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bpo-38250: [Enum] single-bit flags are canonical (GH-24215)

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Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags.

Iterating, repr(), and str() show members in definition order.

When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired:

>>> class Test(Flag, boundary=CONFORM):
...     ONE = 1
...     TWO = 2
...
>>> Test(5)
<Test.ONE: 1>

Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits.

Iteration is now in member definition order.  If member definition order
matches increasing value order, then a more efficient method of flag
decomposition is used; otherwise, sort() is called on the results of
that method to get definition order.


``re`` module:

repr() has been modified to support as closely as possible its previous
output; the big difference is that inverted flags cannot be output as
before because the inversion operation now always returns the comparable
positive result; i.e.

   re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG)

in both of the above terms, the ``value`` is 282.

re's tests have been updated to reflect the modifications to repr().
This commit is contained in:
Ethan Furman 2021-01-25 14:26:19 -08:00 • committed by GitHub
parent 9852cb3811
commit 7aaeb2a3d6
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8 changed files with 750 additions and 288 deletions
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508
Lib/enum.py
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@ -1,6 +1,6 @@
import sys
from types import MappingProxyType, DynamicClassAttribute
from builtins import property as _bltin_property
from builtins import property as _bltin_property, bin as _bltin_bin
__all__ = [
@ -8,9 +8,15 @@ __all__ = [
'Enum', 'IntEnum', 'StrEnum', 'Flag', 'IntFlag',
'auto', 'unique',
'property',
'FlagBoundary', 'STRICT', 'CONFORM', 'EJECT', 'KEEP',
]
# Dummy value for Enum and Flag as there are explicit checks for them
# before they have been created.
# This is also why there are checks in EnumMeta like `if Enum is not None`
Enum = Flag = EJECT = None
def _is_descriptor(obj):
"""
Returns True if obj is a descriptor, False otherwise.
@ -56,6 +62,15 @@ def _is_private(cls_name, name):
else:
return False
def _is_single_bit(num):
"""
True if only one bit set in num (should be an int)
"""
if num == 0:
return False
num &= num - 1
return num == 0
def _make_class_unpicklable(obj):
"""
Make the given obj un-picklable.
@ -71,6 +86,37 @@ def _make_class_unpicklable(obj):
setattr(obj, '__reduce_ex__', _break_on_call_reduce)
setattr(obj, '__module__', '<unknown>')
def _iter_bits_lsb(num):
while num:
b = num & (~num + 1)
yield b
num ^= b
def bin(num, max_bits=None):
"""
Like built-in bin(), except negative values are represented in
twos-compliment, and the leading bit always indicates sign
(0=positive, 1=negative).
>>> bin(10)
'0b0 1010'
>>> bin(~10) # ~10 is -11
'0b1 0101'
"""
ceiling = 2 ** (num).bit_length()
if num >= 0:
s = _bltin_bin(num + ceiling).replace('1', '0', 1)
else:
s = _bltin_bin(~num ^ (ceiling - 1) + ceiling)
sign = s[:3]
digits = s[3:]
if max_bits is not None:
if len(digits) < max_bits:
digits = (sign[-1] * max_bits + digits)[-max_bits:]
return "%s %s" % (sign, digits)
_auto_null = object()
class auto:
"""
@ -92,22 +138,30 @@ class property(DynamicClassAttribute):
try:
return ownerclass._member_map_[self.name]
except KeyError:
raise AttributeError('%r not found in %r' % (self.name, ownerclass.__name__))
raise AttributeError(
'%s: no attribute %r' % (ownerclass.__name__, self.name)
)
else:
if self.fget is None:
raise AttributeError('%s: cannot read attribute %r' % (ownerclass.__name__, self.name))
raise AttributeError(
'%s: no attribute %r' % (ownerclass.__name__, self.name)
)
else:
return self.fget(instance)
def __set__(self, instance, value):
if self.fset is None:
raise AttributeError("%s: cannot set attribute %r" % (self.clsname, self.name))
raise AttributeError(
"%s: cannot set attribute %r" % (self.clsname, self.name)
