convert @babel/helpers to typescript (#13679)

Co-authored-by: Federico Ciardi <fed.ciardi@gmail.com>

Gulpfile.mjs

@@ -149,7 +149,7 @@ async function generateRuntimeHelpers() {
   return generateHelpers(
     `./packages/babel-helpers/scripts/generate-helpers.js`,
     `./packages/babel-helpers/src/`,
-    "helpers-generated.js",
+    "helpers-generated.ts",
     "@babel/helpers"
   );
 }

packages/babel-core/src/tools/build-external-helpers.ts

@@ -7,7 +7,7 @@ import File from "../transformation/file/file";
 // Wrapped to avoid wasting time parsing this when almost no-one uses
 // build-external-helpers.
 const buildUmdWrapper = replacements =>
-  template`
+  template.statement`
     (function (root, factory) {
       if (typeof define === "function" && define.amd) {
         define(AMD_ARGUMENTS, factory);
@@ -21,10 +21,10 @@ const buildUmdWrapper = replacements =>
     });
   `(replacements);
 
-function buildGlobal(allowlist) {
+function buildGlobal(allowlist?: Array<string>) {
   const namespace = t.identifier("babelHelpers");
 
-  const body = [];
+  const body: t.Statement[] = [];
   const container = t.functionExpression(
     null,
     [t.identifier("global")],
@@ -65,8 +65,8 @@ function buildGlobal(allowlist) {
   return tree;
 }
 
-function buildModule(allowlist) {
-  const body = [];
+function buildModule(allowlist?: Array<string>) {
+  const body: t.Statement[] = [];
   const refs = buildHelpers(body, null, allowlist);
 
   body.unshift(
@@ -81,10 +81,10 @@ function buildModule(allowlist) {
   return t.program(body, [], "module");
 }
 
-function buildUmd(allowlist) {
+function buildUmd(allowlist?: Array<string>) {
   const namespace = t.identifier("babelHelpers");
 
-  const body = [];
+  const body: t.Statement[] = [];
   body.push(
     t.variableDeclaration("var", [
       t.variableDeclarator(namespace, t.identifier("global")),
@@ -105,14 +105,14 @@ function buildUmd(allowlist) {
       AMD_ARGUMENTS: t.arrayExpression([t.stringLiteral("exports")]),
       FACTORY_BODY: body,
       UMD_ROOT: t.identifier("this"),
-    }) as t.Statement,
+    }),
   ]);
 }
 
-function buildVar(allowlist) {
+function buildVar(allowlist?: Array<string>) {
   const namespace = t.identifier("babelHelpers");
 
-  const body = [];
+  const body: t.Statement[] = [];
   body.push(
     t.variableDeclaration("var", [
       t.variableDeclarator(namespace, t.objectExpression([])),
@@ -124,8 +124,12 @@ function buildVar(allowlist) {
   return tree;
 }
 
-function buildHelpers(body, namespace, allowlist) {
-  const getHelperReference = name => {
+function buildHelpers(
+  body: t.Statement[],
+  namespace: t.Expression | null,
+  allowlist?: Array<string>,
+) {
+  const getHelperReference = (name: string) => {
     return namespace
       ? t.memberExpression(namespace, t.identifier(name))
       : t.identifier(`_${name}`);
@@ -148,7 +152,7 @@ export default function (
   allowlist?: Array<string>,
   outputType: "global" | "module" | "umd" | "var" = "global",
 ) {
-  let tree;
+  let tree: t.Program;
 
   const build = {
     global: buildGlobal,

packages/babel-core/src/transformation/file/file.ts

@@ -174,7 +174,7 @@ export default class File {
     );
   }
 
-  addHelper(name: string): any {
+  addHelper(name: string): t.Identifier {
     const declar = this.declarations[name];
     if (declar) return t.cloneNode(declar);
 
@@ -209,6 +209,7 @@ export default class File {
     });
 
     nodes.forEach(node => {
+      // @ts-expect-error
       node._compact = true;
     });
 

packages/babel-helpers/src/helpers.ts

@@ -1,13 +1,17 @@
-// @flow
-
 import template from "@babel/template";
+import type * as t from "@babel/types";
 
 import * as generated from "./helpers-generated";
 
-const helpers = { __proto__: null, ...generated };
+interface Helper {
+  minVersion: string;
+  ast: () => t.Program;
+}
+
+const helpers: Record<string, Helper> = { __proto__: null, ...generated };
 export default helpers;
 
