flex（词法分析器）正则表达式 - 重用定义

Question

I have this working definition:我有这个工作定义：

IDENTIFIER   [a-zA-Z][a-zA-Z0-9]*

I don't want to keep repeating the [a-zA-Z] and [0-9], so I made two new definitions我不想一直重复[a-zA-Z]和[0-9]，所以我做了两个新定义

DIGIT    [0-9]
VALID    [a-zA-Z]

How can I rewrite the IDENTIFIER rule to use the DIGIT and VALID definitions?如何重写 IDENTIFIER 规则以使用 DIGIT 和 VALID 定义？

I don't know how to do the "second" match, I'm stuck here:我不知道如何进行“第二场”比赛，我被困在这里：

IDENTIFIER {VALID}[{VALID}{DIGIT}]* // This syntax is incorrect

Thanks.谢谢。

Edit: The entire test program that I'm using: http://pastebin.com/f5b64183f .编辑：我正在使用的整个测试程序： http : //pastebin.com/f5b64183f 。

Answer 1

It looks like you actually want:看起来你真的想要：

IDENTIFIER {VALID}({VALID}|{DIGIT})*

[{VALID}{DIGIT}] resolves to [[A-Za-z][0-9]] which is not a legal construct. [{VALID}{DIGIT}]解析为[[A-Za-z][0-9]]这不是一个合法的结构。

Answer 2

I think this will do it, but I can't test it.我认为这会做到，但我无法测试。 Do you have sample data?你有样本数据吗？

(?:[a-zA-Z])+(?:[0-9])+