Heads up: Crystal is upgrading its Regex engine

NewsBot · 2 March 2023 14:01

A new Crystal blog post/announcement has been posted!

Crystal uses since its inception the PCRE library for dealing with regular expressions. This library has two major versions, and Crystal so far resorted to the first one (PCRE). However, this version reached its end of life. Therefore, for the next release (1.8) we are planning to move to its successor, PCRE2.

PCRE vs PCRE2

The two library versions, PCRE and PCRE2 are mostly compatible with each other. There are some small differences which can cause breaking changes. But we don’t expect many bumps on the ride. Most notably, PCRE2 is stricter than PCRE in some edge cases. This means that PCRE might have accepted some invalid regexes, but PCRE2 will not allow them.

Unfortunately there’s no guide to help with the porting. The most documented list of changes is https://crystal-lang.org/2023/03/02/crystal-is-upgrading-its-regex-engine/