Use ReadonlyArray

packages/babel-core/src/config/config-chain.ts

@@ -12,6 +12,7 @@ import type {
 } from "./validation/options";
 import pathPatternToRegex from "./pattern-to-regex";
 import { ConfigPrinter, ChainFormatter } from "./printer";
+import type { ReadonlyDeepArray } from "./helpers/deep-array";
 
 const debug = buildDebug("babel:config:config-chain");
 
@@ -35,8 +36,6 @@ import type {
   ValidatedFile,
 } from "./config-descriptors";
 
-import ReadonlySet from "./helpers/readonly-set";
-
 export type ConfigChain = {
   plugins: Array<UnloadedDescriptor>;
   presets: Array<UnloadedDescriptor>;
@@ -48,7 +47,7 @@ export type PresetInstance = {
   options: ValidatedOptions;
   alias: string;
   dirname: string;
-  externalDependencies: ReadonlySet<string>;
+  externalDependencies: ReadonlyDeepArray<string>;
 };
 
 export type ConfigContext = {

packages/babel-core/src/config/full.ts

@@ -7,6 +7,8 @@ import * as context from "../index";
 import Plugin from "./plugin";
 import { getItemDescriptor } from "./item";
 import { buildPresetChain } from "./config-chain";
+import { finalize as freezeDeepArray } from "./helpers/deep-array";
+import type { DeepArray, ReadonlyDeepArray } from "./helpers/deep-array";
 import type {
   ConfigContext,
   ConfigChain,
@@ -29,32 +31,27 @@ import loadPrivatePartialConfig from "./partial";
 import type { ValidatedOptions } from "./validation/options";
 
 import * as Context from "./cache-contexts";
-import ReadonlySet from "./helpers/readonly-set";
 
 type LoadedDescriptor = {
   value: {};
   options: {};
   dirname: string;
   alias: string;
-  externalDependencies: Set<string>;
+  externalDependencies: DeepArray<string>;
 };
 
 export type { InputOptions } from "./validation/options";
 
 export type ResolvedConfig = {
   options: any;
   passes: PluginPasses;
-  externalDependencies: ReadonlySet<string>;
+  externalDependencies: ReadonlyDeepArray<string>;
 };
 
 export type { Plugin };
 export type PluginPassList = Array<Plugin>;
 export type PluginPasses = Array<PluginPassList>;
 
-function copy<T>(dest: Set<T>, src: ReadonlySet<T>) {
-  src.forEach(dest.add, dest);
-}
-
 export default gensync<(inputOpts: unknown) => ResolvedConfig | null>(
   function* loadFullConfig(inputOpts) {
     const result = yield* loadPrivatePartialConfig(inputOpts);
@@ -94,7 +91,7 @@ export default gensync<(inputOpts: unknown) => ResolvedConfig | null>(
     const pluginDescriptorsByPass: Array<Array<UnloadedDescriptor>> = [[]];
     const passes: Array<Array<Plugin>> = [];
 
-    const externalDependencies = new Set<string>();
+    const externalDependencies: DeepArray<string> = [];
 
     const ignored = yield* enhanceError(
       context,
@@ -123,7 +120,7 @@ export default gensync<(inputOpts: unknown) => ResolvedConfig | null>(
               throw e;
             }
 
-            copy(externalDependencies, preset.externalDependencies);
+            externalDependencies.push(preset.externalDependencies);
 
             // Presets normally run in reverse order, but if they
             // have their own pass they run after the presets
@@ -205,7 +202,7 @@ export default gensync<(inputOpts: unknown) => ResolvedConfig | null>(
             }
             pass.push(plugin);
 
-            copy(externalDependencies, plugin.externalDependencies);
+            externalDependencies.push(plugin.externalDependencies);
           }
         }
       }
@@ -221,7 +218,7 @@ export default gensync<(inputOpts: unknown) => ResolvedConfig | null>(
     return {
       options: opts,
       passes: passes,
-      externalDependencies: new ReadonlySet(externalDependencies),
+      externalDependencies: freezeDeepArray(externalDependencies),
     };
   },
 );
@@ -248,7 +245,7 @@ function enhanceError<T extends Function>(context, fn: T): T {
 const makeDescriptorLoader = <Context, API>(
   apiFactory: (
     cache: CacheConfigurator<Context>,
-    externalDependencies: Set<string>,
+    externalDependencies: Array<string>,
   ) => API,
 ) =>
   makeWeakCache(function* (
@@ -260,7 +257,7 @@ const makeDescriptorLoader = <Context, API>(
 
     options = options || {};
 
-    const externalDependencies = new Set<string>();
+    const externalDependencies: Array<string> = [];
 
     let item = value;
     if (typeof value === "function") {
@@ -302,12 +299,12 @@ const makeDescriptorLoader = <Context, API>(
     }
 
     if (
-      externalDependencies.size > 0 &&
+      externalDependencies.length > 0 &&
       (!cache.configured() || cache.mode() === "forever")
     ) {
-      const [firstDep] = externalDependencies;
-
-      let error = `A plugin/preset has external untracked dependencies (${firstDep}), but the cache `;
+      let error =
+        `A plugin/preset has external untracked dependencies ` +
+        `(${externalDependencies[0]}), but the cache `;
       if (!cache.configured()) {
         error += `has not been configured to be invalidated when the external dependencies change. `;
       } else {
@@ -400,7 +397,7 @@ const instantiatePlugin = makeWeakCache(function* (
       plugin.visitor || {},
     ]);
 
