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use futures_util::StreamExt;
use static_assertions::assert_impl_all;
use std::{convert::TryInto, sync::Arc};
use crate::{blocking::Connection, utils::block_on, MatchRule, Message, OwnedMatchRule, Result};
/// A blocking wrapper of [`crate::MessageStream`].
///
/// Just like [`crate::MessageStream`] must be continuously polled, you must continuously iterate
/// over this type until it's consumed or dropped.
#[derive(derivative::Derivative, Clone)]
#[derivative(Debug)]
pub struct MessageIterator {
// Wrap it in an `Option` to ensure the stream is dropped in a `block_on` call. This is needed
// for tokio because the proxy spawns a task in its `Drop` impl and that needs a runtime
// context in case of tokio. Moreover, we want to use `AsyncDrop::async_drop` to drop the
// stream to ensure any associated match rule is deregistered before the iterator is
// dropped.
pub(crate) azync: Option<crate::MessageStream>,
}
assert_impl_all!(MessageIterator: Send, Sync, Unpin);
impl MessageIterator {
/// Get a reference to the underlying async message stream.
pub fn inner(&self) -> &crate::MessageStream {
self.azync.as_ref().expect("Inner stream is `None`")
}
/// Get the underlying async message stream, consuming `self`.
pub fn into_inner(mut self) -> crate::MessageStream {
self.azync.take().expect("Inner stream is `None`")
}
/// Create a message iterator for the given match rule.
///
/// This is a wrapper around [`crate::MessageStream::for_match_rule`]. Unlike the underlying
/// `MessageStream`, the match rule is immediately deregistered when the iterator is dropped.
///
/// # Example
///
/// ```
/// use zbus::{blocking::{Connection, MessageIterator}, MatchRule, fdo::NameOwnerChanged};
///
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let conn = Connection::session()?;
/// let rule = MatchRule::builder()
/// .msg_type(zbus::MessageType::Signal)
/// .sender("org.freedesktop.DBus")?
/// .interface("org.freedesktop.DBus")?
/// .member("NameOwnerChanged")?
/// .add_arg("org.freedesktop.zbus.MatchRuleIteratorTest42")?
/// .build();
/// let mut iter = MessageIterator::for_match_rule(
/// rule,
/// &conn,
/// // For such a specific match rule, we don't need a big queue.
/// Some(1),
/// )?;
///
/// let rule_str = "type='signal',sender='org.freedesktop.DBus',\
/// interface='org.freedesktop.DBus',member='NameOwnerChanged',\
/// arg0='org.freedesktop.zbus.MatchRuleIteratorTest42'";
/// assert_eq!(
/// iter.match_rule().map(|r| r.to_string()).as_deref(),
/// Some(rule_str),
/// );
///
/// // We register 2 names, starting with the uninteresting one. If `iter` wasn't filtering
/// // messages based on the match rule, we'd receive method return call for each of these 2
/// // calls first.
/// //
/// // Note that the `NameOwnerChanged` signal will not be sent by the bus for the first name
/// // we register since we setup an arg filter.
/// conn.request_name("org.freedesktop.zbus.MatchRuleIteratorTest44")?;
/// conn.request_name("org.freedesktop.zbus.MatchRuleIteratorTest42")?;
///
/// let msg = iter.next().unwrap()?;
/// let signal = NameOwnerChanged::from_message(msg).unwrap();
/// assert_eq!(signal.args()?.name(), "org.freedesktop.zbus.MatchRuleIteratorTest42");
///
/// # Ok(())
/// # }
/// ```
///
/// # Caveats
///
/// Since this method relies on [`MatchRule::matches`], it inherits its caveats.
pub fn for_match_rule<R>(rule: R, conn: &Connection, max_queued: Option<usize>) -> Result<Self>
where
R: TryInto<OwnedMatchRule>,
R::Error: Into<crate::Error>,
{
block_on(crate::MessageStream::for_match_rule(
rule,
conn.inner(),
max_queued,
))
.map(Some)
.map(|s| Self { azync: s })
}
/// The associated match rule, if any.
pub fn match_rule(&self) -> Option<MatchRule<'_>> {
self.azync
.as_ref()
.expect("Inner stream is `None`")
.match_rule()
}
}
impl Iterator for MessageIterator {
type Item = Result<Arc<Message>>;
fn next(&mut self) -> Option<Self::Item> {
block_on(self.azync.as_mut().expect("Inner stream is `None`").next())
}
}
impl From<Connection> for MessageIterator {
fn from(conn: Connection) -> Self {
let azync = crate::MessageStream::from(conn.into_inner());
Self { azync: Some(azync) }
}
}
impl From<&Connection> for MessageIterator {
fn from(conn: &Connection) -> Self {
Self::from(conn.clone())
}
}
impl From<MessageIterator> for Connection {
fn from(mut iter: MessageIterator) -> Connection {
Connection::from(crate::Connection::from(
iter.azync.take().expect("Inner stream is `None`"),
))
}
}
impl From<&MessageIterator> for Connection {
fn from(iter: &MessageIterator) -> Connection {
Connection::from(crate::Connection::from(
iter.azync.as_ref().expect("Inner stream is `None`"),
))
}
}
impl std::ops::Drop for MessageIterator {
fn drop(&mut self) {
block_on(async {
if let Some(azync) = self.azync.take() {
crate::AsyncDrop::async_drop(azync).await;
}
});
}
}