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-rw-r--r--third_party/rust/tokio-stream/src/stream_ext/map.rs51
1 files changed, 51 insertions, 0 deletions
diff --git a/third_party/rust/tokio-stream/src/stream_ext/map.rs b/third_party/rust/tokio-stream/src/stream_ext/map.rs
new file mode 100644
index 0000000000..e6b47cd258
--- /dev/null
+++ b/third_party/rust/tokio-stream/src/stream_ext/map.rs
@@ -0,0 +1,51 @@
+use crate::Stream;
+
+use core::fmt;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+use pin_project_lite::pin_project;
+
+pin_project! {
+ /// Stream for the [`map`](super::StreamExt::map) method.
+ #[must_use = "streams do nothing unless polled"]
+ pub struct Map<St, F> {
+ #[pin]
+ stream: St,
+ f: F,
+ }
+}
+
+impl<St, F> fmt::Debug for Map<St, F>
+where
+ St: fmt::Debug,
+{
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_struct("Map").field("stream", &self.stream).finish()
+ }
+}
+
+impl<St, F> Map<St, F> {
+ pub(super) fn new(stream: St, f: F) -> Self {
+ Map { stream, f }
+ }
+}
+
+impl<St, F, T> Stream for Map<St, F>
+where
+ St: Stream,
+ F: FnMut(St::Item) -> T,
+{
+ type Item = T;
+
+ fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> {
+ self.as_mut()
+ .project()
+ .stream
+ .poll_next(cx)
+ .map(|opt| opt.map(|x| (self.as_mut().project().f)(x)))
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.stream.size_hint()
+ }
+}