Transform compiled Clojurescript code for React Native/Metro (Updated for RN 0.58)

cljs-metro-transformer.js

/**	
 * Copyright (c) 2015-present, Facebook, Inc.	
 * Copyright (c) 2018 Arctype Corp.	
 *	
 * All rights reserved.	
 *	
 * This source code is licensed under the BSD-style license found in the	
 * LICENSE file in the root directory of the facebook/react source tree. An additional grant	
 * of patent rights can be found in the PATENTS file in the same directory.	
 *	
 * Note: This is a fork of the fb-specific transform.js	
 */

'use strict';

var JsTransformer = require("./node_modules/metro/src/JSTransformer/worker");
var fs = require("fs");

function transformCode(buf, deps) {
  var out = "__d(function (global, _$$_REQUIRE, _$$_IMPORT_DEFAULT, _$$_IMPORT_ALL, module, exports, _dependencyMap) {\n" +
      "var __dependencyIndex = {}\n";

  for (var i = 0; i < deps.length; i++) {
    out += "__dependencyIndex[\"" + deps[i].name + "\"] = _dependencyMap[" + i.toString() + "];\n";
  }

  out += "var __lookupRequire = function(name) { if(__dependencyIndex[name]) { return __dependencyIndex[name]; } else { throw new Error('Module is not defined: ' + name); }};\n" +
    "var require = function(name) { return _$$_REQUIRE(__lookupRequire(name), name); };\n";
  out += buf.toString("utf8") +
    "\n});";

  return out;
}

async function transformAsync(jsTransformer, filename, codebuf, options) {
  if (!options.hot && filename.startsWith("index.") && filename.endsWith(".js")) {
    console.log("Invoking custom TRANSFORM:" + filename);
    var mockBuffer = fs.readFileSync("cljs-deps.js");
    var mock = await jsTransformer.transform(filename, mockBuffer, options);
    return {
      dependencies: mock.dependencies,
      output: [{data: {code: transformCode(codebuf, mock.dependencies), map: []},
                type: 'js/module'}],
      getSource: function() { return codebuf }
    }
  }
  else {
    return await jsTransformer.transform(filename, codebuf, options);
  }
}

class ClosureTransformer {
  constructor(projectRoot, config) {
    this._projectRoot = projectRoot;
    this._config = config;
    this._jsTransformer = new JsTransformer(projectRoot, config);
  }

  transform(filename, codebuf, options) {
    return transformAsync(this._jsTransformer, filename, codebuf, options);
  }
};

module.exports = ClosureTransformer;