1 files changed, 47 insertions, 0 deletions
diff --git a/third_party/rust/futures-util/src/io/lines.rs b/third_party/rust/futures-util/src/io/lines.rs
new file mode 100644
index 0000000000..b5561bfa7d
--- /dev/null
+++ b/third_party/rust/futures-util/src/io/lines.rs
@@ -0,0 +1,47 @@
+use super::read_line::read_line_internal;
+use futures_core::ready;
+use futures_core::stream::Stream;
+use futures_core::task::{Context, Poll};
+use futures_io::AsyncBufRead;
+use pin_project_lite::pin_project;
+use std::io;
+use std::mem;
+use std::pin::Pin;
+
+pin_project! {
+    /// Stream for the [`lines`](super::AsyncBufReadExt::lines) method.
+    #[derive(Debug)]
+    #[must_use = "streams do nothing unless polled"]
+    pub struct Lines<R> {
+        #[pin]
+        reader: R,
+        buf: String,
+        bytes: Vec<u8>,
+        read: usize,
+    }
+}
+
+impl<R: AsyncBufRead> Lines<R> {
+    pub(super) fn new(reader: R) -> Self {
+        Self { reader, buf: String::new(), bytes: Vec::new(), read: 0 }
+    }
+}
+
+impl<R: AsyncBufRead> Stream for Lines<R> {
+    type Item = io::Result<String>;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        let this = self.project();
+        let n = ready!(read_line_internal(this.reader, cx, this.buf, this.bytes, this.read))?;
+        if n == 0 && this.buf.is_empty() {
+            return Poll::Ready(None);
+        }
+        if this.buf.ends_with('\n') {
+            this.buf.pop();
+            if this.buf.ends_with('\r') {
+                this.buf.pop();
+            }
+        }
+        Poll::Ready(Some(Ok(mem::take(this.buf))))
+    }
+}