code: function processFile(file, processor, buildManager) {
      let {compileContext, logger} = buildManager;
      let {handler, options: opts, rext} = processor;
      logger.debug(`compile file ${file.path}, using ${processor.name}: `, opts);
  
      let result = handler(file, Object.assign({
          config: opts
      }, compileContext));
      if (!result) {
          return;
      }
  
      rext && (file.rext = rext);
  
      if (isPromise(result)) {
          buildManager.addAsyncTask(file, result);
          return;
      }
  
      if (result.isSfcComponent) {
          compileComponent(result, file, buildManager);
          result = {content: file.content};
      }
      buildManager.updateFileCompileResult(file, result);
  }
docs: Process file using the given processor
  
  @inner
  @param {Object} file the file to process
  @param {Object} processor the processor to use
  @param {BuildManager} buildManager the build manager