TypeScript core.transformFromAst函数代码示例

function transformDew (ast, source, resolveMap) {
  const { code: dewTransform } = babel.transformFromAst(ast, source, {
    babelrc: false,
    babelrcRoots: false,
    configFile: false,
    highlightCode: false,
    compact: false,
    sourceType: 'script',
    parserOpts: {
      allowReturnOutsideFunction: true,
      plugins: stage3Syntax
    },
    plugins: [[dewTransformPlugin, {
      resolve: (name, opts) => {
        if ((opts.optional || opts.wildcard) && !resolveMap[name])
          return null;
        return resolveMap[name];
      },
      wildcardExtensions: ['.js', '.json', '.node'],
      esmDependencies: resolved => isESM(resolved),
      filename: `import.meta.url.startsWith('file:') ? decodeURI(import.meta.url.slice(7 + (typeof process !== 'undefined' && process.platform === 'win32'))) : new URL(import.meta.url).pathname`,
      dirname: `import.meta.url.startsWith('file:') ? decodeURI(import.meta.url.slice(0, import.meta.url.lastIndexOf('/')).slice(7 + (typeof process !== 'undefined' && process.platform === 'win32'))) : new URL(import.meta.url.slice(0, import.meta.url.lastIndexOf('/'))).pathname`
    }]]
  });
  return dewTransform;
}

 return new Promise<Babel.BabelFileResult | null>((resolve) => {
     Babel.transformFromAst(ast, code, options, (error, res) => {
         if (error != null) {
             console.error("fable: Error transforming Babel AST", error);
             resolve(null);
         } else {
             resolve(res);
         }
     });
 });

const options: babel.TransformOptions = {
    ast: true,
    sourceMaps: true
};

babel.transform("code();", options, (err, result) => {
    const { code, map, ast } = result!;
});

const transformSyncResult = babel.transformSync("code();", options);
if (transformSyncResult) {
    const { code, map, ast } = transformSyncResult;
}

babel.transformFile("filename.js", options, (err, result) => {
    const { code, map, ast } = result!;
});

babel.transformFileSync("filename.js", options)!.code;

const sourceCode = "if (true) return;";
const parsedAst = babel.parse(sourceCode, options);

babel.transformFromAst(parsedAst!, sourceCode, options, (err, result) => {
    const { code, map, ast } = result!;
});

const transformFromAstSyncResult = babel.transformFromAstSync(parsedAst!, sourceCode, options);
const { code, map, ast } = transformFromAstSyncResult!;

//.........这里部分代码省略.........
  if (options.compile === true || options.compile === 'es5') {
    doBabelTransform = true;
    plugins.push(...babelTransformEs2015);
    plugins.push(...babelTransformEs2016);
    plugins.push(...babelTransformEs2017);
    plugins.push(...babelTransformEs2018);
  } else if (options.compile === 'es2015') {
    doBabelTransform = true;
    plugins.push(...babelTransformEs2016);
    plugins.push(...babelTransformEs2017);
    plugins.push(...babelTransformEs2018);
  } else if (options.compile === 'es2016') {
    doBabelTransform = true;
    plugins.push(...babelTransformEs2017);
    plugins.push(...babelTransformEs2018);
  } else if (options.compile === 'es2017') {
    doBabelTransform = true;
    plugins.push(...babelTransformEs2018);
  }
  if (options.moduleResolution === 'node') {
    if (!options.filePath) {
      throw new Error(
          'Cannot perform node module resolution without filePath.');
    }
    doBabelTransform = true;
    plugins.push(resolveBareSpecifiers(
        options.filePath,
        !!options.isComponentRequest,
        options.packageName,
        options.componentDir,
        options.rootDir));
  }

  // When the AMD option is "auto", these options will change based on whether
  // we have a module or not (unless they are already definitely true).
  let transformModulesToAmd = options.transformModulesToAmd;
  if (transformModulesToAmd === true) {
    doBabelTransform = true;
  }

  const maybeDoBabelTransform =
      doBabelTransform || transformModulesToAmd === 'auto';

  if (maybeDoBabelTransform) {
    let ast;
    try {
      ast = babylon.parse(js, {
        // TODO(aomarks) Remove any when typings are updated for babylon 7.
        // tslint:disable-next-line: no-any
        sourceType: transformModulesToAmd === 'auto' ? 'unambiguous' as any :
                                                       'module',
        plugins: [
          'asyncGenerators',
          'dynamicImport',
          // tslint:disable-next-line: no-any
          'importMeta' as any,
          'objectRestSpread',
        ],
      });
    } catch (e) {
      if (options.softSyntaxError && e.constructor.name === 'SyntaxError') {
        console.error(
            'ERROR [polymer-build]: failed to parse JavaScript' +
                (options.filePath ? ` (${options.filePath}):` : ':'),
            e);
        return js;
      } else {
        throw e;
      }
    }

    if (transformModulesToAmd === 'auto' &&
        ast.program.sourceType === 'module') {
      transformModulesToAmd = true;
    }

    if (transformModulesToAmd) {
      doBabelTransform = true;
      plugins.push(...babelTransformModulesAmd);
    }

    if (doBabelTransform) {
      const result = babelCore.transformFromAst(ast, js, {presets, plugins});
      if (result.code === undefined) {
        throw new Error(
            'Babel transform failed: resulting code was undefined.');
      }
      js = result.code;

      if (!options.externalHelpers && options.compile === 'es5' &&
          js.includes('regeneratorRuntime')) {
        js = externalJs.getRegeneratorRuntime() + js;
      }
    }
  }

  js = replaceTemplateObjectNames(js);

  return js;
}