1 files changed, 113 insertions, 0 deletions
diff --git a/third_party/rust/futures-0.1.31/src/stream/take_while.rs b/third_party/rust/futures-0.1.31/src/stream/take_while.rs
new file mode 100644
index 0000000000..732ae855de
--- /dev/null
+++ b/third_party/rust/futures-0.1.31/src/stream/take_while.rs
@@ -0,0 +1,113 @@
+use {Async, Poll, IntoFuture, Future};
+use stream::Stream;
+
+/// A stream combinator which takes elements from a stream while a predicate
+/// holds.
+///
+/// This structure is produced by the `Stream::take_while` method.
+#[derive(Debug)]
+#[must_use = "streams do nothing unless polled"]
+pub struct TakeWhile<S, P, R> where S: Stream, R: IntoFuture {
+    stream: S,
+    pred: P,
+    pending: Option<(R::Future, S::Item)>,
+    done_taking: bool,
+}
+
+pub fn new<S, P, R>(s: S, p: P) -> TakeWhile<S, P, R>
+    where S: Stream,
+          P: FnMut(&S::Item) -> R,
+          R: IntoFuture<Item=bool, Error=S::Error>,
+{
+    TakeWhile {
+        stream: s,
+        pred: p,
+        pending: None,
+        done_taking: false,
+    }
+}
+
+impl<S, P, R> TakeWhile<S, P, R> where S: Stream, R: IntoFuture {
+    /// Acquires a reference to the underlying stream that this combinator is
+    /// pulling from.
+    pub fn get_ref(&self) -> &S {
+        &self.stream
+    }
+
+    /// Acquires a mutable reference to the underlying stream that this
+    /// combinator is pulling from.
+    ///
+    /// Note that care must be taken to avoid tampering with the state of the
+    /// stream which may otherwise confuse this combinator.
+    pub fn get_mut(&mut self) -> &mut S {
+        &mut self.stream
+    }
+
+    /// Consumes this combinator, returning the underlying stream.
+    ///
+    /// Note that this may discard intermediate state of this combinator, so
+    /// care should be taken to avoid losing resources when this is called.
+    pub fn into_inner(self) -> S {
+        self.stream
+    }
+}
+
+// Forwarding impl of Sink from the underlying stream
+impl<S, P, R> ::sink::Sink for TakeWhile<S, P, R>
+    where S: ::sink::Sink + Stream, R: IntoFuture
+{
+    type SinkItem = S::SinkItem;
+    type SinkError = S::SinkError;
+
+    fn start_send(&mut self, item: S::SinkItem) -> ::StartSend<S::SinkItem, S::SinkError> {
+        self.stream.start_send(item)
+    }
+
+    fn poll_complete(&mut self) -> Poll<(), S::SinkError> {
+        self.stream.poll_complete()
+    }
+
+    fn close(&mut self) -> Poll<(), S::SinkError> {
+        self.stream.close()
+    }
+}
+
+impl<S, P, R> Stream for TakeWhile<S, P, R>
+    where S: Stream,
+          P: FnMut(&S::Item) -> R,
+          R: IntoFuture<Item=bool, Error=S::Error>,
+{
+    type Item = S::Item;
+    type Error = S::Error;
+
+    fn poll(&mut self) -> Poll<Option<S::Item>, S::Error> {
+        if self.done_taking {
+            return Ok(Async::Ready(None));
+        }
+
+        if self.pending.is_none() {
+            let item = match try_ready!(self.stream.poll()) {
+                Some(e) => e,
+                None => return Ok(Async::Ready(None)),
+            };
+            self.pending = Some(((self.pred)(&item).into_future(), item));
+        }
+
+        assert!(self.pending.is_some());
+        match self.pending.as_mut().unwrap().0.poll() {
+            Ok(Async::Ready(true)) => {
+                let (_, item) = self.pending.take().unwrap();
+                Ok(Async::Ready(Some(item)))
+            },
+            Ok(Async::Ready(false)) => {
+                self.done_taking = true;
+                Ok(Async::Ready(None))
+            }
+            Ok(Async::NotReady) => Ok(Async::NotReady),
+            Err(e) => {
+                self.pending = None;
+                Err(e)
+            }
+        }
+    }
+}