83 lines
1.9 KiB
Swift
83 lines
1.9 KiB
Swift
//
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// Copyright (c) 2019 Open Whisper Systems. All rights reserved.
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//
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import Foundation
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public extension String {
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var digitsOnly: String {
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return (self as NSString).digitsOnly()
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}
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func rtlSafeAppend(_ string: String) -> String {
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return (self as NSString).rtlSafeAppend(string)
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}
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func substring(from index: Int) -> String {
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return String(self[self.index(self.startIndex, offsetBy: index)...])
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}
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func substring(to index: Int) -> String {
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return String(prefix(index))
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}
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enum StringError: Error {
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case invalidCharacterShift
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}
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}
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// MARK: - Selector Encoding
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private let selectorOffset: UInt32 = 17
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public extension String {
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func caesar(shift: UInt32) throws -> String {
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let shiftedScalars: [UnicodeScalar] = try unicodeScalars.map { c in
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guard let shiftedScalar = UnicodeScalar((c.value + shift) % 127) else {
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throw StringError.invalidCharacterShift
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}
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return shiftedScalar
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}
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return String(String.UnicodeScalarView(shiftedScalars))
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}
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var encodedForSelector: String? {
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guard let shifted = try? self.caesar(shift: selectorOffset) else {
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return nil
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}
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guard let data = shifted.data(using: .utf8) else {
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return nil
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}
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return data.base64EncodedString()
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}
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var decodedForSelector: String? {
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guard let data = Data(base64Encoded: self) else {
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return nil
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}
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guard let shifted = String(data: data, encoding: .utf8) else {
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return nil
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}
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return try? shifted.caesar(shift: 127 - selectorOffset)
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}
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}
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public extension NSString {
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@objc
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var encodedForSelector: String? {
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return (self as String).encodedForSelector
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}
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@objc
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var decodedForSelector: String? {
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return (self as String).decodedForSelector
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}
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}
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