lib: restructure cjs and esm loaders

Create `lib/internal/modules` and restructure the module loaders
to make the purpose of those files clearer.

Also make it clear in the code that the object exported by
`lib/internal/modules/cjs/loader.js` is `CJSModule` instead of the
ambiguous `Module`.

Before:

```
lib
├── ...
├── internal
│       ├── loaders
│       │     ├── CreateDynamicModule.js
│       │     ├── DefaultResolve.js
│       │     ├── Loader.js
│       │     ├── ModuleJob.js
│       │     ├── ModuleMap.js
│       │     ├── ModuleWrap.js
│       │     └── Translators.js
│       └── module.js
└── module.js
```

After:

```
lib
├── ...
├── internal
│       ├── ...
│       └── modules
│              ├── cjs
│              │     ├── helpers.js
│              │     └── loader.js
│              └── esm
│                    ├── CreateDynamicModule.js
│                    ├── DefaultResolve.js
│                    ├── Loader.js
│                    ├── ModuleJob.js
│                    ├── ModuleMap.js
│                    └── Translators.js
└── module.js # deleted in this commit to work with git file mode
```

Backport-PR-URL: #19374
PR-URL: #19177
Refs: #19112
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

lib/internal/bootstrap/loaders.js

@@ -1,6 +1,7 @@
 // This file creates the internal module & binding loaders used by built-in
 // modules. In contrast, user land modules are loaded using
-// lib/module.js (CommonJS Modules) or lib/internal/loader/* (ES Modules).
+// lib/internal/modules/cjs/loader.js (CommonJS Modules) or
+// lib/internal/modules/esm/* (ES Modules).
 //
 // This file is compiled and run by node.cc before bootstrap/node.js
 // was called, therefore the loaders are bootstraped before we start to

lib/internal/bootstrap/node.js

@@ -110,7 +110,7 @@
       process.emitWarning(
         'The ESM module loader is experimental.',
         'ExperimentalWarning', undefined);
-      NativeModule.require('internal/process/modules').setup();
+      NativeModule.require('internal/process/esm_loader').setup();
     }
 
 
@@ -170,22 +170,24 @@
         preloadModules();
         perf.markMilestone(NODE_PERFORMANCE_MILESTONE_PRELOAD_MODULE_LOAD_END);
 
-        const internalModule = NativeModule.require('internal/module');
-        internalModule.addBuiltinLibsToObject(global);
+        const {
+          addBuiltinLibsToObject
+        } = NativeModule.require('internal/modules/cjs/helpers');
+        addBuiltinLibsToObject(global);
         evalScript('[eval]');
       } else if (process.argv[1] && process.argv[1] !== '-') {
         perf.markMilestone(NODE_PERFORMANCE_MILESTONE_MODULE_LOAD_START);
         // make process.argv[1] into a full path
         const path = NativeModule.require('path');
         process.argv[1] = path.resolve(process.argv[1]);
 
-        const Module = NativeModule.require('module');
+        const CJSModule = NativeModule.require('internal/modules/cjs/loader');
 
         // check if user passed `-c` or `--check` arguments to Node.
         if (process._syntax_check_only != null) {
           const fs = NativeModule.require('fs');
           // read the source
-          const filename = Module._resolveFilename(process.argv[1]);
+          const filename = CJSModule._resolveFilename(process.argv[1]);
           const source = fs.readFileSync(filename, 'utf-8');
           checkScriptSyntax(source, filename);
           process.exit(0);
@@ -196,7 +198,7 @@
         preloadModules();
         perf.markMilestone(
           NODE_PERFORMANCE_MILESTONE_PRELOAD_MODULE_LOAD_END);
-        Module.runMain();
+        CJSModule.runMain();
       } else {
         perf.markMilestone(NODE_PERFORMANCE_MILESTONE_MODULE_LOAD_START);
         perf.markMilestone(NODE_PERFORMANCE_MILESTONE_MODULE_LOAD_END);
@@ -321,7 +323,7 @@
 
   function setupGlobalConsole() {
     const originalConsole = global.console;
-    const Module = NativeModule.require('module');
+    const CJSModule = NativeModule.require('internal/modules/cjs/loader');
     // Setup Node.js global.console
     const wrappedConsole = NativeModule.require('console');
     Object.defineProperty(global, 'console', {
@@ -331,22 +333,23 @@
         return wrappedConsole;
       }
     });
-    setupInspector(originalConsole, wrappedConsole, Module);
+    setupInspector(originalConsole, wrappedConsole, CJSModule);
   }
 
