"""A Set class that work similar to JavaScript."""

from __future__ import annotations

from collections.abc import Iterable, Iterator, MutableSet

from contextlib import suppress

from typing import Any, TypeVar

from .ref_map import RefMap

__all__ = ["RefSet"]

T = TypeVar("T")

class RefSet(MutableSet[T]):

"""A set like object that allows mutable objects as elements.

This class keeps the insertion order unlike a normal set.

Note that the implementation is limited to what is needed internally.

"""

_map: RefMap[T, None]

def __init__(self, values: Iterable[T] | None = None) -> None:

super().__init__()

self._map = RefMap()

if values:

self.update(values)

def __contains__(self, key: Any) -> bool:

return key in self._map

def __iter__(self) -> Iterator[T]:

return iter(self._map)

def __len__(self) -> int:

return len(self._map)

def __repr__(self) -> str:

return f"{self.__class__.__name__}({list(self)!r})"

def add(self, value: T) -> None:

"""Add the given item to the set."""

self._map[value] = None

def remove(self, value: T) -> None:

"""Remove the given item from the set."""

del self._map[value]

def discard(self, value: T) -> None:

"""Remove the given item from the set if it exists."""

with suppress(KeyError):

self.remove(value)

def update(self, values: Iterable[T] | None = None) -> None:

"""Update the set with the given items."""

if values:

for item in values:

self.add(item)