add SystemEpochInfoEvent utils

Author: cyberphysic4l

crates/iota-core/src/authority.rs

@@ -4675,24 +4675,8 @@ impl AuthorityState {
             .events
             .data
             .iter()
-            .find(|event| {
-                event.is_system_epoch_info_event_v1() || event.is_system_epoch_info_event_v2()
-            })
-            .map(|event| {
-                if event.is_system_epoch_info_event_v2() {
-                    SystemEpochInfoEvent::V2(
-                        bcs::from_bytes::<SystemEpochInfoEventV2>(&event.contents).expect(
-                            "event deserialization should succeed as type was pre-validated",
-                        ),
-                    )
-                } else {
-                    SystemEpochInfoEvent::V1(
-                        bcs::from_bytes::<SystemEpochInfoEventV1>(&event.contents).expect(
-                            "event deserialization should succeed as type was pre-validated",
-                        ),
-                    )
-                }
-            });
+            .find(|event| event.is_system_epoch_info_event())
+            .map(|event| SystemEpochInfoEvent::from(event));
         // The system epoch info event can be `None` in case if the `advance_epoch`
         // Move function call failed and was executed in the safe mode.
         assert!(system_epoch_info_event.is_some() || system_obj.safe_mode());

crates/iota-core/src/checkpoints/mod.rs

@@ -1452,14 +1452,8 @@ impl CheckpointBuilder {
                 // SAFETY: The number of minted and burnt tokens easily fit into an i64 and due
                 // to those small numbers, no overflows will occur during conversion or
                 // subtraction.
-                let epoch_supply_change = system_epoch_info_event.map_or(0, |event| match event {
-                    SystemEpochInfoEvent::V1(event) => {
-                        event.minted_tokens_amount as i64 - event.burnt_tokens_amount as i64
-                    }
-                    SystemEpochInfoEvent::V2(event) => {
-                        event.minted_tokens_amount as i64 - event.burnt_tokens_amount as i64
-                    }
-                });
+                let epoch_supply_change =
+                    system_epoch_info_event.map_or(0, |event| event.supply_change());
 
                 let committee = system_state_obj
                     .get_current_epoch_committee()

crates/iota-types/src/event.rs

@@ -149,6 +149,10 @@ impl Event {
             && self.type_.module.as_ident_str() == ident_str!("iota_system_state_inner")
             && self.type_.name.as_ident_str() == ident_str!("SystemEpochInfoEventV2")
     }
+
+    pub fn is_system_epoch_info_event(&self) -> bool {
+        self.is_system_epoch_info_event_v1() || self.is_system_epoch_info_event_v2()
+    }
 }
 
 impl Event {
@@ -174,6 +178,35 @@ pub enum SystemEpochInfoEvent {
     V2(SystemEpochInfoEventV2),
 }
 
+impl SystemEpochInfoEvent {
+    pub fn supply_change(&self) -> i64 {
+        match self {
+            SystemEpochInfoEvent::V1(event) => {
+                event.minted_tokens_amount as i64 - event.burnt_tokens_amount as i64
+            }
+            SystemEpochInfoEvent::V2(event) => {
+                event.minted_tokens_amount as i64 - event.burnt_tokens_amount as i64
+            }
+        }
+    }
+}
+
+impl From<Event> for SystemEpochInfoEvent {
+    fn from(event: Event) -> Self {
+        if event.is_system_epoch_info_event_v2() {
+            SystemEpochInfoEvent::V2(
+                bcs::from_bytes::<SystemEpochInfoEventV2>(&event.contents)
+                    .expect("event deserialization should succeed as type was pre-validated"),
+            )
+        } else {
+            SystemEpochInfoEvent::V1(
+                bcs::from_bytes::<SystemEpochInfoEventV1>(&event.contents)
+                    .expect("event deserialization should succeed as type was pre-validated"),
+            )
+        }
+    }
+}
+
 /// Event emitted in move code `fun advance_epoch` in protocol versions 1 to 3
 #[derive(Deserialize)]
 pub struct SystemEpochInfoEventV1 {