1 files changed, 102 insertions, 0 deletions
diff --git a/src/io/task.rs b/src/io/task.rs
new file mode 100644
index 00000000..3c87a32e
--- /dev/null
+++ b/src/io/task.rs
@@ -0,0 +1,102 @@
+use std::cell::RefCell;
+use std::io::{self, Read, Write};
+
+use futures::task::TaskData;
+
+/// Abstraction that allows inserting an I/O object into task-local storage,
+/// returning a handle that can be split.
+///
+/// A `TaskIo<T>` handle implements the `ReadTask` and `WriteTask` and will only
+/// work with the same task that the associated object was inserted into. The
+/// handle may then be optionally `split` into the read/write halves so they can
+/// be worked with independently.
+///
+/// Note that it is important that the future returned from `TaskIo::new`, when
+/// polled, will pin the yielded `TaskIo<T>` object to that specific task. Any
+/// attempt to read or write the object on other tasks will result in a panic.
+pub struct TaskIo<T> {
+    handle: TaskData<RefCell<T>>,
+}
+
+/// The readable half of a `TaskIo<T>` instance returned from `TaskIo::split`.
+///
+/// This handle implements the `ReadTask` trait and can be used to split up an
+/// I/O object into two distinct halves.
+pub struct TaskIoRead<T> {
+    handle: TaskData<RefCell<T>>,
+}
+
+/// The writable half of a `TaskIo<T>` instance returned from `TaskIo::split`.
+///
+/// This handle implements the `WriteTask` trait and can be used to split up an
+/// I/O object into two distinct halves.
+pub struct TaskIoWrite<T> {
+    handle: TaskData<RefCell<T>>,
+}
+
+impl<T> TaskIo<T> {
+    /// Returns a new future which represents the insertion of the I/O object
+    /// `T` into task local storage, returning a `TaskIo<T>` handle to it.
+    ///
+    /// The returned future will never resolve to an error.
+    pub fn new(t: T) -> TaskIo<T> {
+        TaskIo {
+            handle: TaskData::new(RefCell::new(t)),
+        }
+    }
+}
+
+impl<T> TaskIo<T>
+    where T: Read + Write,
+{
+    /// For an I/O object which is both readable and writable, this method can
+    /// be used to split the handle into two independently owned halves.
+    ///
+    /// The returned pair implements the `ReadTask` and `WriteTask` traits,
+    /// respectively, and can be used to pass around the object to different
+    /// combinators if necessary.
+    pub fn split(self) -> (TaskIoRead<T>, TaskIoWrite<T>) {
+        (TaskIoRead { handle: self.handle.clone() },
+         TaskIoWrite { handle: self.handle })
+    }
+}
+
+impl<T> Read for TaskIo<T>
+    where T: io::Read,
+{
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.handle.with(|t| t.borrow_mut().read(buf))
+    }
+}
+
+impl<T> Write for TaskIo<T>
+    where T: io::Write,
+{
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.handle.with(|t| t.borrow_mut().write(buf))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.handle.with(|t| t.borrow_mut().flush())
+    }
+}
+
+impl<T> Read for TaskIoRead<T>
+    where T: io::Read,
+{
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.handle.with(|t| t.borrow_mut().read(buf))
+    }
+}
+
+impl<T> Write for TaskIoWrite<T>
+    where T: io::Write,
+{
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.handle.with(|t| t.borrow_mut().write(buf))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.handle.with(|t| t.borrow_mut().flush())
+    }
+}