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"""
Part of the tagit module.
A copy of the license is provided with the project.
Author: Matthias Baumgartner, 2022
"""
# standard imports
from collections import abc
from functools import partial
from inspect import isclass
import typing
# exports
__all__: typing.Sequence[str] = (
'BuilderBase',
'InvalidFactoryName',
)
## code ##
class InvalidFactoryName(KeyError): pass
class BuilderBase(abc.Mapping, abc.Hashable):
_factories = dict()
def __getitem__(self, key):
return self.get(key)
def __contains__(self, key):
return key in self._factories
def __iter__(self):
return iter(self._factories.keys())
def __hash__(self):
return hash(frozenset(self._factories.items()))
def __len__(self):
return len(self._factories)
def __eq__(self, other):
return type(self) == type(other) and self._factories == other._factories
def get(self, key):
if key not in self._factories:
raise InvalidFactoryName(key)
return self._factories[key]
@classmethod
def keys(self):
return self._factories.keys()
@classmethod
def items(self):
return self._factories.items()
@classmethod
def describe(cls, key):
if key not in cls._factories:
raise InvalidFactoryName(key)
desc = cls._factories[key].__doc__
return desc if desc is not None else ''
def prepare(self, key, *args, **kwargs):
# If building is to be customized, overwrite this function.
return partial(self[key], *args, **kwargs)
def build(self, key, *args, **kwargs):
fu = self.prepare(key, *args, **kwargs)
return fu()
def key_from_instance(self, cls):
for key, clbk in self._factories.items():
if isclass(clbk) and isinstance(cls, clbk):
return key
if not isclass(clbk) and cls == clbk:
return key
raise KeyError(type(cls))
## EOF ##
|
