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use termwiz::cell::AttributeChange;
use termwiz::color::{AnsiColor, ColorAttribute, RgbColor};
use termwiz::lineedit::*;
#[derive(Default)]
struct Host {
history: BasicHistory,
}
impl LineEditorHost for Host {
// Render the prompt with a darkslateblue background color if
// the terminal supports true color, otherwise render it with
// a navy blue ansi color.
fn render_prompt(&self, prompt: &str) -> Vec<OutputElement> {
vec![
OutputElement::Attribute(AttributeChange::Background(
ColorAttribute::TrueColorWithPaletteFallback(
RgbColor::from_named("darkslateblue").unwrap(),
AnsiColor::Navy.into(),
),
)),
OutputElement::Text(prompt.to_owned()),
]
}
fn history(&mut self) -> &mut dyn History {
&mut self.history
}
/// Demo of the completion API for words starting with "h" or "he"
fn complete(&self, line: &str, cursor_position: usize) -> Vec<CompletionCandidate> {
let mut candidates = vec![];
if let Some((range, word)) = word_at_cursor(line, cursor_position) {
let words = &["hello", "help", "he-man"];
for w in words {
if w.starts_with(word) {
candidates.push(CompletionCandidate {
range: range.clone(),
text: w.to_string(),
});
}
}
}
candidates
}
}
/// This is a conceptually simple function that computes the bounds
/// of the whitespace delimited word at the specified cursor position
/// in the supplied line string.
/// It returns the range and the corresponding slice out of the line.
/// This function is sufficient for example purposes; in a real application
/// the equivalent function would need to be aware of quoting and other
/// application specific context.
fn word_at_cursor(line: &str, cursor_position: usize) -> Option<(std::ops::Range<usize>, &str)> {
let char_indices: Vec<(usize, char)> = line.char_indices().collect();
if char_indices.is_empty() {
return None;
}
let char_position = char_indices
.iter()
.position(|(idx, _)| *idx == cursor_position)
.unwrap_or(char_indices.len());
// Look back until we find whitespace
let mut start_position = char_position;
while start_position > 0
&& start_position <= char_indices.len()
&& !char_indices[start_position - 1].1.is_whitespace()
{
start_position -= 1;
}
// Look forwards until we find whitespace
let mut end_position = char_position;
while end_position < char_indices.len() && !char_indices[end_position].1.is_whitespace() {
end_position += 1;
}
if end_position > start_position {
let range = char_indices[start_position].0
..char_indices
.get(end_position)
.map(|c| c.0 + 1)
.unwrap_or(line.len());
Some((range.clone(), &line[range]))
} else {
None
}
}
fn main() -> anyhow::Result<()> {
println!("Type `exit` to quit this example, or start a word with `h` and press Tab.");
let mut terminal = line_editor_terminal()?;
let mut editor = LineEditor::new(&mut terminal);
let mut host = Host::default();
loop {
if let Some(line) = editor.read_line(&mut host)? {
println!("read line: {:?}", line);
if line == "exit" {
break;
}
host.history().add(&line);
}
}
Ok(())
}
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