[#boost-urls-ipv6_address_rule]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::ipv6_address_rule
:relfileprefix: ../../
:mrdocs:

Rule for An IP version 6 style address

== Synopsis

Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/rfc/ipv6_address_rule.hpp#L125[boost/url/rfc/ipv6_address_rule.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr /* implementation-defined */ ipv6_address_rule = {};
----

== Description

== Value Type
[,cpp]
----
using value_type = ipv6_address;
----
== Example
Rules are used with the function xref:boost/urls/grammar/parse-09.adoc[`grammar::parse`].

[,cpp]
----
system::result< ipv6_address > rv = grammar::parse( "2001:0db8:85a3:0000:0000:8a2e:0370:7334", ipv6_address_rule );
----
== BNF
[,cpp]
----
IPv6address =                            6( h16 ":" ) ls32
            /                       "::" 5( h16 ":" ) ls32
            / [               h16 ] "::" 4( h16 ":" ) ls32
            / [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
            / [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
            / [ *3( h16 ":" ) h16 ] "::"    h16 ":"   ls32
            / [ *4( h16 ":" ) h16 ] "::"              ls32
            / [ *5( h16 ":" ) h16 ] "::"              h16
            / [ *6( h16 ":" ) h16 ] "::"

ls32        = ( h16 ":" h16 ) / IPv4address
            ; least-significant 32 bits of address

h16         = 1*4HEXDIG
            ; 16 bits of address represented in hexadecimal
----
== Specification
* https://datatracker.ietf.org/doc/html/rfc4291[]
* https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.2[]

== See Also

xref:boost/urls/ipv6_address.adoc[`ipv6&lowbar;address`], xref:boost/urls/parse_ipv6_address.adoc[`parse&lowbar;ipv6&lowbar;address`], xref:boost/urls/grammar/parse-09.adoc[`grammar&colon;&colon;parse`]&period;


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