What do you mean "expensive"? When I've seen people roll their own state machines to replace a moderately-complex regex, the result is frequently hundreds of b

What do you mean "expensive"? When I've seen people roll their own state machines to replace a moderately-complex regex, the result is frequently hundreds of bug-ridden lines and rarely matches the performance of a decent regex engine. This laborious learning experience often results in reverting to the regex. It's the ignorance that's expensive.