base: Us and_then() instead of map() + flatten()

matrix_sdk_base/src/client.rs

@@ -104,7 +104,7 @@ pub fn hoist_and_deserialize_state_event(
 
     if let AnySyncStateEvent::RoomMember(ref mut member) = ev {
         if member.prev_content.is_none() {
-            member.prev_content = prev_content.map(|e| e.deserialize().ok()).flatten();
+            member.prev_content = prev_content.and_then(|e| e.deserialize().ok());
         }
     }
 
@@ -121,7 +121,7 @@ fn hoist_member_event(
     let mut e = event.deserialize()?;
 
     if e.prev_content.is_none() {
-        e.prev_content = prev_content.map(|e| e.deserialize().ok()).flatten();
+        e.prev_content = prev_content.and_then(|e| e.deserialize().ok());
     }
 
     Ok(e)
@@ -133,8 +133,7 @@ fn hoist_room_event_prev_content(
     let prev_content = serde_json::from_str::<AdditionalEventData>(event.json().get())
         .map(|more_unsigned| more_unsigned.unsigned)
         .map(|additional| additional.prev_content)?
-        .map(|p| p.deserialize().ok())
+        .and_then(|p| p.deserialize().ok());
-        .flatten();
 
     let mut ev = event.deserialize()?;
 
@@ -950,8 +949,7 @@ impl BaseClient {
             for member in response.chunk.iter().filter_map(|e| {
                 hoist_member_event(e)
                     .ok()
-                    .map(|e| MemberEvent::try_from(e).ok())
+                    .and_then(|e| MemberEvent::try_from(e).ok())
-                    .flatten()
             }) {
                 if self
                     .store

matrix_sdk_base/src/rooms/normal.rs

@@ -336,14 +336,13 @@ impl Room {
             .store
             .get_state_event(self.room_id(), EventType::RoomPowerLevels, "")
             .await?
-            .map(|e| {
+            .and_then(|e| {
                 if let AnySyncStateEvent::RoomPowerLevels(e) = e {
                     Some(e)
                 } else {
                     None
                 }
-            })
+            });
-            .flatten();
 
         let ambiguous = self
             .store

matrix_sdk_base/src/store/mod.rs

@@ -193,27 +193,26 @@ impl Store {
     }
 
     pub fn get_joined_room(&self, room_id: &RoomId) -> Option<JoinedRoom> {
-        self.get_room(room_id).map(|r| r.joined()).flatten()
+        self.get_room(room_id).and_then(|r| r.joined())
     }
 
     pub fn get_invited_room(&self, room_id: &RoomId) -> Option<InvitedRoom> {
-        self.get_room(room_id).map(|r| r.invited()).flatten()
+        self.get_room(room_id).and_then(|r| r.invited())
     }
 
     pub fn get_left_room(&self, room_id: &RoomId) -> Option<LeftRoom> {
-        self.get_room(room_id).map(|r| r.left()).flatten()
+        self.get_room(room_id).and_then(|r| r.left())
     }
 
     pub fn get_room(&self, room_id: &RoomId) -> Option<RoomState> {
         self.get_bare_room(room_id)
-            .map(|r| match r.room_type() {
+            .and_then(|r| match r.room_type() {
                 RoomType::Joined => Some(RoomState::Joined(JoinedRoom { inner: r })),
                 RoomType::Left => Some(RoomState::Left(LeftRoom { inner: r })),
                 RoomType::Invited => self
                     .get_stripped_room(room_id)
                     .map(|r| RoomState::Invited(InvitedRoom { inner: r })),
             })
-            .flatten()
     }
 
     fn get_stripped_room(&self, room_id: &RoomId) -> Option<StrippedRoom> {

matrix_sdk_base/src/store/sled_store/mod.rs

@@ -351,8 +351,7 @@ impl SledStore {
                                 .encode();
 
                             let display_name = profile_changes
-                                .map(|p| p.get(&event.state_key))
+                                .and_then(|p| p.get(&event.state_key))
-                                .flatten()
                                 .as_ref()
                                 .map(|m| m.displayname.as_deref())
                                 .unwrap_or_else(|| Some(event.state_key.localpart()))
@@ -390,7 +389,7 @@ impl SledStore {
                             )?;
 
                             if let Some(profile) =
-                                profile_changes.map(|p| p.get(&event.state_key)).flatten()
+                                profile_changes.and_then(|p| p.get(&event.state_key))
                             {
                                 profiles.insert(
                                     key.as_slice(),