mirror of https://github.com/python/cpython
575 lines
22 KiB
Python
575 lines
22 KiB
Python
import sys
|
|
from collections import OrderedDict
|
|
from types import MappingProxyType, DynamicClassAttribute
|
|
|
|
__all__ = ['Enum', 'IntEnum', 'unique']
|
|
|
|
|
|
def _is_descriptor(obj):
|
|
"""Returns True if obj is a descriptor, False otherwise."""
|
|
return (
|
|
hasattr(obj, '__get__') or
|
|
hasattr(obj, '__set__') or
|
|
hasattr(obj, '__delete__'))
|
|
|
|
|
|
def _is_dunder(name):
|
|
"""Returns True if a __dunder__ name, False otherwise."""
|
|
return (name[:2] == name[-2:] == '__' and
|
|
name[2:3] != '_' and
|
|
name[-3:-2] != '_' and
|
|
len(name) > 4)
|
|
|
|
|
|
def _is_sunder(name):
|
|
"""Returns True if a _sunder_ name, False otherwise."""
|
|
return (name[0] == name[-1] == '_' and
|
|
name[1:2] != '_' and
|
|
name[-2:-1] != '_' and
|
|
len(name) > 2)
|
|
|
|
|
|
def _make_class_unpicklable(cls):
|
|
"""Make the given class un-picklable."""
|
|
def _break_on_call_reduce(self, proto):
|
|
raise TypeError('%r cannot be pickled' % self)
|
|
cls.__reduce_ex__ = _break_on_call_reduce
|
|
cls.__module__ = '<unknown>'
|
|
|
|
|
|
class _EnumDict(dict):
|
|
"""Track enum member order and ensure member names are not reused.
|
|
|
|
EnumMeta will use the names found in self._member_names as the
|
|
enumeration member names.
|
|
|
|
"""
|
|
def __init__(self):
|
|
super().__init__()
|
|
self._member_names = []
|
|
|
|
def __setitem__(self, key, value):
|
|
"""Changes anything not dundered or not a descriptor.
|
|
|
|
If an enum member name is used twice, an error is raised; duplicate
|
|
values are not checked for.
|
|
|
|
Single underscore (sunder) names are reserved.
|
|
|
|
"""
|
|
if _is_sunder(key):
|
|
raise ValueError('_names_ are reserved for future Enum use')
|
|
elif _is_dunder(key):
|
|
pass
|
|
elif key in self._member_names:
|
|
# descriptor overwriting an enum?
|
|
raise TypeError('Attempted to reuse key: %r' % key)
|
|
elif not _is_descriptor(value):
|
|
if key in self:
|
|
# enum overwriting a descriptor?
|
|
raise TypeError('Key already defined as: %r' % self[key])
|
|
self._member_names.append(key)
|
|
super().__setitem__(key, 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):
|
|
return _EnumDict()
|
|
|
|
def __new__(metacls, cls, bases, classdict):
|
|
# 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
|
|
# class will fail).
|
|
member_type, first_enum = metacls._get_mixins_(bases)
|
|
__new__, save_new, use_args = metacls._find_new_(classdict, member_type,
|
|
first_enum)
|
|
|
|
# save enum items into separate mapping so they don't get baked into
|
|
# the new class
|
|
members = {k: classdict[k] for k in classdict._member_names}
|
|
for name in classdict._member_names:
|
|
del classdict[name]
|
|
|
|
# check for illegal enum names (any others?)
|
|
invalid_names = set(members) & {'mro', }
|
|
if invalid_names:
|
|
raise ValueError('Invalid enum member name: {0}'.format(
|
|
','.join(invalid_names)))
|
|
|
|
# create a default docstring if one has not been provided
|
|
if '__doc__' not in classdict:
|
|
classdict['__doc__'] = 'An enumeration.'
