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from collections import namedtuple
from io import BytesIO
from .abstract import AbstractType
from .types import Schema
class Struct(AbstractType):
SCHEMA = Schema()
def __init__(self, *args, **kwargs):
if len(args) == len(self.SCHEMA.fields):
for i, name in enumerate(self.SCHEMA.names):
self.__dict__[name] = args[i]
elif len(args) > 0:
raise ValueError('Args must be empty or mirror schema')
else:
self.__dict__.update(kwargs)
# overloading encode() to support both class and instance
self.encode = self._encode_self
@classmethod
def encode(cls, item):
bits = []
for i, field in enumerate(cls.SCHEMA.fields):
bits.append(field.encode(item[i]))
return b''.join(bits)
def _encode_self(self):
return self.SCHEMA.encode(
[self.__dict__[name] for name in self.SCHEMA.names]
)
@classmethod
def decode(cls, data):
if isinstance(data, bytes):
data = BytesIO(data)
return cls(*[field.decode(data) for field in cls.SCHEMA.fields])
def __repr__(self):
key_vals =['%s=%r' % (name, self.__dict__[name])
for name in self.SCHEMA.names]
return self.__class__.__name__ + '(' + ', '.join(key_vals) + ')'
"""
class MetaStruct(type):
def __new__(cls, clsname, bases, dct):
nt = namedtuple(clsname, [name for (name, _) in dct['SCHEMA']])
bases = tuple([Struct, nt] + list(bases))
return super(MetaStruct, cls).__new__(cls, clsname, bases, dct)
"""
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