Regular expression captureGroups

captureGroups.swift

import Foundation

struct Regex {
    let pattern: String
}

protocol RegexMatchable : StringProtocol {
    var regex: Regex { get }
    func matches(regex: Regex, options: NSRegularExpression.Options) -> [String]
    func capturedGroups(regex: Regex, options: NSRegularExpression.Options) -> [String]
}

extension Matchable {
     var regex: Regex { return  Regex(pattern: String(self)) }
}

extension String : RegexMatchable {
    

    public func capturedGroups(with regex: Regex, options: NSRegularExpression.Options = []) -> [String] {
        let m = matches(with: regex, options: options)
        return m.count>1 ? Array(m.dropFirst()) : []
    }
    
    public func matches(with regex: Regex, options: NSRegularExpression.Options = []) -> [String] {
        guard let match = (try? NSRegularExpression(pattern: regex.pattern, options: options))?.firstMatch(in: self, options: [], range: NSRange(startIndex..., in: self)) else { return [] }
        return (0..<match.numberOfRanges).compactMap {
            return match.range(at: $0).location == NSNotFound ? nil : Range(match.range(at: $0), in: self).flatMap { String(self[$0]) }
        }
    }
}

"hi hello".capturedGroups(regex: "(\\w*)\\s(\\w*)".regex) // ["hi", "hello"]
"hi hello".matches(regex: "(\\w*)\\s(\\w*)".regex)        // ["hi hello", "hi", "hello"]