code: function (tplContent, name) {
      if (tplContent) {
        var ret;
        try {
          ret = parser.parse(tplContent, name);
        } catch (err) {
          var e;
          if (err instanceof Error) {
            e = err;
          } else {
            e = new Error(err);
          }
          var errorStr = 'XTemplate error ';
          e.stack = errorStr + e.stack;
          e.message = errorStr + e.message;
          throw e;
        }
        return ret;
      } else {
        return {
          statements: []
        };
      }
    }
docs: get ast of template
  @param {String} [name] xtemplate name
  @param {String} tplContent
  @return {Object}