60 lines
2.4 KiB
Swift
60 lines
2.4 KiB
Swift
//
|
||
// Copyright 2024 Signal Messenger, LLC
|
||
// SPDX-License-Identifier: AGPL-3.0-only
|
||
//
|
||
|
||
import Foundation
|
||
|
||
/// Replaces extended grapheme clusters having too many combining marks with the unicode replacement character.
|
||
///
|
||
/// Example usage:
|
||
/// ```
|
||
/// let sanitizer = StringSanitizer("Jack said, “H̴̬̪̤̗̪̳̑̓e̵̱̗͇̰̽̊͛̿̒̚͠r̶̨̯̻̹̪̫̣̪̹͇̗̀͌̃̍̄͗̎͊͌ę̶̣͍̗̘̺̪̱̇̈́̈́͗͌̀̊̏ͅ'̷̧̧̭̜̱̜͉̟͇̣̉̃ͅs̸̪̻̯͔̤̣̱̾̽̌̇̃̒͋͂̈́̀͌̍̚ ̶͙́̓͊̈́̉̂͗̆͗̑͂̕J̵̨̧̧̠̩͈̹͈̦̩̣͙͐̿̇̈́̓ͅͅo̵̡̥̪͘h̵̡̧̢̘̟͓͖̤̼̟̺͓̰͈͓̎͋̎͝ņ̶̛͖̻̻̝͗̃͋͠n̶̮͈̯̩̘̠̻͔̈̌̐͘̚͝y̵̧̡̛͙͈̹̹̹̗̤̙͖̜̰̰͌͆̏̑͐̽̍͜!̸̡͈͔͆”)
|
||
/// if (sanitizer.needsSanitization) {
|
||
/// print(sanitizer.sanitized); // Jack said, “<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>”
|
||
/// }
|
||
/// ```
|
||
@objc
|
||
public class StringSanitizer: NSObject {
|
||
private static let maxCodePoints = 16
|
||
private let string: String
|
||
|
||
@objc(initWithString:)
|
||
public init(_ string: String) {
|
||
self.string = string
|
||
}
|
||
|
||
/// Indicates if the string needs to be modified. This is slightly cheaper than calling `sanitized`.
|
||
@objc
|
||
private(set) public lazy var needsSanitization: Bool = {
|
||
return string.contains(where: Self.isExtremelyLongGraphemeCluster)
|
||
}()
|
||
|
||
/// Returns a modified version of the string if sanitization is needed, or the original string otherwise.
|
||
@objc
|
||
private(set) public lazy var sanitized: String = {
|
||
return Self.sanitize(string)
|
||
}()
|
||
|
||
public static func isExtremelyLongGraphemeCluster(_ c: Character) -> Bool {
|
||
return c.unicodeScalars.count > Self.maxCodePoints
|
||
}
|
||
|
||
public static func sanitize(_ original: String, shouldRemove: (Character) -> Bool = isExtremelyLongGraphemeCluster) -> String {
|
||
guard original.contains(where: shouldRemove) else {
|
||
return original
|
||
}
|
||
var remaining = original[...]
|
||
var result = ""
|
||
// An overestimate, because we will shorten at least one Character.
|
||
result.reserveCapacity(original.utf8.count)
|
||
while let nextBadCharIndex = remaining.firstIndex(where: shouldRemove) {
|
||
result.append(contentsOf: remaining[..<nextBadCharIndex])
|
||
result.append("\u{FFFD}")
|
||
remaining = remaining[nextBadCharIndex...].dropFirst()
|
||
}
|
||
result.append(contentsOf: remaining)
|
||
return result
|
||
}
|
||
}
|