|
|
|
|
# create our new Enum type
|
|
enum_class = super().__new__(metacls, cls, bases, classdict)
|
|
enum_class._member_names_ = [] # names in definition order
|
|
enum_class._member_map_ = OrderedDict() # name->value map
|
|
enum_class._member_type_ = member_type
|
|
|
|
# save attributes from super classes so we know if we can take
|
|
# the shortcut of storing members in the class dict
|
|
base_attributes = {a for b in bases for a in b.__dict__}
|
|
|
|
# Reverse value->name map for hashable values.
|
|
enum_class._value2member_map_ = {}
|
|
|
|
# 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
|
|
# from the source, sabotage the pickle protocol for this class so
|
|
# that pickle.dumps also fails.
|
|
#
|
|
# However, if the new class implements its own __reduce_ex__, do not
|
|
# sabotage -- it's on them to make sure it works correctly. We use
|
|
# __reduce_ex__ instead of any of the others as it is preferred by
|
|
# pickle over __reduce__, and it handles all pickle protocols.
|
|
if '__reduce_ex__' not in classdict:
|
|
if member_type is not object:
|
|
methods = ('__getnewargs_ex__', '__getnewargs__',
|
|
'__reduce_ex__', '__reduce__')
|
|
if not any(m in member_type.__dict__ for m in methods):
|
|
_make_class_unpicklable(enum_class)
|
|
|
|
# instantiate them, checking for duplicates as we go
|
|
# we instantiate first instead of checking for duplicates first in case
|
|
# a custom __new__ is doing something funky with the values -- such as
|
|
# auto-numbering ;)
|
|
for member_name in classdict._member_names:
|
|
value = members[member_name]
|
|
if not isinstance(value, tuple):
|
|
args = (value, )
|
|
else:
|
|
args = value
|
|
if member_type is tuple: # special case for tuple enums
|
|
args = (args, ) # wrap it one more time
|
|
if not use_args:
|
|
enum_member = __new__(enum_class)
|
|
if not hasattr(enum_member, '_value_'):
|
|
enum_member._value_ = value
|
|
else:
|
|
enum_member = __new__(enum_class, *args)
|
|
if not hasattr(enum_member, '_value_'):
|
|
enum_member._value_ = member_type(*args)
|
|
value = enum_member._value_
|
|
enum_member._name_ = member_name
|
|
enum_member.__objclass__ = enum_class
|
|
enum_member.__init__(*args)
|
|
# 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():
|
|
if canonical_member._value_ == enum_member._value_:
|
|
enum_member = canonical_member
|
|
break
|
|
else:
|
|
# Aliases don't appear in member names (only in __members__).
|
|
enum_class._member_names_.append(member_name)
|
|
# performance boost for any member that would not shadow
|
|
# a DynamicClassAttribute
|
|
if member_name not in base_attributes:
|
|
setattr(enum_class, member_name, enum_member)
|
|
# now add to _member_map_
|
|
enum_class._member_map_[member_name] = enum_member
|
|
try:
|
|
# 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
|
|
except TypeError:
|
|
pass
|
|
|
|
# double check that repr and friends are not the mixin's or various
|
|
# things break (such as pickle)
|
|
for name in ('__repr__', '__str__', '__format__', '__reduce_ex__'):
|
|
class_method = getattr(enum_class, name)
|
|
obj_method = getattr(member_type, name, None)
|
|
enum_method = getattr(first_enum, name, None)
|
|
if obj_method is not None and obj_method is class_method:
|
|
setattr(enum_class, name, enum_method)
|
|
|
|
# replace any other __new__ with our own (as long as Enum is not None,
|
|
# anyway) -- again, this is to support pickle
|
|
if Enum is not None:
|
|
# if the user defined their own __new__, save it before it gets
|
|
# clobbered in case they subclass later
|
|
if save_new:
|
|
enum_class.__new_member__ = __new__
|
|
enum_class.__new__ = Enum.__new__
|
|
return enum_class
|
|
|
|
def __bool__(self):
|
|
"""
|
|
classes/types should always be True.
|
|
"""
|
|
return True
|
|
|
|
def __call__(cls, value, names=None, *, module=None, qualname=None, type=None, start=1):
|
|
"""Either returns an existing member, or creates a new enum class.
|
|
|
|
This method is used both when an enum class is given a value to match
|
|
to an enumeration member (i.e. Color(3)) and for the functional API
|
|
(i.e. Color = Enum('Color', names='red green blue')).
|
|
|
|
When used for the functional API:
|
|
|
|
`value` will be the name of the new class.
|
|
|
|
`names` should be either a string of white-space/comma delimited names
|
|
(values will start at `start`), or an iterator/mapping of name, value pairs.