)
else:
return self.fset(instance, value)
def __delete__(self, instance):
if self.fdel is None:
raise AttributeError("%s: cannot delete attribute %r" % (self.clsname, self.name))
raise AttributeError(
"%s: cannot delete attribute %r" % (self.clsname, self.name)
)
else:
return self.fdel(instance)
@ -148,11 +202,17 @@ class _proto_member:
if enum_class._member_type_ is object:
enum_member._value_ = value
else:
enum_member._value_ = enum_class._member_type_(*args)
try:
enum_member._value_ = enum_class._member_type_(*args)
except Exception as exc:
raise TypeError(
'_value_ not set in __new__, unable to create it'
) from None
value = enum_member._value_
enum_member._name_ = member_name
enum_member.__objclass__ = enum_class
enum_member.__init__(*args)
enum_member._sort_order_ = len(enum_class._member_names_)
# If another member with the same value was already defined, the
# new member becomes an alias to the existing one.
for name, canonical_member in enum_class._member_map_.items():
@ -160,8 +220,21 @@ class _proto_member:
enum_member = canonical_member
break
else:
# no other instances found, record this member in _member_names_
enum_class._member_names_.append(member_name)
# this could still be an alias if the value is multi-bit and the
# class is a flag class
if (
Flag is None
or not issubclass(enum_class, Flag)
):
# no other instances found, record this member in _member_names_
enum_class._member_names_.append(member_name)
elif (
Flag is not None
and issubclass(enum_class, Flag)
and _is_single_bit(value)
):
# no other instances found, record this member in _member_names_
enum_class._member_names_.append(member_name)
# get redirect in place before adding to _member_map_
# but check for other instances in parent classes first
need_override = False
@ -193,7 +266,7 @@ class _proto_member:
# This may fail if value is not hashable. We can't add the value
# to the map, and by-value lookups for this value will be
# linear.
enum_class._value2member_map_[value] = enum_member
enum_class._value2member_map_.setdefault(value, enum_member)
except TypeError:
pass
@ -228,6 +301,7 @@ class _EnumDict(dict):
if key not in (
'_order_', '_create_pseudo_member_',
'_generate_next_value_', '_missing_', '_ignore_',
'_iter_member_', '_iter_member_by_value_', '_iter_member_by_def_',
):
raise ValueError(
'_sunder_ names, such as %r, are reserved for future Enum use'
@ -265,10 +339,7 @@ class _EnumDict(dict):
if isinstance(value, auto):
if value.value == _auto_null:
value.value = self._generate_next_value(
key,
1,
len(self._member_names),
self._last_values[:],
key, 1, len(self._member_names), self._last_values[:],
)
self._auto_called = True
value = value.value
@ -287,15 +358,11 @@ class _EnumDict(dict):
self[name] = value
# Dummy value for Enum as EnumMeta explicitly checks for it, but of course
# until EnumMeta finishes running the first time the Enum class doesn't exist.
# This is also why there are checks in EnumMeta like `if Enum is not None`
Enum = None
class EnumMeta(type):
"""
Metaclass for Enum
"""
@classmethod
def __prepare__(metacls, cls, bases, **kwds):
# check that previous enum members do not exist
@ -311,7 +378,7 @@ class EnumMeta(type):
)
return enum_dict
def __new__(metacls, cls, bases, classdict, **kwds):
def __new__(metacls, cls, bases, classdict, boundary=None, **kwds):
# an Enum class is final once enumeration items have been defined; it
# cannot be mixed with other types (int, float, etc.) if it has an
# inherited __new__ unless a new __new__ is defined (or the resulting
@ -346,15 +413,29 @@ class EnumMeta(type):
classdict['_use_args_'] = use_args
#
# convert future enum members into temporary _proto_members
# and record integer values in case this will be a Flag
flag_mask = 0
for name in member_names:
classdict[name] = _proto_member(classdict[name])
value = classdict[name]
if isinstance(value, int):
flag_mask |= value
classdict[name] = _proto_member(value)
#
# house keeping structures
# house-keeping structures
classdict['_member_names_'] = []
classdict['_member_map_'] = {}
