Set the host to an address
Depending on the contents of the passed string, this function sets the host:
If the string is a valid IPv4 address,        then the host is set to the address.        The host type is host_type::ipv4.
If the string is a valid IPv6 address,        then the host is set to that address.        The host type is host_type::ipv6.
If the string is a valid IPvFuture,        then the host is set to that address.        The host type is host_type::ipvfuture.
Otherwise, the host name is set to        the string, which may be empty.        Reserved characters in the string are        percent-escaped in the result.        The host type is host_type::name.
In all cases, when this function returns, the URL contains an authority.
assert( url( "http://www.example.com" ).set_host_address( "127.0.0.1" ).buffer() == "http://127.0.0.1" );
this->has_authority() == true
Linear in s.size().
Strong guarantee. Calls to allocate may throw.
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
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
IPvFuture     = "v" 1*HEXDIG "." 1*( unreserved / sub-delims / ":" )
reg-name    = *( unreserved / pct-encoded / "-" / ".")
*this
| Name | Description | 
|---|---|
| s | The string to set. | 
set_encoded_host, set_encoded_host_address, set_encoded_host_name, set_host, set_host_address, set_host_ipv4, set_host_ipv6, set_host_ipvfuture, set_host_name.