docs: function processFile(file, encoding) {
      var fileContent = file.contents.toString(encoding),
          matches = fileContent.match(reg$$Global),
          expression,
          tempRegResults,
          name,
          value,
          replaceStr;
  
      if(null === matches) {
          return file;
      }
      for(var i = 0, len = matches.length; i < len; i ++) {
          expression = matches[i];
          tempRegResults = expression.match(reg$$);
          name = tempRegResults[1];
          value = tempRegResults[2];
  
          replaceStr = (resolvers[name] || loop)(file, valueProcess(name, value));
          //替换表达式的值为应该替换的那一部分
          fileContent = fileContent.replace(expression, replaceStr.replace("$", "$$$$"));
      }
  
      file.contents = new Buffer(fileContent);
      return file;
  }