add text editor example

Cargo.toml

@@ -20,3 +20,7 @@ required-features = ["crossterm"]
 [[example]]
 name = "termion"
 required-features = ["termion"]
+
+[[example]]
+name = "editor"
+required-features = ["crossterm"]

README.md

@@ -49,6 +49,7 @@ cargo run --example minimal
 
 - [minimal](./examples/minimal.rs): Minimal usage with [crossterm][] support
 - [termion](./examples/termion.rs): Minimal usage with [termion][] support
+- [editor](./examples/editor.rs): Simple text editor to edit multiple files
 
 ## Minimal Usage
 
@@ -473,6 +474,8 @@ loop {
 }
 ```
 
+See [`editor` example](./examples/editor.rs) for working example.
+
 ## Contributing to tui-textarea
 
 This project is developed [on GitHub][repo].

examples/editor.rs

@@ -0,0 +1,191 @@
+use crossterm::event::{DisableMouseCapture, EnableMouseCapture};
+use crossterm::terminal::{
+    disable_raw_mode, enable_raw_mode, is_raw_mode_enabled, EnterAlternateScreen,
+    LeaveAlternateScreen,
+};
+use std::env;
+use std::fs;
+use std::io;
+use std::io::{BufRead, Write};
+use std::path::PathBuf;
+use tui::backend::CrosstermBackend;
+use tui::layout::{Constraint, Direction, Layout};
+use tui::style::{Color, Modifier, Style};
+use tui::text::{Span, Spans};
+use tui::widgets::Paragraph;
+use tui::Terminal;
+use tui_textarea::{Input, Key, TextArea};
+
+macro_rules! error {
+    ($fmt: expr, $($args:tt),+) => {{
+        Err(io::Error::new(io::ErrorKind::Other, format!($fmt, $($args),+)))
+    }};
+    ($msg: expr) => {{
+        Err(io::Error::new(io::ErrorKind::Other, $msg))
+    }};
+}
+
+struct Buffer<'a> {
+    textarea: TextArea<'a>,
+    path: PathBuf,
+}
+
+impl<'a> Buffer<'a> {
+    fn new(path: PathBuf) -> io::Result<Self> {
+        let mut textarea = if let Ok(md) = path.metadata() {
+            if md.is_file() {
+                io::BufReader::new(fs::File::open(&path)?)
+                    .lines()
+                    .collect::<Result<_, _>>()?
+            } else {
+                return error!("{:?} is not a file", path);
+            }
+        } else {
+            TextArea::default()
+        };
+        textarea.set_line_number_style(Style::default().fg(Color::DarkGray));
+        Ok(Self { textarea, path })
+    }
+
+    fn save(&self) -> io::Result<()> {
+        let mut f = io::BufWriter::new(fs::File::create(&self.path)?);
+        for line in self.textarea.lines() {
+            f.write_all(line.as_bytes())?;
+            f.write_all(b"\n")?;
+        }
+        Ok(())
+    }
+}
+
+struct Editor<'a> {
+    current: usize,
+    buffers: Vec<Buffer<'a>>,
+    term: Terminal<CrosstermBackend<io::Stdout>>,
+    message: Option<&'static str>,
+}
+
+impl<'a> Editor<'a> {
+    fn new<I>(paths: I) -> io::Result<Self>
+    where
+        I: Iterator,
+        I::Item: Into<PathBuf>,
+    {
+        let buffers = paths
+            .map(|p| Buffer::new(p.into()))
+            .collect::<io::Result<Vec<_>>>()?;
+        if buffers.is_empty() {
+            return error!("USAGE: cargo run --example editor FILE1 [FILE2...]");
+        }
+        let mut stdout = io::stdout();
+        if !is_raw_mode_enabled()? {
+            enable_raw_mode()?;
+            crossterm::execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;
+        }
+        let backend = CrosstermBackend::new(stdout);
+        let term = Terminal::new(backend)?;
+        Ok(Self {
+            current: 0,
+            buffers,
+            term,
+            message: None,
+        })
+    }
+
+    fn run(&mut self) -> io::Result<()> {
+        let layout = Layout::default()
+            .direction(Direction::Vertical)
+            .constraints(
+                [
+                    Constraint::Min(1),
+                    Constraint::Length(1),
+                    Constraint::Length(1),
+                ]
+                .as_ref(),
+            );
+
+        loop {
+            self.term.draw(|f| {
+                let buffer = &self.buffers[self.current];
+                let textarea = &buffer.textarea;
+                let chunks = layout.split(f.size());
+                let widget = textarea.widget();
+                f.render_widget(widget, chunks[0]);
+
+                let status = format!(
+                    "[{}/{}] {:?}",
+                    self.current + 1,
+                    self.buffers.len(),
+                    buffer.path,
+                );
+                let status =
+                    Paragraph::new(status).style(Style::default().add_modifier(Modifier::REVERSED));
+                f.render_widget(status, chunks[1]);
+
+                let message = if let Some(message) = self.message.take() {
+                    Spans::from(message)
+                } else {
+                    Spans::from(vec![
+                        Span::raw("Press "),
+                        Span::styled("^Q", Style::default().add_modifier(Modifier::BOLD)),
+                        Span::raw(" to quit, "),
+                        Span::styled("^S", Style::default().add_modifier(Modifier::BOLD)),
+                        Span::raw(" to save, "),
+                        Span::styled("^X", Style::default().add_modifier(Modifier::BOLD)),
+                        Span::raw(" to switch buffer"),
+                    ])
+                };
+                f.render_widget(Paragraph::new(message), chunks[2]);
+            })?;
+
+            match Input::from(crossterm::event::read()?) {
+                Input {
+                    key: Key::Char('q'),
+                    ctrl: true,
+                    ..
+                } => break,
+                Input {
+                    key: Key::Char('x'),
+                    ctrl: true,
+                    ..
+                } => {
+                    self.current += 1;
+                    if self.current >= self.buffers.len() {
+                        self.current = 0;
+                    }
+                }
+                Input {
+                    key: Key::Char('s'),
+                    ctrl: true,
+                    ..
+                } => {
+                    self.buffers[self.current].save()?;
+                    self.message = Some("Saved!");
+                }
+                input => self.buffers[self.current].textarea.input(input),
+            }
+        }
+
+        Ok(())
+    }
+}
+
+impl<'a> Drop for Editor<'a> {
+    fn drop(&mut self) {
+        self.term.show_cursor().unwrap();
+        if !is_raw_mode_enabled().unwrap() {
+            return;
+        }
+        disable_raw_mode().unwrap();
+        crossterm::execute!(
+            self.term.backend_mut(),
+            LeaveAlternateScreen,
+            DisableMouseCapture
+        )
+        .unwrap();
+    }
+}
+
+fn main() -> io::Result<()> {
+    let mut editor = Editor::new(env::args_os().skip(1))?;
+    editor.run()
+}