Word match in group collection

Question

For successful parsing I need to meet two conditions. I have following pattern currently being used for multiple word matches at first condition-1:

^(?=.*\b(?:goods?|things?|items?)\b)(?=.*\bid\b).*$

On condition-2 I would like this pattern to work in combination of another pattern.

(?=.\bfor|of|from\b)(?=.\b(?:goods?|things?|items?)\b)(?=.*\bid\b)

so if (?=.*\bfor|of|from\b) matches on its own the user will get error that you have forgot to enter something (i.e. things id etc)

and if this can also work in reverse order:

so if (?=.*\b(?:goods?|things?|items?)\b)(?=.*\bid\b) matches on its own the user will get error saying you have missed (?=.*\bfor|of|from\b)`

Thanks in advance.

Answer 1

You're using a programming language. Wouldn't it make more sense to take advantage of that? How about:

Match has_for_of_from = Regex.Match(input, @"\b(for|of|from)\b");
Match has_good_thing = Regex.Match(input, @"\b(?:good|thing|item)s?\b");
Match has_id = Regex.Match(input, @"\bid\b");
if (has_for_of_from && not (has_good_thing && has_id)) {
  // error about missing items/id
}
if (has_good_thing && has_id && not has_for_from) {
  // error about missing for/of/from
}

I moved the optional s outside the alternation (making it easier to read but still doing the same thing). I wasn't sure from the description whether the logic is exactly what you wanted (should that first conditional say has_for && not (has_good || has_id)?), but I'm sure you can figure it out from here.

You'd need a pretty messy regex to do this in just one match, and it wouldn't necessarily suggest which condition triggered the issue, so you won't have an informative error message.

Disclaimer: I do not know c# or .net, so my syntax may be slightly off.