chore: add filter example

Cargo.toml

@@ -87,3 +87,7 @@ required-features = ["crossterm"]
 [[example]]
 name = "user_input"
 required-features = ["crossterm"]
+
+[[example]]
+name = "filter"
+required-features = ["crossterm"]

examples/filter.rs

@@ -0,0 +1,182 @@
+use crossterm::{
+    event::{self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode},
+    execute,
+    terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
+};
+use std::{error::Error, io};
+use tui::{
+    backend::{Backend, CrosstermBackend},
+    layout::{Constraint, Direction, Layout},
+    style::{Color, Modifier, Style},
+    text::{Span, Spans, Text},
+    widgets::{Block, Borders, List, ListItem, Paragraph},
+    Frame, Terminal,
+};
+use unicode_width::UnicodeWidthStr;
+
+enum InputMode {
+    Normal,
+    Editing,
+}
+
+/// App holds the state of the application
+struct App<'a> {
+    filter: String,
+    input_mode: InputMode,
+    words: Vec<&'a str>,
+}
+
+impl<'a> App<'a> {
+    fn new(words: impl IntoIterator<Item = &'a str>) -> Self {
+        App {
+            filter: String::new(),
+            input_mode: InputMode::Normal,
+            words: words.into_iter().collect(),
+        }
+    }
+}
+
+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 app = App::new(WORDS);
+    let res = run_app(&mut terminal, app);
+
+    // 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) -> io::Result<()> {
+    loop {
+        terminal.draw(|f| ui(f, &mut app))?;
+
+        if let Event::Key(key) = event::read()? {
+            match app.input_mode {
+                InputMode::Normal => match key.code {
+                    KeyCode::Char('e') => {
+                        app.input_mode = InputMode::Editing;
+                    }
+                    KeyCode::Char('q') => {
+                        return Ok(());
+                    }
+                    _ => {}
+                },
+                InputMode::Editing => match key.code {
+                    KeyCode::Char(c) => {
+                        app.filter.push(c);
+                    }
+                    KeyCode::Backspace => {
+                        app.filter.pop();
+                    }
+                    KeyCode::Esc => {
+                        app.input_mode = InputMode::Normal;
+                    }
+                    _ => {}
+                },
+            }
+        }
+    }
+}
+
+fn ui<B: Backend>(f: &mut Frame<B>, app: &App) {
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .margin(2)
+        .constraints(
+            [
+                Constraint::Length(1),
+                Constraint::Length(3),
+                Constraint::Min(1),
+            ]
+            .as_ref(),
+        )
+        .split(f.size());
+
+    let (msg, style) = match app.input_mode {
+        InputMode::Normal => (
+            vec![
+                Span::raw("Press "),
+                Span::styled("q", Style::default().add_modifier(Modifier::BOLD)),
+                Span::raw(" to exit, "),
+                Span::styled("e", Style::default().add_modifier(Modifier::BOLD)),
+                Span::raw(" to start editing."),
+            ],
+            Style::default().add_modifier(Modifier::RAPID_BLINK),
+        ),
+        InputMode::Editing => (
+            vec![
+                Span::raw("Press "),
+                Span::styled("Esc", Style::default().add_modifier(Modifier::BOLD)),
+                Span::raw(" to stop editing."),
+            ],
+            Style::default(),
+        ),
+    };
+    let mut text = Text::from(Spans::from(msg));
+    text.patch_style(style);
+    let help_message = Paragraph::new(text);
+    f.render_widget(help_message, chunks[0]);
+
+    let input = Paragraph::new(app.filter.as_ref())
+        .style(match app.input_mode {
+            InputMode::Normal => Style::default(),
+            InputMode::Editing => Style::default().fg(Color::Yellow),
+        })
+        .block(Block::default().borders(Borders::ALL).title("Input"));
+    f.render_widget(input, chunks[1]);
+    match app.input_mode {
+        InputMode::Normal =>
+            // Hide the cursor. `Frame` does this by default, so we don't need to do anything here
+            {}
+        InputMode::Editing => {
+            // Make the cursor visible and ask tui-rs to put it at the specified coordinates after rendering
+            f.set_cursor(
+                // Put cursor past the end of the input text
+                chunks[1].x + app.filter.width() as u16 + 1,
+                // Move one line down, from the border to the input line
+                chunks[1].y + 1,
+            )
+        }
+    }
+
+    let items: Vec<ListItem> = app
+        .words
+        .iter()
+        .filter(|m| m.contains(&app.filter))
+        .map(|m| {
+            let content = vec![Spans::from(Span::raw(*m))];
+            ListItem::new(content)
+        })
+        .collect();
+    let list = List::new(items).block(Block::default().borders(Borders::ALL).title("Messages"));
+    f.render_widget(list, chunks[2]);
+}
+
+const WORDS: [&'static str; 100] = [
+    "the", "at", "there", "some", "my", "of", "be", "use", "her", "than", "and", "this", "an",
+    "would", "first", "a", "have", "each", "make", "water", "to", "from", "which", "like", "been",
+    "in", "or", "she", "him", "call", "is", "one", "do", "into", "who", "you", "had", "how",
+    "time", "oil", "that", "by", "their", "has", "its", "it", "word", "if", "look", "now", "he",
+    "but", "will", "two", "find", "was", "not", "up", "more", "long", "for", "what", "other",
+    "write", "down", "on", "all", "about", "go", "day", "are", "were", "out", "see", "did", "as",
+    "we", "many", "number", "get", "with", "when", "then", "no", "come", "his", "your", "them",
+    "way", "made", "they", "can", "these", "could", "may", "I", "said", "so", "people", "part",
+];