Remove manual Serialize impl, use derive macro instead

ruma-events-macros/src/gen.rs

@@ -6,7 +6,7 @@ use syn::{
     parse_quote,
     punctuated::Punctuated,
     spanned::Spanned,
-    Attribute, Field, Ident, LitStr, Token, Type,
+    Attribute, Field, Ident, LitStr, Token,
 };
 
 use crate::parse::{Content, EventKind, RumaEventInput};
@@ -89,7 +89,6 @@ impl ToTokens for RumaEvent {
         };
 
         let name = &self.name;
-        let name_str = format!("{}", name);
         let content_docstring = format!("The payload for `{}`.", name);
 
         let content = match &self.content {
@@ -126,60 +125,6 @@ impl ToTokens for RumaEvent {
             Content::Typedef(_) => TokenStream::new(),
         };
 
-        // Only custom events will already have an event_type field, since we don't handle
-        // custom events we start at one.
-        let mut base_field_count: usize = 1;
-
-        // Keep track of all the optional fields, because we'll need to check at runtime if they
-        // are `Some` in order to increase the number of fields we tell serde to serialize.
-        let mut optional_field_idents = Vec::with_capacity(event_fields.len());
-
-        let mut serialize_field_calls: Vec<TokenStream> = Vec::with_capacity(event_fields.len());
-
-        for field in event_fields {
-            let ident = field.ident.clone().unwrap();
-
-            let ident_str = if ident == "event_type" {
-                "type".to_string()
-            } else {
-                format!("{}", ident)
-            };
-
-            let span = field.span();
-
-            // Does the same thing as #[serde(skip_serializing_if = "Option::is_none")]
-            let serialize_field_call = if is_option(&field.ty) {
-                optional_field_idents.push(ident.clone());
-
-                quote_spanned! {span=>
-                    if self.#ident.is_some() {
-                        state.serialize_field(#ident_str, &self.#ident)?;
-                    }
-                }
-            } else {
-                base_field_count += 1;
-
-                quote_spanned! {span=>
-                    state.serialize_field(#ident_str, &self.#ident)?;
-                }
-            };
-
-            serialize_field_calls.push(serialize_field_call);
-        }
-
-        let increment_struct_len_statements: Vec<TokenStream> = optional_field_idents
-            .iter()
-            .map(|ident| {
-                let span = ident.span();
-
-                quote_spanned! {span=>
-                    if self.#ident.is_some() {
-                        len += 1;
-                    }
-                }
-            })
-            .collect();
-
         let impl_room_event = match self.kind {
             EventKind::RoomEvent | EventKind::StateEvent => {
                 quote! {
@@ -269,42 +214,19 @@ impl ToTokens for RumaEvent {
                 TokenStream::new()
             };
 
-        let stripped_fields = event_fields
+        let event_type_name = self.event_type.value();
-            .iter()
-            .map(|event_field| strip_serde_attrs(event_field));
-
         let output = quote!(
             #(#attrs)*
-            #[derive(Clone, PartialEq, Debug, ruma_events_macros::FromRaw)]
+            #[derive(Clone, PartialEq, Debug, serde::Serialize, ruma_events_macros::FromRaw)]
+            #[serde(rename = #event_type_name, tag = "type")]
             pub struct #name {
-                #(#stripped_fields),*
+                #(#event_fields),*
             }
 
             #content
 
             #impl_event_result_compatible_for_content
 
-            impl serde::Serialize for #name {
-                fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-                where
-                    S: serde::Serializer
-                {
-                    use serde::ser::SerializeStruct as _;
-                    use ::ruma_events::Event as _;
-
-                    let mut len = #base_field_count;
-
-                    #(#increment_struct_len_statements)*
-
-                    let mut state = serializer.serialize_struct(#name_str, len)?;
-
-                    #(#serialize_field_calls)*
-                    state.serialize_field("type", &self.event_type())?;
-
-                    state.end()
-                }
-            }
-
             impl ::ruma_events::Event for #name {
                 /// The type of this event's `content` field.
                 type Content = #content_name;
@@ -367,12 +289,14 @@ fn populate_room_event_fields(content_name: Ident, fields: Vec<Field>) -> Vec<Fi
         pub origin_server_ts: js_int::UInt,
 
         /// The unique identifier for the room associated with this event.
+        #[serde(skip_serializing_if = "Option::is_none")]
         pub room_id: Option<ruma_identifiers::RoomId>,
 
         /// The unique identifier for the user who sent this event.
         pub sender: ruma_identifiers::UserId,
 
         /// Additional key-value pairs not signed by the homeserver.
+        #[serde(skip_serializing_if = "Option::is_none")]
         pub unsigned: Option<serde_json::Value>,
     };
 
@@ -387,6 +311,7 @@ fn populate_state_fields(content_name: Ident, fields: Vec<Field>) -> Vec<Field>
 
     let punctuated_fields: Punctuated<ParsableNamedField, Token![,]> = parse_quote! {
         /// The previous content for this state key, if any.
+        #[serde(skip_serializing_if = "Option::is_none")]
         pub prev_content: Option<#content_name>,
 
         /// A key that determines which piece of room state the event represents.
@@ -398,15 +323,6 @@ fn populate_state_fields(content_name: Ident, fields: Vec<Field>) -> Vec<Field>
     fields
 }
 
