def __init__(self, value = [], template = None):
"""Initialize a new packet.
value -- an input list, or packet. Note that any meta-data such as template of an input packet will be lost.
template -- the template used to generate this packet. Useful for updating etc...
"""
list.__init__(self, utilities.flattenList(value))
self.template = template
def _encode_(self, encodeValue, inProcessPacket):
"""Returns the checksum value of the in-process packet.
inProcessPacket -- contains a third-pass in-process packet whose checksum should be computed.
"""
if len(inProcessPacket)>0: #an inProcess packet has been provided
# create list of all the ints. At this point that should be everything but the checksum token
checksumList = list(itertools.ifilter(lambda token: type(token) == int, utilities.flattenList(inProcessPacket)))
return self.CRCInstance.generate(checksumList) #generate and return checksum
else: return self
def _encode_(self, encodeValue, inProcessPacket):
"""Returns the length of the inProcessPacket, either including or nor itself.
inProcessPacket -- contains a second-pass in-process packet whose length should be measured.
NOTES:
-Assumes that there are not multiple length tokens in a single packet.
-Because checksums are encoded last, they are not counted in the length value reported by this function.
"""
if len(inProcessPacket)>0: #an inProcess packet has been provided
#create and count a list only containing integers from the flattened inProcessPacket
length = len(list(itertools.ifilter(lambda token: type(token) == int, utilities.flattenList(inProcessPacket))))
if self.countSelf: length += 1
return utilities.unsignedIntegerToBytes(length, self.size) #convert to integer of lenth self.size
else: return self #no in-process packet has been provided.