Extract string array from string based on regex? - Swift

Question

So what I am trying to achieve:

I have an input string that looks like this:

let inputString = "1*1 (10, 10) (5, 5)"

Note the space after the first digit within the brackets.

To separate this input, I am using:

inputString.components(separatedBy: " ")

Which returns the following array:

0: 1*1

1 "(10,"

2 "10)"

3 "(5,"

4: "5)"

Where as the result I want is:

0: "1*1"

1: "(10, 10)"

2: "(5, 5)"

The issue is that the space within the coordinate is causing the string to separate again, when I don't want it to.

I have also tried to separate them using:

inputString.replacingOccurrences(of: " ", with: "").components(separatedBy: CharacterSet.init(charactersIn: "\"([{)")).filter({ $0 != "" })

But this removes the "(" and ")" from the strings, which I need to keep.

Any suggestions would be welcome. Thanks

See https://stackoverflow.com/a/47985411/3832970. Just replace the `else` with `else { finalArr.append("(\(value))")` — Wiktor Stribiżew, Dec 07 '21 at 15:36

Wiktor Stribiżew · Answer 1 · 2021-12-08T08:52:37.920

Without regex

You can split with ( and ) and get odd chunks back while wrapping them with parentheses. You may re-use the code from :

let inputString = "1*1 (10, 10) (5, 5)"
let newArr = inputString.components(separatedBy: ["(", ")"])

var finalArr = [String]()

for (index, value) in newArr.enumerated() {

    if (index + 1) % 2 == 1 {
        finalArr.append(contentsOf: value.components(separatedBy: " ").filter { $0 != "" })
    }
    else {
        finalArr.append("(\(value))")
    }
}
print(finalArr)
// => ["1*1", "(10, 10)", "(5, 5)"]

With regex

You can match one or more occurrences of any substring inside parentheses or any char other than whitespace and parentheses:

import Foundation

func matches(for regex: String, in text: String) -> [String] {
  do {
        let regex = try NSRegularExpression(pattern: regex)
        let results = regex.matches(in: text,
                                    range: NSRange(text.startIndex..., in: text))
        return results.map {
            String(text[Range($0.range(at: 0), in: text)!])
        }
    } catch let error {
        print("invalid regex: \(error.localizedDescription)")
        return []
    }
}
let originalString = "1*1 (10, 10) (5, 5)"
print(matches(for: #"(?:\([^()]*\)|[^()\s])+"#, in: originalString))
// => ["1*1", "(10, 10)", "(5, 5)"]

See the regex demo. Details:

(?: - start of a non-capturing group:
- \( - a ( char
- [^()]* - zero or more chars other than ( and )
- \) - a ) char
| - or
- [^()\s] - any char other than (, ) and whitespace
)+ - end of the group, one or more occurrences.

The matches function [looks familiar](https://stackoverflow.com/a/27880748/1187415) :) — Martin R, Dec 07 '21 at 17:30
@MartinR Very possible, I save good snippets and re-use them to showcase regular expression work. — Wiktor Stribiżew, Dec 07 '21 at 17:51
@WiktorStribiżew Which solution would you say is the best / cleanest to achieve what I am looking for? Either the first comment you posted or the matches function? Thanks! — Liam, Dec 08 '21 at 08:49
@Liam I did not benchmark but I believe a non-regex solution would be faster. — Wiktor Stribiżew, Dec 08 '21 at 08:50

Extract string array from string based on regex? - Swift

1 Answers1