from typing import List, Optional
from ._models import ServerSentEvent
class SSEDecoder:
def __init__(self) -> None:
self._event = ""
self._data: List[str] = []
self._last_event_id = ""
self._retry: Optional[int] = None
def decode(self, line: str) -> Optional[ServerSentEvent]:
# See: https://html.spec.whatwg.org/multipage/server-sent-events.html#event-stream-interpretation # noqa: E501
if not line:
if (
not self._event
and not self._data
and not self._last_event_id
and self._retry is None
):
return None
sse = ServerSentEvent(
event=self._event,
data="\n".join(self._data),
id=self._last_event_id,
retry=self._retry,
)
# NOTE: as per the SSE spec, do not reset last_event_id.
self._event = ""
self._data = []
self._retry = None
return sse
if line.startswith(":"):
return None
fieldname, _, value = line.partition(":")
if value.startswith(" "):
value = value[1:]
if fieldname == "event":
self._event = value
elif fieldname == "data":
self._data.append(value)
elif fieldname == "id":
if "\0" in value:
pass
else:
self._last_event_id = value
elif fieldname == "retry":
try:
self._retry = int(value)
except (TypeError, ValueError):
pass
else:
pass # Field is ignored.
return None