Basic naive watcher

Author: Roland Peelen

src/helpers.rs

@@ -1,3 +1,4 @@
+use std::ffi::OsString;
 use std::fs;
 use std::path::Component;
 use std::path::Path;
@@ -119,3 +120,13 @@ pub fn create_build_path(build_path: &str) {
 pub fn get_bsc(root_path: &str) -> String {
     get_node_modules_path(root_path) + "/rescript/darwinarm64/bsc.exe"
 }
+
+pub fn string_ends_with_any(s: &PathBuf, suffixes: &[&str]) -> bool {
+    suffixes.iter().any(|&suffix| {
+        s.extension()
+            .unwrap_or(&OsString::new())
+            .to_str()
+            .unwrap_or("")
+            == suffix
+    })
+}

src/main.rs

@@ -17,6 +17,9 @@ fn main() {
         "build" => {
             build::build(&folder);
         }
+        "watch" => {
+            let _modules = build::build(&folder);
+            watcher::start(&folder);
         }
         _ => println!("Not a valid build command"),
     }

src/watcher.rs

@@ -1,9 +1,12 @@
+use crate::build;
+use crate::helpers;
 use futures::{
     channel::mpsc::{channel, Receiver},
     SinkExt, StreamExt,
 };
 use notify::{Config, Event, RecommendedWatcher, RecursiveMode, Watcher};
 use std::path::Path;
+pub static FILE_TYPES: &[&str] = &["re", "res", "ml", "rei", "resi", "mli"];
 
 fn async_watcher() -> notify::Result<(RecommendedWatcher, Receiver<notify::Result<Event>>)> {
     let (mut tx, rx) = channel(1);
@@ -22,17 +25,32 @@ fn async_watcher() -> notify::Result<(RecommendedWatcher, Receiver<notify::Resul
     Ok((watcher, rx))
 }
 
-async fn async_watch<P: AsRef<Path>>(path: P) -> notify::Result<()> {
+async fn async_watch(path: String) -> notify::Result<()> {
     let (mut watcher, mut rx) = async_watcher()?;
 
     // Add a path to be watched. All files and directories at that path and
     // below will be monitored for changes.
     watcher.watch(path.as_ref(), RecursiveMode::Recursive)?;
 
     while let Some(res) = rx.next().await {
-        match res {
-            Ok(event) => println!("changed: {:?}", event),
-            Err(e) => println!("watch error: {:?}", e),
+        let files_to_compile = res
+            .iter()
+            .map(|event| {
+                event
+                    .paths
+                    .iter()
+                    .map(|path| path.to_path_buf())
+                    .filter(|path| helpers::string_ends_with_any(path, FILE_TYPES))
+                    .collect::<Vec<PathBuf>>()
+            })
+            .flatten()
+            .into_iter()
+            .collect::<Vec<PathBuf>>();
+
+        let delay = Duration::from_millis(10);
+        if files_to_compile.len() > 0 {
+            thread::sleep(delay);
+            build::build(&path);
         }
     }
 
@@ -41,7 +59,7 @@ async fn async_watch<P: AsRef<Path>>(path: P) -> notify::Result<()> {
 
 pub fn start(folder: &str) {
     futures::executor::block_on(async {
-        if let Err(e) = async_watch(folder).await {
+        if let Err(e) = async_watch(folder.to_string()).await {
             println!("error: {:?}", e)
         }
     });