1 files changed, 48 insertions, 0 deletions
diff --git a/src/chunked_bufreader.rs b/src/chunked_bufreader.rs
new file mode 100644
index 0000000..02c2bb8
--- /dev/null
+++ b/src/chunked_bufreader.rs
@@ -0,0 +1,48 @@
+use std::pin::Pin;
+
+use async_std::prelude::*;
+use async_std::io::BufReader;
+use async_std::io::Read;
+use futures::task::{Context, Poll};
+use pin_project::pin_project;
+
+const CHUNK_SIZE: usize = 4096;
+
+#[pin_project]
+pub struct ChunkedBufReader<T>
+    where T: Read + Unpin {
+    #[pin]
+    reader: BufReader<T>,
+}
+
+impl<T> ChunkedBufReader<T>
+    where T: Read + Unpin {
+    pub fn new(reader: BufReader<T>) -> Self {
+        Self {
+            reader,
+        }
+    }
+}
+
+impl<T> Stream for ChunkedBufReader<T>
+    where T: Read + Unpin {
+    type Item = Vec<u8>;
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        let this = self.project();
+        // This is quite wasteful, but perfomance is fine and the only real optimization (other
+        // than some zero-copy shenanigans) would be to not initialize this vec, with unsafe{}
+        let mut chunk = vec![0; CHUNK_SIZE];
+        match this.reader.poll_read(cx, &mut chunk[0..(CHUNK_SIZE - 1)]) {
+            Poll::Ready(Ok(size)) => {
+                if size == 0 {
+                    Poll::Ready(None)
+                } else {
+                    chunk.truncate(size);
+                    Poll::Ready(Some(chunk))
+                }
+            },
+            Poll::Ready(Err(_)) => Poll::Ready(None),
+            Poll::Pending => Poll::Pending,
+        }
+    }
+}