Add Client.get_room_by_alias

src/matrix-client.vala

@@ -205,4 +205,16 @@ public interface Matrix.Client : GLib.Object {
     public abstract Room
     get_room_by_id(string room_id)
         throws Matrix.Error;
+
+    /**
+     * Get a room object by the room alias specified
+     * in @param room_alias. If room data is not cached yet,
+     * {@link Matrix.Error.UNAVAILABLE} is thrown.
+     *
+     * @param room_alias a room alias
+     * @return a Matrix.Room object
+     */
+    public abstract Room
+    get_room_by_alias(string room_alias)
+        throws Matrix.Error;
 }

src/matrix-http-client.vala

@@ -453,4 +453,24 @@ public class Matrix.HTTPClient : Matrix.HTTPAPI, Matrix.Client {
 
         return room;
     }
+
+    public Room
+    get_room_by_alias(string room_alias)
+        throws Matrix.Error
+    {
+        foreach (var entry in _rooms.entries) {
+            var room = entry.value;
+
+            if (room.canonical_alias == room_alias) {
+                return room;
+            }
+
+            if (room_alias in room.aliases) {
+                return room;
+            }
+        }
+
+        throw new Matrix.Error.UNAVAILABLE(
+                "Noo room data found for alias %s", room_alias);
+    }
 }