classdict['_value2member_map_'] = {}
classdict['_member_type_'] = member_type
#
# Flag structures (will be removed if final class is not a Flag
classdict['_boundary_'] = (
boundary
or getattr(first_enum, '_boundary_', None)
)
classdict['_flag_mask_'] = flag_mask
classdict['_all_bits_'] = 2 ** ((flag_mask).bit_length()) - 1
classdict['_inverted_'] = None
#
# If a custom type is mixed into the Enum, and it does not know how
# to pickle itself, pickle.dumps will succeed but pickle.loads will
# fail. Rather than have the error show up later and possibly far
@ -408,11 +489,75 @@ class EnumMeta(type):
enum_class.__new__ = Enum.__new__
#
# py3 support for definition order (helps keep py2/py3 code in sync)
#
# _order_ checking is spread out into three/four steps
# - if enum_class is a Flag:
# - remove any non-single-bit flags from _order_
# - remove any aliases from _order_
# - check that _order_ and _member_names_ match
#
# step 1: ensure we have a list
if _order_ is not None:
if isinstance(_order_, str):
_order_ = _order_.replace(',', ' ').split()
#
# remove Flag structures if final class is not a Flag
if (
Flag is None and cls != 'Flag'
or Flag is not None and not issubclass(enum_class, Flag)
):
delattr(enum_class, '_boundary_')
delattr(enum_class, '_flag_mask_')
delattr(enum_class, '_all_bits_')
delattr(enum_class, '_inverted_')
elif Flag is not None and issubclass(enum_class, Flag):
# ensure _all_bits_ is correct and there are no missing flags
single_bit_total = 0
multi_bit_total = 0
for flag in enum_class._member_map_.values():
flag_value = flag._value_
if _is_single_bit(flag_value):
single_bit_total |= flag_value
else:
# multi-bit flags are considered aliases
multi_bit_total |= flag_value
if enum_class._boundary_ is not KEEP:
missed = list(_iter_bits_lsb(multi_bit_total & ~single_bit_total))
if missed:
raise TypeError(
'invalid Flag %r -- missing values: %s'
% (cls, ', '.join((str(i) for i in missed)))
)
enum_class._flag_mask_ = single_bit_total
#
# set correct __iter__
member_list = [m._value_ for m in enum_class]
if member_list != sorted(member_list):
enum_class._iter_member_ = enum_class._iter_member_by_def_
if _order_:
# _order_ step 2: remove any items from _order_ that are not single-bit
_order_ = [
o
for o in _order_
if o not in enum_class._member_map_ or _is_single_bit(enum_class[o]._value_)
]
#
if _order_:
# _order_ step 3: remove aliases from _order_
_order_ = [
o
for o in _order_
if (
o not in enum_class._member_map_
or
(o in enum_class._member_map_ and o in enum_class._member_names_)
)]
# _order_ step 4: verify that _order_ and _member_names_ match
if _order_ != enum_class._member_names_:
raise TypeError('member order does not match _order_')
raise TypeError(
'member order does not match _order_:\n%r\n%r'
% (enum_class._member_names_, _order_)
)
#
return enum_class
@ -422,7 +567,7 @@ class EnumMeta(type):
"""
return True
def __call__(cls, value, names=None, *, module=None, qualname=None, type=None, start=1):
def __call__(cls, value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None):
"""
Either returns an existing member, or creates a new enum class.
@ -457,6 +602,7 @@ class EnumMeta(type):
qualname=qualname,
type=type,
start=start,
boundary=boundary,
)
def __contains__(cls, member):
@ -539,7 +685,7 @@ class EnumMeta(type):
raise AttributeError('Cannot reassign members.')
super().__setattr__(name, value)
def _create_(cls, class_name, names, *, module=None, qualname=None, type=None, start=1):
def _create_(cls, class_name, names, *, module=None, qualname=None, type=None, start=1, boundary=None):
"""
Convenience method to create a new Enum class.
@ -589,9 +735,9 @@ class EnumMeta(type):
if qualname is not None:
classdict['__qualname__'] = qualname
return metacls.__new__(metacls, class_name, bases, classdict)
return metacls.__new__(metacls, class_name, bases, classdict, boundary=boundary)
def _convert_(cls, name, module, filter, source=None):
def _convert_(cls, name, module, filter, source=None, boundary=None):
"""
