I was wondering how PHP gets compiled to OpCodes and how does that all work, there is a nice post that talks about OpCode caching in general (a bit outdated now) and also gives a good example of how php code is tokenized for OpCode https://support.cloud.engineyard.com/hc/en-us/articles/205411888-PHP-Performance-I-Everything-You-Need-to-Know-About-OpCode-Caches