code: private SyntaxNode buildByTokenHolder(TokenHolder tokenHolder) throws XpathSyntaxErrorException {
          Preconditions.checkArgument(!tokenHolder.type.equals(Token.OPERATOR));
          // return TokenNodeFactory.hintAndGen(tokenHolder);
          return TokenAnalysisRegistry.findHandler(tokenHolder.getType()).parseToken(tokenHolder.expression);
      }
docs: 非操作符的节点构建,如函数,xpath表达式,常量,数字等,他们的构造方法和计算树无关,是表达式里面最原始的计算叶节点
  
  @param tokenHolder token数据
  @return 用来挂在计算树上面的叶节点