fix TLA with esnext syntax

package.json

@@ -12,7 +12,9 @@
   },
   "dependencies": {
     "@babel/core": "^7.5.5",
+    "@babel/generator": "^7.5.5",
     "@babel/parser": "^7.5.5",
+    "@babel/plugin-proposal-async-generator-functions": "^7.2.0",
     "@babel/plugin-proposal-class-properties": "^7.1.0",
     "@babel/plugin-proposal-decorators": "^7.4.4",
     "@babel/plugin-proposal-do-expressions": "^7.0.0",
@@ -30,10 +32,12 @@
     "@babel/plugin-proposal-partial-application": "^7.4.4",
     "@babel/plugin-proposal-pipeline-operator": "^7.0.0",
     "@babel/plugin-proposal-throw-expressions": "^7.2.0",
+    "@babel/plugin-proposal-unicode-property-regex": "^7.4.4",
     "@babel/plugin-syntax-bigint": "^7.0.0",
     "@babel/plugin-syntax-import-meta": "^7.0.0",
     "@babel/plugin-transform-modules-commonjs": "^7.5.0",
     "@babel/plugin-transform-typescript": "^7.5.5",
+    "@babel/traverse": "^7.5.5",
     "bluebird": "^3.5.2",
     "chalk": "^2.4.1",
     "cheerio": "^0.22.0",
@@ -44,7 +48,6 @@
     "json5": "^2.1.0",
     "node-fetch": "^2.3.0",
     "prettier": "^1.14.3",
-    "recast": "^0.18.1",
     "shell-escape": "^0.2.0",
     "superagent": "^3.8.3"
   },

src/plugins/js-eval/__tests__/jsEvalPlugin-test.js

@@ -90,14 +90,28 @@ describe('jsEvalPlugin', () => {
     expect(output).toEqual(`(okay) undefined`);
   });
 
-  it('handles top-level await', async () => {
-    const output = await testEval('n> let x=await `wat`; x // test');
-    expect(output).toEqual(`(okay) 'wat'`);
-  });
+  describe('top-level-await', () => {
+    it('works', async () => {
+      expect([
+        await testEval('n> var x = await Promise.resolve(2n); x'),
+        await testEval('b> var x = await Promise.resolve(2n); x'),
+        await testEval('n> var x = await Promise.resolve(2n); if (x) {}'),
+        await testEval('b> var x = await Promise.resolve(2n); if (x) {}'),
+      ]).toEqual([
+        '(okay) 2n',
+        '(okay) 2n',
+        '(okay) undefined',
+        '(okay) undefined',
+      ])
+    });
 
-  it('handles top-level await with babel', async () => {
-    const output = await testEval('b> await `wat` // test');
-    expect(output).toEqual(`(okay) 'wat'`);
+    it('works with comments', async () => {
+      const output = await testEval('n> let x=await `wat`; x // test');
+      expect(output).toEqual(`(okay) 'wat'`);
+
+      const output2 = await testEval('b> await `wat` // test');
+      expect(output2).toEqual(`(okay) 'wat'`);
+    });
   });
 
