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|
use std::io::Write;
#[derive(Debug)]
pub enum Error {
EOF,
IOError(std::io::Error),
}
pub struct Readline {
reader: Option<KeyReader>,
buffer: String,
prompt: String,
wrote_prompt: bool,
echo: bool,
}
impl Readline {
fn process_event(
&mut self,
event: crossterm::InputEvent,
) -> std::result::Result<futures::Async<String>, Error> {
match event {
crossterm::InputEvent::Keyboard(e) => {
return self.process_keyboard_event(e)
}
_ => {}
}
return Ok(futures::Async::NotReady);
}
fn process_keyboard_event(
&mut self,
event: crossterm::KeyEvent,
) -> std::result::Result<futures::Async<String>, Error> {
match event {
crossterm::KeyEvent::Char(c) => {
self.echo(c).map_err(|e| Error::IOError(e))?;
if c == '\n' {
return Ok(futures::Async::Ready(self.buffer.clone()));
}
self.buffer.push(c);
}
crossterm::KeyEvent::Ctrl(c) => {
if c == 'd' {
if self.buffer.is_empty() {
self.echo('\n').map_err(|e| Error::IOError(e))?;
return Err(Error::EOF);
}
}
if c == 'c' {
self.buffer = String::new();
self.echo('\n').map_err(|e| Error::IOError(e))?;
self.prompt().map_err(|e| Error::IOError(e))?;
}
}
_ => {}
}
return Ok(futures::Async::NotReady);
}
fn write(&self, buf: &[u8]) -> std::io::Result<()> {
let stdout = std::io::stdout();
let mut stdout = stdout.lock();
stdout.write(buf)?;
stdout.flush()
}
fn prompt(&self) -> std::io::Result<()> {
self.write(self.prompt.as_bytes())
}
fn echo(&self, c: char) -> std::io::Result<()> {
if c == '\n' {
self.write(b"\r\n")?;
return Ok(());
}
if !self.echo {
return Ok(());
}
let mut buf = [0u8; 4];
self.write(c.encode_utf8(&mut buf[..]).as_bytes())
}
}
impl futures::future::Future for Readline {
type Item = String;
type Error = Error;
fn poll(&mut self) -> futures::Poll<Self::Item, Self::Error> {
if !self.wrote_prompt {
self.prompt().map_err(|e| Error::IOError(e))?;
self.wrote_prompt = true;
}
let reader = self.reader.get_or_insert_with(|| {
KeyReader::new(tokio::prelude::task::current())
});
if let Some(event) = reader.poll() {
self.process_event(event)
} else {
Ok(futures::Async::NotReady)
}
}
}
pub fn readline(prompt: &str, echo: bool) -> Readline {
Readline {
reader: None,
buffer: String::new(),
prompt: prompt.to_string(),
wrote_prompt: false,
echo,
}
}
struct KeyReader {
events: std::sync::mpsc::Receiver<crossterm::InputEvent>,
quit: std::sync::mpsc::Sender<()>,
}
impl KeyReader {
fn new(task: tokio::prelude::task::Task) -> Self {
let reader = crossterm::input().read_sync();
let (events_tx, events_rx) = std::sync::mpsc::channel();
let (quit_tx, quit_rx) = std::sync::mpsc::channel();
std::thread::spawn(move || {
for event in reader {
let newline = event
== crossterm::InputEvent::Keyboard(
crossterm::KeyEvent::Char('\n'),
);
events_tx.send(event).unwrap();
task.notify();
if newline {
break;
}
if let Ok(_) = quit_rx.try_recv() {
break;
}
}
});
KeyReader {
events: events_rx,
quit: quit_tx,
}
}
fn poll(&self) -> Option<crossterm::InputEvent> {
if let Ok(event) = self.events.try_recv() {
return Some(event);
}
None
}
}
impl Drop for KeyReader {
fn drop(&mut self) {
// don't care if it fails to send, this can happen if the thread
// terminates due to seeing a newline before the keyreader goes out of
// scope
match self.quit.send(()) {
_ => {}
}
}
}
|
