events: Optimize deserialization helpers

crates/ruma-events-macros/src/event_enum.rs

@@ -161,10 +161,10 @@ fn expand_any_with_deser(
                 use #serde::de::Error as _;
 
                 let json = Box::<#serde_json::value::RawValue>::deserialize(deserializer)?;
-                let #ruma_events::EventDeHelper { ev_type, .. } =
+                let #ruma_events::EventTypeDeHelper { ev_type, .. } =
                     #ruma_events::from_raw_json_value(&json)?;
 
-                match ev_type.as_str() {
+                match &*ev_type {
                     #(
                         #variant_attrs #events => {
                             let event = #serde_json::from_str::<#content>(json.get())
@@ -609,7 +609,7 @@ fn expand_redacted_enum(
                     D: #serde::de::Deserializer<'de>,
                 {
                     let json = Box::<#serde_json::value::RawValue>::deserialize(deserializer)?;
-                    let #ruma_events::EventDeHelper { unsigned, .. } =
+                    let #ruma_events::RedactionDeHelper { unsigned } =
                         #ruma_events::from_raw_json_value(&json)?;
 
                     Ok(match unsigned {

crates/ruma-events/src/enums.rs

@@ -1,10 +1,10 @@
 use ruma_common::MilliSecondsSinceUnixEpoch;
 use ruma_events_macros::event_enum;
 use ruma_identifiers::{EventId, RoomId, RoomVersionId, UserId};
-use serde::{de, Serialize};
+use serde::{de, Deserialize, Serialize};
 use serde_json::value::RawValue as RawJsonValue;
 
-use crate::{from_raw_json_value, room::redaction::SyncRedactionEvent, EventDeHelper, Redact};
+use crate::{from_raw_json_value, room::redaction::SyncRedactionEvent, Redact, UnsignedDeHelper};
 
 event_enum! {
     /// Any global account data event.
@@ -197,13 +197,20 @@ impl AnySyncRoomEvent {
     }
 }
 
-impl<'de> de::Deserialize<'de> for AnyRoomEvent {
+#[derive(Deserialize)]
+#[allow(clippy::exhaustive_structs)]
+struct EventDeHelper {
+    pub state_key: Option<de::IgnoredAny>,
+    pub unsigned: Option<UnsignedDeHelper>,
+}
+
+impl<'de> Deserialize<'de> for AnyRoomEvent {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: de::Deserializer<'de>,
     {
         let json = Box::<RawJsonValue>::deserialize(deserializer)?;
-        let EventDeHelper { state_key, unsigned, .. } = from_raw_json_value(&json)?;
+        let EventDeHelper { state_key, unsigned } = from_raw_json_value(&json)?;
 
         if state_key.is_some() {
             Ok(match unsigned {
@@ -223,13 +230,13 @@ impl<'de> de::Deserialize<'de> for AnyRoomEvent {
     }
 }
 
-impl<'de> de::Deserialize<'de> for AnySyncRoomEvent {
+impl<'de> Deserialize<'de> for AnySyncRoomEvent {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: de::Deserializer<'de>,
     {
         let json = Box::<RawJsonValue>::deserialize(deserializer)?;
-        let EventDeHelper { state_key, unsigned, .. } = from_raw_json_value(&json)?;
+        let EventDeHelper { state_key, unsigned } = from_raw_json_value(&json)?;
 
         if state_key.is_some() {
             Ok(match unsigned {

crates/ruma-events/src/lib.rs

@@ -430,45 +430,36 @@ pub enum HasDeserializeFields {
     Optional,
 }
 
-/// Helper struct to determine if the event has been redacted.
+/// Helper struct to determine the event kind from a `serde_json::value::RawValue`.
 #[doc(hidden)]
-#[derive(Debug, Deserialize)]
+#[derive(Deserialize)]
+#[allow(clippy::exhaustive_structs)]
+pub struct EventTypeDeHelper<'a> {
+    #[serde(borrow, rename = "type")]
+    pub ev_type: std::borrow::Cow<'a, str>,
+}
+
+/// Helper struct to determine if an event has been redacted.
+#[doc(hidden)]
+#[derive(Deserialize)]
+pub struct RedactionDeHelper {
+    /// Used to check whether redacted_because exists.
+    pub unsigned: Option<UnsignedDeHelper>,
+}
+
+#[doc(hidden)]
+#[derive(Deserialize)]
 #[allow(clippy::exhaustive_structs)]
 pub struct UnsignedDeHelper {
     /// This is the field that signals an event has been redacted.
     pub redacted_because: Option<IgnoredAny>,
 }
 
-/// Helper struct to determine the event kind from a `serde_json::value::RawValue`.
-#[doc(hidden)]
-#[derive(Debug, Deserialize)]
-#[allow(clippy::exhaustive_structs)]
-pub struct EventDeHelper {
-    /// the Matrix event type string "m.room.whatever".
-    #[serde(rename = "type")]
-    pub ev_type: String,
-
-    /// If `state_key` is present the event will be deserialized as a state event.
-    pub state_key: Option<IgnoredAny>,
-
-    /// If no `state_key` is found but an `event_id` is present the event
-    /// will be deserialized as a message event.
-    pub event_id: Option<IgnoredAny>,
-
-    /// If no `event_id` or `state_key` are found but a `room_id` is present
-    /// the event will be deserialized as an ephemeral event.
-    pub room_id: Option<IgnoredAny>,
-
-    /// If this `UnsignedData` contains a `redacted_because` key the event is
-    /// immediately deserialized as a redacted event.
-    pub unsigned: Option<UnsignedDeHelper>,
-}
-
 /// Helper function for `serde_json::value::RawValue` deserialization.
 #[doc(hidden)]
-pub fn from_raw_json_value<T, E>(val: &RawJsonValue) -> Result<T, E>
+pub fn from_raw_json_value<'a, T, E>(val: &'a RawJsonValue) -> Result<T, E>
 where
-    T: de::DeserializeOwned,
+    T: de::Deserialize<'a>,
     E: de::Error,
 {
     serde_json::from_str(val.get()).map_err(E::custom)