   it('works with engine262', async () => {

src/plugins/js-eval/babelPlugins.js

@@ -0,0 +1,54 @@
+// all babel proposal plugins https://github.com/babel/babel/tree/master/packages (preset-stage-n packages are depreacted https://babeljs.io/docs/en/next/babel-preset-stage-1)
+// if there are new ones, feel free to add them
+exports.transformPlugins = [
+  '@babel/plugin-proposal-async-generator-functions',
+  '@babel/plugin-transform-typescript',
+  '@babel/plugin-transform-modules-commonjs', // required by dynamicImport
+  ['@babel/plugin-proposal-decorators', { decoratorsBeforeExport: false }], // must be before class-properties https://babeljs.io/docs/en/babel-plugin-proposal-decorators#note-compatibility-with-babel-plugin-proposal-class-properties
+  '@babel/plugin-proposal-class-properties',
+  '@babel/plugin-proposal-do-expressions',
+  '@babel/plugin-proposal-export-default-from',
+  '@babel/plugin-proposal-export-namespace-from',
+  '@babel/plugin-proposal-function-sent',
+  '@babel/plugin-proposal-function-bind',
+  '@babel/plugin-proposal-json-strings',
+  '@babel/plugin-proposal-logical-assignment-operators',
+  '@babel/plugin-proposal-nullish-coalescing-operator',
+  '@babel/plugin-proposal-numeric-separator',
+  '@babel/plugin-proposal-optional-catch-binding',
+  '@babel/plugin-proposal-optional-chaining',
+  '@babel/plugin-proposal-partial-application',
+  ['@babel/plugin-proposal-pipeline-operator', { proposal: 'minimal' }],
+  '@babel/plugin-proposal-throw-expressions',
+  '@babel/plugin-proposal-dynamic-import',
+  '@babel/plugin-syntax-bigint',
+  '@babel/plugin-syntax-import-meta',
+  '@babel/plugin-proposal-unicode-property-regex'
+];
+
+
+// @babel/parser plugins https://babeljs.io/docs/en/next/babel-parser.html#ecmascript-proposals-https-githubcom-babel-proposals
+exports.parserPlugins = [
+  'asyncGenerators',
+  'bigInt',
+  ['decorators', { decoratorsBeforeExport: true }],
+  'classProperties',
+  'classPrivateProperties',
+  'classPrivateMethods',
+  'doExpressions',
+  'dynamicImport',
+  'exportDefaultFrom',
+  'exportNamespaceFrom',
+  'functionBind',
+  'functionSent',
+  'importMeta',
+  'logicalAssignment',
+  'nullishCoalescingOperator',
+  'numericSeparator',
+  // 'objectRestSpread', // no need, node has it since a long time
+  'optionalCatchBinding',
+  'optionalChaining',
+  'partialApplication',
+  ['pipelineOperator', { proposal: 'minimal' }],
+  'throwExpressions'
+]

src/plugins/js-eval/jsEvalPlugin.js

@@ -1,54 +1,41 @@
 const cp = require('child_process');
 const babel = require('@babel/core');
+const babelGenerator = require('@babel/generator').default;
 const jsEval = require('./jsEval');
 const processTopLevelAwait = require('./processTopLevelAwait');
+const { transformPlugins } = require('./babelPlugins');
 
-const helpMsg = `n> node stable, h> node harmony, b> babel, s> node vm.Script, m> node vm.SourceTextModule, e> engine262`;
+
+const helpMsg = `n> node stable, h> node --harmony, b> babel, s> node vm.Script, m> node vm.SourceTextModule, e> engine262`;
 
 // default jseval run command
 const CMD = ['node', '--no-warnings', '/run/run.js'];
 const CMD_SHIMS = ['node', '-r', '/run/node_modules/airbnb-js-shims/target/es2019', '--no-warnings', '/run/run.js'];
 const CMD_HARMONY = ['node', '--harmony', '--experimental-vm-modules', '--experimental-modules', '--no-warnings', '/run/run.js'];
 
+
 const jsEvalPlugin = async ({ mentionUser, respond, message, selfConfig = {} }) => {
   if (!/^[nhbsme?]>/.test(message)) return;
   const mode = message[0];
   if (mode === '?') return respond((mentionUser ? `${mentionUser}, ` : '') + helpMsg);
   let code = message.slice(2);
 
-  if (mode === 'b') {
-    code = (await babel.transformAsync(code, {
-      parserOpts: {
-        allowAwaitOutsideFunction: true,
-        allowReturnOutsideFunction: true,
-      },
-      plugins: [
-        '@babel/plugin-transform-typescript',
-        '@babel/plugin-transform-modules-commonjs', // required by dynamicImport
-        ['@babel/plugin-proposal-decorators', { decoratorsBeforeExport: false }], // must be before class-properties https://babeljs.io/docs/en/babel-plugin-proposal-decorators#note-compatibility-with-babel-plugin-proposal-class-properties
-        '@babel/plugin-proposal-class-properties',
-        '@babel/plugin-proposal-do-expressions',
-        '@babel/plugin-proposal-export-default-from',
-        '@babel/plugin-proposal-export-namespace-from',
-        '@babel/plugin-proposal-function-sent',
-        '@babel/plugin-proposal-function-bind',
-        '@babel/plugin-proposal-json-strings',
-        '@babel/plugin-proposal-logical-assignment-operators',
-        '@babel/plugin-proposal-nullish-coalescing-operator',
-        '@babel/plugin-proposal-numeric-separator',
-        '@babel/plugin-proposal-optional-catch-binding',
-        '@babel/plugin-proposal-optional-chaining',
-        '@babel/plugin-proposal-partial-application',
-        ['@babel/plugin-proposal-pipeline-operator', { proposal: 'minimal' }],
-        '@babel/plugin-proposal-throw-expressions',
-        '@babel/plugin-proposal-dynamic-import',
-        '@babel/plugin-syntax-bigint',
-        '@babel/plugin-syntax-import-meta',
-      ]
-    })).code;
+  const hasMaybeTLA = /\bawait\b/.test(code);
+
+  if (mode === 'b' && !hasMaybeTLA) {
+    code = (await babel.transformAsync(code, { plugins: transformPlugins })).code;
   }
 
