Source code for zict.keymap

from __future__ import annotations

from import Callable, Iterator, MutableMapping
from typing import Generic, TypeVar

from zict.common import KT, VT, ZictBase, close, discard, flush, locked

JT = TypeVar("JT")

[docs] class KeyMap(ZictBase[KT, VT], Generic[KT, JT, VT]): """Translate the keys of a MutableMapping with a pair of input/output functions Parameters ---------- fn: callable Function to call on a key of the KeyMap to transform it to a key of the wrapped mapping. It must be pure (if called twice on the same key it must return the same result) and it must not generate collisions. In other words, ``fn(a) == fn(b) iff a == b``. d: MutableMapping Wrapped mapping See Also -------- Func Examples -------- Use any python object as keys of a File, instead of just strings, as long as their str representation is unique: >>> from zict import File >>> z = KeyMap(str, File("myfile")) # doctest: +SKIP >>> z[1] = 10 # doctest: +SKIP """ fn: Callable[[KT], JT] d: MutableMapping[JT, VT] keymap: dict[KT, JT] def __init__(self, fn: Callable[[KT], JT], d: MutableMapping[JT, VT]): super().__init__() self.fn = fn self.d = d self.keymap = {} @locked def __setitem__(self, key: KT, value: VT) -> None: j = self.fn(key) self.keymap[key] = j with self.unlock(): self.d[j] = value if key not in self.keymap: # Race condition with __delitem__ discard(self.d, j) def __getitem__(self, key: KT) -> VT: j = self.keymap[key] return self.d[j] @locked def __delitem__(self, key: KT) -> None: j = self.keymap.pop(key) del self.d[j] def __contains__(self, key: object) -> bool: return key in self.keymap def __iter__(self) -> Iterator[KT]: return iter(self.keymap) def __len__(self) -> int: return len(self.keymap) def flush(self) -> None: flush(self.d)
[docs] def close(self) -> None: close(self.d)