Swift 正则分割字符串

自己的项目中使用正则表达式解析 HTML，为此实现了对字符串的正则分割，在这里记录一下。

// 定义一个结构体来承载分割后的结果
struct SplitedResult {
    let fragment: String
    let isMatched: Bool
    let captures: [String?]
}

extension String {
    /// 正则分割字符串
    func split(
        usingRegex pattern: String,
        options: NSRegularExpression.Options = .dotMatchesLineSeparators
    ) -> [SplitedResult] {
        do {
            let regex = try NSRegularExpression(pattern: pattern, options: options)
            let matches = regex.matches(in: self, options: [], range: NSRange(location: 0, length: utf16.count))
            
            var currentIndex = startIndex
            var range: Range<String.Index>
            var captures: [String?] = []
            var results: [SplitedResult] = []
            for match in matches {
                range = Range(match.range, in: self)!
                if range.lowerBound > currentIndex {
                    results.append(SplitedResult(fragment: String(self[currentIndex..<range.lowerBound]), isMatched: false, captures: []))
                }
                
                if match.numberOfRanges > 1 {
                    for i in 1..<match.numberOfRanges {
                        if let _range = Range(match.range(at: i), in: self) {
                            captures.append(String(self[_range]))
                        } else {
                            captures.append(nil)
                        }
                    }
                }
                
                results.append(SplitedResult(fragment: String(self[range]), isMatched: true, captures: captures))
                currentIndex = range.upperBound
                captures.removeAll()
            }
            
            if endIndex > currentIndex {
                results.append(SplitedResult(fragment: String(self[currentIndex..<endIndex]), isMatched: false, captures: []))
            }
            
            return results
        } catch {
            fatalError("正则表达式有误，请更正后再试！")
        }
    }
}