Add support for the Meriyah parser

Meriyah is a fast and modern implementation of ECMAScript parser

Author: prantlf

.github/workflows/main.yml

@@ -2,28 +2,28 @@ name: CI
 
 on:
   push:
-    branches: [ master ]
+    branches: [master]
   pull_request:
-    branches: [ master ]
+    branches: [master]
 
 jobs:
   test:
     name: Test on node ${{ matrix.node_version }} and ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        node_version: ['10.x', '12.x', '14.x', '15.x', '16.x']
+        node_version: ["10.x", "12.x", "14.x", "15.x", "16.x"]
         os: [ubuntu-latest]
 
     steps:
-    - uses: actions/checkout@v2
-    - name: Use Node.js ${{ matrix.node_version }}
-      uses: actions/setup-node@v1
-      with:
-        node-version: ${{ matrix.node_version }}
+      - uses: actions/checkout@v2
+      - name: Use Node.js ${{ matrix.node_version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node_version }}
 
-    - name: npm install, build and test
-      run: |
-        npm install
-        npm run build --if-present
-        npm test
+      - name: npm install, build and test
+        run: |
+          npm install
+          npm run build --if-present
+          npm test

README.md

@@ -168,7 +168,7 @@ const tsAst = recast.parse(source, {
 });
 ```
 
-**Note:** Some of these parsers import npm packages that Recast does not directly depend upon, so please be aware you may have to run `npm install babylon@next` to use the `typescript`, `flow`, or `babylon` parsers, or `npm install acorn` to use the `acorn` parser. Only Esprima is installed by default when Recast is installed.
+**Note:** Some of these parsers import npm packages that Recast does not directly depend upon, so please be aware you may have to run `npm install babylon@next` to use the `typescript`, `flow`, or `babylon` parsers, or `npm install acorn` to use the `acorn` parser, or `npm install meriyah` to use the `meriyah` parser. Only Esprima is installed by default when Recast is installed.
 
 After calling `recast.parse`, if you're going to transform the AST, make sure that the `.original` property is preserved. With Babel, for instance, if you call `transformFromAST`, you must pass `cloneInputAst: false` in its options. ([More detail](https://github.com/babel/babel/issues/12882).
 

lib/parser.ts

@@ -78,8 +78,8 @@ export function parse(source: string, options?: Partial<Options>) {
     program = ast;
     // In order to ensure we reprint leading and trailing program
     // comments, wrap the original Program node with a File node. Only
-    // ESTree parsers (Acorn and Esprima) return a Program as the root AST
-    // node. Most other (Babylon-like) parsers return a File.
+    // ESTree parsers (Acorn, Esprima, Meriyah) return a Program as the root
+    // AST node. Most other (Babylon-like) parsers return a File.
     file = b.file(ast, options.sourceFileName || null);
     file.loc = {
       start: lines.firstPos(),

package-lock.json

@@ -61,6 +61,7 @@
     "flow-parser": "0.156.0",
     "glob": "7.2.0",
     "lint-staged": "^12.4.1",
+    "meriyah": "^4.2.1",
     "mocha": "9.0.2",
     "prettier": "^2.6.2",
     "reify": "0.20.12",

package.json

@@ -0,0 +1,36 @@
+// This module is suitable for passing as options.parser when calling
+// recast.parse to process JavaScript code with Meriyah:
+//
+//   const ast = recast.parse(source, {
+//     parser: require("recast/parsers/meriyah")
+//   });
+//
+import { getOption } from "../lib/util";
+
+function convertComment(comment: any): any {
+  let { type } = comment;
+  type = type[0] === "S" ? "Line" : "Block"; // SingleLine/MultiLine
+  return { ...comment, type };
+}
+
+export function parse(source: string, options?: any) {
+  const comments: any[] = [];
+  const tokens: any[] = [];
+  const ast = require("meriyah").parse(source, {
+    module: getOption(options, "sourceType", "module") === "module",
+    specDeviation: getOption(options, "tolerant", true),
+    jsx: getOption(options, "jsx", false),
+    ranges: getOption(options, "range", false),
+    loc: true,
+    raw: true,
+    next: true,
+    globalReturn: true,
+    onComment: comments,
+    onToken: tokens,
+  });
+
+  ast.comments = comments.map(convertComment);
+  ast.tokens = tokens;
+
+  return ast;
+}

parsers/meriyah.ts

@@ -23,6 +23,7 @@ const nodeMajorVersion = parseInt(process.versions.node, 10);
 describe("comments", function () {
   [
     "../parsers/acorn",
+    "../parsers/meriyah",
     "../parsers/babel",
     "../parsers/esprima",
     "../parsers/flow",
@@ -180,6 +181,7 @@ function runTestsForParser(parserId: any) {
     const info = (
       {
         acorn: esprimaInfo,
+        meriyah: esprimaInfo,
         babel: babelInfo,
         esprima: esprimaInfo,
         flow: babelInfo,

test/comments.ts

@@ -15,6 +15,7 @@ const nodeMajorVersion = parseInt(process.versions.node, 10);
 describe("parser", function () {
   [
     "../parsers/acorn",
+    "../parsers/meriyah",
     "../parsers/babel",
     "../parsers/esprima",
     "../parsers/flow",
@@ -84,6 +85,7 @@ function runTestsForParser(parserId: string) {
 
   const lineCommentTypes: { [name: string]: string } = {
     acorn: "Line",
+    meriyah: "Line",
     babel: "CommentLine",
     esprima: "Line",
     flow: "CommentLine",

test/parser.ts

@@ -1692,6 +1692,7 @@ describe("printer", function () {
 
     checkWith(require("../parsers/esprima"));
     checkWith(require("../parsers/acorn"));
+    checkWith(require("../parsers/meriyah"));
 
     if (nodeMajorVersion >= 6) {
       checkWith(require("../parsers/babel"));

test/printer.ts

@@ -14,8 +14,5 @@
     "importHelpers": true,
     "stripInternal": true
   },
-  "exclude": [
-    "node_modules",
-    "test/data"
-  ]
+  "exclude": ["node_modules", "test/data"]
 }