code: function process(file, options) {
      let content = file.content.toString();
      let {config: rules, logger} = options;
  
      let result = content;
      try {
          result = doReplacement(content, rules || [], file);
      }
      catch (ex) {
          let tip;
          if (ex === 'devServer') {
              tip = ', please execute `npm run dev:server` script or start with `--server` option';
          }
          logger.error('unknown replacement variable:', ex + (tip || ''));
      }
  
      return {
          content: result
      };
  }
docs: Replacement the file content using the given pattern
  
  @param {Object} file the file to process
  @param {Object} options the compile options
  @return {{content: string}}