# https://tools.ietf.org/html/rfc2812#section-2.3.1
p_chanstring= r"[^\x00\x07\r\n ,:]"
p_channelid = "[a-z0-9]{5}"
p_user      = r"[^\x00\r\n @]+"
p_key       = r"[\z01-05\x07-08\x0C\x0E-F1\x21-7F]{1,23}"
p_letter    = "[a-zA-Z0-9]"
p_digit     = "[0-9]"
p_hexdigit  = "("+p_digit+")|[A-F]"
p_special   = r"[\x5B-60\x7B-7D]"
p_nospcrlfcl= r"[^\x00\x007\r\n :]"
p_wildone   = r"\x3F"
p_wildmany  = r"\x2A"
p_nowild    = r"[\x01-29\x2B-3E\x40-FF]"
p_noesc     = r"[\x01-5B\5D-FF]"


p_mask      = "(("+p_nowild+")|("+p_noesc+p_wildone+")|("+p_noesc+p_wildmany+"))*"
p_targetmask= "\$|#"+p_mask
p_channel   = "(#|+|(!"+p_channelid+")|&)+("+p_chanstring+")(:"+p_chanstring+")?"
p_nickname  = "("+p_letter+")|("+p_special+")(("+p_letter+")|("+p_digit+")|("+p_special+")){8}"

p_shortname = "("+p_letter+")|("+p_digit+")(("+p_letter+")|("+p_digit+")|(-)*(("+p_letter+")|("+p_digit+"))*"
p_hostname  = "("+p_shortname+")(."+p_shortname+")" # dot
p_servername= p_hostname
p_ip4addr   = "("+p_digit+"){1,3}."+"("+p_digit+"){1,3}."+"("+p_digit+"){1,3}."+"("+p_digit+"){1,3}"
p_ip6addr   = "(("+p_hexdigit+")+(:("+p_hexdigit+")+){7})"\
            + "|(0:0:0:0:0:(0|(FFFF):"+p_ip4addr+")"
p_hostaddr  = "("+p_ip4addr+")|("+p_ip6addr+")"
p_host      = "("+p_hostname+")|("+p_hostaddr+")"

p_middle    = p_nospcrlfcl+"(:|("+p_nospcrlfcl+"))*"
p_trailing  = "(:| |("+p_nospcrlfcl+"))*"
p_params    = "(( "+p_middle+"){0,13}( :"+p_trailing+")?)|(( "+p_middle+"){14}( :?"+p_trailing+")?)"
p_command   = "(\w+)|(\d{3})"
p_prefix    = "("+p_servername+")|("+p_nickname+"((!"+p_user+")?@"+p_host+")?"
p_message   = "(:"+p_prefix+" )?"+p_command+"("+p_params+")?"

p_target    = "("+p_nickname+")|("+p_servername+")" #p_server
p_msgto     = "("+p_channel+")"\
            +"|("+p_user+"(%"+p_host+")@"+p_servername+")"\
            +"|("+p_user+"%"+p_host+")"\
            +"|("+p_targetmask+")"\
            +"|("+p_nickname+")"\
            +"|("+p_nickname+"!"+p_user+"@"+p_host+")"
p_msgtarget = p_msgto+"(,"+p_msgto+")*"