-/// Checks if a type is an `Option`.
-fn is_option(ty: &Type) -> bool {
-    if let Type::Path(ref type_path) = ty {
-        type_path.path.segments.first().unwrap().ident == "Option"
-    } else {
-        panic!("struct field had unexpected non-path type");
-    }
-}
-
 /// Splits the given `event_type` string on `.` and `_` removing the `m.` then
 /// camel casing to give the `EventType` variant.
 fn to_camel_case(name: String) -> String {
@@ -433,10 +349,3 @@ impl Parse for ParsableNamedField {
         Ok(Self { field })
     }
 }
-
-/// Removes `serde` attributes from struct fields.
-pub fn strip_serde_attrs(field: &Field) -> Field {
-    let mut field = field.clone();
-    field.attrs.retain(|attr| !attr.path.is_ident("serde"));
-    field
-}

src/direct.rs

@@ -43,7 +43,7 @@ mod tests {
         assert_eq!(
             to_string(&event).unwrap(),
             format!(
-                r#"{{"content":{{"{}":["{}"]}},"type":"m.direct"}}"#,
+                r#"{{"type":"m.direct","content":{{"{}":["{}"]}}}}"#,
                 alice.to_string(),
                 room[0].to_string()
             )
@@ -60,8 +60,8 @@ mod tests {
 
         let json_data = format!(
             r#"{{
-            "content": {{ "{}": ["{}", "{}"] }},
+            "type": "m.direct",
-            "type": "m.direct"
+            "content": {{ "{}": ["{}", "{}"] }}
         }}"#,
             alice.to_string(),
             rooms[0].to_string(),

src/dummy.rs

@@ -34,7 +34,7 @@ mod tests {
         let dummy_event = DummyEvent { content: Empty };
 
         let actual = serde_json::to_string(&dummy_event).unwrap();
-        let expected = r#"{"content":{},"type":"m.dummy"}"#;
+        let expected = r#"{"type":"m.dummy","content":{}}"#;
 
         assert_eq!(actual, expected);
     }

src/presence.rs

@@ -96,7 +96,7 @@ mod tests {
             sender: UserId::try_from("@example:localhost").unwrap(),
         };
 
-        let json = r#"{"content":{"avatar_url":"mxc://localhost:wefuiwegh8742w","currently_active":false,"last_active_ago":2478593,"presence":"online","status_msg":"Making cupcakes"},"sender":"@example:localhost","type":"m.presence"}"#;
+        let json = r#"{"type":"m.presence","content":{"avatar_url":"mxc://localhost:wefuiwegh8742w","currently_active":false,"last_active_ago":2478593,"presence":"online","status_msg":"Making cupcakes"},"sender":"@example:localhost"}"#;
 
         assert_eq!(to_string(&event).unwrap(), json);
     }
@@ -115,7 +115,7 @@ mod tests {
             sender: UserId::try_from("@example:localhost").unwrap(),
         };
 
-        let json = r#"{"content":{"avatar_url":"mxc://localhost:wefuiwegh8742w","currently_active":false,"last_active_ago":2478593,"presence":"online","status_msg":"Making cupcakes"},"sender":"@example:localhost","type":"m.presence"}"#;
+        let json = r#"{"type":"m.presence","content":{"avatar_url":"mxc://localhost:wefuiwegh8742w","currently_active":false,"last_active_ago":2478593,"presence":"online","status_msg":"Making cupcakes"},"sender":"@example:localhost"}"#;
 
         assert_eq!(
             serde_json::from_str::<EventResult<PresenceEvent>>(json)

src/room/member.rs

@@ -249,6 +249,7 @@ mod tests {
             prev_content: None,
         };
         let json = json!({
+            "type": "m.room.member",
             "content": {
                 "membership": "join"
             },
@@ -256,8 +257,7 @@ mod tests {
             "origin_server_ts": 1,
             "room_id": "!n8f893n9:example.com",
             "sender": "@carl:example.com",
-            "state_key": "example.com",
+            "state_key": "example.com"
-            "type": "m.room.member"
         });
         serde_json_eq_try_from_raw(event, json);
     }
@@ -287,6 +287,7 @@ mod tests {
             }),
         };
         let json = json!({
+            "type": "m.room.member",
             "content": {
                 "membership": "join"
             },
@@ -297,8 +298,7 @@ mod tests {
             },
             "room_id": "!n8f893n9:example.com",
             "sender": "@carl:example.com",
-            "state_key": "example.com",
+            "state_key": "example.com"
-            "type": "m.room.member"
         });
         serde_json_eq_try_from_raw(event, json);
     }
@@ -337,6 +337,7 @@ mod tests {
             prev_content: None,
         };
         let json = json!({
+            "type": "m.room.member",
             "content": {
                 "avatar_url": "mxc://example.org/SEsfnsuifSDFSSEF",
                 "displayname": "Alice Margatroid",
@@ -359,8 +360,7 @@ mod tests {
             "origin_server_ts":233,
             "room_id": "!jEsUZKDJdhlrceRyVU:example.org",
             "sender": "@alice:example.org",
-            "state_key": "@alice:example.org",
+            "state_key": "@alice:example.org"
-            "type": "m.room.member"
         });
         serde_json_eq_try_from_raw(event, json);
     }
@@ -405,6 +405,7 @@ mod tests {
             }),
         };
         let json = json!({
+            "type": "m.room.member",
             "content": {
                 "membership": "join"
             },
@@ -430,8 +431,7 @@ mod tests {
             },
             "room_id": "!jEsUZKDJdhlrceRyVU:example.org",
             "sender": "@alice:example.org",
-            "state_key": "@alice:example.org",
+            "state_key": "@alice:example.org"
-            "type": "m.room.member"
         });
         serde_json_eq_try_from_raw(event, json);
     }