from __future__ import absolute_import
from io import BytesIO
from .abstract import AbstractType
from .types import Schema
from ..util import WeakMethod
[docs]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:
for name in self.SCHEMA.names:
self.__dict__[name] = kwargs.pop(name, None)
if kwargs:
raise ValueError('Keyword(s) not in schema %s: %s'
% (list(self.SCHEMA.names),
', '.join(kwargs.keys())))
# overloading encode() to support both class and instance
# Without WeakMethod() this creates circular ref, which
# causes instances to "leak" to garbage
self.encode = WeakMethod(self._encode_self)
@classmethod
[docs] def encode(cls, item): # pylint: disable=E0202
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
[docs] 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 = []
for name, field in zip(self.SCHEMA.names, self.SCHEMA.fields):
key_vals.append('%s=%s' % (name, field.repr(self.__dict__[name])))
return self.__class__.__name__ + '(' + ', '.join(key_vals) + ')'
def __hash__(self):
return hash(self.encode())
def __eq__(self, other):
if self.SCHEMA != other.SCHEMA:
return False
for attr in self.SCHEMA.names:
if self.__dict__[attr] != other.__dict__[attr]:
return False
return True
"""
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)
"""