-const helper = (minVersion: string) => tpl => ({
+const helper = (minVersion: string) => (tpl: TemplateStringsArray) => ({
   minVersion,
   ast: () => template.program.ast(tpl),
 });

packages/babel-helpers/src/index.ts

@@ -1,8 +1,10 @@
+import type { File } from "@babel/core";
+import type { NodePath, Visitor } from "@babel/traverse";
 import traverse from "@babel/traverse";
 import * as t from "@babel/types";
 import helpers from "./helpers";
 
-function makePath(path) {
+function makePath(path: NodePath) {
   const parts = [];
 
   for (; path.parentPath; path = path.parentPath) {
@@ -14,23 +16,35 @@ function makePath(path) {
 }
 
 let fileClass = undefined;
+
+interface HelperMetadata {
+  globals: string[];
+  localBindingNames: string[];
+  dependencies: Map<t.Identifier, string>;
+  exportBindingAssignments: string[];
+  exportPath: string;
+  exportName: string;
+  importBindingsReferences: string[];
+  importPaths: string[];
+}
+
 /**
  * Given a file AST for a given helper, get a bunch of metadata about it so that Babel can quickly render
  * the helper is whatever context it is needed in.
  */
-function getHelperMetadata(file) {
-  const globals = new Set();
-  const localBindingNames = new Set();
+function getHelperMetadata(file: File): HelperMetadata {
+  const globals = new Set<string>();
+  const localBindingNames = new Set<string>();
   // Maps imported identifier -> helper name
-  const dependencies = new Map();
+  const dependencies = new Map<t.Identifier, string>();
 
-  let exportName;
-  let exportPath;
-  const exportBindingAssignments = [];
-  const importPaths = [];
-  const importBindingsReferences = [];
+  let exportName: string | undefined;
+  let exportPath: string | undefined;
+  const exportBindingAssignments: string[] = [];
+  const importPaths: string[] = [];
+  const importBindingsReferences: string[] = [];
 
-  const dependencyVisitor = {
+  const dependencyVisitor: Visitor = {
     ImportDeclaration(child) {
       const name = child.node.source.value;
       if (!helpers[name]) {
@@ -75,7 +89,7 @@ function getHelperMetadata(file) {
     },
   };
 
-  const referenceVisitor = {
+  const referenceVisitor: Visitor = {
     Program(path) {
       const bindings = path.scope.getAllBindings();
 
@@ -88,7 +102,7 @@ function getHelperMetadata(file) {
     },
     ReferencedIdentifier(child) {
       const name = child.node.name;
-      const binding = child.scope.getBinding(name, /* noGlobal */ true);
+      const binding = child.scope.getBinding(name);
       if (!binding) {
         globals.add(name);
       } else if (dependencies.has(binding.identifier)) {
@@ -135,10 +149,18 @@ function getHelperMetadata(file) {
   };
 }
 
+type GetDependency = (name: string) => t.Expression;
+
 /**
  * Given a helper AST and information about how it will be used, update the AST to match the usage.
  */
-function permuteHelperAST(file, metadata, id, localBindings, getDependency) {
+function permuteHelperAST(
+  file: File,
+  metadata: HelperMetadata,
+  id?: t.Identifier | t.MemberExpression,
+  localBindings?: string[],
+  getDependency?: GetDependency,
+) {
   if (localBindings && !id) {
     throw new Error("Unexpected local bindings for module-based helpers.");
   }
@@ -155,13 +177,13 @@ function permuteHelperAST(file, metadata, id, localBindings, getDependency) {
     importPaths,
   } = metadata;
 
-  const dependenciesRefs = {};
+  const dependenciesRefs: Record<string, t.Expression> = {};
   dependencies.forEach((name, id) => {
     dependenciesRefs[id.name] =
       (typeof getDependency === "function" && getDependency(name)) || id;
   });
 
-  const toRename = {};
+  const toRename: Record<string, string> = {};
   const bindings = new Set(localBindings || []);
   localBindingNames.forEach(name => {
     let newName = name;
@@ -174,13 +196,16 @@ function permuteHelperAST(file, metadata, id, localBindings, getDependency) {
     toRename[exportName] = id.name;
   }
 
