Handle digit separator `_` about go-mnd HOT 4 CLOSED

@benoitmasson That's totally right. Thanks for putting me on the right path! It's so easy sometimes 🙈

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@benoitmasson
Thanks for the report. I'll check this asap.

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Hi @benoitmasson,

I have made two attempts to implement this so far. Because I got your point. But the documentation isn't really helpful here and I also couldn't find a package which does a conversion of the numbers. Because for numbers like 1000 it seems easy on the first glance. But for example you can write 1234567890 like 1234_567_890 or 1_234_567_890 but also like this 1_234_567_89_0. So I need to generate this combinations in a general way to find every time all occurrences when you give me for example the number 1234567890 to ignore.

But unfortunately I couldn't find one so far. So that I'm stuck here and didn't have the time to go further here.

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Generating all combinations can be done, as follows using recursion for example:

func generateNumberVariants(num int) []string {
	sign := ""
	if num < 0 {
		sign = "-"
		num = -num
	}

	return generateNumberVariantsAux(strconv.Itoa(num), sign)
}

func generateNumberVariantsAux(num, prefix string) []string {
	if len(num) <= 1 {
		return []string{prefix + num}
	}

	variantsWithoutUnderscore := generateNumberVariantsAux(num[1:], prefix+num[0:1])
	variantsWithUnderscore := generateNumberVariantsAux(num[1:], prefix+num[0:1]+"_")
	return append(
		variantsWithoutUnderscore,
		variantsWithUnderscore...,
	)
}

but it is computationally heavy, and generates a lot of elements if the input number is large (2^log(n) variants for n).

Wouldn't it be easier to do the opposite, i.e., for every magic number found in the code, normalize it by removing _'s and check whether this normalized form should be ignored?

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