1 files changed, 18 insertions, 9 deletions
diff --git a/src/Common/UserLists/UserListDiff.h b/src/Common/UserLists/UserListDiff.h
index 41b8e81..5000adf 100644
--- a/src/Common/UserLists/UserListDiff.h
+++ b/src/Common/UserLists/UserListDiff.h
@@ -25,6 +25,7 @@
 #include "UserListEntry.h"
 #include <Core/Exception.h>
 
+#include <boost/bimap.hpp>
 #include <set>
 
 namespace Mad {
@@ -34,14 +35,16 @@ namespace UserLists {
 class UserList;
 
 class MAD_COMMON_EXPORT UserListDiff {
+  public:
+    typedef boost::bimap<boost::bimaps::set_of<UserListEntry>, boost::bimaps::set_of<UserListEntry> > EntryListMap;
+
   private:
     std::set<UserListEntry> addedUsers;
     std::set<UserListEntry> deletedUsers;
-    std::set<UserListEntry> unchangedUsers;
+    EntryListMap updatedUsers;
 
   public:
     UserListDiff() {}
-    UserListDiff(const UserList *oldList, const UserList *newList);
 
     void invert() {
       addedUsers.swap(deletedUsers);
@@ -55,29 +58,35 @@ class MAD_COMMON_EXPORT UserListDiff {
       return deletedUsers;
     }
 
-    const std::set<UserListEntry>& getUnchangedUsers() const {
-      return unchangedUsers;
+    const EntryListMap& getUpdatedUsers() const {
+      return updatedUsers;
     }
 
     bool insertAddedUser(UserListEntry user) {
-      if(deletedUsers.count(user) || unchangedUsers.count(user))
+      if(updatedUsers.right.count(user))
         return false;
 
       return addedUsers.insert(user).second;
     }
 
     bool insertDeletedUser(UserListEntry user) {
-      if(addedUsers.count(user) || unchangedUsers.count(user))
+      if(updatedUsers.left.count(user))
         return false;
 
       return deletedUsers.insert(user).second;
     }
 
-    bool insertUnchangedUser(UserListEntry user) {
-      if(addedUsers.count(user) || deletedUsers.count(user))
+    bool insertUpdatedUser(UserListEntry oldUser, UserListEntry newUser) {
+      if(deletedUsers.count(oldUser) || addedUsers.count(newUser))
+        return false;
+
+      // this won't allow exchanging two users, but that's ok for now...
+      if(updatedUsers.left.count(oldUser) || updatedUsers.right.count(newUser))
+        return false;
+      if(updatedUsers.right.count(oldUser) || updatedUsers.left.count(newUser))
         return false;
 
-      return unchangedUsers.insert(user).second;
+      return updatedUsers.left.insert(std::make_pair(oldUser, newUser)).second;
     }
 };