67 lines
1.7 KiB
Python
67 lines
1.7 KiB
Python
import threading
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import contextlib
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_localdata = threading.local()
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class Context(dict):
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def __init__(self, _parent=None, **kwargs):
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self._parent = _parent
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self._deleted = set()
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super().__init__(**kwargs)
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def __delitem__(self, key):
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with contextlib.suppress(KeyError):
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super().__delitem__(key)
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self._deleted.add(key)
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def __getitem__(self, key):
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if key in self._deleted:
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raise KeyError("{} deleted in context".format(key))
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if key not in self:
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if self._parent is not None:
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return self._parent[key]
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return super().__getitem__(key)
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def __setitem__(self, key, value):
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if key in self._deleted:
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self._deleted.remove(key)
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super().__setitem__(key, value)
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def get(self, key, default=None):
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with contextlib.suppress(KeyError):
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return self[key]
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return default
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def _get_current_context():
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if not hasattr(_localdata, 'contexts'):
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_localdata.contexts = [Context(_parent=GlobalContext)]
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return _localdata.contexts[-1]
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class MetaContext:
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def __delitem__(self, item):
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return _get_current_context().__delitem__(item)
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def __getattribute__(self, key):
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return _get_current_context().__getattribute__(key)
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def __setitem__(self, item, value):
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return _get_current_context().__setitem__(item, value)
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def __getitem__(self, item):
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return _get_current_context().__getitem__(item)
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@contextlib.contextmanager
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def enter_context(**kwargs):
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_get_current_context()
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_localdata.contexts.append(Context(_parent=_localdata.contexts[-1], **kwargs))
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yield
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_localdata.contexts.pop()
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CurrentContext = MetaContext()
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GlobalContext = Context()
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