iri: scheme ":" ihier_part ("?" iquery)? ("#" ifragment)?

iri_reference: iri | irelative_ref

absolute_iri: scheme ":" ihier_part ("?" iquery)?

scheme: alpha (alpha | digit | "+" | "-" | ".")*

ihier_part: "//" iauthority ipath_abempty
          | ipath_absolute
          | ipath_rootless
          | ipath_empty

irelative_ref: irelative_part ("?" iquery)? ("#" ifragment)?

irelative_part: "//" iauthority ipath_abempty
              | ipath_absolute
              | ipath_noscheme
              | ipath_empty

iauthority: (iuserinfo "@")? ihost (":" port)?

iuserinfo: (iunreserved | pct_encoded | sub_delims | ":")*

ihost: ip_literal | ipv4address | ireg_name

ireg_name: (iunreserved | pct_encoded | sub_delims)*

ipath: ipath_abempty
     | ipath_absolute
     | ipath_noscheme
     | ipath_rootless
     | ipath_empty

ipath_abempty: ("/" isegment)*

ipath_absolute: "/" (isegment_nz ("/" isegment)*)?

ipath_noscheme: isegment_nz_nc ("/" isegment)*

ipath_rootless: isegment_nz ("/" isegment)*

ipath_empty: -> empty

isegment: ipchar*

isegment_nz: ipchar+

isegment_nz_nc: (iunreserved | pct_encoded | sub_delims | "@")+

ipchar: iunreserved | pct_encoded | sub_delims | ":" | "@"

iquery: (ipchar | iprivate | "/" | "?")*

ifragment: (ipchar | "/" | "?")*

iunreserved: alpha | digit | "-" | "." | "_" | "~" | ucschar

ucschar: /[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]/
iprivate: /[\uE000-\uF8FF]/

sub_delims: "!" | "$" | "&" | "'" | "(" | ")"
          | "*" | "+" | "," | ";" | "="

ip_literal: "[" (ipv6address | ipvfuture) "]"

ipvfuture: "v" hexdig+ "." (unreserved | sub_delims | ":")+

ipv6address: h16 ":" h16 ":" h16 ":" h16 ":" h16 ":" h16 ":" ls32
           | "::" h16 ":" h16 ":" h16 ":" h16 ":" h16 ":" ls32
           | h16 "::" h16 ":" h16 ":" h16 ":" h16 ":" ls32
           | h16 ":" h16 "::" h16 ":" h16 ":" h16 ":" ls32
           | h16 ":" h16 ":" h16 "::" h16 ":" h16 ":" ls32
           | h16 ":" h16 ":" h16 ":" h16 "::" h16 ":" ls32
           | h16 ":" h16 ":" h16 ":" h16 ":" h16 "::" ls32
           | h16 ":" h16 ":" h16 ":" h16 ":" h16 ":" h16 "::" h16
           | h16 ":" h16 ":" h16 ":" h16 ":" h16 ":" h16 ":" h16 "::"

h16: hexdig
   | hexdig hexdig
   | hexdig hexdig hexdig
   | hexdig hexdig hexdig hexdig

ls32: h16 ":" h16 | ipv4address

ipv4address: dec_octet "." dec_octet "." dec_octet "." dec_octet

dec_octet: digit
         | non_zero digit
         | "1" digit digit
         | "2" ("0".."4") digit
         | "25" ("0".."5")

digit: T_DIGIT
T_DIGIT: /[0-9]/

non_zero: T_NON_ZERO
T_NON_ZERO: /[1-9]/

unreserved: alpha | digit | "-" | "." | "_" | "~"

alpha: T_ALPHA
T_ALPHA: /[A-Za-z]/

hexdig: T_HEXDIG
T_HEXDIG: /[0-9A-Fa-f]/

port: digit*

pct_encoded: "%" hexdig hexdig