Vendor dependencies

Let's see how I like this workflow.

vendor/tui/examples/list.rs

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+use crossterm::{
+    event::{self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode},
+    execute,
+    terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
+};
+use std::{
+    error::Error,
+    io,
+    time::{Duration, Instant},
+};
+use tui::{
+    backend::{Backend, CrosstermBackend},
+    layout::{Constraint, Corner, Direction, Layout},
+    style::{Color, Modifier, Style},
+    text::{Span, Spans},
+    widgets::{Block, Borders, List, ListItem, ListState},
+    Frame, Terminal,
+};
+
+struct StatefulList<T> {
+    state: ListState,
+    items: Vec<T>,
+}
+
+impl<T> StatefulList<T> {
+    fn with_items(items: Vec<T>) -> StatefulList<T> {
+        StatefulList {
+            state: ListState::default(),
+            items,
+        }
+    }
+
+    fn next(&mut self) {
+        let i = match self.state.selected() {
+            Some(i) => {
+                if i >= self.items.len() - 1 {
+                    0
+                } else {
+                    i + 1
+                }
+            }
+            None => 0,
+        };
+        self.state.select(Some(i));
+    }
+
+    fn previous(&mut self) {
+        let i = match self.state.selected() {
+            Some(i) => {
+                if i == 0 {
+                    self.items.len() - 1
+                } else {
+                    i - 1
+                }
+            }
+            None => 0,
+        };
+        self.state.select(Some(i));
+    }
+
+    fn unselect(&mut self) {
+        self.state.select(None);
+    }
+}
+
+/// This struct holds the current state of the app. In particular, it has the `items` field which is a wrapper
+/// around `ListState`. Keeping track of the items state let us render the associated widget with its state
+/// and have access to features such as natural scrolling.
+///
+/// Check the event handling at the bottom to see how to change the state on incoming events.
+/// Check the drawing logic for items on how to specify the highlighting style for selected items.
+struct App<'a> {
+    items: StatefulList<(&'a str, usize)>,
+    events: Vec<(&'a str, &'a str)>,
+}
+
+impl<'a> App<'a> {
+    fn new() -> App<'a> {
+        App {
+            items: StatefulList::with_items(vec![
+                ("Item0", 1),
+                ("Item1", 2),
+                ("Item2", 1),
+                ("Item3", 3),
+                ("Item4", 1),
+                ("Item5", 4),
+                ("Item6", 1),
+                ("Item7", 3),
+                ("Item8", 1),
+                ("Item9", 6),
+                ("Item10", 1),
+                ("Item11", 3),
+                ("Item12", 1),
+                ("Item13", 2),
+                ("Item14", 1),
+                ("Item15", 1),
+                ("Item16", 4),
+                ("Item17", 1),
+                ("Item18", 5),
+                ("Item19", 4),
+                ("Item20", 1),
+                ("Item21", 2),
+                ("Item22", 1),
+                ("Item23", 3),
+                ("Item24", 1),
+            ]),
+            events: vec![
+                ("Event1", "INFO"),
+                ("Event2", "INFO"),
+                ("Event3", "CRITICAL"),
+                ("Event4", "ERROR"),
+                ("Event5", "INFO"),
+                ("Event6", "INFO"),
+                ("Event7", "WARNING"),
+                ("Event8", "INFO"),
+                ("Event9", "INFO"),
+                ("Event10", "INFO"),
+                ("Event11", "CRITICAL"),
+                ("Event12", "INFO"),
+                ("Event13", "INFO"),
+                ("Event14", "INFO"),
+                ("Event15", "INFO"),
+                ("Event16", "INFO"),
+                ("Event17", "ERROR"),
+                ("Event18", "ERROR"),
+                ("Event19", "INFO"),
+                ("Event20", "INFO"),
+                ("Event21", "WARNING"),
+                ("Event22", "INFO"),
+                ("Event23", "INFO"),
+                ("Event24", "WARNING"),
+                ("Event25", "INFO"),
+                ("Event26", "INFO"),
+            ],
+        }
+    }
+
+    /// Rotate through the event list.
+    /// This only exists to simulate some kind of "progress"
+    fn on_tick(&mut self) {
+        let event = self.events.remove(0);
+        self.events.push(event);
+    }
+}
+
+fn main() -> Result<(), Box<dyn Error>> {
+    // setup terminal
+    enable_raw_mode()?;
+    let mut stdout = io::stdout();
+    execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;
+    let backend = CrosstermBackend::new(stdout);
