babel/packages/babel-core/src/parser/index.js

import type { Handler } from "gensync";
import { parse } from "@babel/parser";
import { codeFrameColumns } from "@babel/code-frame";
import generateMissingPluginMessage from "./util/missing-plugin-helper";

type AstRoot = BabelNodeFile | BabelNodeProgram;

export type ParseResult = AstRoot;

export default function* parser(
  pluginPasses: PluginPasses,
  { parserOpts, highlightCode = true, filename = "unknown" }: Object,
  code: string,
): Handler<ParseResult> {
  try {
    const results = [];
    for (const plugins of pluginPasses) {
      for (const plugin of plugins) {
        const { parserOverride } = plugin;
        if (parserOverride) {
          const ast = parserOverride(code, parserOpts, parse);

          if (ast !== undefined) results.push(ast);
        }
      }
    }

    if (results.length === 0) {
      return parse(code, parserOpts);
    } else if (results.length === 1) {
      yield* []; // If we want to allow async parsers
      if (typeof results[0].then === "function") {
        throw new Error(
          `You appear to be using an async parser plugin, ` +
            `which your current version of Babel does not support. ` +
            `If you're using a published plugin, you may need to upgrade ` +
            `your @babel/core version.`,
        );
      }
      return results[0];
    }
    throw new Error("More than one plugin attempted to override parsing.");
  } catch (err) {
    if (err.code === "BABEL_PARSER_SOURCETYPE_MODULE_REQUIRED") {
      err.message +=
        "\nConsider renaming the file to '.mjs', or setting sourceType:module " +
        "or sourceType:unambiguous in your Babel config for this file.";
      // err.code will be changed to BABEL_PARSE_ERROR later.
    }

    const { loc, missingPlugin } = err;
    if (loc) {
      const codeFrame = codeFrameColumns(
        code,
        {
          start: {
            line: loc.line,
            column: loc.column + 1,
          },
        },
        {
          highlightCode,
        },
      );
      if (missingPlugin) {
        err.message =
          `${filename}: ` +
          generateMissingPluginMessage(missingPlugin[0], loc, codeFrame);
      } else {
        err.message = `${filename}: ${err.message}\n\n` + codeFrame;
      }
      err.code = "BABEL_PARSE_ERROR";
    }
    throw err;
  }
}