-    copy(externalDependencies, inherits.externalDependencies);
+    externalDependencies.push(inherits.externalDependencies);
   }
 
   return new Plugin(plugin, options, alias, externalDependencies);
@@ -450,7 +447,7 @@ function* loadPresetDescriptor(
   context: Context.FullPreset,
 ): Handler<{
   chain: ConfigChain | null;
-  externalDependencies: ReadonlySet<string>;
+  externalDependencies: ReadonlyDeepArray<string>;
 }> {
   const preset = instantiatePreset(
     yield* presetDescriptorLoader(descriptor, context),
@@ -473,7 +470,7 @@ const instantiatePreset = makeWeakCacheSync(
       options: validate("preset", value),
       alias,
       dirname,
-      externalDependencies: new ReadonlySet(externalDependencies),
+      externalDependencies: freezeDeepArray(externalDependencies),
     };
   },
 );

packages/babel-core/src/config/helpers/config-api.ts

@@ -78,7 +78,7 @@ export function makeConfigAPI<SideChannel extends Context.SimpleConfig>(
 
 export function makePresetAPI<SideChannel extends Context.SimplePreset>(
   cache: CacheConfigurator<SideChannel>,
-  externalDependencies: Set<string>,
+  externalDependencies: Array<string>,
 ): PresetAPI {
   const targets = () =>
     // We are using JSON.parse/JSON.stringify because it's only possible to cache
@@ -88,15 +88,15 @@ export function makePresetAPI<SideChannel extends Context.SimplePreset>(
     JSON.parse(cache.using(data => JSON.stringify(data.targets)));
 
   const addExternalDependency = (ref: string) => {
-    externalDependencies.add(ref);
+    externalDependencies.push(ref);
   };
 
   return { ...makeConfigAPI(cache), targets, addExternalDependency };
 }
 
 export function makePluginAPI<SideChannel extends Context.SimplePlugin>(
   cache: CacheConfigurator<SideChannel>,
-  externalDependencies: Set<string>,
+  externalDependencies: Array<string>,
 ): PluginAPI {
   const assumption = name => cache.using(data => data.assumptions[name]);
 

packages/babel-core/src/config/helpers/deep-array.ts

@@ -0,0 +1,23 @@
+export type DeepArray<T> = Array<T | ReadonlyDeepArray<T>>;
+
+// Just to make sure that DeepArray<T> is not assignable to ReadonlyDeepArray<T>
+declare const __marker: unique symbol;
+export type ReadonlyDeepArray<T> = ReadonlyArray<T | ReadonlyDeepArray<T>> & {
+  [__marker]: true;
+};
+
+export function finalize<T>(deepArr: DeepArray<T>): ReadonlyDeepArray<T> {
+  return Object.freeze(deepArr) as ReadonlyDeepArray<T>;
+}
+
+export function flattenToSet<T>(arr: ReadonlyDeepArray<T>): Set<T> {
+  const result = new Set<T>();
+  const stack = [arr];
+  while (stack.length > 0) {
+    for (const el of stack.pop()) {
+      if (Array.isArray(el)) stack.push(el as ReadonlyDeepArray<T>);
+      else result.add(el as T);
+    }
+  }
+  return result;
+}

packages/babel-core/src/config/plugin.ts

@@ -1,5 +1,6 @@
+import { finalize } from "./helpers/deep-array";
+import type { DeepArray, ReadonlyDeepArray } from "./helpers/deep-array";
 import type { PluginObject } from "./validation/plugins";
-import ReadonlySet from "./helpers/readonly-set";
 
 export default class Plugin {
   key: string | undefined | null;
@@ -13,13 +14,13 @@ export default class Plugin {
 
   options: {};
 
-  externalDependencies: ReadonlySet<string>;
+  externalDependencies: ReadonlyDeepArray<string>;
 
   constructor(
     plugin: PluginObject,
     options: {},
     key?: string,
-    externalDependencies: Set<string> = new Set(),
+    externalDependencies: DeepArray<string> = [],
   ) {
     this.key = plugin.name || key;
 
@@ -32,6 +33,6 @@ export default class Plugin {
 
     this.options = options;
 
-    this.externalDependencies = new ReadonlySet(externalDependencies);
+    this.externalDependencies = finalize(externalDependencies);
   }
 }

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

@@ -13,7 +13,7 @@ import normalizeFile from "./normalize-file";
 import generateCode from "./file/generate";
 import type File from "./file/file";
 
-import type ReadonlySet from "../config/helpers/readonly-set";
+import { flattenToSet } from "../config/helpers/deep-array";
 
 export type FileResultCallback = {
   (err: Error, file: null): any;
@@ -27,7 +27,7 @@ export type FileResult = {
   code: string | null;
   map: SourceMap | null;
   sourceType: "string" | "module";
-  externalDependencies: ReadonlySet<string>;
+  externalDependencies: Set<string>;
 };
 
 export function* run(
@@ -73,7 +73,7 @@ export function* run(
     code: outputCode === undefined ? null : outputCode,
     map: outputMap === undefined ? null : outputMap,
     sourceType: file.ast.program.sourceType,
-    externalDependencies: config.externalDependencies,
+    externalDependencies: flattenToSet(config.externalDependencies),
   };
 }