Related to this, couldn't it also be made case insensitive to simplify it?
https://go.dev/play/p/5qJTAcmkowg
On Tue, Feb 14, 2023, 1:51 p.m. Rob Pike <r...@golang.org> wrote:
> I suggest two changes.
>
> First, always use backquotes `` around regular expressions to avoid
> misunderstandings should a backslash occur.
>
> Second, in this case if M|m is just a choice and not a subexpression you
> need to track, you can make it easier to read by using character classes to
> reduce the number of parentheses. It is easier to read therefore. You will
> need to adjust the code that uses subexpression matching. I did this by
> hand and didn't test it, but it will give you the idea:
>
> `([Mm][Pp])[34])|([Ff][Ll][Aa][Cc])$`
>
> In fact, if you don't need subexpressions there are no parentheses needed,
> as the alternation operator groups as you would expect.
>
> `[Mm][Pp][34]|[Ff][Ll][Aa][Cc]$`
>
> However, I suspect at least some of the elements must be parenthesized for
> the job at hand.
>
> -rob
>
>
> On Wed, Feb 15, 2023 at 2:51 AM Howard C. Shaw III <howardcs...@gmail.com>
> wrote:
>
>> var ExtRegex =
>> regexp.MustCompile("(M|m)(p|P)(3|4))|((F|f)(L|l)(A|a)(C|c))$")
>>
>> with a
>> ./prog.go:10:18:
>> regexp.MustCompile("((M|m)(p|P)(3|4))|((F|f)(L|l)(A|a)(C|c))$") (value of
>> type *regexp.Regexp) is not constant
>>
>>
>> Actual error I get is "error parsing regexp: unexpected ):
>> `(M|m)(p|P)(3|4))|((F|f)(L|l)(A|a)(C|c))$`"
>> It is missing a parentheses. This compiles fine:
>>
>> var ExtRegex =
>> regexp.MustCompile("((M|m)(p|P)(3|4))|((F|f)(L|l)(A|a)(C|c))$")
>> Note that there are two parentheses after the double-quote.
>>
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