45 lines
1.1 KiB
Python
45 lines
1.1 KiB
Python
from typing import Generic
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from typing import Iterable
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from typing import Mapping
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from typing import TypeVar
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from babi._types import Protocol
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TKey = TypeVar('TKey', contravariant=True)
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TValue = TypeVar('TValue', covariant=True)
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class FDict(Generic[TKey, TValue]):
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def __init__(self, dct: Mapping[TKey, TValue]) -> None:
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self._dct = dct
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def __getitem__(self, k: TKey) -> TValue:
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return self._dct[k]
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def __contains__(self, k: TKey) -> bool:
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return k in self._dct
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def __repr__(self) -> str:
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return f'{type(self).__name__}({self._dct})'
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def values(self) -> Iterable[TValue]:
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return self._dct.values()
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class Indexable(Generic[TKey, TValue], Protocol):
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def __getitem__(self, key: TKey) -> TValue: ...
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class FChainMap(Generic[TKey, TValue]):
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def __init__(self, *mappings: Indexable[TKey, TValue]) -> None:
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self._mappings = mappings
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def __getitem__(self, key: TKey) -> TValue:
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for mapping in reversed(self._mappings):
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try:
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return mapping[key]
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except KeyError:
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pass
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else:
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raise KeyError(key)
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