Added async_stdin_until function to be used in cursor_pos

src/async.rs

 use std::io::{self, Read};
 use std::sync::mpsc;
 use std::thread;
+use std::io::BufReader;
+use std::io::BufRead;
 
 use sys::tty::get_tty;
 
+/// Construct an asynchronous handle to the TTY standard input, with a delimiter byte.
+///
+/// This has the same advantages as async_stdin(), but also allows specifying a delimiter byte. The
+/// reader will stop reading after consuming the delimiter byte.
+pub fn async_stdin_until(delimiter: u8) -> AsyncReader {
+    let (send, recv) = mpsc::channel();
+
+    thread::spawn(move || for i in get_tty().unwrap().bytes() {
+
+        match i {
+            Ok(byte) => {
+                let end_of_stream = &byte == &delimiter;
+                let send_error = send.send(Ok(byte)).is_err();
+
+                if end_of_stream || send_error { return; }
+            },
+            Err(e) => { return; }
+        }
+    });
+
+    AsyncReader { recv: recv }
+}
+
 /// Construct an asynchronous handle to the TTY standard input.
 ///
 /// This allows you to read from standard input _without blocking_ the current thread.

src/cursor.rs

@@ -2,7 +2,7 @@
 
 use std::fmt;
 use std::io::{self, Write, Error, ErrorKind, Read};
-use async::async_stdin;
+use async::async_stdin_until;
 use std::time::{SystemTime, Duration};
 use raw::CONTROL_SEQUENCE_TIMEOUT;
 
@@ -94,7 +94,8 @@ pub trait DetectCursorPos {
 
 impl<W: Write> DetectCursorPos for W {
     fn cursor_pos(&mut self) -> io::Result<(u16, u16)> {
-        let mut stdin = async_stdin();
+        let delimiter = b'R';
+        let mut stdin = async_stdin_until(delimiter);
 
         // Where is the cursor?
         // Use `ESC [ 6 n`.
@@ -108,7 +109,7 @@ impl<W: Write> DetectCursorPos for W {
         let now = SystemTime::now();
 
         // Either consume all data up to R or wait for a timeout.
-        while buf[0] != b'R' && now.elapsed().unwrap() < timeout {
+        while buf[0] != delimiter && now.elapsed().unwrap() < timeout {
             if stdin.read(&mut buf)? > 0 {
                 read_chars.push(buf[0]);
             }