-  const visitor = {
+  const visitor: Visitor = {
     Program(path) {
       // We need to compute these in advance because removing nodes would
       // invalidate the paths.
-      const exp = path.get(exportPath);
-      const imps = importPaths.map(p => path.get(p));
-      const impsBindingRefs = importBindingsReferences.map(p => path.get(p));
+      const exp: NodePath<t.ExportDefaultDeclaration> = path.get(exportPath);
+      const imps: NodePath<t.ImportDeclaration>[] = importPaths.map(p =>
+        path.get(p),
+      );
+      const impsBindingRefs: NodePath<t.Identifier>[] =
+        importBindingsReferences.map(p => path.get(p));
 
       const decl = exp.get("declaration");
       if (id.type === "Identifier") {
@@ -188,13 +213,15 @@ function permuteHelperAST(file, metadata, id, localBindings, getDependency) {
           exp.replaceWith(decl);
         } else {
           exp.replaceWith(
-            t.variableDeclaration("var", [t.variableDeclarator(id, decl.node)]),
+            t.variableDeclaration("var", [
+              t.variableDeclarator(id, decl.node as t.Expression),
+            ]),
           );
         }
       } else if (id.type === "MemberExpression") {
         if (decl.isFunctionDeclaration()) {
           exportBindingAssignments.forEach(assignPath => {
-            const assign = path.get(assignPath);
+            const assign: NodePath<t.Expression> = path.get(assignPath);
             assign.replaceWith(t.assignmentExpression("=", id, assign.node));
           });
           exp.replaceWith(decl);
@@ -206,7 +233,9 @@ function permuteHelperAST(file, metadata, id, localBindings, getDependency) {
           );
         } else {
           exp.replaceWith(
-            t.expressionStatement(t.assignmentExpression("=", id, decl.node)),
+            t.expressionStatement(
+              t.assignmentExpression("=", id, decl.node as t.Expression),
+            ),
           );
         }
       } else {
@@ -231,8 +260,21 @@ function permuteHelperAST(file, metadata, id, localBindings, getDependency) {
   traverse(file.ast, visitor, file.scope);
 }
 
-const helperData = Object.create(null);
-function loadHelper(name) {
+interface HelperData {
+  build: (
+    getDependency: GetDependency,
+    id: t.Identifier | t.MemberExpression,
+    localBindings: string[],
+  ) => {
+    nodes: t.Program["body"];
+    globals: string[];
+  };
+  minVersion: () => string;
+  dependencies: Map<t.Identifier, string>;
+}
+
+const helperData: Record<string, HelperData> = Object.create(null);
+function loadHelper(name: string) {
   if (!helperData[name]) {
     const helper = helpers[name];
     if (!helper) {
@@ -242,7 +284,7 @@ function loadHelper(name) {
       });
     }
 
-    const fn = () => {
+    const fn = (): File => {
       const file = { ast: t.file(helper.ast()) };
       if (fileClass) {
         return new fileClass(
@@ -252,7 +294,7 @@ function loadHelper(name) {
           file,
         );
       }
-      return file;
+      return file as File;
     };
 
     const metadata = getHelperMetadata(fn());
@@ -278,9 +320,9 @@ function loadHelper(name) {
 }
 
 export function get(
-  name,
-  getDependency?: string => ?t.Expression,
-  id?,
+  name: string,
+  getDependency?: GetDependency,
+  id?: t.Identifier | t.MemberExpression,
   localBindings?: string[],
 ) {
   return loadHelper(name).build(getDependency, id, localBindings);
@@ -290,7 +332,7 @@ export function minVersion(name: string) {
   return loadHelper(name).minVersion();
 }
 
-export function getDependencies(name: string): $ReadOnlyArray<string> {
+export function getDependencies(name: string): ReadonlyArray<string> {
   return Array.from(loadHelper(name).dependencies.values());
 }
 

packages/babel-traverse/src/scope/index.ts

@@ -1031,7 +1031,7 @@ export default class Scope {
    * Walks the scope tree and gathers **all** bindings.
    */
 
-  getAllBindings(): any {
+  getAllBindings(): Record<string, Binding> {
     const ids = Object.create(null);
 
     let scope: Scope = this;

tsconfig.json

@@ -24,6 +24,7 @@
     "./packages/babel-helper-transform-fixture-test-runner/src/**/*.ts",
     "./packages/babel-helper-validator-identifier/src/**/*.ts",
     "./packages/babel-helper-validator-option/src/**/*.ts",
+    "./packages/babel-helpers/src/**/*.ts",
     "./packages/babel-highlight/src/**/*.ts",
     "./packages/babel-plugin-bugfix-v8-spread-parameters-in-optional-chaining/src/**/*.ts",
     "./packages/babel-plugin-proposal-async-do-expressions/src/**/*.ts",
@@ -107,6 +108,9 @@
       "@babel/helper-validator-option": [
         "./packages/babel-helper-validator-option/src"
       ],
+      "@babel/helpers": [
+        "./packages/babel-helpers/src"
+      ],
       "@babel/highlight": [
         "./packages/babel-highlight/src"
       ],