-  function setupInspector(originalConsole, wrappedConsole, Module) {
+  function setupInspector(originalConsole, wrappedConsole, CJSModule) {
     if (!process.config.variables.v8_enable_inspector) {
       return;
     }
     const { addCommandLineAPI, consoleCall } = process.binding('inspector');
     // Setup inspector command line API
-    const { makeRequireFunction } = NativeModule.require('internal/module');
+    const { makeRequireFunction } =
+      NativeModule.require('internal/modules/cjs/helpers');
     const path = NativeModule.require('path');
     const cwd = tryGetCwd(path);
 
-    const consoleAPIModule = new Module('<inspector console>');
+    const consoleAPIModule = new CJSModule('<inspector console>');
     consoleAPIModule.paths =
-        Module._nodeModulePaths(cwd).concat(Module.globalPaths);
+        CJSModule._nodeModulePaths(cwd).concat(CJSModule.globalPaths);
     addCommandLineAPI('require', makeRequireFunction(consoleAPIModule));
     const config = {};
     for (const key of Object.keys(wrappedConsole)) {
@@ -461,13 +464,13 @@
   }
 
   function evalScript(name) {
-    const Module = NativeModule.require('module');
+    const CJSModule = NativeModule.require('internal/modules/cjs/loader');
     const path = NativeModule.require('path');
     const cwd = tryGetCwd(path);
 
-    const module = new Module(name);
+    const module = new CJSModule(name);
     module.filename = path.join(cwd, name);
-    module.paths = Module._nodeModulePaths(cwd);
+    module.paths = CJSModule._nodeModulePaths(cwd);
     const body = wrapForBreakOnFirstLine(process._eval);
     const script = `global.__filename = ${JSON.stringify(name)};\n` +
                    'global.exports = exports;\n' +
@@ -486,21 +489,26 @@
   // Load preload modules
   function preloadModules() {
     if (process._preload_modules) {
-      NativeModule.require('module')._preloadModules(process._preload_modules);
+      const {
+        _preloadModules
+      } = NativeModule.require('internal/modules/cjs/loader');
+      _preloadModules(process._preload_modules);
     }
   }
 
   function checkScriptSyntax(source, filename) {
-    const Module = NativeModule.require('module');
+    const CJSModule = NativeModule.require('internal/modules/cjs/loader');
     const vm = NativeModule.require('vm');
-    const internalModule = NativeModule.require('internal/module');
+    const {
+      stripShebang, stripBOM
+    } = NativeModule.require('internal/modules/cjs/helpers');
 
     // remove Shebang
-    source = internalModule.stripShebang(source);
+    source = stripShebang(source);
     // remove BOM
-    source = internalModule.stripBOM(source);
+    source = stripBOM(source);
     // wrap it
-    source = Module.wrap(source);
+    source = CJSModule.wrap(source);
     // compile the script, this will throw if it fails
     new vm.Script(source, { displayErrors: true, filename });
   }

lib/module.js → lib/internal/modules/cjs/loader.js

@@ -34,7 +34,12 @@ const {
   internalModuleReadFile,
   internalModuleStat
 } = process.binding('fs');
-const internalModule = require('internal/module');
+const {
+  makeRequireFunction,
+  requireDepth,
+  stripBOM,
+  stripShebang
+} = require('internal/modules/cjs/helpers');
 const preserveSymlinks = !!process.binding('config').preserveSymlinks;
 const experimentalModules = !!process.binding('config').experimentalModules;
 
@@ -43,9 +48,9 @@ const errors = require('internal/errors');
 module.exports = Module;
 