-  code = processTopLevelAwait(code) || code; // it returns null when no TLA is found
+  if (hasMaybeTLA) { // there's maybe a TLA await
+    const iiafe = processTopLevelAwait(code);
+    if (iiafe) { // there's a TLA
+      if (mode === 'b') {
+        code = (await babel.transformFromAstAsync(iiafe, code, { plugins: transformPlugins })).code;
+      } else {
+        code = babelGenerator(iiafe).code;
+      }
+    }
+  }
 
   try {
     const result = await jsEval(

src/plugins/js-eval/processTopLevelAwait.js

@@ -1,18 +1,19 @@
 const babelParser = require('@babel/parser');
-const recast = require('recast');
-
-const b = recast.types.builders;
-
+const babelTraverse = require('@babel/traverse').default;
+const { parserPlugins } = require('./babelPlugins');
+
+/**
+ * 
+ * @param {string} src 
+ * @return {object} ast
+ */
 function processTopLevelAwait(src) {
   let root;
 
   try {
-    root = recast.parse(src, {
-      parser: {
-        parse(src) {
-          return babelParser.parse(src, { allowAwaitOutsideFunction: true });
-        }
-      }
+    root = babelParser.parse(src, {
+      allowAwaitOutsideFunction: true,
+      plugins: parserPlugins
     });
   } catch (error) {
     return null; // if code is not valid, don't bother
@@ -21,33 +22,30 @@ function processTopLevelAwait(src) {
   let containsAwait = false;
   let containsReturn = false;
 
-  recast.visit(root, {
-    visitNode: function (path) {
-      const node = path.value;
-
-      switch (node.type) {
+  babelTraverse(root, {
+    enter(path) {
+      switch (path.type) {
+        case 'FunctionDeclaration':
         case 'FunctionExpression':
         case 'ArrowFunctionExpression':
         case 'MethodDefinition':
+        case 'ClassMethod':
           // stop when entering a new function scope:
-          return false;
+          return path.stop();
 
         case 'ForOfStatement':
-          if (node.await === true) {
+          if (path.node.await === true) {
             containsAwait = true;
           }
-          return this.traverse(path);
+          return;
 
         case 'AwaitExpression':
           containsAwait = true;
-          return this.traverse(path);
+          return;
 
         case 'ReturnStatement':
           containsReturn = true;
-          return this.traverse(path);
-
-        default:
-          return this.traverse(path);
+          return;
       }
     }
   });
@@ -60,25 +58,39 @@ function processTopLevelAwait(src) {
   }
 
   let last = root.program.body[root.program.body.length - 1];
+
+  // replace last node with a returnStatement of this node, if the last node is an expression
   if (last.type === 'ExpressionStatement') {
-    last = last.expression;
+    root.program.body[root.program.body.length - 1] = {
+      type: 'ReturnStatement',
+      argument: last.expression
+    };
   }
 
-  // replace last node with a returnStatement of this node
-  root.program.body[root.program.body.length - 1] = b.returnStatement(last);
 
-  const iiafe = b.callExpression(
-    b.arrowFunctionExpression(
-      [],
-      b.blockStatement(root.program.body),
-      true
-    ),
-    []
-  );
-
-  iiafe.callee.async = true;
+  const iiafe = {
+    type: 'Program',
+    sourceType: 'script',
+    body: [{
+      type: 'ExpressionStatement',
+      expression: {
+        type: 'CallExpression',
+        callee: {
+          type: 'ArrowFunctionExpression',
+          async: true,
+          params: [],
+          body: {
+            type: 'BlockStatement',
+            body: root.program.body
+          },
+        },
+        arguments: []
+      }
+    }],
+  };
+  // const iiafe = t.program([t.expressionStatement(t.callExpression(t.arrowFunctionExpression([], t.blockStatement(root.program.body)), []))]) // with @babel/types
 
-  return recast.print(iiafe).code;
+  return iiafe;
 }
 
 module.exports = processTopLevelAwait;

src/plugins/js-eval/run.js

@@ -13,7 +13,7 @@ const inspect = (val) => {
       maxArrayLength: 20,
       breakLength: Infinity,
       colors: false,
-      compact: 10,
+      compact: true,
       depth: 10,
     });
   } catch {