51 lines
1.4 KiB
Python
51 lines
1.4 KiB
Python
"""
|
|
Binary Data Interfaces
|
|
|
|
Abstract:
|
|
Helper classes for working with binary data structures. This simplifies data
|
|
field extraction from a binary buffer.
|
|
|
|
Author: Patrick C. McGinty (pyweather@tuxcoder.com)
|
|
Date: 2010-06-025
|
|
"""
|
|
|
|
|
|
import struct
|
|
|
|
|
|
class Struct(struct.Struct):
|
|
"""
|
|
Implements a reusable class for working with a binary data structure. It
|
|
provides a named fields interface, similar to C structures.
|
|
|
|
Usage: 1) subclass and extend _post_unpack method
|
|
2) instantiate directly, if no 'post unpack' processing needed
|
|
|
|
Arguments:
|
|
See `struct.Struct` class definition.
|
|
"""
|
|
def __init__(self, fmt, order='@'):
|
|
self.fields, fmt_t = list(zip(*fmt))
|
|
super(Struct, self).__init__(order + ''.join(fmt_t))
|
|
|
|
def unpack(self, buf):
|
|
"""
|
|
see unpack_from()
|
|
"""
|
|
return self.unpack_from(buf, offset=0)
|
|
|
|
def unpack_from(self, buf, offset=0):
|
|
"""
|
|
unpacks data from 'buf' and returns a dictation of named fields. the
|
|
fields can be post-processed by extending the _post_unpack() method.
|
|
"""
|
|
data = super(Struct, self).unpack_from(buf, offset)
|
|
items = dict(list(zip(self.fields, data)))
|
|
return self._post_unpack(items)
|
|
|
|
def _post_unpack(self, items):
|
|
"""
|
|
perform data modification of any values, after unpacking from a buffer.
|
|
"""
|
|
return items
|