hyperframe/src/hyperframe/flags.py at master · python-hyper/hyperframe · GitHub

47 lines (34 loc) · 1.26 KB

"""

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)

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