Add poll_{read,write} on halves

Closes #32

src/io/split.rs

@@ -1,8 +1,11 @@
 use std::cell::RefCell;
 use std::io::{self, Read, Write};
 
+use futures::Async;
 use futures::task::TaskRc;
 
+use io::Io;
+
 /// The readable half of an object returned from `Io::split`.
 pub struct ReadHalf<T> {
     handle: TaskRc<RefCell<T>>,
@@ -13,11 +16,27 @@ pub struct WriteHalf<T> {
     handle: TaskRc<RefCell<T>>,
 }
 
-pub fn split<T: Read + Write>(t: T) -> (ReadHalf<T>, WriteHalf<T>) {
+pub fn split<T: Io>(t: T) -> (ReadHalf<T>, WriteHalf<T>) {
     let rc = TaskRc::new(RefCell::new(t));
     (ReadHalf { handle: rc.clone() }, WriteHalf { handle: rc })
 }
 
+impl<T: Io> ReadHalf<T> {
+    /// Calls the underlying `poll_read` function on this handling, testing to
+    /// see if it's ready to be read from.
+    pub fn poll_read(&mut self) -> Async<()> {
+        self.handle.with(|t| t.borrow_mut().poll_read())
+    }
+}
+
+impl<T: Io> WriteHalf<T> {
+    /// Calls the underlying `poll_write` function on this handling, testing to
+    /// see if it's ready to be written to.
+    pub fn poll_write(&mut self) -> Async<()> {
+        self.handle.with(|t| t.borrow_mut().poll_write())
+    }
+}
+
 impl<T: Read> Read for ReadHalf<T> {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         self.handle.with(|t| t.borrow_mut().read(buf))