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#!/usr/bin/env python
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
#
"""
Utility code to translate between python objects and AMQP encoded data
fields.
"""
from cStringIO import StringIO
from struct import *
class EOF(Exception):
pass
class Codec:
def __init__(self, stream):
self.stream = stream
self.nwrote = 0
self.nread = 0
self.incoming_bits = []
self.outgoing_bits = []
def read(self, n):
data = self.stream.read(n)
if n > 0 and len(data) == 0:
raise EOF()
self.nread += len(data)
return data
def write(self, s):
self.flushbits()
self.stream.write(s)
self.nwrote += len(s)
def flush(self):
self.flushbits()
self.stream.flush()
def flushbits(self):
if len(self.outgoing_bits) > 0:
bytes = []
index = 0
for b in self.outgoing_bits:
if index == 0: bytes.append(0)
if b: bytes[-1] |= 1 << index
index = (index + 1) % 8
del self.outgoing_bits[:]
for byte in bytes:
self.encode_octet(byte)
def pack(self, fmt, *args):
self.write(pack(fmt, *args))
def unpack(self, fmt):
size = calcsize(fmt)
data = self.read(size)
values = unpack(fmt, data)
if len(values) == 1:
return values[0]
else:
return values
def encode(self, type, value):
getattr(self, "encode_" + type)(value)
def decode(self, type):
return getattr(self, "decode_" + type)()
# bit
def encode_bit(self, o):
if o:
self.outgoing_bits.append(True)
else:
self.outgoing_bits.append(False)
def decode_bit(self):
if len(self.incoming_bits) == 0:
bits = self.decode_octet()
for i in range(8):
self.incoming_bits.append(bits >> i & 1 != 0)
return self.incoming_bits.pop(0)
# octet
def encode_octet(self, o):
self.pack("!B", o)
def decode_octet(self):
return self.unpack("!B")
# short
def encode_short(self, o):
self.pack("!H", o)
def decode_short(self):
return self.unpack("!H")
# long
def encode_long(self, o):
self.pack("!L", o)
def decode_long(self):
return self.unpack("!L")
# longlong
def encode_longlong(self, o):
self.pack("!Q", o)
def decode_longlong(self):
return self.unpack("!Q")
def enc_str(self, fmt, s):
size = len(s)
self.pack(fmt, size)
self.write(s)
def dec_str(self, fmt):
size = self.unpack(fmt)
return self.read(size)
# shortstr
def encode_shortstr(self, s):
self.enc_str("!B", s)
def decode_shortstr(self):
return self.dec_str("!B")
# longstr
def encode_longstr(self, s):
if isinstance(s, dict):
self.encode_table(s)
else:
self.enc_str("!L", s)
def decode_longstr(self):
return self.dec_str("!L")
# table
def encode_table(self, tbl):
enc = StringIO()
codec = Codec(enc)
for key, value in tbl.items():
codec.encode_shortstr(key)
if isinstance(value, basestring):
codec.write("S")
codec.encode_longstr(value)
else:
codec.write("I")
codec.encode_long(value)
s = enc.getvalue()
self.encode_long(len(s))
self.write(s)
def decode_table(self):
size = self.decode_long()
start = self.nread
result = {}
while self.nread - start < size:
key = self.decode_shortstr()
type = self.read(1)
if type == "S":
value = self.decode_longstr()
elif type == "I":
value = self.decode_long()
else:
raise ValueError(repr(type))
result[key] = value
return result
def test(type, value):
if isinstance(value, (list, tuple)):
values = value
else:
values = [value]
stream = StringIO()
codec = Codec(stream)
for v in values:
codec.encode(type, v)
codec.flush()
enc = stream.getvalue()
stream.reset()
dup = []
for i in xrange(len(values)):
dup.append(codec.decode(type))
if values != dup:
raise AssertionError("%r --> %r --> %r" % (values, enc, dup))
if __name__ == "__main__":
def dotest(type, value):
args = (type, value)
test(*args)
for value in ("1", "0", "110", "011", "11001", "10101", "10011"):
for i in range(10):
dotest("bit", map(lambda x: x == "1", value*i))
for value in ({}, {"asdf": "fdsa", "fdsa": 1, "three": 3}, {"one": 1}):
dotest("table", value)
for type in ("octet", "short", "long", "longlong"):
for value in range(0, 256):
dotest(type, value)
for type in ("shortstr", "longstr"):
for value in ("", "a", "asdf"):
dotest(type, value)
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