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Diffstat (limited to 'netaddr/core.py')
| -rw-r--r-- | netaddr/core.py | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/netaddr/core.py b/netaddr/core.py new file mode 100644 index 0000000..0fdbb40 --- /dev/null +++ b/netaddr/core.py @@ -0,0 +1,210 @@ +#----------------------------------------------------------------------------- +# Copyright (c) 2008 by David P. D. Moss. All rights reserved. +# +# Released under the BSD license. See the LICENSE file for details. +#----------------------------------------------------------------------------- +"""Common code shared between various netaddr sub modules""" + +import sys as _sys +import pprint as _pprint + +from netaddr.compat import _callable, _iter_dict_keys + +#: True if platform is natively big endian, False otherwise. +BIG_ENDIAN_PLATFORM = _sys.byteorder == 'big' + +#: Use inet_pton() semantics instead of inet_aton() when parsing IPv4. +P = INET_PTON = 1 + +#: Remove any preceding zeros from IPv4 address octets before parsing. +Z = ZEROFILL = 2 + +#: Remove any host bits found to the right of an applied CIDR prefix. +N = NOHOST = 4 + +#: Use legacy ``inet_aton()`` semantics when parsing IPv4. +INET_ATON = 8 + +#----------------------------------------------------------------------------- +# Custom exceptions. +#----------------------------------------------------------------------------- +class AddrFormatError(Exception): + """ + An Exception indicating a network address is not correctly formatted. + """ + pass + + +class AddrConversionError(Exception): + """ + An Exception indicating a failure to convert between address types or + notations. + """ + pass + + +class NotRegisteredError(Exception): + """ + An Exception indicating that an OUI or IAB was not found in the IEEE + Registry. + """ + pass + + +try: + a = 42 + a.bit_length() + # No exception, must be Python 2.7 or 3.1+ -> can use bit_length() + del a + def num_bits(int_val): + """ + :param int_val: an unsigned integer. + + :return: the minimum number of bits needed to represent value provided. + """ + return int_val.bit_length() +except AttributeError: + # a.bit_length() excepted, must be an older Python version. + def num_bits(int_val): + """ + :param int_val: an unsigned integer. + + :return: the minimum number of bits needed to represent value provided. + """ + numbits = 0 + while int_val: + numbits += 1 + int_val >>= 1 + return numbits + + +class Subscriber(object): + """ + An abstract class defining the interface expected by a Publisher. + """ + + def update(self, data): + """ + A callback method used by a Publisher to notify this Subscriber about + updates. + + :param data: a Python object containing data provided by Publisher. + """ + raise NotImplementedError('cannot invoke virtual method!') + + +class PrettyPrinter(Subscriber): + """ + A concrete Subscriber that employs the pprint in the standard library to + format all data from updates received, writing them to a file-like + object. + + Useful as a debugging aid. + """ + + def __init__(self, fh=_sys.stdout, write_eol=True): + """ + Constructor. + + :param fh: a file-like object to write updates to. + Default: sys.stdout. + + + :param write_eol: if ``True`` this object will write newlines to + output, if ``False`` it will not. + """ + self.fh = fh + self.write_eol = write_eol + + def update(self, data): + """ + A callback method used by a Publisher to notify this Subscriber about + updates. + + :param data: a Python object containing data provided by Publisher. + """ + self.fh.write(_pprint.pformat(data)) + if self.write_eol: + self.fh.write("\n") + + +class Publisher(object): + """ + A 'push' Publisher that maintains a list of Subscriber objects notifying + them of state changes by passing them update data when it encounter events + of interest. + """ + + def __init__(self): + """Constructor""" + self.subscribers = [] + + def attach(self, subscriber): + """ + Add a new subscriber. + + :param subscriber: a new object that implements the Subscriber object + interface. + """ + if hasattr(subscriber, 'update') and _callable(subscriber.update): + if subscriber not in self.subscribers: + self.subscribers.append(subscriber) + else: + raise TypeError('%r does not support required interface!' % subscriber) + + def detach(self, subscriber): + """ + Remove an existing subscriber. + + :param subscriber: a new object that implements the Subscriber object + interface. + """ + try: + self.subscribers.remove(subscriber) + except ValueError: + pass + + def notify(self, data): + """ + Send update data to to all registered Subscribers. + + :param data: the data to be passed to each registered Subscriber. + """ + for subscriber in self.subscribers: + subscriber.update(data) + + +class DictDotLookup(object): + """ + Creates objects that behave much like a dictionaries, but allow nested + key access using object '.' (dot) lookups. + + Recipe 576586: Dot-style nested lookups over dictionary based data + structures - http://code.activestate.com/recipes/576586/ + + """ + + def __init__(self, d): + for k in d: + if isinstance(d[k], dict): + self.__dict__[k] = DictDotLookup(d[k]) + elif isinstance(d[k], (list, tuple)): + l = [] + for v in d[k]: + if isinstance(v, dict): + l.append(DictDotLookup(v)) + else: + l.append(v) + self.__dict__[k] = l + else: + self.__dict__[k] = d[k] + + def __getitem__(self, name): + if name in self.__dict__: + return self.__dict__[name] + + def __iter__(self): + return _iter_dict_keys(self.__dict__) + + def __repr__(self): + return _pprint.pformat(self.__dict__) |