events: Introduce Redact trait

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

@@ -486,9 +486,10 @@ fn expand_redact(
 
         Some(quote! {
             #[automatically_derived]
-            impl #ident {
-                /// Redacts `Self` given a valid `Redaction[Sync]Event`.
-                pub fn redact(
+            impl #ruma_events::Redact for #ident {
+                type Redacted = #redacted_enum;
+
+                fn redact(
                     self,
                     redaction: #ruma_events::room::redaction::SyncRedactionEvent,
                     version: &#ruma_identifiers::RoomVersionId,

crates/ruma-events/src/enums.rs

@@ -4,7 +4,7 @@ use ruma_identifiers::{EventId, RoomId, RoomVersionId, UserId};
 use serde::{de, Serialize};
 use serde_json::value::RawValue as RawJsonValue;
 
-use crate::{from_raw_json_value, room::redaction::SyncRedactionEvent, EventDeHelper};
+use crate::{from_raw_json_value, room::redaction::SyncRedactionEvent, EventDeHelper, Redact};
 
 event_enum! {
     /// Any global account data event.

crates/ruma-events/src/lib.rs

@@ -275,6 +275,18 @@ pub trait EventContent: Sized + Serialize {
     fn from_parts(event_type: &str, content: Box<RawJsonValue>) -> Result<Self, serde_json::Error>;
 }
 
+/// Trait to define the behavior of redacting an event.
+pub trait Redact {
+    /// The redacted form of the event.
+    type Redacted;
+
+    /// Transforms `self` into a redacted form (removing most fields) according to the spec.
+    ///
+    /// A small number of events have room-version specific redaction behavior, so a version has to
+    /// be specified.
+    fn redact(self, redaction: SyncRedactionEvent, version: &RoomVersionId) -> Self::Redacted;
+}
+
 /// Trait to define the behavior of redact an event's content object.
 pub trait RedactContent {
     /// The redacted form of the event's content.

crates/ruma-events/tests/redacted.rs

@@ -10,7 +10,7 @@ use ruma_events::{
         redaction::{RedactionEventContent, SyncRedactionEvent},
     },
     AnyMessageEvent, AnyRedactedMessageEvent, AnyRedactedSyncMessageEvent,
-    AnyRedactedSyncStateEvent, AnyRoomEvent, AnySyncRoomEvent, RedactedMessageEvent,
+    AnyRedactedSyncStateEvent, AnyRoomEvent, AnySyncRoomEvent, Redact, RedactedMessageEvent,
     RedactedSyncMessageEvent, RedactedSyncStateEvent, RedactedUnsigned, Unsigned,
 };
 use ruma_identifiers::{event_id, room_id, user_id, RoomVersionId};