Move and rename member_display_name to RoomMember::disambiguated_name.

This makes more sense as all the required information is now available
on `RoomMember`. We also don't have to handle the case of the missing
member since now you have to actually get a `RoomMember` before you can
ask for their name.

matrix_sdk_base/src/models/room.rs

@@ -13,7 +13,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::borrow::Cow;
 use std::collections::{BTreeMap, HashMap, HashSet};
 use std::convert::TryFrom;
 
@@ -319,34 +318,6 @@ impl Room {
         self.encrypted.as_ref()
     }
 
-    /// Get the disambiguated display name for a member of this room.
-    ///
-    /// If a member has no display name set, returns the MXID as a fallback.
-    ///
-    /// This method never fails, even if user with the supplied MXID is not a member in the room.
-    /// In this case we still return the supplied MXID as a fallback.
-    ///
-    /// When displaying a room member's display name, clients *must* use this method to obtain the
-    /// name instead of displaying the `RoomMember::display_name` directly. This is because
-    /// multiple members can share the same display name in which case the display name has to be
-    /// disambiguated.
-    pub fn member_display_name<'a>(&'a self, id: &'a UserId) -> Cow<'a, str> {
-        let member = self.get_member(id);
-
-        match member {
-            Some(member) => {
-                if member.display_name_ambiguous {
-                    member.unique_name().into()
-                } else {
-                    member.name().into()
-                }
-            }
-
-            // Even if there is no such member, we return the MXID that was given to us.
-            None => id.as_ref().into(),
-        }
-    }
-
     /// Process the join or invite event for a new room member.
     ///
     /// This method should be called only on events which add new members, not on existing ones.
@@ -1347,7 +1318,7 @@ mod test {
         {
             let room = client.get_joined_room(&room_id).await.unwrap();
             let room = room.read().await;
-            let display_name1 = room.member_display_name(&user_id1);
+            let display_name1 = room.get_member(&user_id1).unwrap().disambiguated_name();
 
             assert_eq!("example", display_name1);
         }
@@ -1366,9 +1337,9 @@ mod test {
         {
             let room = client.get_joined_room(&room_id).await.unwrap();
             let room = room.read().await;
-            let display_name1 = room.member_display_name(&user_id1);
+            let display_name1 = room.get_member(&user_id1).unwrap().disambiguated_name();
-            let display_name2 = room.member_display_name(&user_id2);
+            let display_name2 = room.get_member(&user_id2).unwrap().disambiguated_name();
-            let display_name3 = room.member_display_name(&user_id3);
+            let display_name3 = room.get_member(&user_id3).unwrap().disambiguated_name();
 
             assert_eq!(format!("example ({})", user_id1), display_name1);
             assert_eq!(format!("example ({})", user_id2), display_name2);
@@ -1385,7 +1356,7 @@ mod test {
             let room = client.get_joined_room(&room_id).await.unwrap();
             let room = room.read().await;
 
-            let display_name1 = room.member_display_name(&user_id1);
+            let display_name1 = room.get_member(&user_id1).unwrap().disambiguated_name();
 
             assert_eq!("example", display_name1);
         }
@@ -1401,8 +1372,8 @@ mod test {
             let room = client.get_joined_room(&room_id).await.unwrap();
             let room = room.read().await;
 
-            let display_name1 = room.member_display_name(&user_id1);
+            let display_name1 = room.get_member(&user_id1).unwrap().disambiguated_name();
-            let display_name2 = room.member_display_name(&user_id2);
+            let display_name2 = room.get_member(&user_id2).unwrap().disambiguated_name();
 
             assert_eq!(format!("example ({})", user_id1), display_name1);
             assert_eq!(format!("example ({})", user_id2), display_name2);
@@ -1419,8 +1390,8 @@ mod test {
             let room = client.get_joined_room(&room_id).await.unwrap();
             let room = room.read().await;
 
-            let display_name1 = room.member_display_name(&user_id1);
+            let display_name1 = room.get_member(&user_id1).unwrap().disambiguated_name();
-            let display_name2 = room.member_display_name(&user_id2);
+            let display_name2 = room.get_member(&user_id2).unwrap().disambiguated_name();
 
             assert_eq!("changed", display_name1);
             assert_eq!("example", display_name2);
@@ -1437,8 +1408,8 @@ mod test {
             let room = client.get_joined_room(&room_id).await.unwrap();
             let room = room.read().await;
 
-            let display_name1 = room.member_display_name(&user_id1);
+            let display_name1 = room.get_member(&user_id1).unwrap().disambiguated_name();
-            let display_name2 = room.member_display_name(&user_id2);
+            let display_name2 = room.get_member(&user_id2).unwrap().disambiguated_name();
 
             assert_eq!(format!("changed ({})", user_id1), display_name1);
             assert_eq!(format!("changed ({})", user_id2), display_name2);

matrix_sdk_base/src/models/room_member.rs

@@ -105,7 +105,8 @@ impl RoomMember {
         }
     }
 
-    /// Returns the most ergonomic name available for the member.
+    /// Returns the most ergonomic (but potentially ambiguous/non-unique) name available for the
+    /// member.
     ///
     /// This is the member's display name if it is set, otherwise their MXID.
     pub fn name(&self) -> String {
@@ -114,16 +115,39 @@ impl RoomMember {
             .unwrap_or_else(|| format!("{}", self.user_id))
     }
 
-    /// Returns a name for the member which is guaranteed to be unique.
+    /// Returns a name for the member which is guaranteed to be unique, but not necessarily the
+    /// most ergonomic.
     ///
-    /// This is either of the format "DISPLAY_NAME (MXID)" if the display name is set for the
+    /// This is either a name in the format "DISPLAY_NAME (MXID)" if the member's display name is
-    /// member, or simply "MXID" if not.
+    /// set, or simply "MXID" if not.
     pub fn unique_name(&self) -> String {
         self.display_name
             .clone()
             .map(|d| format!("{} ({})", d, self.user_id))
             .unwrap_or_else(|| format!("{}", self.user_id))
     }
+
+    /// Get the disambiguated display name for the member which is as ergonomic as possible while
+    /// still guaranteeing it is unique.
+    ///
+    /// If the member's display name is currently ambiguous (i.e. shared by other room members),
+    /// this method will return the same result as `RoomMember::unique_name`. Otherwise, this
+    /// method will return the same result as `RoomMember::name`.
+    ///
+    /// This is usually the name you want when showing room messages from the member or when
+    /// showing the member in the member list.
+    ///
+    /// **Warning**: When displaying a room member's display name, clients *must* use
+    /// a disambiguated name, so they *must not* use `RoomMember::display_name` directly. Clients
+    /// *should* use this method to obtain the name, but an acceptable alternative is to use
+    /// `RoomMember::unique_name` in certain situations.
+    pub fn disambiguated_name(&self) -> String {
+        if self.display_name_ambiguous {
+            self.unique_name().into()
+        } else {
+            self.name().into()
+        }
+    }
 }
 
 #[cfg(test)]