URI Grammar fragment with Arpeggio

# -*- coding: utf-8 -*-
from __future__ import print_function
from __future__ import unicode_literals, print_function
try:
   text=unicode
except:
   text=str

from arpeggio import Optional, ZeroOrMore, OneOrMore, EOF, \
    ParserPython, PTNodeVisitor, visit_parse_tree
from arpeggio import RegExMatch as _

def authority():
    return Optional(userinfo, '@'), host, Optional(':', port)

def userinfo():
    return ZeroOrMore([ unreserved, pct_encoded, sub_delims, ':'])

def host():
    return [ ip_literal, ipv4address, reg_name ]

def port():
    return _('\d*')

def ip_literal():
    return '[', [ ipv6address, ipvfuture ], ']'

def ipvfuture():
    return 'v', OneOrMore(hexdig), '.', OneOrMore((unreserved, sub_delims, ':'))

def ipv6address():
    return [ (h16, ':', h16, ':', h16, ':', h16, ':', h16, ':', h16, ':', ls32),
             ('::', h16, ':', h16, ':', h16, ':', h16, ':', h16, ':', ls32),
             (Optional(h16), '::', h16, ':', h16, ':', h16, ':', h16, ':', ls32) ]

def ipv4address():
    return dec_octect, '.', dec_octect, '.', dec_octect, '.', dec_octect

def ls32():
    return [ (h16, ':', h16), ipv4address ]

def h16():
    return [ (hexdig,) * i for i in range(1, 5) ]

def dec_octect():
    return [ _('25[0-5]'),
             _('2[0-4]\d'),
             _('1\d\d'),
             _('[1-9]\d'),
             _('\d') ]

def reg_name():
    return ZeroOrMore([ unreserved, pct_encoded, sub_delims])

def hexdig():
    return _('[0-9a-fA-F]')

def pchar():
    return [ unreserved, pct_encoded, sub_delims, ':', '@' ]

def unreserved():
    # return [ alpha, digit, '-', '.', '_', '~' ]
    return _('[A-Za-z0-9._~-]')

def pct_encoded():
    # return '%', hexdig, hexdig
    return _('%[0-9A-Fa-f][0-9A-Fa-f]')

def sub_delims():
    # return [ '!', '$', '&', "'", '(', ')', '*', '+', ',', ';', '=' ]
    return _('[!$&\'()*+,;=]')

def alpha():
    return _('[A-Za-z]')

def digit():
    return _('\d')

parser = ParserPython(authority)
parser.parse('//') # it does not match authority rule