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