sample/in-place.rb
require 'abnf'
p /\A#{ABNF.regexp <<'End'}\z/o =~ "::13.1.68.3"
IPv6address = "::" /
7( hex4 ":" ) hex4 /
1*8( hex4 ":" ) ":" /
7( hex4 ":" ) ( ":" hex4 ) /
6( hex4 ":" ) 1*2( ":" hex4 ) /
5( hex4 ":" ) 1*3( ":" hex4 ) /
4( hex4 ":" ) 1*4( ":" hex4 ) /
3( hex4 ":" ) 1*5( ":" hex4 ) /
2( hex4 ":" ) 1*6( ":" hex4 ) /
( hex4 ":" ) 1*7( ":" hex4 ) /
":" 1*8( ":" hex4 ) /
6( hex4 ":" ) IPv4address /
6( hex4 ":" ) ":" IPv4address /
5( hex4 ":" ) ":" 0*1( hex4 ":" ) IPv4address /
4( hex4 ":" ) ":" 0*2( hex4 ":" ) IPv4address /
3( hex4 ":" ) ":" 0*3( hex4 ":" ) IPv4address /
2( hex4 ":" ) ":" 0*4( hex4 ":" ) IPv4address /
( hex4 ":" ) ":" 0*5( hex4 ":" ) IPv4address /
"::" 0*6( hex4 ":" ) IPv4address
IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT
hex4 = 1*4HEXDIG
End