Use thiserror for room errors.

client/src/room.rs

@@ -1,10 +1,9 @@
-use std::collections;
-use std::error;
-use std::fmt;
+use std::collections::{HashMap, HashSet};
 use std::mem;
 
 use serde::{Deserialize, Serialize};
 use solstice_proto::{server, User};
+use thiserror::Error;
 
 /// This enumeration is the list of possible membership states for a chat room.
 #[derive(Clone, Copy, Debug, Eq, PartialEq, Serialize, Deserialize)]
@@ -57,9 +56,9 @@ pub struct Room {
   /// The name of the room's owner, if any.
   pub owner: Option<String>,
   /// The names of the room's operators.
-  pub operators: collections::HashSet<String>,
+  pub operators: HashSet<String>,
   /// The names of the room's members.
-  pub members: collections::HashSet<String>,
+  pub members: HashSet<String>,
   /// The messages sent to this chat room, in chronological order.
   pub messages: Vec<Message>,
   /// The tickers displayed in this room.
@@ -75,8 +74,8 @@ impl Room {
       operated: false,
       user_count: user_count,
       owner: None,
-      operators: collections::HashSet::new(),
-      members: collections::HashSet::new(),
+      operators: HashSet::new(),
+      members: HashSet::new(),
       messages: Vec::new(),
       tickers: Vec::new(),
     }
@@ -84,37 +83,13 @@ impl Room {
 }
 
 /// The error returned by RoomMap functions.
-#[derive(Debug)]
-pub enum Error {
+#[derive(Debug, Error)]
+pub enum RoomError {
+  #[error("room {0} not found")]
   RoomNotFound(String),
-  MembershipChangeInvalid(Membership, Membership),
-}
-
-impl fmt::Display for Error {
-  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    match *self {
-      Error::RoomNotFound(ref room_name) => {
-        write!(f, "room {:?} not found", room_name)
-      }
-
-      Error::MembershipChangeInvalid(old_membership, new_membership) => {
-        write!(
-          f,
-          "cannot change membership from {:?} to {:?}",
-          old_membership, new_membership
-        )
-      }
-    }
-  }
-}
 
-impl error::Error for Error {
-  fn description(&self) -> &str {
-    match *self {
-      Error::RoomNotFound(_) => "room not found",
-      Error::MembershipChangeInvalid(_, _) => "cannot change membership",
-    }
-  }
+  #[error("cannot change membership from {0:?} to {1:?}")]
+  MembershipChangeInvalid(Membership, Membership),
 }
 
 /// Contains the mapping from room names to room data and provides a clean
@@ -122,7 +97,7 @@ impl error::Error for Error {
 #[derive(Debug, Default)]
 pub struct RoomMap {
   /// The actual map from room names to room data.
-  map: collections::HashMap<String, Room>,
+  map: HashMap<String, Room>,
 }
 
 impl RoomMap {
@@ -141,19 +116,22 @@ impl RoomMap {
   /// Looks up the given room name in the map, returning an immutable
   /// reference to the associated data if found, or an error if not found.
   #[cfg(test)]
-  pub fn get_strict(&self, room_name: &str) -> Result<&Room, Error> {
+  pub fn get_strict(&self, room_name: &str) -> Result<&Room, RoomError> {
     match self.map.get(room_name) {
       Some(room) => Ok(room),
-      None => Err(Error::RoomNotFound(room_name.to_string())),
+      None => Err(RoomError::RoomNotFound(room_name.to_string())),
     }
   }
 
   /// Looks up the given room name in the map, returning a mutable
   /// reference to the associated data if found, or an error if not found.
-  fn get_mut_strict(&mut self, room_name: &str) -> Result<&mut Room, Error> {
+  fn get_mut_strict(
+    &mut self,
+    room_name: &str,
+  ) -> Result<&mut Room, RoomError> {
     match self.map.get_mut(room_name) {
       Some(room) => Ok(room),
-      None => Err(Error::RoomNotFound(room_name.to_string())),
+      None => Err(RoomError::RoomNotFound(room_name.to_string())),
     }
   }
 
