Use our own stringset instead of menge's

irc/client.go

 	"github.com/ergochat/irc-go/ircfmt"
 	"github.com/ergochat/irc-go/ircmsg"
 	"github.com/ergochat/irc-go/ircreader"
-	"github.com/soroushj/menge"
 	"github.com/xdg-go/scram"
 
 	"github.com/ergochat/ergo/irc/caps"
 	capVersion   caps.Version
 
 	stateMutex             sync.RWMutex // tier 1
-	subscribedMetadataKeys menge.StringSet
+	subscribedMetadataKeys utils.StringSet
 
 	registrationMessages int
 
 		proxiedIP:              proxiedIP,
 		isTor:                  wConn.Config.Tor,
 		hideSTS:                wConn.Config.Tor || wConn.Config.HideSTS,
-		subscribedMetadataKeys: menge.NewStringSet(),
+		subscribedMetadataKeys: make(utils.StringSet),
 	}
 	client.sessions = []*Session{session}
 

irc/handlers.go

 				continue
 			}
 
-			if len(rb.session.subscribedMetadataKeys)+len(addedKeys) > config.MaxSubs {
+			if rb.session.subscribedMetadataKeys.Size() > config.MaxSubs {
 				rb.Add(nil, server.name, ERR_METADATATOOMANYSUBS, client.nick, key)
 				break
 			}
 			}
 
 			addedKeys = append(addedKeys, key)
+			rb.session.subscribedMetadataKeys.Add(key)
 		}
-		rb.session.subscribedMetadataKeys.Add(addedKeys...)
 
 		if len(addedKeys) > 0 {
 			rb.Add(nil, server.name, RPL_METADATASUBOK, client.nick, strings.Join(addedKeys, " "))
 			}
 
 			removedKeys = append(removedKeys, key)
+			rb.session.subscribedMetadataKeys.Remove(key)
 		}
-		rb.session.subscribedMetadataKeys.Remove(removedKeys...)
 
 		if len(removedKeys) > 0 {
 			rb.Add(nil, server.name, RPL_METADATAUNSUBOK, client.nick, strings.Join(removedKeys, " "))
 		defer rb.session.stateMutex.RUnlock()
 		if rb.session.subscribedMetadataKeys.Size() > 0 {
 			//TODO: loop and return subscriptions with multiple numerics if we need to
-			rb.Add(nil, server.name, RPL_METADATASUBS, client.nick, strings.Join(rb.session.subscribedMetadataKeys.AsSlice(), " "))
+			rb.Add(nil, server.name, RPL_METADATASUBS, client.nick, strings.Join(rb.session.subscribedMetadataKeys.Keys(), " "))
 		}
 		rb.Add(nil, server.name, RPL_METADATAEND, client.nick, "end of metadata")
 	}

irc/utils/types.go

 func (s StringSet) Add(str string) {
 	s[str] = empty{}
 }
+
+func (s StringSet) Remove(str string) {
+	_, ok := s[str]
+	if ok {
+		delete(s, str)
+	}
+}
+
+func (s StringSet) Size() int {
+	return len(s)
+}
+
+func (s StringSet) Keys() (keys []string) {
+	for key := range s {
+		keys = append(keys, key)
+	}
+
+	return keys
+}