"""
Basic Flag and Flags data structures.
"""
from __future__ import annotations
from collections.abc import Iterable, Iterator, MutableSet
from typing import NamedTuple
class Flag(NamedTuple):
name: str
bit: int
class Flags(MutableSet): # type: ignore
"""
A simple MutableSet implementation that will only accept known flags as
elements.
Will behave like a regular set(), except that a ValueError will be thrown
when .add()ing unexpected flags.
"""
def __init__(self, defined_flags: Iterable[Flag]) -> None:
self._valid_flags = {flag.name for flag in defined_flags}
self._flags: set[str] = set()
def __repr__(self) -> str:
return repr(sorted(self._flags))
def __contains__(self, x: object) -> bool:
return self._flags.__contains__(x)
def __iter__(self) -> Iterator[str]:
return self._flags.__iter__()
def __len__(self) -> int:
return self._flags.__len__()
def discard(self, value: str) -> None:
return self._flags.discard(value)
def add(self, value: str) -> None:
if value not in self._valid_flags:
msg = f"Unexpected flag: {value}. Valid flags are: {self._valid_flags}"
raise ValueError(msg)
return self._flags.add(value)