1 files changed, 208 insertions, 0 deletions
diff --git a/tools/esmify/use-import-export-declarations.js b/tools/esmify/use-import-export-declarations.js
new file mode 100644
index 0000000000..fe8c4dd286
--- /dev/null
+++ b/tools/esmify/use-import-export-declarations.js
@@ -0,0 +1,208 @@
+/* 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/. */
+
+// jscodeshift rule to replace EXPORTED_SYMBOLS with export declarations,
+// and also convert existing ChromeUtils.importESModule to static import.
+
+/* eslint-env node */
+
+const _path = require("path");
+const {
+  warnForPath,
+  getPrevStatement,
+  getNextStatement,
+} = require(_path.resolve(__dirname, "./utils.js"));
+const {
+  isImportESModuleCall,
+  replaceImportESModuleCall,
+} = require(_path.resolve(__dirname, "./static-import.js"));
+
+module.exports = function (fileInfo, api) {
+  const { jscodeshift } = api;
+  const root = jscodeshift(fileInfo.source);
+  doTranslate(fileInfo.path, jscodeshift, root);
+  return root.toSource({ lineTerminator: "\n" });
+};
+
+module.exports.doTranslate = doTranslate;
+
+// Move the comment for `path.node` to adjacent statement, keeping the position
+// as much as possible.
+function moveComments(inputFile, path) {
+  const next = getNextStatement(path);
+  if (next) {
+    if (next.comments) {
+      next.comments = [...path.node.comments, ...next.comments];
+    } else {
+      next.comments = path.node.comments;
+    }
+    path.node.comments = [];
+
+    return;
+  }
+
+  const prev = getPrevStatement(path);
+  if (prev) {
+    path.node.comments.forEach(c => {
+      c.leading = false;
+      c.trailing = true;
+    });
+
+    if (prev.comments) {
+      prev.comments = [...prev.comments, ...path.node.comments];
+    } else {
+      prev.comments = path.node.comments;
+    }
+    path.node.comments = [];
+
+    return;
+  }
+
+  warnForPath(
+    inputFile,
+    path,
+    `EXPORTED_SYMBOLS has comments and it cannot be preserved`
+  );
+}
+
+function collectAndRemoveExportedSymbols(inputFile, root) {
+  const nodes = root.findVariableDeclarators("EXPORTED_SYMBOLS");
+  if (!nodes.length) {
+    throw Error(`EXPORTED_SYMBOLS not found`);
+  }
+
+  let path = nodes.get(0);
+  const obj = nodes.get(0).node.init;
+  if (!obj) {
+    throw Error(`EXPORTED_SYMBOLS is not statically known`);
+  }
+
+  if (path.parent.node.declarations.length !== 1) {
+    throw Error(`EXPORTED_SYMBOLS shouldn't be declared with other variables`);
+  }
+
+  if (path.parent.node.comments && path.parent.node.comments.length) {
+    moveComments(inputFile, path.parent);
+  }
+
+  path.parent.prune();
+
+  const EXPORTED_SYMBOLS = new Set();
+  if (obj.type !== "ArrayExpression") {
+    throw Error(`EXPORTED_SYMBOLS is not statically known`);
+  }
+
+  for (const elem of obj.elements) {
+    if (elem.type !== "Literal") {
+      throw Error(`EXPORTED_SYMBOLS is not statically known`);
+    }
+    var name = elem.value;
+    if (typeof name !== "string") {
+      throw Error(`EXPORTED_SYMBOLS item must be a string`);
+    }
+    EXPORTED_SYMBOLS.add(name);
+  }
+
+  return EXPORTED_SYMBOLS;
+}
+
+function isTopLevel(path) {
+  return path.parent.node.type === "Program";
+}
+
+function convertToExport(jscodeshift, path, name) {
+  const e = jscodeshift.exportNamedDeclaration(path.node);
+  e.comments = [];
+  e.comments = path.node.comments;
+  path.node.comments = [];
+
+  path.replace(e);
+}
+
+function doTranslate(inputFile, jscodeshift, root) {
+  const EXPORTED_SYMBOLS = collectAndRemoveExportedSymbols(inputFile, root);
+
+  root.find(jscodeshift.FunctionDeclaration).forEach(path => {
+    if (!isTopLevel(path)) {
+      return;
+    }
+    const name = path.node.id.name;
+    if (!EXPORTED_SYMBOLS.has(name)) {
+      return;
+    }
+    EXPORTED_SYMBOLS.delete(name);
+    convertToExport(jscodeshift, path, name);
+  });
+
+  root.find(jscodeshift.ClassDeclaration).forEach(path => {
+    if (!isTopLevel(path)) {
+      return;
+    }
+    const name = path.node.id.name;
+    if (!EXPORTED_SYMBOLS.has(name)) {
+      return;
+    }
+    EXPORTED_SYMBOLS.delete(name);
+    convertToExport(jscodeshift, path, name);
+  });
+
+  root.find(jscodeshift.VariableDeclaration).forEach(path => {
+    if (!isTopLevel(path)) {
+      return;
+    }
+
+    let exists = false;
+    let name;
+    for (const decl of path.node.declarations) {
+      if (decl.id.type === "Identifier") {
+        name = decl.id.name;
+        if (EXPORTED_SYMBOLS.has(name)) {
+          exists = true;
+          break;
+        }
+      }
+
+      if (decl.id.type === "ObjectPattern") {
+        if (decl.id.properties.length === 1) {
+          const prop = decl.id.properties[0];
+          if (prop.shorthand) {
+            if (prop.key.type === "Identifier") {
+              name = prop.key.name;
+              if (EXPORTED_SYMBOLS.has(name)) {
+                exists = true;
+                break;
+              }
+            }
+          }
+        }
+      }
+    }
+    if (!exists) {
+      return;
+    }
+
+    if (path.node.declarations.length !== 1) {
+      throw Error(
+        `exported variable shouldn't be declared with other variables`
+      );
+    }
+
+    EXPORTED_SYMBOLS.delete(name);
+    convertToExport(jscodeshift, path, name);
+  });
+
+  if (EXPORTED_SYMBOLS.size !== 0) {
+    throw Error(
+      `exported symbols ${[...EXPORTED_SYMBOLS].join(", ")} not found`
+    );
+  }
+
+  root.find(jscodeshift.CallExpression).forEach(path => {
+    if (isImportESModuleCall(path.node)) {
+      // This file is not yet renamed. Skip the extension check.
+      // Also skip the isTargetESM.
+      replaceImportESModuleCall(inputFile, jscodeshift, path, true);
+    }
+  });
+}