TokenStrea
     }
 }
 
-fn needs_redacted(input: &DeriveInput) -> bool {
-    input
-        .attrs
-        .iter()
-        .flat_map(|a| a.parse_args::<EventMeta>().ok())
-        .find(|a| a == &EventMeta::CustomRedacted)
-        .is_none()
+fn needs_redacted(input: &[MetaAttrs]) -> bool {
+    // `is_custom` means that the content struct does not need a generated
+    // redacted struct also. If no `custom_redacted` attrs are found the content
+    // needs a redacted struct generated.
+    !input.iter().any(|a| a.is_custom())
+}
+
+fn needs_redacted_from_input(input: &DeriveInput) -> bool {
+    !input.attrs.iter().flat_map(|a| a.parse_args::<MetaAttrs>().ok()).any(|a| a.is_custom())
 }
diff --git a/ruma-events/src/room/aliases.rs b/ruma-events/src/room/aliases.rs
index 4fd42c40..9c0095f4 100644
--- a/ruma-events/src/room/aliases.rs
+++ b/ruma-events/src/room/aliases.rs
@@ -15,8 +15,7 @@ pub type AliasesEvent = StateEvent<AliasesEventContent>;
 /// The payload for `AliasesEvent`.
 #[derive(Clone, Debug, Deserialize, Serialize, StateEventContent)]
 #[non_exhaustive]
-#[ruma_event(type = "m.room.aliases")]
-#[ruma_event(custom_redacted)]
+#[ruma_event(type = "m.room.aliases", custom_redacted)]
 pub struct AliasesEventContent {
     /// A list of room aliases.
     pub aliases: Vec<RoomAliasId>,