Differential D3417 Diff 12208 swh/model/collections.py

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swh/model/collections.py

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				# Copyright (C) 2020 The Software Heritage developers
				# See the AUTHORS file at the top-level directory of this distribution
				# License: GNU General Public License version 3, or any later version
				# See top-level LICENSE file for more information

				from collections.abc import Mapping
				from typing import Dict, Generic, Iterable, Optional, Tuple, TypeVar, Union

				KT = TypeVar("KT")
				VT = TypeVar("VT")
				ardumontUnsubmitted Not Done Inline Actions What does KT and VT stands for? KeyType and ValueType? ardumont: What does KT and VT stands for? KeyType and ValueType?
				vlorentzAuthorUnsubmitted Done Inline Actions Yes. I'm reusing the names from `typing.py`. vlorentz: Yes. I'm reusing the names from `typing.py`.


				class ImmutableDict(Mapping, Generic[KT, VT]):
				data: Tuple[Tuple[KT, VT], ...]

				def __init__(self, data: Union[Iterable[Tuple[KT, VT]], Dict[KT, VT]] = {}):
				if isinstance(data, dict):
				self.data = tuple(item for item in data.items())
				else:
				self.data = tuple(data)

				def __getitem__(self, key):
				for (k, v) in self.data:
				if k == key:
				return v
				raise KeyError(key)

				def __iter__(self):
				for (k, v) in self.data:
				yield k

				def __len__(self):
				return len(self.data)

				def items(self):
				yield from self.data

				def copy_pop(self, popped_key) -> Tuple[Optional[VT], "ImmutableDict[KT, VT]"]:
				"""Returns a copy of this ImmutableDict without the given key,
				as well as the value associated to the key."""
				popped_value = None
				new_items = []
				for (key, value) in self.data:
				if key == popped_key:
				popped_value = value
				else:
				new_items.append((key, value))

				return (popped_value, ImmutableDict(new_items))