# -*- coding: utf-8 -*-
"""
hyperframe/flags
~~~~~~~~~~~~~~~~
Defines basic Flag and Flags data structures.
"""
from collections.abc import MutableSet
from typing import NamedTuple, Iterable, Set, Iterator
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]):
self._valid_flags = set(flag.name for flag in defined_flags)
self._flags: Set[str] = set()
def __repr__(self) -> str:
return repr(sorted(list(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:
raise ValueError(
"Unexpected flag: {}. Valid flags are: {}".format(
value, self._valid_flags
)
)
return self._flags.add(value)