问题

我在PHP和其他代码中有以下的正则表达式，它的工作效果很好。

/^(?:(?=[^ ]+\d)(?:[A-Z0-9]+))|(?:[A-Z0-9]+) +?(?=.*\d)(?:[A-Z0-9]+)?

结果发现Go语言不支持lookahead，我不知道如何转换这个正则表达式。

Debuggex链接中有一些我之前用来测试代码的数据。

英文:

I have the following Regex in PHP and other code that is doing a great job.

/^(?:(?=[^ ]+\d)(?:[A-Z0-9]+))|(?:[A-Z0-9]+) +?(?=.*\d)(?:[A-Z0-9]+)?

It turns out that Go doesn't support lookheads and I'm at a loss on how to convert it across.

The Debuggex link has some test data I was using to qualify the code before.

答案1

得分: 1

首先，替代项/^...的左侧不匹配任何内容，因为/永远不会出现在输入的开头之前。

剩下的只有(?:[A-Z0-9]+) +?(?=.*\d)，可以表示为：

((?:[A-Z0-9]+) ).*\d.*

使用的" +?"与" "的效果完全相同。

但请注意，这比原始表达式消耗更多的输入，这是不可避免的。您原始匹配现在在第1组中。

英文:

Firstly, the left hand side of the alternation /^... matches nothing, because / can never appear before start of input.

That leaves just (?:[A-Z0-9]+) +?(?=.*\d), which can be expressed as:

((?:[A-Z0-9]+) ).*\d.*

The term " +?" as used is identical in effect to just " ".

Note however that this consumes more input than the original, which is unavoidable. Your original match is now in group 1.

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