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extern crate crossterm; extern crate futures; extern crate unicode_segmentation; extern crate unicode_width; use std::{ io::{stdout, Write}, pin::Pin, task::{Context, Poll}, }; use crossterm::{ event::{Event, EventStream}, terminal::{disable_raw_mode, enable_raw_mode}, }; use futures::{future::poll_fn, Stream}; use unicode_segmentation::UnicodeSegmentation; pub use crossterm::Result; pub struct ReadLines { stream: EventStream, buffer: String, } impl ReadLines { pub fn new() -> Result<Self> { enable_raw_mode()?; Ok(Self { stream: EventStream::new(), buffer: String::new(), }) } pub async fn next(&mut self) -> Result<String> { poll_fn(|cx| Pin::new(&mut *self).poll_next(cx)).await } pub fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<String>> { let res = Stream::poll_next(self, cx); match res { Poll::Pending => Poll::Pending, Poll::Ready(None) => Poll::Ready(Err(crossterm::ErrorKind::IoError( std::io::ErrorKind::UnexpectedEof.into(), ))), Poll::Ready(Some(res)) => Poll::Ready(res), } } } impl Drop for ReadLines { fn drop(&mut self) { disable_raw_mode().ok(); } } fn print_flush<S: AsRef<str>>(string: S) -> std::io::Result<()> { let mut stdout = stdout(); stdout.write(string.as_ref().as_bytes())?; stdout.flush() } macro_rules! print_flush { ($($arg:tt)*) => (print_flush(format!($($arg)*)).unwrap()); } fn delete_string<S: AsRef<str>>(string: S) -> std::io::Result<()> { let len = unicode_width::UnicodeWidthStr::width(string.as_ref()); let bs = "\x08".repeat(len); let sp = " ".repeat(len); print_flush(format!("{}{}{}", bs, sp, bs)) } fn pop_grapheme(s: &mut String) -> Option<String> { match s.graphemes(true).last().map(std::borrow::ToOwned::to_owned) { None => None, Some(g) => { s.replace_range((s.len() - g.len()).., ""); Some(g) } } } impl Stream for ReadLines { type Item = Result<String>; fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Option<<Self as futures::Stream>::Item>> { let this = Pin::get_mut(self); loop { match Pin::new(&mut this.stream).poll_next(cx) { Poll::Pending => return Poll::Pending, Poll::Ready(None) => { if this.buffer.is_empty() { return Poll::Ready(None); } else { let res = this.buffer.clone(); this.buffer.clear(); return Poll::Ready(Some(Ok(res))); } } Poll::Ready(Some(Err(err))) => return Poll::Ready(Some(Err(err))), Poll::Ready(Some(Ok(Event::Key(key)))) => match key.code { crossterm::event::KeyCode::Backspace => { pop_grapheme(&mut this.buffer).map(|x| delete_string(x).unwrap()); } crossterm::event::KeyCode::Enter => { let res = this.buffer.clone(); this.buffer.clear(); print_flush!("\r\n"); return Poll::Ready(Some(Ok(res))); } crossterm::event::KeyCode::Tab => { this.buffer.push('\t'); print_flush!("\t"); } crossterm::event::KeyCode::Char(c) => { this.buffer.push(c); print_flush!("{}", c); } _ => {} }, _ => {} } } } }