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"""
Base classes for the representation of frames and data structures.
"""
import logging
import struct
import typing
from pamqp import common, decode, encode
LOGGER = logging.getLogger(__name__)
class _AMQData:
"""Base class for AMQ methods and properties for encoding and decoding"""
__annotations__: typing.Dict = {}
__slots__: typing.List = []
name = '_AMQData'
def __contains__(self, item: str) -> bool:
"""Return if the item is in the attribute list"""
return item in self.__slots__
def __getitem__(self, item: str) -> common.FieldValue:
"""Return an attribute as if it were a dict
:param item: The key to use to retrieve the value
:rtype: :const:`pamqp.common.FieldValue`
:raises: KeyError
"""
return getattr(self, item)
def __iter__(self) \
-> typing.Generator[typing.Tuple[str, common.FieldValue],
None, None]:
"""Iterate the attributes and values as key, value pairs
:rtype: (:class:`str`, :const:`pamqp.common.FieldValue`)
"""
for attribute in self.__slots__:
yield attribute, getattr(self, attribute)
def __len__(self) -> int:
"""Return the length of the attribute list"""
return len(self.__slots__)
def __repr__(self) -> str:
"""Return the representation of the frame object"""
return '<{} object at {}>'.format(self.name, hex(id(self)))
@classmethod
def amqp_type(cls, attr: str) -> str:
"""Return the AMQP data type for an attribute
:param attr: The attribute name
"""
return getattr(cls, '_' + attr)
@classmethod
def attributes(cls) -> list:
"""Return the list of attributes"""
return cls.__slots__
class Frame(_AMQData):
"""Base Class for AMQ Methods for encoding and decoding"""
frame_id = 0
index = 0
synchronous = False
valid_responses: typing.List = []
def marshal(self) -> bytes:
"""Dynamically encode the frame by taking the list of attributes and
encode them item by item getting the value form the object attribute
and the data type from the class attribute.
"""
self.validate()
byte, offset, output, processing_bitset = -1, 0, [], False
for argument in self.__slots__:
data_type = self.amqp_type(argument)
if not processing_bitset and data_type == 'bit':
byte, offset, processing_bitset = 0, 0, True
data_value = getattr(self, argument, 0)
if processing_bitset:
if data_type != 'bit':
processing_bitset = False
output.append(encode.octet(byte))
else:
byte = encode.bit(data_value, byte, offset)
offset += 1
if offset == 8: # pragma: nocover
output.append(encode.octet(byte))
processing_bitset = False
continue # pragma: nocover
output.append(encode.by_type(data_value, data_type))
if processing_bitset:
output.append(encode.octet(byte))
return b''.join(output)
def unmarshal(self, data: bytes) -> None:
"""Dynamically decode the frame data applying the values to the method
object by iterating through the attributes in order and decoding them.
:param data: The raw AMQP frame data
"""
offset, processing_bitset = 0, False
for argument in self.__slots__:
data_type = self.amqp_type(argument)
if offset == 7 and processing_bitset: # pragma: nocover
data = data[1:]
offset = 0
if processing_bitset and data_type != 'bit':
offset = 0
processing_bitset = False
data = data[1:]
consumed, value = decode.by_type(data, data_type, offset)
if data_type == 'bit':
offset += 1
processing_bitset = True
consumed = 0
setattr(self, argument, value)
if consumed:
data = data[consumed:]
def validate(self) -> None:
"""Validate the frame data ensuring all domains or attributes adhere
to the protocol specification.
:raises: ValueError
"""
class BasicProperties(_AMQData):
"""Provide a base object that marshals and unmarshals the Basic.Properties
object values.
"""
flags: typing.Dict[str, int] = {}
name = 'BasicProperties'
def __eq__(self, other: object) -> bool:
if not isinstance(other, BasicProperties):
raise NotImplementedError
return all(
getattr(self, k, None) == getattr(other, k, None)
for k in self.__slots__)
def encode_property(self, name: str, value: common.FieldValue) -> bytes:
"""Encode a single property value
:param name: The name of the property to encode
:param value: The property to encode
:type value: :const:`pamqp.common.FieldValue`
:raises: TypeError
"""
return encode.by_type(value, self.amqp_type(name))
def marshal(self) -> bytes:
"""Take the Basic.Properties data structure and marshal it into the
data structure needed for the ContentHeader.
"""
flags = 0
parts = []
for property_name in self.__slots__:
property_value = getattr(self, property_name)
if property_value is not None and property_value != '':
flags = flags | self.flags[property_name]
parts.append(
self.encode_property(property_name, property_value))
flag_pieces = []
while True:
remainder = flags >> 16
partial_flags = flags & 0xFFFE
if remainder != 0: # pragma: nocover
partial_flags |= 1
flag_pieces.append(struct.pack('>H', partial_flags))
flags = remainder
if not flags: # pragma: nocover
break
return b''.join(flag_pieces + parts)
def unmarshal(self, flags: int, data: bytes) -> None:
"""Dynamically decode the frame data applying the values to the method
object by iterating through the attributes in order and decoding them.
"""
for property_name in self.__slots__:
if flags & self.flags[property_name]:
data_type = getattr(self.__class__, '_' + property_name)
consumed, value = decode.by_type(data, data_type)
setattr(self, property_name, value)
data = data[consumed:]
def validate(self) -> None:
"""Validate the frame data ensuring all domains or attributes adhere
to the protocol specification.
:raises: ValueError
"""
if self.cluster_id != '':
raise ValueError('cluster_id must be empty')
if self.delivery_mode is not None and self.delivery_mode not in [1, 2]:
raise ValueError('Invalid delivery_mode value: {}'.format(
self.delivery_mode))
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