hmr support watchFile

Author: ije

commands/dev.ts

@@ -58,8 +58,11 @@ const handleHMRSocket = (req: Request): Response => {
     if (util.isFilledString(e.data)) {
       try {
         const { type, specifier } = JSON.parse(e.data);
-        if (type === "hotAccept" && util.isFilledString(specifier)) {
-          emitter.on(`hotUpdate:${specifier}`, () => send({ type: "modify", specifier }));
+        if ((type === "modify" || type === "hotUpdate") && util.isFilledString(specifier)) {
+          emitter.on(
+            type === "modify" ? `modify:${specifier}` : `hotUpdate:${specifier}`,
+            () => send({ type: "modify", specifier }),
+          );
         }
       } catch (_e) {
         log.error("invlid socket message:", e.data);
@@ -103,7 +106,6 @@ if (import.meta.main) {
     if (kind === "modify") {
       emitters.forEach((e) => {
         e.emit(`modify:${specifier}`, { specifier });
-        // emit HMR event
         if (e.all.has(`hotUpdate:${specifier}`)) {
           e.emit(`hotUpdate:${specifier}`, { specifier });
         } else if (specifier !== "./routes.gen.ts") {

framework/core/hmr.ts

@@ -1,3 +1,4 @@
+import util from "../../lib/util.ts";
 import events from "./events.ts";
 
 // ESM Hot Module Replacement (ESM-HMR) Specification
@@ -32,6 +33,18 @@ class Module {
     this.accept();
   }
 
+  watchFile(filename: string, callback: () => void) {
+    const specifier = "." + util.cleanPath(filename);
+    const handler = (data: Record<string, unknown>) => {
+      if (data.specifier === specifier) {
+        callback();
+      }
+    };
+    events.on("hmr:modify", handler);
+    sendMessage({ specifier, type: "modify" });
+    return () => events.off("hmr:modify", handler);
+  }
+
   // don't accept updates if the module is locked
   lock(): void {
     this._isLocked = true;
@@ -118,21 +131,23 @@ function connect() {
         const { type, specifier, routePattern } = JSON.parse(data);
         switch (type) {
           case "create": {
-            events.emit("create-file", { routePattern, specifier });
+            events.emit("hmr:create", { specifier, routePattern });
             break;
           }
           case "modify": {
             const mod = modules.get(specifier);
             if (mod) {
               mod.applyUpdate();
+            } else {
+              events.emit("hmr:modify", { specifier });
             }
             break;
           }
           case "remove": {
             if (modules.has(specifier)) {
               modules.delete(specifier);
             }
-            events.emit("remove-file", { specifier });
+            events.emit("hmr:remove", { specifier });
             break;
           }
           case "reload": {

types.d.ts

@@ -69,6 +69,7 @@ declare interface Middleware {
 
 declare interface ImportMeta {
   readonly hot?: {
+    watchFile: (filename: string, callback: () => void) => () => void;
     accept: (callback?: (module: unknown) => void) => void;
     decline: () => void;
   };