Rule for an IP version 4 style address
<include/boost/url/rfc/ipv4_address_rule.hpp>
constexpr
_implementation-defined_ ipv4_address_rule = {};
using value_type = ipv4_address;
system::result< ipv4_address > rv = grammar::parse( "192.168.0.1", ipv4_address_rule );
IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet
dec-octet = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255