 // these are below module.exports for the circular reference
-const internalESModule = require('internal/process/modules');
-const ModuleJob = require('internal/loader/ModuleJob');
-const createDynamicModule = require('internal/loader/CreateDynamicModule');
+const asyncESM = require('internal/process/esm_loader');
+const ModuleJob = require('internal/modules/esm/ModuleJob');
+const createDynamicModule = require('internal/modules/esm/CreateDynamicModule');
 
 function stat(filename) {
   filename = path.toNamespacedPath(filename);
@@ -456,7 +461,7 @@ Module._load = function(request, parent, isMain) {
   }
 
   if (experimentalModules && isMain) {
-    internalESModule.loaderPromise.then((loader) => {
+    asyncESM.loaderPromise.then((loader) => {
       return loader.import(getURLFromFilePath(request).pathname);
     })
     .catch((e) => {
@@ -562,7 +567,7 @@ Module.prototype.load = function(filename) {
   this.loaded = true;
 
   if (experimentalModules) {
-    const ESMLoader = internalESModule.ESMLoader;
+    const ESMLoader = asyncESM.ESMLoader;
     const url = getURLFromFilePath(filename);
     const urlString = `${url}`;
     const exports = this.exports;
@@ -605,7 +610,7 @@ var resolvedArgv;
 // Returns exception, if any.
 Module.prototype._compile = function(content, filename) {
 
-  content = internalModule.stripShebang(content);
+  content = stripShebang(content);
 
   // create wrapper function
   var wrapper = Module.wrap(content);
@@ -638,8 +643,8 @@ Module.prototype._compile = function(content, filename) {
     }
   }
   var dirname = path.dirname(filename);
-  var require = internalModule.makeRequireFunction(this);
-  var depth = internalModule.requireDepth;
+  var require = makeRequireFunction(this);
+  var depth = requireDepth;
   if (depth === 0) stat.cache = new Map();
   var result;
   if (inspectorWrapper) {
@@ -657,15 +662,15 @@ Module.prototype._compile = function(content, filename) {
 // Native extension for .js
 Module._extensions['.js'] = function(module, filename) {
   var content = fs.readFileSync(filename, 'utf8');
-  module._compile(internalModule.stripBOM(content), filename);
+  module._compile(stripBOM(content), filename);
 };
 
 
 // Native extension for .json
 Module._extensions['.json'] = function(module, filename) {
   var content = fs.readFileSync(filename, 'utf8');
   try {
-    module.exports = JSON.parse(internalModule.stripBOM(content));
+    module.exports = JSON.parse(stripBOM(content));
   } catch (err) {
     err.message = filename + ': ' + err.message;
     throw err;

lib/internal/loader/DefaultResolve.js → lib/internal/modules/esm/DefaultResolve.js

@@ -1,7 +1,7 @@
 'use strict';
 
 const { URL } = require('url');
-const CJSmodule = require('module');
+const CJSmodule = require('internal/modules/cjs/loader');
 const internalFS = require('internal/fs');
 const { NativeModule, internalBinding } = require('internal/bootstrap/loaders');
 const { extname } = require('path');

lib/internal/loader/Loader.js → lib/internal/modules/esm/Loader.js

@@ -1,11 +1,11 @@
 'use strict';
 
 const errors = require('internal/errors');
-const ModuleMap = require('internal/loader/ModuleMap');
-const ModuleJob = require('internal/loader/ModuleJob');
-const defaultResolve = require('internal/loader/DefaultResolve');
-const createDynamicModule = require('internal/loader/CreateDynamicModule');
-const translators = require('internal/loader/Translators');
+const ModuleMap = require('internal/modules/esm/ModuleMap');
+const ModuleJob = require('internal/modules/esm/ModuleJob');
+const defaultResolve = require('internal/modules/esm/DefaultResolve');
+const createDynamicModule = require('internal/modules/esm/CreateDynamicModule');
+const translators = require('internal/modules/esm/Translators');
 
 const FunctionBind = Function.call.bind(Function.prototype.bind);
 

lib/internal/loader/ModuleMap.js → lib/internal/modules/esm/ModuleMap.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const ModuleJob = require('internal/loader/ModuleJob');
+const ModuleJob = require('internal/modules/esm/ModuleJob');
 const { SafeMap } = require('internal/safe_globals');
 const debug = require('util').debuglog('esm');
 const errors = require('internal/errors');