|
|
|
|
`module` should be set to the module this class is being created in;
|
|
if it is not set, an attempt to find that module will be made, but if
|
|
it fails the class will not be picklable.
|
|
|
|
`qualname` should be set to the actual location this class can be found
|
|
at in its module; by default it is set to the global scope. If this is
|
|
not correct, unpickling will fail in some circumstances.
|
|
|
|
`type`, if set, will be mixed in as the first base class.
|
|
|
|
"""
|
|
if names is None: # simple value lookup
|
|
return cls.__new__(cls, value)
|
|
# otherwise, functional API: we're creating a new Enum type
|
|
return cls._create_(value, names, module=module, qualname=qualname, type=type, start=start)
|
|
|
|
def __contains__(cls, member):
|
|
return isinstance(member, cls) and member._name_ in cls._member_map_
|
|
|
|
def __delattr__(cls, attr):
|
|
# nicer error message when someone tries to delete an attribute
|
|
# (see issue19025).
|
|
if attr in cls._member_map_:
|
|
raise AttributeError(
|
|
"%s: cannot delete Enum member." % cls.__name__)
|
|
super().__delattr__(attr)
|
|
|
|
def __dir__(self):
|
|
return (['__class__', '__doc__', '__members__', '__module__'] +
|
|
self._member_names_)
|
|
|
|
def __getattr__(cls, name):
|
|
"""Return the enum member matching `name`
|
|
|
|
We use __getattr__ instead of descriptors or inserting into the enum
|
|
class' __dict__ in order to support `name` and `value` being both
|
|
properties for enum members (which live in the class' __dict__) and
|
|
enum members themselves.
|
|
|
|
"""
|
|
if _is_dunder(name):
|
|
raise AttributeError(name)
|
|
try:
|
|
return cls._member_map_[name]
|
|
except KeyError:
|
|
raise AttributeError(name) from None
|
|
|
|
def __getitem__(cls, name):
|
|
return cls._member_map_[name]
|
|
|
|
def __iter__(cls):
|
|
return (cls._member_map_[name] for name in cls._member_names_)
|
|
|
|
def __len__(cls):
|
|
return len(cls._member_names_)
|
|
|
|
@property
|
|
def __members__(cls):
|
|
"""Returns a mapping of member name->value.
|
|
|
|
This mapping lists all enum members, including aliases. Note that this
|
|
is a read-only view of the internal mapping.
|
|
|
|
"""
|
|
return MappingProxyType(cls._member_map_)
|
|
|
|
def __repr__(cls):
|
|
return "<enum %r>" % cls.__name__
|
|
|
|
def __reversed__(cls):
|
|
return (cls._member_map_[name] for name in reversed(cls._member_names_))
|
|
|
|
def __setattr__(cls, name, value):
|
|
"""Block attempts to reassign Enum members.
|
|
|
|
A simple assignment to the class namespace only changes one of the
|
|
several possible ways to get an Enum member from the Enum class,
|
|
resulting in an inconsistent Enumeration.
|
|
|
|
"""
|
|
member_map = cls.__dict__.get('_member_map_', {})
|
|
if name in member_map:
|
|
raise AttributeError('Cannot reassign members.')
|
|
super().__setattr__(name, value)
|
|
|
|
def _create_(cls, class_name, names=None, *, module=None, qualname=None, type=None, start=1):
|
|
"""Convenience method to create a new Enum class.
|
|
|
|
`names` can be:
|
|
|
|
* A string containing member names, separated either with spaces or
|
|
commas. Values are incremented by 1 from `start`.
|
|
* An iterable of member names. Values are incremented by 1 from `start`.
|
|
* An iterable of (member name, value) pairs.
|
|
* A mapping of member name -> value pairs.
