re2r 0.1.0

Return the number of capturing subpatterns

Usage

get_number_of_groups(pattern, ...)

Arguments

pattern
a pre-compiled regular expression or a string
...
further arguments passed to re2

Value

a integer

Description

Return the number of capturing subpatterns, or -1 if the regexp wasn't valid on construction. The overall match ($0) does not count: if the regexp is "(a)(b)", returns 2.

Examples

regexp = re2("1")
get_number_of_groups(regexp)



[1] 0




get_number_of_groups(re2("((?P<a>123)(12))"))



[1] 3




# uncaptured groups
get_number_of_groups(re2("(?:(?:(?:(?:(?:.)?){100})*)+)"))



[1] 0