lib/internal/loader/Translators.js → lib/internal/modules/esm/Translators.js

@@ -2,10 +2,13 @@
 
 const { NativeModule, internalBinding } = require('internal/bootstrap/loaders');
 const { ModuleWrap } = internalBinding('module_wrap');
-const internalCJSModule = require('internal/module');
-const CJSModule = require('module');
+const {
+  stripShebang,
+  stripBOM
+} = require('internal/modules/cjs/helpers');
+const CJSModule = require('internal/modules/cjs/loader');
 const internalURLModule = require('internal/url');
-const createDynamicModule = require('internal/loader/CreateDynamicModule');
+const createDynamicModule = require('internal/modules/esm/CreateDynamicModule');
 const fs = require('fs');
 const { _makeLong } = require('path');
 const { SafeMap } = require('internal/safe_globals');
@@ -24,7 +27,7 @@ translators.set('esm', async (url) => {
   const source = `${await readFileAsync(new URL(url))}`;
   debug(`Translating StandardModule ${url}`);
   return {
-    module: new ModuleWrap(internalCJSModule.stripShebang(source), url),
+    module: new ModuleWrap(stripShebang(source), url),
     reflect: undefined
   };
 });
@@ -82,7 +85,7 @@ translators.set('json', async (url) => {
     const pathname = internalURLModule.getPathFromURL(new URL(url));
     const content = readFileSync(pathname, 'utf8');
     try {
-      const exports = JsonParse(internalCJSModule.stripBOM(content));
+      const exports = JsonParse(stripBOM(content));
       reflect.exports.default.set(exports);
     } catch (err) {
       err.message = pathname + ': ' + err.message;

lib/internal/process/modules.js → lib/internal/process/esm_loader.js

@@ -6,7 +6,7 @@ const {
 } = internalBinding('module_wrap');
 
 const { getURLFromFilePath } = require('internal/url');
-const Loader = require('internal/loader/Loader');
+const Loader = require('internal/modules/esm/Loader');
 const path = require('path');
 const { URL } = require('url');
 

lib/repl.js

@@ -42,7 +42,11 @@
 
 'use strict';
 
-const internalModule = require('internal/module');
+const {
+  builtinLibs,
+  makeRequireFunction,
+  addBuiltinLibsToObject
+} = require('internal/modules/cjs/helpers');
 const internalUtil = require('internal/util');
 const { isTypedArray } = require('internal/util/types');
 const util = require('util');
@@ -54,7 +58,7 @@ const path = require('path');
 const fs = require('fs');
 const { Interface } = require('readline');
 const { Console } = require('console');
-const Module = require('module');
+const CJSModule = require('internal/modules/cjs/loader');
 const domain = require('domain');
 const debug = util.debuglog('repl');
 const errors = require('internal/errors');
@@ -90,7 +94,7 @@ try {
 }
 
 // Hack for repl require to work properly with node_modules folders
-module.paths = Module._nodeModulePaths(module.filename);
+module.paths = CJSModule._nodeModulePaths(module.filename);
 
 // If obj.hasOwnProperty has been overridden, then calling
 // obj.hasOwnProperty(prop) will break.
@@ -103,7 +107,7 @@ function hasOwnProperty(obj, prop) {
 // This is the default "writer" value if none is passed in the REPL options.
 exports.writer = util.inspect;
 
-exports._builtinLibs = internalModule.builtinLibs;
+exports._builtinLibs = builtinLibs;
 
 function REPLServer(prompt,
                     stream,
@@ -673,14 +677,15 @@ REPLServer.prototype.createContext = function() {
     }
   }
 
-  var module = new Module('<repl>');
-  module.paths = Module._resolveLookupPaths('<repl>', parentModule, true) || [];
+  var module = new CJSModule('<repl>');
+  module.paths =
+    CJSModule._resolveLookupPaths('<repl>', parentModule, true) || [];
 
-  var require = internalModule.makeRequireFunction(module);
+  var require = makeRequireFunction(module);
   context.module = module;
   context.require = require;
 
-  internalModule.addBuiltinLibsToObject(context);
+  addBuiltinLibsToObject(context);
 
   return context;
 };
@@ -889,7 +894,7 @@ function complete(line, callback) {
     } else if (/^\.\.?\//.test(completeOn)) {
       paths = [process.cwd()];
     } else {
-      paths = module.paths.concat(Module.globalPaths);
+      paths = module.paths.concat(CJSModule.globalPaths);
     }
 
     for (i = 0; i < paths.length; i++) {