"""
Contains structures for representing header fields with associated metadata.
"""
from __future__ import annotations
from typing import TYPE_CHECKING, Any
if TYPE_CHECKING:
from typing_extensions import Self, TypeAlias # pragma: no cover
class HeaderTuple(tuple[bytes, bytes]):
"""
A data structure that stores a single header field.
HTTP headers can be thought of as tuples of ``(field name, field value)``.
A single header block is a sequence of such tuples.
In HTTP/2, however, certain bits of additional information are required for
compressing these headers: in particular, whether the header field can be
safely added to the HPACK compression context.
This class stores a header that can be added to the compression context. In
all other ways it behaves exactly like a tuple.
"""
__slots__ = ()
indexable = True
def __new__(cls, *args: Any) -> Self:
return tuple.__new__(cls, args)
class NeverIndexedHeaderTuple(HeaderTuple):
"""
A data structure that stores a single header field that cannot be added to
a HTTP/2 header compression context.
"""
__slots__ = ()
indexable = False
def __new__(cls, *args: Any) -> Self:
return tuple.__new__(cls, args)
Header: TypeAlias = "HeaderTuple | NeverIndexedHeaderTuple | tuple[bytes, bytes]"
HeaderWeaklyTyped: TypeAlias = "HeaderTuple | NeverIndexedHeaderTuple | tuple[bytes | str, bytes | str]"