[codeplea]

Is your solution broken for the cases where keywords are prefixes or suffixes of each other? This situation is very common in my use-case. Also, does your solution work if a keyword appears multiple times?

I get what you're saying, but it's not quite as easy as you imply.

Pulling in an entire programming language is a much bigger dependency and maintenance cost than spending a couple hours writing an algorithm. It would make more sense to just use a C extension.

I did try PHP's regex. It was much, much slower.

[bmn__]

You are right, the solution is broken. I can't make it work, so I take back what I said.

I learnt something valuable, thank you for that.