__all__ = ('Flags',)
import struct
[docs]class Flags(object):
"""
Convenience class for handling bit flags.
"""
def __init__(self, binary_format, flags):
object.__setattr__(self, 'binary_format', binary_format)
object.__setattr__(self, 'flags', flags)
object.__setattr__(self, '_value', 0)
object.__setattr__(self, '_cache', struct.Struct(binary_format))
[docs] def pack(self):
"""
A shortcut for `struct.pack(flag.binary_format, flag.value)`.
"""
return self._cache.pack(self.value)
@property
def value(self):
"""
The numeric value of the bitfield.
"""
return self._value
[docs] def unpack(self, source):
"""
A shortcut for `struct.unpack(flag.binary_format, <bytes>)`.
"""
self._value = self._cache.unpack(source)[0]
[docs] def get(self, name):
"""
Returns the value of the field `name`.
"""
return bool(self.flags[name] & self.value)
[docs] def set(self, name, value):
"""
Sets the value of the field `name` to `value`, which is `True` or
`False`.
"""
flag = self.flags[name]
self._value = (self.value | flag) if value else (self.value & ~flag)
def __getattr__(self, attr):
if attr not in self.flags:
return object.__getattr__(self, attr)
return self.get(attr)
def __setattr__(self, attr, value):
if attr not in self.flags:
return object.__setattr__(self, attr, value)
self.set(attr, value)
[docs] def to_dict(self):
"""
Returns this `Flags` object's fields as a dictionary.
"""
return dict((k, self.get(k)) for k in self.flags.keys())