Conditional regex in vim?

Question

Is it possible to do conditional regex (like the one described in http://www.regular-expressions.info/conditional.html) in Vim?

Answer 1

Vim regex does not have this feature, so you will need to use a bit of repetition to create the same behaviour:

/\(\%(condition\)\@=then\|\%(condition\)\@!else\)

Note that you have to use the condition twice in the Vim version and the lookahead/lookbehind must always be the opposite in the then/else parts otherwise your regex will not be correct.