Match all substrings in string except specific pattern

Question

in this string: "TESTING (hello) 123 (HOW ARE YOU)"

I would like to match:

TESTING
123

Please help.. thanks!

I am only able to use (\\$.*?$) to match \(hello) and \(HOW ARE YOU), how can i match the counterpart of this strings?

So you actually have let s = "TESTING \\(hello) 123 \\(HOW ARE YOU)" as input, right? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jun 6, 2019 at 9:28
@maymaymaymaymay See Wiktor Stribiżew's solution. It's much faster than mine. — Sweeper
– Sweeper, Commented Jun 6, 2019 at 9:43

Wiktor Stribiżew · Accepted Answer · 2019-06-06 09:55:17Z

1

There is no way with ICU (the regex library used in Swift) regex to match a text chunk that is not equal to some multicharacter string. You could do it if you wanted to match any 1 or more chars other than some specific character. You can't do it if you are "negating" a whole sequence of chars.

You may use

let str = "TESTING \\(hello) 123 \\(HOW ARE YOU)"
let pattern = "\\s*\\\\\\([^()]*\\)\\s*"
let result = str.replacingOccurrences(of: pattern, with: "\0", options: .regularExpression)
print(result.components(separatedBy: "\0").filter({ $0 != ""}))

Output: ["TESTING", "123"]

The idea is to match what you do not need and replace them with a null char, and then split the string with that null char.

Pattern details

\s* - 0+ whitespaces
\\\( - a \( substring
[^()]* - 0+ chars other than ( and )
\) - a ) char
\s* - 0+ whitespaces.

The results are likely to contain empty strings, hence .filter({ $0 != ""}) is used to filter them out.

edited Jun 6, 2019 at 9:55

answered Jun 6, 2019 at 9:41

Wiktor Stribiżew

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3 Comments

maymaymaymaymay Over a year ago

What if i have two strings: a = "HELLO HOW ARE YOU" b = "TESTING \\(hello) 123 \\(HOW ARE YOU)" is it possible to have a regex that matches "HELLO HOW ARE YOU" in a and "TESTING", "123" in b?

Wiktor Stribiżew Over a year ago

@maymaymaymaymay For your a string, the result is ["HELLO HOW ARE YOU"]. For the b string, I get ["TESTING", "123"]. Just what you ask for.

Wiktor Stribiżew Over a year ago

@maymaymaymaymay To clear it out for you: there is no way with ICU regex to match a text chunk that is not equal to some multicharacter string. You could do it if you wanted to match any 1 or more chars other than some specific character. You can't do it if you are "negating" a whole sequence of chars.

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