mdr 0.3.0

A lightweight Markdown viewer with live reload and multiple rendering backends
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use notify_debouncer_mini::{new_debouncer, DebouncedEventKind};
use std::path::Path;
use std::sync::mpsc::{self, Receiver};
use std::time::Duration;

/// Start watching a file for changes with 300ms debounce.
/// Returns a Receiver that gets a () signal on each change.
pub fn watch_file(path: &Path) -> Result<Receiver<()>, Box<dyn std::error::Error>> {
    let (tx, rx) = mpsc::channel();
    let path = path.canonicalize()?;
    let watch_path = path.clone();

    let mut debouncer = new_debouncer(Duration::from_millis(300), move |res: Result<Vec<notify_debouncer_mini::DebouncedEvent>, notify::Error>| {
        if let Ok(events) = res {
            for event in &events {
                if event.kind == DebouncedEventKind::Any && event.path == path {
                    let _ = tx.send(());
                    return;
                }
            }
        }
    })?;

    let parent = watch_path.parent().unwrap_or(&watch_path);
    debouncer.watcher().watch(parent, notify::RecursiveMode::NonRecursive)?;

    // Leak the debouncer so it lives for the program duration
    std::mem::forget(debouncer);

    Ok(rx)
}