import Foundation
let pattern = #"(?<=begin{DoxyCode})([\s\S]+?[^\\])([_%])([\s\S]+?)(?=end{DoxyCode})"#
let regex = try! NSRegularExpression(pattern: pattern)
let testString = #"""
\begin{DoxyCode}
17 This is some code that contains an_undersc_ore and
18 an escaped\_underscore. Plus another unescaped_unders_core
19 for good measure.
20 As if that was not "bad" enough, it also contains a %percent sign
21 that is unescaped.
\end{DoxyCode}
Here is some other stuff that may contain \index{things_not_to_be_escaped}.
\begin{DoxyCode}
17 This is some code that contains an_underscore and
18 an escaped\_underscore. Plus another unescaped_underscore
19 for good measure.
20 As if that was not "bad" enough, it also contains a \%percent sign
21 that is escaped.
\end{DoxyCode}
"""#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let matches = regex.matches(in: testString, range: stringRange)
var result: [[String]] = []
for match in matches {
var groups: [String] = []
for rangeIndex in 1 ..< match.numberOfRanges {
let nsRange = match.range(at: rangeIndex)
guard !NSEqualRanges(nsRange, NSMakeRange(NSNotFound, 0)) else { continue }
let string = (testString as NSString).substring(with: nsRange)
groups.append(string)
}
if !groups.isEmpty {
result.append(groups)
}
}
print(result)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Swift 5.2, please visit: https://developer.apple.com/documentation/foundation/nsregularexpression