Create a new Enum subclass that replaces a collection of global constants
"""
@ -618,7 +764,7 @@ class EnumMeta(type):
except TypeError:
# unless some values aren't comparable, in which case sort by name
members.sort(key=lambda t: t[0])
cls = cls(name, members, module=module)
cls = cls(name, members, module=module, boundary=boundary or KEEP)
cls.__reduce_ex__ = _reduce_ex_by_name
module_globals.update(cls.__members__)
module_globals[name] = cls
@ -733,6 +879,7 @@ class Enum(metaclass=EnumMeta):
Derive from this class to define new enumerations.
"""
def __new__(cls, value):
# all enum instances are actually created during class construction
# without calling this method; this method is called by the metaclass'
@ -761,6 +908,11 @@ class Enum(metaclass=EnumMeta):
result = None
if isinstance(result, cls):
return result
elif (
Flag is not None and issubclass(cls, Flag)
and cls._boundary_ is EJECT and isinstance(result, int)
):
return result
else:
ve_exc = ValueError("%r is not a valid %s" % (value, cls.__qualname__))
if result is None and exc is None:
@ -770,7 +922,8 @@ class Enum(metaclass=EnumMeta):
'error in %s._missing_: returned %r instead of None or a valid member'
% (cls.__name__, result)
)
exc.__context__ = ve_exc
if not isinstance(exc, ValueError):
exc.__context__ = ve_exc
raise exc
def _generate_next_value_(name, start, count, last_values):
@ -875,14 +1028,14 @@ class StrEnum(str, Enum):
# it must be a string
if not isinstance(values[0], str):
raise TypeError('%r is not a string' % (values[0], ))
if len(values) > 1:
if len(values) >= 2:
# check that encoding argument is a string
if not isinstance(values[1], str):
raise TypeError('encoding must be a string, not %r' % (values[1], ))
if len(values) > 2:
# check that errors argument is a string
if not isinstance(values[2], str):
raise TypeError('errors must be a string, not %r' % (values[2], ))
if len(values) == 3:
# check that errors argument is a string
if not isinstance(values[2], str):
raise TypeError('errors must be a string, not %r' % (values[2]))
value = str(*values)
member = str.__new__(cls, value)
member._value_ = value
@ -900,7 +1053,22 @@ class StrEnum(str, Enum):
def _reduce_ex_by_name(self, proto):
return self.name
class Flag(Enum):
class FlagBoundary(StrEnum):
"""
control how out of range values are handled
"strict" -> error is raised [default for Flag]
"conform" -> extra bits are discarded
"eject" -> lose flag status [default for IntFlag]
"keep" -> keep flag status and all bits
"""
STRICT = auto()
CONFORM = auto()
EJECT = auto()
KEEP = auto()
STRICT, CONFORM, EJECT, KEEP = FlagBoundary
class Flag(Enum, boundary=STRICT):
"""
Support for flags
"""
@ -916,45 +1084,108 @@ class Flag(Enum):
"""
if not count:
return start if start is not None else 1
for last_value in reversed(last_values):
try:
high_bit = _high_bit(last_value)
break
except Exception:
raise TypeError('Invalid Flag value: %r' % last_value) from None
last_value = max(last_values)
try:
high_bit = _high_bit(last_value)
except Exception:
raise TypeError('Invalid Flag value: %r' % last_value) from None
return 2 ** (high_bit+1)
@classmethod
def _iter_member_by_value_(cls, value):
"""
Extract all members from the value in definition (i.e. increasing value) order.
"""
for val in _iter_bits_lsb(value & cls._flag_mask_):
yield cls._value2member_map_.get(val)
_iter_member_ = _iter_member_by_value_
@classmethod
def _iter_member_by_def_(cls, value):
"""
Extract all members from the value in definition order.
"""
yield from sorted(
cls._iter_member_by_value_(value),
key=lambda m: m._sort_order_,
)
@classmethod
def _missing_(cls, value):
"""
Returns member (possibly creating it) if one can be found for value.
"""
original_value = value
if value < 0:
value = ~value
possible_member = cls._create_pseudo_member_(value)
if original_value < 0:
possible_member = ~possible_member
return possible_member
@classmethod
def _create_pseudo_member_(cls, value):
"""
Create a composite member iff value contains only members.
"""
pseudo_member = cls._value2member_map_.get(value, None)
