e1da4930_tionals_in_Regular_Expressions__Supports_real_conditionals
[Language] PHP [Supports "fake conditionals"] Yes (buggy) [Notes] Tested using PHP Regex Tester. Performs correctly in more cases if you explicitly state the condition twice, like so: "(?=(?:a)()|())(?:a)?b(?:\1c| \2d)". [Supports real conditionals] 
Yes
Y e s
N o
Flagrant Badassery: Faking Conditionals in Regular Expressions
Supports real conditionals