In order to aid some string comparisons, I have just introduced constant string arrays in rsyslog. Look at this construct:
if $msg contains ["event12", "event15","event19"] then
This will match if $msg contains any of the three strings given inside the array, so it works like an implicit "or". I have seen this in a couple of customer configs and I am confident that this will ease rsyslog configuration. In later releases, it will also provide room for performance optimizations.
This feature will be part of 7.1.7.
 Starting with rsyslog 7.3.6, string array comparisons are notably faster, especially if the array is large. At most, there are log(n) comparisons required (where n is the array size).