if pseudo_member is None:
# verify all bits are accounted for
_, extra_flags = _decompose(cls, value)
if extra_flags:
raise ValueError("%r is not a valid %s" % (value, cls.__qualname__))
if not isinstance(value, int):
raise ValueError(
"%r is not a valid %s" % (value, cls.__qualname__)
)
# check boundaries
# - value must be in range (e.g. -16 <-> +15, i.e. ~15 <-> 15)
# - value must not include any skipped flags (e.g. if bit 2 is not
# defined, then 0d10 is invalid)
flag_mask = cls._flag_mask_
all_bits = cls._all_bits_
neg_value = None
if (
not ~all_bits <= value <= all_bits
or value & (all_bits ^ flag_mask)
):
if cls._boundary_ is STRICT:
max_bits = max(value.bit_length(), flag_mask.bit_length())
raise ValueError(
"%s: invalid value: %r\n given %s\n allowed %s" % (
cls.__name__, value, bin(value, max_bits), bin(flag_mask, max_bits),
))
elif cls._boundary_ is CONFORM:
value = value & flag_mask
elif cls._boundary_ is EJECT:
return value
elif cls._boundary_ is KEEP:
if value < 0:
value = (
max(all_bits+1, 2**(value.bit_length()))
+ value
)
else:
raise ValueError(
'unknown flag boundary: %r' % (cls._boundary_, )
)
if value < 0:
neg_value = value
value = all_bits + 1 + value
# get members and unknown
unknown = value & ~flag_mask
member_value = value & flag_mask
if unknown and cls._boundary_ is not KEEP:
raise ValueError(
'%s(%r) --> unknown values %r [%s]'
% (cls.__name__, value, unknown, bin(unknown))
)
# normal Flag?
__new__ = getattr(cls, '__new_member__', None)
if cls._member_type_ is object and not __new__:
# construct a singleton enum pseudo-member
pseudo_member = object.__new__(cls)
pseudo_member._name_ = None
else:
pseudo_member = (__new__ or cls._member_type_.__new__)(cls, value)
if not hasattr(pseudo_member, 'value'):
pseudo_member._value_ = value
# use setdefault in case another thread already created a composite
# with this value
if member_value:
pseudo_member._name_ = '|'.join([
m._name_ for m in cls._iter_member_(member_value)
])
if unknown:
pseudo_member._name_ += '|0x%x' % unknown
else:
pseudo_member._name_ = None
# use setdefault in case another thread already created a composite
# with this value, but only if all members are known
# note: zero is a special case -- add it
if not unknown:
pseudo_member = cls._value2member_map_.setdefault(value, pseudo_member)
if neg_value is not None:
cls._value2member_map_[neg_value] = pseudo_member
return pseudo_member
def __contains__(self, other):
@ -965,38 +1196,33 @@ class Flag(Enum):
raise TypeError(
"unsupported operand type(s) for 'in': '%s' and '%s'" % (
type(other).__qualname__, self.__class__.__qualname__))
if other._value_ == 0 or self._value_ == 0:
return False
return other._value_ & self._value_ == other._value_
def __iter__(self):
"""
Returns flags in decreasing value order.
Returns flags in definition order.
"""
members, extra_flags = _decompose(self.__class__, self.value)
return (m for m in members if m._value_ != 0)
yield from self._iter_member_(self._value_)
def __len__(self):
return self._value_.bit_count()
def __repr__(self):
cls = self.__class__
if self._name_ is not None:
return '<%s.%s: %r>' % (cls.__name__, self._name_, self._value_)
members, uncovered = _decompose(cls, self._value_)
return '<%s.%s: %r>' % (
cls.__name__,
'|'.join([str(m._name_ or m._value_) for m in members]),
self._value_,
)
else:
# only zero is unnamed by default
return '<%s: %r>' % (cls.__name__, self._value_)
def __str__(self):
cls = self.__class__
if self._name_ is not None:
return '%s.%s' % (cls.__name__, self._name_)
members, uncovered = _decompose(cls, self._value_)
if len(members) == 1 and members[0]._name_ is None:
return '%s.%r' % (cls.__name__, members[0]._value_)
else:
return '%s.%s' % (
cls.__name__,
'|'.join([str(m._name_ or m._value_) for m in members]),
)
return '%s(%s)' % (cls.__name__, self._value_)
def __bool__(self):
return bool(self._value_)
@ -1017,86 +1243,56 @@ class Flag(Enum):
return self.__class__(self._value_ ^ other._value_)
def __invert__(self):
members, uncovered = _decompose(self.__class__, self._value_)
