mirror of
https://github.com/revng/revng
synced 2026-06-21 14:07:57 +00:00
Tommaso Fontana
32 lines
882 B
Python
32 lines
882 B
Python
#
|
|
# This file is distributed under the MIT License. See LICENSE.md for details.
|
|
#
|
|
|
|
from collections.abc import Mapping
|
|
from typing import Callable, Dict, Generic, TypeVar
|
|
|
|
K = TypeVar("K")
|
|
V = TypeVar("V")
|
|
|
|
|
|
class DefaultDictFromKey(Generic[K, V], Mapping[K, V]):
|
|
"""
|
|
A dictionary that, when queried with a key not currently present in the dictionary,
|
|
automatically creates it initializing it using a custom function of the key.
|
|
"""
|
|
|
|
def __init__(self, factory: Callable[[K], V]):
|
|
self._dictionary: Dict[K, V] = {}
|
|
self._factory = factory
|
|
|
|
def __getitem__(self, key: K) -> V:
|
|
if key not in self._dictionary:
|
|
self._dictionary[key] = self._factory(key)
|
|
return self._dictionary[key]
|
|
|
|
def __iter__(self):
|
|
return self._dictionary.__iter__()
|
|
|
|
def __len__(self):
|
|
return self._dictionary.__len__()
|