Add support for the Meriyah parser

[prantlf]

Meriyah is a fast and modern implementation of ECMAScript parser.

Making the comment types SingleLine and MultiLine recognised by ast-types would make the parse wrapper shorter and on par with the recognition of other comment types returned by Esprima/Babel. I just converted the comment types, so that the tests succeeded and the first version of this submission was shorter.

// 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 === "SingleLine" ? "Line" : "Block";
  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;
}

[gnprice]

Neat that it's so much faster than Acorn or Esprima. How does the speed compare to Babel?

Small code comments below.

[prantlf]

Neat that it's so much faster than Acorn or Esprima. How does the speed compare to Babel?

Babel is among the slowest, but my benchmark uses only jQuery and Marionette.CollectionView.

I replaced an old esprima in the RequireJS optimizer with meriyah to gain better performance and support of modern language. It works well so far.

[gnprice]

Good to know, thanks. These changes look good to me! The maintainers may have other comments.

[mrienstra]

Bump -- this looks like a good addition.

In case it's helpful: Meriyah is used by astring & nexe. And indirectly by react-scanner, by way of astray.

[eventualbuddha]

This isn't something I feel I can decide whether to incorporate. I'll leave it to @benjamn.