inverted = self.__class__(0)
for m in self.__class__:
if m not in members and not (m._value_ & self._value_):
inverted = inverted | m
return self.__class__(inverted)
if self._inverted_ is None:
if self._boundary_ is KEEP:
# use all bits
self._inverted_ = self.__class__(~self._value_)
else:
# calculate flags not in this member
self._inverted_ = self.__class__(self._flag_mask_ ^ self._value_)
self._inverted_._inverted_ = self
return self._inverted_
class IntFlag(int, Flag):
class IntFlag(int, Flag, boundary=EJECT):
"""
Support for integer-based Flags
"""
@classmethod
def _missing_(cls, value):
"""
Returns member (possibly creating it) if one can be found for value.
"""
if not isinstance(value, int):
raise ValueError("%r is not a valid %s" % (value, cls.__qualname__))
new_member = cls._create_pseudo_member_(value)
return new_member
@classmethod
def _create_pseudo_member_(cls, value):
"""
Create a composite member iff value contains only members.
"""
pseudo_member = cls._value2member_map_.get(value, None)
if pseudo_member is None:
need_to_create = [value]
# get unaccounted for bits
_, extra_flags = _decompose(cls, value)
# timer = 10
while extra_flags:
# timer -= 1
bit = _high_bit(extra_flags)
flag_value = 2 ** bit
if (flag_value not in cls._value2member_map_ and
flag_value not in need_to_create
):
need_to_create.append(flag_value)
if extra_flags == -flag_value:
extra_flags = 0
else:
extra_flags ^= flag_value
for value in reversed(need_to_create):
# construct singleton pseudo-members
pseudo_member = int.__new__(cls, value)
pseudo_member._name_ = None
pseudo_member._value_ = value
# use setdefault in case another thread already created a composite
# with this value
pseudo_member = cls._value2member_map_.setdefault(value, pseudo_member)
return pseudo_member
def __or__(self, other):
if not isinstance(other, (self.__class__, int)):
if isinstance(other, self.__class__):
other = other._value_
elif isinstance(other, int):
other = other
else:
return NotImplemented
result = self.__class__(self._value_ | self.__class__(other)._value_)
return result
value = self._value_
return self.__class__(value | other)
def __and__(self, other):
if not isinstance(other, (self.__class__, int)):
if isinstance(other, self.__class__):
other = other._value_
elif isinstance(other, int):
other = other
else:
return NotImplemented
return self.__class__(self._value_ & self.__class__(other)._value_)
value = self._value_
return self.__class__(value & other)
def __xor__(self, other):
if not isinstance(other, (self.__class__, int)):
if isinstance(other, self.__class__):
other = other._value_
elif isinstance(other, int):
other = other
else:
return NotImplemented
return self.__class__(self._value_ ^ self.__class__(other)._value_)
value = self._value_
return self.__class__(value ^ other)
__ror__ = __or__
__rand__ = __and__
__rxor__ = __xor__
def __invert__(self):
result = self.__class__(~self._value_)
return result
__invert__ = Flag.__invert__
def _high_bit(value):
"""
@ -1119,31 +1315,7 @@ def unique(enumeration):
(enumeration, alias_details))
return enumeration
def _decompose(flag, value):
"""
Extract all members from the value.
"""
# _decompose is only called if the value is not named
not_covered = value
negative = value < 0
members = []
for member in flag:
member_value = member.value
if member_value and member_value & value == member_value:
members.append(member)
not_covered &= ~member_value
if not negative:
tmp = not_covered
while tmp:
flag_value = 2 ** _high_bit(tmp)
if flag_value in flag._value2member_map_:
members.append(flag._value2member_map_[flag_value])
not_covered &= ~flag_value
tmp &= ~flag_value
if not members and value in flag._value2member_map_:
members.append(flag._value2member_map_[value])
members.sort(key=lambda m: m._value_, reverse=True)
if len(members) > 1 and members[0].value == value:
# we have the breakdown, don't need the value member itself
members.pop(0)
return members, not_covered
def _power_of_two(value):
if value < 1:
return False
return value == 2 ** _high_bit(value)