1 files changed, 81 insertions, 0 deletions
diff --git a/tools/esmify/is-esmified.js b/tools/esmify/is-esmified.js
new file mode 100644
index 0000000000..872b4cd877
--- /dev/null
+++ b/tools/esmify/is-esmified.js
@@ -0,0 +1,81 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// A utility to check if given JSM is already ESM-ified.
+
+/* eslint-env node */
+
+const fs = require("fs");
+const _path = require("path");
+const { esmifyExtension } = require(_path.resolve(__dirname, "./utils.js"));
+
+let json_map;
+if (process.env.ESMIFY_MAP_JSON) {
+  json_map = _path.resolve(process.env.ESMIFY_MAP_JSON);
+} else {
+  json_map = _path.resolve(__dirname, "./map.json");
+}
+const uri_map = JSON.parse(fs.readFileSync(json_map));
+const esm_uri_map = generateESMURIMap(uri_map);
+
+function generateESMURIMap(jsm_map) {
+  const esm_map = {};
+
+  for (let [uri, jsms] of Object.entries(jsm_map)) {
+    if (typeof jsms === "string") {
+      jsms = [jsms];
+    }
+    esm_map[esmifyExtension(uri)] = jsms.map(esmifyExtension);
+  }
+
+  return esm_map;
+}
+
+function isESMifiedSlow(resourceURI) {
+  if (!(resourceURI in uri_map)) {
+    console.log(`WARNING: Unknown module: ${resourceURI}`);
+    return { result: false, jsms: [] };
+  }
+
+  let jsms = uri_map[resourceURI];
+  if (typeof jsms === "string") {
+    jsms = [jsms];
+  }
+
+  const prefix = "../../";
+  for (const jsm of jsms) {
+    if (fs.existsSync(prefix + jsm)) {
+      return { result: false, jsms };
+    }
+    const esm = esmifyExtension(jsm);
+    if (!fs.existsSync(prefix + esm)) {
+      return { result: false, jsms };
+    }
+  }
+
+  return { result: true, jsms };
+}
+
+const isESMified_memo = {};
+function isESMified(resourceURI, files) {
+  if (!(resourceURI in isESMified_memo)) {
+    isESMified_memo[resourceURI] = isESMifiedSlow(resourceURI);
+  }
+
+  for (const jsm of isESMified_memo[resourceURI].jsms) {
+    files.push(esmifyExtension(jsm));
+  }
+
+  return isESMified_memo[resourceURI].result;
+}
+
+function getESMFiles(resourceURI) {
+  if (resourceURI in esm_uri_map) {
+    return esm_uri_map[resourceURI];
+  }
+  return [];
+}
+
+exports.isESMified = isESMified;
+exports.getESMFiles = getESMFiles;