In all cases listed below, I want to match only ___ (three underscores).
To make it clear, I am trying to match 3 underscores either not immediately preceded or not immediately followed with an underscore character and:
_ precedes the ___, match last 3 (test3____)_ follows the ___, match first 3 (_______test5).See my current attempt:
((?<=_)___|___(?=_)|___)
Tested with:
test1___(test2 ___)
test3____ ___
___test4 + ____test5
All cases are matching correctly except for "test3": it matches first 3 underscores instead of the last 3.
You can use
(?<!_)___(?=_*[^\s_])|(?<=[^\s_]_*)___(?!_)|(?<!_)___(?!_)
See the regex demo. Details:
(?<!_)___(?=_*[^\s_]) - a ___ string not immediately preceded with a _ char and that is immediately followed with any zero or more underscores and then any char other than whitespace and _| - or(?<=[^\s_]_*)___(?!_) - a ___ string that is not immediately followed with another _ char and immediately preceded with any char other than whitespace and _ and then any zero or more underscores| - or(?<!_)___(?!_) - three underscores neither preceded nor followed with another _ char.