steal-es6-module-loader/src/transpiler.js

An ES6 Module Loader shim

/*
 * Traceur and Babel transpile hook for Loader
 */
(function(Loader) {
  var g = __global;

  function getTranspilerModule(loader, globalName) {
    return loader.newModule({ 'default': g[globalName], __useDefault: true });
  }

  // use Traceur by default
  Loader.prototype.transpiler = 'babel';

  Loader.prototype.transpile = function(load) {
    var self = this;

    // pick up Transpiler modules from existing globals on first run if set
    if (!self.transpilerHasRun) {
      if (g.traceur && !self.has('traceur'))
        self.set('traceur', getTranspilerModule(self, 'traceur'));
      if (g.babel && !self.has('babel'))
        self.set('babel', getTranspilerModule(self, 'babel'));
      self.transpilerHasRun = true;
    }

    return self['import'](self.transpiler).then(function(transpiler) {
      if (transpiler.__useDefault)
        transpiler = transpiler['default'];
      return 'var __moduleAddress = "' + load.address + '";' + (transpiler.Compiler ? traceurTranspile : babelTranspile).call(self, load, transpiler);
    });
  };

  Loader.prototype.instantiate = function(load) {
    var self = this;
    return Promise.resolve(self.normalize(self.transpiler))
    .then(function(transpilerNormalized) {
      // load transpiler as a global (avoiding System clobbering)
      if (load.name === transpilerNormalized) {
        return {
          deps: [],
          execute: function() {
            var curSystem = g.System;
            var curLoader = g.Reflect.Loader;
            // ensure not detected as CommonJS
            __eval('(function(require,exports,module){' + load.source + '})();', g, load);
            g.System = curSystem;
            g.Reflect.Loader = curLoader;
            return getTranspilerModule(self, load.name);
          }
        };
      }
    });
  };

  function traceurTranspile(load, traceur) {
    var options = this.traceurOptions || {};
    options.modules = 'instantiate';
    options.script = false;
    options.sourceMaps = 'inline';
    options.filename = load.address;
    options.inputSourceMap = load.metadata.sourceMap;
    options.moduleName = false;

    var compiler = new traceur.Compiler(options);
    var source = doTraceurCompile(load.source, compiler, options.filename);

    // add "!eval" to end of Traceur sourceURL
    // I believe this does something?
    source += '!eval';

    return source;
  }
  function doTraceurCompile(source, compiler, filename) {
    try {
      return compiler.compile(source, filename);
    }
    catch(e) {
      // traceur throws an error array
      throw e[0];
    }
  }

  function babelTranspile(load, babel) {
    babel = babel.Babel || babel.babel || babel;
    var options = this.babelOptions || {};
    options.sourceMap = 'inline';
    options.filename = load.address;
    options.code = true;
    options.ast = false;

    var babelVersion = babel.version ? +babel.version.split(".")[0] : 6;
    if(!babelVersion) babelVersion = 6;

    if(babelVersion >= 6) {
      // delete the old babel options if they are present in config
      delete options.optional;
      delete options.whitelist;
      delete options.blacklist;
      // If the user didn't provide presets/plugins, use the defaults
      if(!options.presets && !options.plugins) {
        options.presets = [
          "es2015-no-commonjs", "react", "stage-0"
        ];
        options.plugins = [
          "transform-es2015-modules-systemjs"
        ];
      }
    } else {
      options.modules = 'system';
      if (!options.blacklist)
        options.blacklist = ['react'];
    }

    var source = babel.transform(load.source, options).code;

    // add "!eval" to end of Babel sourceURL
    // I believe this does something?
    return source + '\n//# sourceURL=' + load.address + '!eval';
  }


})(__global.LoaderPolyfill);