+    let mut terminal = Terminal::new(backend)?;
+
+    // create app and run it
+    let tick_rate = Duration::from_millis(250);
+    let app = App::new();
+    let res = run_app(&mut terminal, app, tick_rate);
+
+    // restore terminal
+    disable_raw_mode()?;
+    execute!(
+        terminal.backend_mut(),
+        LeaveAlternateScreen,
+        DisableMouseCapture
+    )?;
+    terminal.show_cursor()?;
+
+    if let Err(err) = res {
+        println!("{:?}", err)
+    }
+
+    Ok(())
+}
+
+fn run_app<B: Backend>(
+    terminal: &mut Terminal<B>,
+    mut app: App,
+    tick_rate: Duration,
+) -> io::Result<()> {
+    let mut last_tick = Instant::now();
+    loop {
+        terminal.draw(|f| ui(f, &mut app))?;
+
+        let timeout = tick_rate
+            .checked_sub(last_tick.elapsed())
+            .unwrap_or_else(|| Duration::from_secs(0));
+        if crossterm::event::poll(timeout)? {
+            if let Event::Key(key) = event::read()? {
+                match key.code {
+                    KeyCode::Char('q') => return Ok(()),
+                    KeyCode::Left => app.items.unselect(),
+                    KeyCode::Down => app.items.next(),
+                    KeyCode::Up => app.items.previous(),
+                    _ => {}
+                }
+            }
+        }
+        if last_tick.elapsed() >= tick_rate {
+            app.on_tick();
+            last_tick = Instant::now();
+        }
+    }
+}
+
+fn ui<B: Backend>(f: &mut Frame<B>, app: &mut App) {
+    // Create two chunks with equal horizontal screen space
+    let chunks = Layout::default()
+        .direction(Direction::Horizontal)
+        .constraints([Constraint::Percentage(50), Constraint::Percentage(50)].as_ref())
+        .split(f.size());
+
+    // Iterate through all elements in the `items` app and append some debug text to it.
+    let items: Vec<ListItem> = app
+        .items
+        .items
+        .iter()
+        .map(|i| {
+            let mut lines = vec![Spans::from(i.0)];
+            for _ in 0..i.1 {
+                lines.push(Spans::from(Span::styled(
+                    "Lorem ipsum dolor sit amet, consectetur adipiscing elit.",
+                    Style::default().add_modifier(Modifier::ITALIC),
+                )));
+            }
+            ListItem::new(lines).style(Style::default().fg(Color::Black).bg(Color::White))
+        })
+        .collect();
+
+    // Create a List from all list items and highlight the currently selected one
+    let items = List::new(items)
+        .block(Block::default().borders(Borders::ALL).title("List"))
+        .highlight_style(
+            Style::default()
+                .bg(Color::LightGreen)
+                .add_modifier(Modifier::BOLD),
+        )
+        .highlight_symbol(">> ");
+
+    // We can now render the item list
+    f.render_stateful_widget(items, chunks[0], &mut app.items.state);
+
+    // Let's do the same for the events.
+    // The event list doesn't have any state and only displays the current state of the list.
+    let events: Vec<ListItem> = app
+        .events
+        .iter()
+        .rev()
+        .map(|&(event, level)| {
+            // Colorcode the level depending on its type
+            let s = match level {
+                "CRITICAL" => Style::default().fg(Color::Red),
+                "ERROR" => Style::default().fg(Color::Magenta),
+                "WARNING" => Style::default().fg(Color::Yellow),
+                "INFO" => Style::default().fg(Color::Blue),
+                _ => Style::default(),
+            };
+            // Add a example datetime and apply proper spacing between them
+            let header = Spans::from(vec![
+                Span::styled(format!("{:<9}", level), s),
+                Span::raw(" "),
+                Span::styled(
+                    "2020-01-01 10:00:00",
+                    Style::default().add_modifier(Modifier::ITALIC),
+                ),
+            ]);
+            // The event gets its own line
+            let log = Spans::from(vec![Span::raw(event)]);
+
+            // Here several things happen:
+            // 1. Add a `---` spacing line above the final list entry
+            // 2. Add the Level + datetime
+            // 3. Add a spacer line
+            // 4. Add the actual event
+            ListItem::new(vec![
+                Spans::from("-".repeat(chunks[1].width as usize)),
+                header,
+                Spans::from(""),
+                log,
+            ])
+        })
+        .collect();
+    let events_list = List::new(events)
+        .block(Block::default().borders(Borders::ALL).title("List"))
+        .start_corner(Corner::BottomLeft);
+    f.render_widget(events_list, chunks[1]);
+}