Move tokio-io into the git repository. (#96)

The crates remain separate, but are now developed in the same git
repository using cargo workspaces.

This facilitates making coordinated changes.

tokio-io/src/split.rs

@@ -0,0 +1,80 @@
+use std::io::{self, Read, Write};
+
+use futures::{Async, Poll};
+use futures::sync::BiLock;
+use bytes::{Buf, BufMut};
+
+use {AsyncRead, AsyncWrite};
+
+/// The readable half of an object returned from `AsyncRead::split`.
+#[derive(Debug)]
+pub struct ReadHalf<T> {
+    handle: BiLock<T>,
+}
+
+/// The writable half of an object returned from `AsyncRead::split`.
+#[derive(Debug)]
+pub struct WriteHalf<T> {
+    handle: BiLock<T>,
+}
+
+pub fn split<T: AsyncRead + AsyncWrite>(t: T) -> (ReadHalf<T>, WriteHalf<T>) {
+    let (a, b) = BiLock::new(t);
+    (ReadHalf { handle: a }, WriteHalf { handle: b })
+}
+
+fn would_block() -> io::Error {
+    io::Error::new(io::ErrorKind::WouldBlock, "would block")
+}
+
+impl<T: AsyncRead> Read for ReadHalf<T> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        match self.handle.poll_lock() {
+            Async::Ready(mut l) => l.read(buf),
+            Async::NotReady => Err(would_block()),
+        }
+    }
+}
+
+impl<T: AsyncRead> AsyncRead for ReadHalf<T> {
+    fn read_buf<B: BufMut>(&mut self, buf: &mut B) -> Poll<usize, io::Error> {
+        match self.handle.poll_lock() {
+            Async::Ready(mut l) => l.read_buf(buf),
+            Async::NotReady => Err(would_block()),
+        }
+    }
+}
+
+impl<T: AsyncWrite> Write for WriteHalf<T> {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        match self.handle.poll_lock() {
+            Async::Ready(mut l) => l.write(buf),
+            Async::NotReady => Err(would_block()),
+        }
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        match self.handle.poll_lock() {
+            Async::Ready(mut l) => l.flush(),
+            Async::NotReady => Err(would_block()),
+        }
+    }
+}
+
+impl<T: AsyncWrite> AsyncWrite for WriteHalf<T> {
+    fn shutdown(&mut self) -> Poll<(), io::Error> {
+        match self.handle.poll_lock() {
+            Async::Ready(mut l) => l.shutdown(),
+            Async::NotReady => Err(would_block()),
+        }
+    }
+
+    fn write_buf<B: Buf>(&mut self, buf: &mut B) -> Poll<usize, io::Error>
+        where Self: Sized,
+    {
+        match self.handle.poll_lock() {
+            Async::Ready(mut l) => l.write_buf(buf),
+            Async::NotReady => Err(would_block()),
+        }
+    }
+}