def parse_ip_network()

in lambda/netaddr/ip/__init__.py [0:0]
51 lines of code
17 McCabe index (conditional complexity)

def parse_ip_network(module, addr, implicit_prefix=False, flags=0):
    if isinstance(addr, tuple):
        #   CIDR integer tuple
        if len(addr) != 2:
            raise AddrFormatError('invalid %s tuple!' % module.family_name)
        value, prefixlen = addr

        if not(0 <= value <= module.max_int):
            raise AddrFormatError('invalid address value for %s tuple!'
                % module.family_name)
        if not(0 <= prefixlen <= module.width):
            raise AddrFormatError('invalid prefix for %s tuple!' \
                % module.family_name)
    elif isinstance(addr, _str_type):
        #   CIDR-like string subnet
        if implicit_prefix:
            #TODO: deprecate this option in netaddr 0.8.x
            addr = cidr_abbrev_to_verbose(addr)

        if '/' in addr:
            val1, val2 = addr.split('/', 1)
        else:
            val1 = addr
            val2 = None

        try:
            ip = IPAddress(val1, module.version, flags=INET_PTON)
        except AddrFormatError:
            if module.version == 4:
                #   Try a partial IPv4 network address...
                expanded_addr = _ipv4.expand_partial_address(val1)
                ip = IPAddress(expanded_addr, module.version, flags=INET_PTON)
            else:
                raise AddrFormatError('invalid IPNetwork address %s!' % addr)
        value = ip._value

        try:
            #   Integer CIDR prefix.
            prefixlen = int(val2)
        except TypeError:
            if val2 is None:
                #   No prefix was specified.
                prefixlen = module.width
        except ValueError:
            #   Not an integer prefix, try a netmask/hostmask prefix.
            mask = IPAddress(val2, module.version, flags=INET_PTON)
            if mask.is_netmask():
                prefixlen = module.netmask_to_prefix[mask._value]
            elif mask.is_hostmask():
                prefixlen = module.hostmask_to_prefix[mask._value]
            else:
                raise AddrFormatError('addr %r is not a valid IPNetwork!' \
                    % addr)

        if not 0 <= prefixlen <= module.width:
            raise AddrFormatError('invalid prefix for %s address!' \
                % module.family_name)
    else:
        raise TypeError('unexpected type %s for addr arg' % type(addr))

    if flags & NOHOST:
        #   Remove host bits.
        netmask = module.prefix_to_netmask[prefixlen]
        value = value & netmask

    return value, prefixlen