|
|
|
|
"""
|
|
metacls = cls.__class__
|
|
bases = (cls, ) if type is None else (type, cls)
|
|
classdict = metacls.__prepare__(class_name, bases)
|
|
|
|
# special processing needed for names?
|
|
if isinstance(names, str):
|
|
names = names.replace(',', ' ').split()
|
|
if isinstance(names, (tuple, list)) and isinstance(names[0], str):
|
|
names = [(e, i) for (i, e) in enumerate(names, start)]
|
|
|
|
# Here, names is either an iterable of (name, value) or a mapping.
|
|
for item in names:
|
|
if isinstance(item, str):
|
|
member_name, member_value = item, names[item]
|
|
else:
|
|
member_name, member_value = item
|
|
classdict[member_name] = member_value
|
|
enum_class = metacls.__new__(metacls, class_name, bases, classdict)
|
|
|
|
# TODO: replace the frame hack if a blessed way to know the calling
|
|
# module is ever developed
|
|
if module is None:
|
|
try:
|
|
module = sys._getframe(2).f_globals['__name__']
|
|
except (AttributeError, ValueError) as exc:
|
|
pass
|
|
if module is None:
|
|
_make_class_unpicklable(enum_class)
|
|
else:
|
|
enum_class.__module__ = module
|
|
if qualname is not None:
|
|
enum_class.__qualname__ = qualname
|
|
|
|
return enum_class
|
|
|
|
@staticmethod
|
|
def _get_mixins_(bases):
|
|
"""Returns the type for creating enum members, and the first inherited
|
|
enum class.
|
|
|
|
bases: the tuple of bases that was given to __new__
|
|
|
|
"""
|
|
if not bases:
|
|
return object, Enum
|
|
|
|
# double check that we are not subclassing a class with existing
|
|
# enumeration members; while we're at it, see if any other data
|
|
# type has been mixed in so we can use the correct __new__
|
|
member_type = first_enum = None
|
|
for base in bases:
|
|
if (base is not Enum and
|
|
issubclass(base, Enum) and
|
|
base._member_names_):
|
|
raise TypeError("Cannot extend enumerations")
|
|
# base is now the last base in bases
|
|
if not issubclass(base, Enum):
|
|
raise TypeError("new enumerations must be created as "
|
|
"`ClassName([mixin_type,] enum_type)`")
|
|
|
|
# get correct mix-in type (either mix-in type of Enum subclass, or
|
|
# first base if last base is Enum)
|
|
if not issubclass(bases[0], Enum):
|
|
member_type = bases[0] # first data type
|
|
first_enum = bases[-1] # enum type
|
|
else:
|
|
for base in bases[0].__mro__:
|
|
# most common: (IntEnum, int, Enum, object)
|
|
# possible: (<Enum 'AutoIntEnum'>, <Enum 'IntEnum'>,
|
|
# <class 'int'>, <Enum 'Enum'>,
|
|
# <class 'object'>)
|
|
if issubclass(base, Enum):
|
|
if first_enum is None:
|
|
first_enum = base
|
|
else:
|
|
if member_type is None:
|
|
member_type = base
|
|
|
|
return member_type, first_enum
|
|
|
|
@staticmethod
|
|
def _find_new_(classdict, member_type, first_enum):
|
|
"""Returns the __new__ to be used for creating the enum members.
|
|
|
|
classdict: the class dictionary given to __new__
|
|
member_type: the data type whose __new__ will be used by default
|
|
first_enum: enumeration to check for an overriding __new__
|
|
|
|
"""
|
|
# now find the correct __new__, checking to see of one was defined
|
|
# by the user; also check earlier enum classes in case a __new__ was
|
|
# saved as __new_member__
|
|
__new__ = classdict.get('__new__', None)
|
|
|
|
# should __new__ be saved as __new_member__ later?
|
|
save_new = __new__ is not None
|
|
|
|
if __new__ is None:
|
|
# check all possibles for __new_member__ before falling back to
|
|
# __new__
|
|
for method in ('__new_member__', '__new__'):
|
|
for possible in (member_type, first_enum):
|
|
target = getattr(possible, method, None)
|
|
if target not in {
|
|
None,
|
|
None.__new__,
|
|
object.__new__,
|
|
Enum.__new__,
|
|
}:
|
|
__new__ = target
|
|
break
|
|
if __new__ is not None:
|
|
break
|
|
else:
|
|
__new__ = object.__new__
|
|
|
|
# if a non-object.__new__ is used then whatever value/tuple was
|
|
# assigned to the enum member name will be passed to __new__ and to the
|
|
# new enum member's __init__
|
|
if __new__ is object.__new__:
|
|
use_args = False
|
|
else:
|
|
use_args = True
|
|
|
|
return __new__, save_new, use_args
|
|
|
|
|
|
class Enum(metaclass=EnumMeta):
|
|
"""Generic enumeration.
