feat(compartment-mapper): CommonJS with lexical analysis

packages/compartment-mapper/NEWS.md

@@ -2,7 +2,8 @@ User-visible changes to the compartment mapper:
 
 ## Next release
 
-* No changes yet.
+* Reenables CommonJS support with a fast lexer and without a dependency on
+  Babel.
 
 ## 0.2.4 (2021-03-30)
 

packages/compartment-mapper/README.md

@@ -1,8 +1,5 @@
 # Compartment mapper
 
-> :warning: CommonJS support is temporarily disabled, pending a solution for
-> heuristic static analysis that does not entrain any Node.js built-ins.
-
 The compartment mapper builds _compartment maps_ for Node.js style
 applications, finding their dependencies and describing how to create
 [Compartments][] for each package in the application.

packages/compartment-mapper/package.json

@@ -25,6 +25,7 @@
     "test": "ava"
   },
   "dependencies": {
+    "@endo/lexer": "^0.1.0",
     "ses": "^0.12.7"
   },
   "devDependencies": {

packages/compartment-mapper/src/node-modules.js

@@ -135,9 +135,9 @@ const findPackage = async (readDescriptor, directory, name) => {
   }
 };
 
-const languages = ['mjs', 'json'];
-const uncontroversialParsers = { mjs: 'mjs', json: 'json' };
-const commonParsers = uncontroversialParsers;
+const languages = ['mjs', 'cjs', 'json'];
+const uncontroversialParsers = { cjs: 'cjs', mjs: 'mjs', json: 'json' };
+const commonParsers = { js: 'cjs', ...uncontroversialParsers };
 const moduleParsers = { js: 'mjs', ...uncontroversialParsers };
 
 /**
@@ -152,7 +152,7 @@ const inferParsers = (descriptor, location) => {
       throw new Error(
         `Cannot interpret parser map ${JSON.stringify(
           parsers,
-        )} of package at ${location}, must be an object mapping file extensions to corresponding languages (mjs for ECMAScript modules or json for JSON modules`,
+        )} of package at ${location}, must be an object mapping file extensions to corresponding languages (mjs for ECMAScript modules, cjs for CommonJS modules, or json for JSON modules`,
       );
     }
     const invalidLanguages = values(parsers).filter(
@@ -162,7 +162,7 @@ const inferParsers = (descriptor, location) => {
       throw new Error(
         `Cannot interpret parser map language values ${JSON.stringify(
           invalidLanguages,
-        )} of package at ${location}, must be an object mapping file extensions to corresponding languages (mjs for ECMAScript modules or json for JSON modules`,
+        )} of package at ${location}, must be an object mapping file extensions to corresponding languages (mjs for ECMAScript modules, cjs for CommonJS modules, or json for JSON modules`,
       );
     }
     return { ...uncontroversialParsers, ...parsers };

packages/compartment-mapper/src/parse.js

@@ -1,6 +1,7 @@
 // @ts-check
 /// <reference types="ses" />
 
+import { analyzeCommonJS } from '@endo/lexer';
 import { parseExtension } from './extension.js';
 import * as json from './json.js';
 
@@ -48,6 +49,7 @@ export const parseJson = async (
   const source = textDecoder.decode(bytes);
   /** @type {Readonly<Array<string>>} */
   const imports = freeze([]);
+
   /**
    * @param {Object} exports
    */
@@ -57,13 +59,77 @@ export const parseJson = async (
   return {
     parser: 'json',
     bytes,
-    record: freeze({ imports, execute }),
+    record: freeze({ imports, exports: freeze(['default']), execute }),
+  };
+};
+
+/** @type {ParseFn} */
+export const parseCjs = async (
+  bytes,
+  _specifier,
+  location,
+  _packageLocation,
+) => {
+  const source = textDecoder.decode(bytes);
+
+  if (typeof location !== 'string') {
+    throw new TypeError(
+      `Cannot create CommonJS static module record, module location must be a string, got ${location}`,
+    );
+  }
+
+  const { requires: imports, exports, reexports } = analyzeCommonJS(
+    source,
+    location,
+  );
+
+  /**
+   * @param {Object} moduleExports
+   * @param {Compartment} compartment
+   * @param {Record<string, string>} resolvedImports
+   */
+  const execute = async (moduleExports, compartment, resolvedImports) => {
+    const functor = compartment.evaluate(
+      `(function (require, exports, module, __filename, __dirname) { ${source} //*/\n})\n//# sourceURL=${location}`,
+    );
+
+    const module = freeze({
+      get exports() {
+        return moduleExports;
+      },
+      set exports(value) {
+        moduleExports.default = value;
+      },
+    });
+
+    const require = freeze(importSpecifier => {
+      const namespace = compartment.importNow(resolvedImports[importSpecifier]);
+      if (namespace.default !== undefined) {
+        return namespace.default;
+      }
+      return namespace;
+    });
+
+    functor(
+      require,
+      moduleExports,
+      module,
+      location, // __filename
+      new URL('./', location).toString(), // __dirname
+    );
+  };
+
+  return {
+    parser: 'cjs',
+    bytes,
+    record: freeze({ imports, exports, reexports, execute }),
   };
 };
 
 /** @type {Record<string, ParseFn>} */
 export const parserForLanguage = {
   mjs: parseMjs,
+  cjs: parseCjs,
   json: parseJson,
 };
 

packages/compartment-mapper/test/test-main.js

@@ -30,14 +30,20 @@ const assertFixture = (t, namespace) => {
     avery,
     brooke,
     clarke,
+    danny,
     builtin,
     receivedGlobalProperty,
     receivedGlobalLexical,
+    typecommon,
+    typemodule,
+    typehybrid,
+    typeparsers,
   } = namespace;
 
   t.is(avery, 'Avery', 'exports avery');
   t.is(brooke, 'Brooke', 'exports brooke');
   t.is(clarke, 'Clarke', 'exports clarke');
+  t.is(danny, 'Danny', 'exports danny');
 
   t.is(builtin, 'builtin', 'exports builtin');
 
@@ -47,9 +53,25 @@ const assertFixture = (t, namespace) => {
     globalLexicals.globalLexical,
     'exports global lexical',
   );
+  t.deepEqual(
+    typecommon,
+    [42, 42, 42, 42],
+    'type=common package carries exports',
+  );
+  t.deepEqual(
+    typemodule,
+    [42, 42, 42, 42],
+    'type=module package carries exports',
+  );
+  t.deepEqual(
+    typeparsers,
+    [42, 42, 42, 42],
+    'parsers-specifying package carries exports',
+  );
+  t.is(typehybrid, 42, 'type=module and module= package carries exports');
 };
 
-const fixtureAssertionCount = 6;
+const fixtureAssertionCount = 11;
 
 // The "create builtin" test prepares a builtin module namespace object that
 // gets threaded into all subsequent tests to satisfy the "builtin" module