92 lines
2.7 KiB
Python
92 lines
2.7 KiB
Python
import enum
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from types import DynamicClassAttribute
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from django.utils.functional import Promise
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__all__ = ['Choices', 'IntegerChoices', 'TextChoices']
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class ChoicesMeta(enum.EnumMeta):
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"""A metaclass for creating a enum choices."""
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def __new__(metacls, classname, bases, classdict, **kwds):
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labels = []
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for key in classdict._member_names:
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value = classdict[key]
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if (
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isinstance(value, (list, tuple)) and
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len(value) > 1 and
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isinstance(value[-1], (Promise, str))
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):
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*value, label = value
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value = tuple(value)
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else:
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label = key.replace('_', ' ').title()
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labels.append(label)
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# Use dict.__setitem__() to suppress defenses against double
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# assignment in enum's classdict.
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dict.__setitem__(classdict, key, value)
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cls = super().__new__(metacls, classname, bases, classdict, **kwds)
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for member, label in zip(cls.__members__.values(), labels):
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member._label_ = label
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return enum.unique(cls)
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def __contains__(cls, member):
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if not isinstance(member, enum.Enum):
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# Allow non-enums to match against member values.
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return any(x.value == member for x in cls)
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return super().__contains__(member)
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@property
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def names(cls):
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empty = ['__empty__'] if hasattr(cls, '__empty__') else []
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return empty + [member.name for member in cls]
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@property
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def choices(cls):
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empty = [(None, cls.__empty__)] if hasattr(cls, '__empty__') else []
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return empty + [(member.value, member.label) for member in cls]
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@property
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def labels(cls):
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return [label for _, label in cls.choices]
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@property
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def values(cls):
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return [value for value, _ in cls.choices]
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class Choices(enum.Enum, metaclass=ChoicesMeta):
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"""Class for creating enumerated choices."""
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@DynamicClassAttribute
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def label(self):
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return self._label_
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@property
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def do_not_call_in_templates(self):
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return True
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def __str__(self):
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"""
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Use value when cast to str, so that Choices set as model instance
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attributes are rendered as expected in templates and similar contexts.
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"""
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return str(self.value)
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# A similar format was proposed for Python 3.10.
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def __repr__(self):
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return f'{self.__class__.__qualname__}.{self._name_}'
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class IntegerChoices(int, Choices):
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"""Class for creating enumerated integer choices."""
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pass
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class TextChoices(str, Choices):
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"""Class for creating enumerated string choices."""
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def _generate_next_value_(name, start, count, last_values):
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return name
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