code: function parseConfig(contents) {
      var config = {};
  
      contents = contents.replace(rSeajsConfig, function ($) {
          $.replace(rAlias, function (_, $1) {
              config.alias = evalConfig($1);
          });
  
          $.replace(rPaths, function (_, $1) {
              config.paths = evalConfig($1);
          });
  
          $.replace(rVars, function (_, $1) {
              config.vars = evalConfig($1);
          });
  
          return '';
      });
  
      return {
          contents: contents,
          config: config
      };
  }
docs: /*
  解析config字符串，尝试提取alias、paths、vars
  param{ String } 文件内容
  return{ Object } 提取出来的配置和提取后的文件内容