39 lines
1.8 KiB
Swift
39 lines
1.8 KiB
Swift
//
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// Copyright 2024 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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//
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import Foundation
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public enum StringSanitizer {
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private static let maxCodePoints = 16
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public static func isExtremelyLongGraphemeCluster(_ c: Character) -> Bool {
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return c.unicodeScalars.count > Self.maxCodePoints
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}
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/// Replaces extended grapheme clusters having too many combining marks with the unicode replacement character.
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///
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/// Example usage:
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/// ```swift
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/// let sanitized = StringSanitizer.sanitize("Jack said, "H̴̬̪̤̗̪̳̑̓e̵̱̗͇̰̽̊͛̿̒̚͠r̶̨̯̻̹̪̫̣̪̹͇̗̀͌̃̍̄͗̎͊͌ę̶̣͍̗̘̺̪̱̇̈́̈́͗͌̀̊̏ͅ'̷̧̧̭̜̱̜͉̟͇̣̉̃ͅs̸̪̻̯͔̤̣̱̾̽̌̇̃̒͋͂̈́̀͌̍̚ ̶͙́̓͊̈́̉̂͗̆͗̑͂̕J̵̨̧̧̠̩͈̹͈̦̩̣͙͐̿̇̈́̓ͅͅo̵̡̥̪͘h̵̡̧̢̘̟͓͖̤̼̟̺͓̰͈͓̎͋̎͝ņ̶̛͖̻̻̝͗̃͋͠n̶̮͈̯̩̘̠̻͔̈̌̐͘̚͝y̵̧̡̛͙͈̹̹̹̗̤̙͖̜̰̰͌͆̏̑͐̽̍͜!̸̡͈͔͆")
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/// print(sanitized) // Jack said, "<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>"
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/// ```
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public static func sanitize(_ original: String, shouldRemove: (Character) -> Bool = isExtremelyLongGraphemeCluster) -> String {
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guard original.contains(where: shouldRemove) else {
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return original
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}
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var remaining = original[...]
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var result = ""
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// An overestimate, because we will shorten at least one Character.
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result.reserveCapacity(original.utf8.count)
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while let nextBadCharIndex = remaining.firstIndex(where: shouldRemove) {
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result.append(contentsOf: remaining[..<nextBadCharIndex])
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result.append("\u{FFFD}")
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remaining = remaining[nextBadCharIndex...].dropFirst()
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}
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result.append(contentsOf: remaining)
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return result
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}
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}
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