Add fallback support to group matches

Signed-off-by: Knut Ahlers <knut@ahlers.me>

functions_irc.go

@@ -23,12 +23,16 @@ func init() {
 	tplFuncs.Register("fixUsername", plugins.GenericTemplateFunctionGetter(func(username string) string { return strings.TrimLeft(username, "@#") }))
 
 	tplFuncs.Register("group", func(m *irc.Message, r *plugins.Rule, fields map[string]interface{}) interface{} {
-		return func(idx int) (string, error) {
+		return func(idx int, fallback ...string) (string, error) {
 			fields := r.GetMatchMessage().FindStringSubmatch(m.Trailing())
 			if len(fields) <= idx {
 				return "", errors.New("group not found")
 			}
 
+			if fields[idx] == "" && len(fallback) > 0 {
+				return fallback[0], nil
+			}
+
 			return fields[idx], nil
 		}
 	})

wiki/Home.md

@@ -160,7 +160,7 @@ Additionally there are some functions available in the templates:
 - `displayName <username> [fallback]` - Returns the display name the specified user set for themselves
 - `fixUsername <username>` - Ensures the username no longer contains the `@` or `#` prefix
 - `followDate <from> <to>` - Looks up when `from` followed `to`
-- `group <idx>` - Gets matching group specified by index from `match_message` regular expression
+- `group <idx> [fallback]` - Gets matching group specified by index from `match_message` regular expression, when `fallback` is defined, it is used when group has an empty match
 - `recentGame <username> [fallback]` - Returns the last played game name of the specified user (see shoutout example) or the `fallback` if the game could not be fetched. If no fallback was supplied the message will fail and not be sent.
 - `tag <tagname>` - Takes the message sent to the channel, returns the value of the tag specified
 - `toLower <string>` - Converts the given string to lower-case