def enqueue(self, msg: ForwardMsg) -> None:
if msg.HasField(
"page_config_changed") and not self._set_page_config_allowed:
raise StreamlitAPIException(
"`set_page_config()` can only be called once per app, " +
"and must be called as the first Streamlit command in your script.\n\n"
+ "For more information refer to the [docs]" +
"(https://docs.streamlit.io/en/stable/api.html#streamlit.set_page_config)."
)
if msg.HasField("delta") or msg.HasField("page_config_changed"):
self._set_page_config_allowed = False
self._enqueue(msg)
def enqueue(self, msg: ForwardMsg) -> None:
"""Add message into queue, possibly composing it with another message."""
with self._lock:
if not msg.HasField("delta"):
self._queue.append(msg)
return
# If there's a Delta message with the same delta_path already in
# the queue - meaning that it refers to the same location in
# the app - we attempt to combine this new Delta into the old
# one. This is an optimization that prevents redundant Deltas
# from being sent to the frontend.
delta_key = tuple(msg.metadata.delta_path)
if delta_key in self._delta_index_map:
index = self._delta_index_map[delta_key]
old_msg = self._queue[index]
composed_delta = _maybe_compose_deltas(old_msg.delta,
msg.delta)
if composed_delta is not None:
new_msg = ForwardMsg()
new_msg.delta.CopyFrom(composed_delta)
new_msg.metadata.CopyFrom(msg.metadata)
self._queue[index] = new_msg
return
# No composition occured. Append this message to the queue, and
# store its index for potential future composition.
self._delta_index_map[delta_key] = len(self._queue)
self._queue.append(msg)
def enqueue(self, msg: ForwardMsg) -> None:
if msg.HasField(
"page_config_changed") and not self._set_page_config_allowed:
raise StreamlitAPIException(
"`set_page_config()` can only be called once per app, " +
"and must be called as the first Streamlit command in your script.\n\n"
+ "For more information refer to the [docs]" +
"(https://docs.streamlit.io/library/api-reference/utilities/st.set_page_config)."
)
# We want to disallow set_page config if one of the following occurs:
# - set_page_config was called on this message
# - The script has already started and a different st call occurs (a delta)
if msg.HasField("page_config_changed") or (msg.HasField("delta") and
self._has_script_started):
self._set_page_config_allowed = False
self._enqueue(msg)
def _is_composable_message(msg: ForwardMsg) -> bool:
"""True if the ForwardMsg is potentially composable with other ForwardMsgs."""
if not msg.HasField("delta"):
# Non-delta messages are never composable.
return False
# We never compose add_rows messages in Python, because the add_rows
# operation can raise errors, and we don't have a good way of handling
# those errors in the message queue.
delta_type = msg.delta.WhichOneof("type")
return delta_type != "add_rows" and delta_type != "arrow_add_rows"
