implement watch mode

Cargo.lock

@@ -959,6 +959,12 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "19b17cddbe7ec3f8bc800887bab5e717348c95ea2ca0b1bf0837fb964dc67099"
 
+[[package]]
+name = "pico-args"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db8bcd96cb740d03149cbad5518db9fd87126a10ab519c011893b1754134c468"
+
 [[package]]
 name = "pkg-config"
 version = "0.3.22"
@@ -1389,6 +1395,7 @@ dependencies = [
  "anyhow",
  "minifb",
  "notify",
+ "pico-args",
  "wasmtime",
 ]
 

Cargo.toml

@@ -10,3 +10,4 @@ wasmtime = "0.30"
 anyhow = "1"
 minifb = "0.19"
 notify = "4"
+pico-args = "0.4"

src/main.rs

@@ -1,18 +1,48 @@
-use anyhow::{anyhow, Result};
+use std::path::PathBuf;
+use std::sync::mpsc;
+use std::time::Duration;
+
+use anyhow::{bail, Result};
 use microw8::MicroW8;
+use notify::{DebouncedEvent, Watcher};
+use pico_args::Arguments;
 
 mod microw8;
 
 fn main() -> Result<()> {
-    let filename = std::env::args()
-        .nth(1)
-        .ok_or_else(|| anyhow!("Missing .uw8 file path"))?;
+    let mut args = Arguments::from_env();
+
+    let watch_mode = args.contains(["-w", "--watch"]);
+
+    let filename = args.free_from_os_str::<PathBuf, bool>(|s| Ok(s.into()))?;
 
     let mut uw8 = MicroW8::new()?;
 
-    uw8.load_from_file(filename)?;
+    let (tx, rx) = mpsc::channel();
+    let mut watcher = notify::watcher(tx, Duration::from_millis(100))?;
+
+    if watch_mode {
+        watcher.watch(&filename, notify::RecursiveMode::NonRecursive)?;
+    }
+
+    if let Err(err) = uw8.load_from_file(&filename) {
+        if !watch_mode {
+            return Err(err);
+        }
+        eprintln!("Load error: {}", err);
+    }
 
     while uw8.is_open() {
+        match rx.try_recv() {
+            Ok(DebouncedEvent::Create(_) | DebouncedEvent::Write(_)) => {
+                if let Err(err) = uw8.load_from_file(&filename) {
+                    eprintln!("Load error: {}", err)
+                }
+            }
+            Err(mpsc::TryRecvError::Disconnected) => bail!("File watcher disconnected"),
+            _ => (),
+        }
+
         uw8.run_frame()?;
     }