import Foundation
let pattern = ##"""
(?(DEFINE)
(?<curly> \{ \g<content>*? \} )
(?<square> \[ \g<content>*? \] )
(?<pascal> \bbegin\b \g<content>*? \bend\b )
(?<lua> --\[ \g<content>*? --\] )
(?<nested> \g<curly> | \g<square> | \g<pascal> | \g<lua> )
(?<content>
# Math non-recursive content (atomically)
(?: (?! [{}\[\]] | \bbegin\b | \bend\b | --[\[\]] ) .)++
# Or recurse
| \g<nested>
)
)
\g<nested>
"""##
let regex = try! NSRegularExpression(pattern: pattern, options: [.allowCommentsAndWhitespace, .dotMatchesLineSeparators])
let testString = #"""
EVENLY BALANCED curly braces
{{{}}}
{ test1 { test2 { test3 { test4 } } } }
UNEVENLY BALANCED curly braces
{{{{}}} end <-- this is needed, otherwise this line balances with the line below :)
{ test1 { test2 { test3 { test4 } } } } }
MULTI-LINE EVENLY BALANCED curly braces
{
}
MULTI-LINE UNEVENLY BALANCED curly braces
{{
}
EVENLY BALANCED square braces
[ test1 [ test2 [ test3 [ test4 ] ] ] ]
EVENLY BALANCED square and curly braces
{ test1 [ test2 { test3 [ test4 ] } ] }
UNEVENLY BALANCED square and curly braces
{ test1 [ test2 { test3 [ test4 ] } } ]
"""#
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