1 files changed, 61 insertions, 0 deletions
diff --git a/src/tokio_write.rs b/src/tokio_write.rs
new file mode 100644
index 000000000..47f62a584
--- /dev/null
+++ b/src/tokio_write.rs
@@ -0,0 +1,61 @@
+// TODO Submit this file upstream into tokio-io/src/io/write.rs
+use std::io;
+use std::mem;
+
+use futures::{Future, Poll};
+use tokio::io::AsyncWrite;
+
+/// A future used to write some data to a stream.
+///
+/// This is created by the [`write`] top-level method.
+///
+/// [`write`]: fn.write.html
+#[derive(Debug)]
+pub struct Write<A, T> {
+  state: State<A, T>,
+}
+
+#[derive(Debug)]
+enum State<A, T> {
+  Pending { a: A, buf: T },
+  Empty,
+}
+
+/// Creates a future that will write some of the buffer `buf` to
+/// the stream `a` provided.
+///
+/// Any error which happens during writing will cause both the stream and the
+/// buffer to get destroyed.
+pub fn write<A, T>(a: A, buf: T) -> Write<A, T>
+where
+  A: AsyncWrite,
+  T: AsRef<[u8]>,
+{
+  Write {
+    state: State::Pending { a: a, buf: buf },
+  }
+}
+
+impl<A, T> Future for Write<A, T>
+where
+  A: AsyncWrite,
+  T: AsRef<[u8]>,
+{
+  type Item = (A, T, usize);
+  type Error = io::Error;
+
+  fn poll(&mut self) -> Poll<(A, T, usize), io::Error> {
+    let nwritten = match self.state {
+      State::Pending {
+        ref mut a,
+        ref mut buf,
+      } => try_ready!(a.poll_write(buf.as_ref())),
+      State::Empty => panic!("poll a Read after it's done"),
+    };
+
+    match mem::replace(&mut self.state, State::Empty) {
+      State::Pending { a, buf } => Ok((a, buf, nwritten).into()),
+      State::Empty => panic!("invalid internal state"),
+    }
+  }
+}