@@ -164,7 +142,7 @@ impl RoomMap {
     name: String,
     visibility: Visibility,
     user_count: u32,
-    old_map: &mut collections::HashMap<String, Room>,
+    old_map: &mut HashMap<String, Room>,
   ) {
     let room = match old_map.remove(&name) {
       None => Room::new(Visibility::Public, user_count as usize),
@@ -183,7 +161,7 @@ impl RoomMap {
   /// server response.
   pub fn set_room_list(&mut self, mut response: server::RoomListResponse) {
     // Replace the old mapping with an empty one.
-    let mut old_map = mem::replace(&mut self.map, collections::HashMap::new());
+    let mut old_map = mem::replace(&mut self.map, HashMap::new());
 
     // Add all public rooms.
     for (name, user_count) in response.rooms.drain(..) {
@@ -221,7 +199,7 @@ impl RoomMap {
   /// Records that we are now trying to join the given room.
   /// If the room is not found, or if its membership is not `NonMember`,
   /// returns an error.
-  pub fn start_joining(&mut self, room_name: &str) -> Result<(), Error> {
+  pub fn start_joining(&mut self, room_name: &str) -> Result<(), RoomError> {
     let room = self.get_mut_strict(room_name)?;
 
     match room.membership {
@@ -230,7 +208,7 @@ impl RoomMap {
         Ok(())
       }
 
-      membership => Err(Error::MembershipChangeInvalid(
+      membership => Err(RoomError::MembershipChangeInvalid(
         membership,
         Membership::Joining,
       )),
@@ -245,7 +223,7 @@ impl RoomMap {
     owner: Option<String>,
     mut operators: Vec<String>,
     members: &[User],
-  ) -> Result<&Room, Error> {
+  ) -> Result<&Room, RoomError> {
     // First look up the room struct.
     let room = self.get_mut_strict(room_name)?;
 
@@ -280,7 +258,7 @@ impl RoomMap {
   /// Records that we are now trying to leave the given room.
   /// If the room is not found, or if its membership status is not `Member`,
   /// returns an error.
-  pub fn start_leaving(&mut self, room_name: &str) -> Result<(), Error> {
+  pub fn start_leaving(&mut self, room_name: &str) -> Result<(), RoomError> {
     let room = self.get_mut_strict(room_name)?;
 
     match room.membership {
@@ -289,7 +267,7 @@ impl RoomMap {
         Ok(())
       }
 
-      membership => Err(Error::MembershipChangeInvalid(
+      membership => Err(RoomError::MembershipChangeInvalid(
         membership,
         Membership::Leaving,
       )),
@@ -297,7 +275,7 @@ impl RoomMap {
   }
 
   /// Records that we have now left the given room.
-  pub fn leave(&mut self, room_name: &str) -> Result<(), Error> {
+  pub fn leave(&mut self, room_name: &str) -> Result<(), RoomError> {
     let room = self.get_mut_strict(room_name)?;
 
     match room.membership {
@@ -318,7 +296,7 @@ impl RoomMap {
     &mut self,
     room_name: &str,
     message: Message,
-  ) -> Result<(), Error> {
+  ) -> Result<(), RoomError> {
     let room = self.get_mut_strict(room_name)?;
     room.messages.push(message);
     Ok(())
@@ -330,7 +308,7 @@ impl RoomMap {
     &mut self,
     room_name: &str,
     user_name: String,
-  ) -> Result<(), Error> {
+  ) -> Result<(), RoomError> {
     let room = self.get_mut_strict(room_name)?;
     room.members.insert(user_name);
     Ok(())
@@ -342,7 +320,7 @@ impl RoomMap {
     &mut self,
     room_name: &str,
     user_name: &str,
-  ) -> Result<(), Error> {
+  ) -> Result<(), RoomError> {
     let room = self.get_mut_strict(room_name)?;
     room.members.remove(user_name);
     Ok(())
@@ -356,7 +334,7 @@ impl RoomMap {
     &mut self,
     room_name: &str,
     tickers: Vec<(String, String)>,
-  ) -> Result<(), Error> {
+  ) -> Result<(), RoomError> {
     let room = self.get_mut_strict(room_name)?;
     room.tickers = tickers;
     Ok(())