|
|
|
|
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'
|
|
# __call__ (i.e. Color(3) ), and by pickle
|
|
if type(value) is cls:
|
|
# For lookups like Color(Color.red)
|
|
return value
|
|
# by-value search for a matching enum member
|
|
# see if it's in the reverse mapping (for hashable values)
|
|
try:
|
|
if value in cls._value2member_map_:
|
|
return cls._value2member_map_[value]
|
|
except TypeError:
|
|
# not there, now do long search -- O(n) behavior
|
|
for member in cls._member_map_.values():
|
|
if member._value_ == value:
|
|
return member
|
|
raise ValueError("%r is not a valid %s" % (value, cls.__name__))
|
|
|
|
def __repr__(self):
|
|
return "<%s.%s: %r>" % (
|
|
self.__class__.__name__, self._name_, self._value_)
|
|
|
|
def __str__(self):
|
|
return "%s.%s" % (self.__class__.__name__, self._name_)
|
|
|
|
def __dir__(self):
|
|
added_behavior = [
|
|
m
|
|
for cls in self.__class__.mro()
|
|
for m in cls.__dict__
|
|
if m[0] != '_' and m not in self._member_map_
|
|
]
|
|
return (['__class__', '__doc__', '__module__'] + added_behavior)
|
|
|
|
def __format__(self, format_spec):
|
|
# mixed-in Enums should use the mixed-in type's __format__, otherwise
|
|
# we can get strange results with the Enum name showing up instead of
|
|
# the value
|
|
|
|
# pure Enum branch
|
|
if self._member_type_ is object:
|
|
cls = str
|
|
val = str(self)
|
|
# mix-in branch
|
|
else:
|
|
cls = self._member_type_
|
|
val = self._value_
|
|
return cls.__format__(val, format_spec)
|
|
|
|
def __hash__(self):
|
|
return hash(self._name_)
|
|
|
|
def __reduce_ex__(self, proto):
|
|
return self.__class__, (self._value_, )
|
|
|
|
# DynamicClassAttribute is used to provide access to the `name` and
|
|
# `value` properties of enum members while keeping some measure of
|
|
# protection from modification, while still allowing for an enumeration
|
|
# to have members named `name` and `value`. This works because enumeration
|
|
# members are not set directly on the enum class -- __getattr__ is
|
|
# used to look them up.
|
|
|
|
@DynamicClassAttribute
|
|
def name(self):
|
|
"""The name of the Enum member."""
|
|
return self._name_
|
|
|
|
@DynamicClassAttribute
|
|
def value(self):
|
|
"""The value of the Enum member."""
|
|
return self._value_
|
|
|
|
@classmethod
|
|
def _convert(cls, name, module, filter, source=None):
|
|
"""
|
|
Create a new Enum subclass that replaces a collection of global constants
|
|
"""
|
|
# convert all constants from source (or module) that pass filter() to
|
|
# a new Enum called name, and export the enum and its members back to
|
|
# module;
|
|
# also, replace the __reduce_ex__ method so unpickling works in
|
|
# previous Python versions
|
|
module_globals = vars(sys.modules[module])
|
|
if source:
|
|
source = vars(source)
|
|
else:
|
|
source = module_globals
|
|
members = {name: value for name, value in source.items()
|
|
if filter(name)}
|
|
cls = cls(name, members, module=module)
|
|
cls.__reduce_ex__ = _reduce_ex_by_name
|
|
module_globals.update(cls.__members__)
|
|
module_globals[name] = cls
|
|
return cls
|
|
|
|
|
|
class IntEnum(int, Enum):
|
|
"""Enum where members are also (and must be) ints"""
|
|
|
|
|
|
def _reduce_ex_by_name(self, proto):
|
|
return self.name
|
|
|
|
def unique(enumeration):
|
|
"""Class decorator for enumerations ensuring unique member values."""
|
|
duplicates = []
|
|
for name, member in enumeration.__members__.items():
|
|
if name != member.name:
|
|
duplicates.append((name, member.name))
|
|
if duplicates:
|
|
alias_details = ', '.join(
|
|
["%s -> %s" % (alias, name) for (alias, name) in duplicates])
|
|
raise ValueError('duplicate values found in %r: %s' %
|
|
(enumeration, alias_details))
|
|
return enumeration
|