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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
@_spi(_Unicode)
import Swift
extension UInt8 {
/// Whether this is the starting byte of a sub-300 (i.e. pre-combining scalar) scalars
var _isSub300StartingByte: Bool { self < 0xCC }
}
extension UnicodeScalar {
/// Checks whether the scalar is in NFC form.
var isNFC: Bool { Character(self).singleNFCScalar == self }
}
extension Character {
/// If the given character consists of a single NFC scalar, returns it. If
/// there are multiple NFC scalars, returns `nil`.
var singleNFCScalar: UnicodeScalar? {
// SwiftStdlib is always >= 5.7 for a shipped StringProcessing.
guard #available(SwiftStdlib 5.7, *) else { return nil }
var nfcIter = String(self)._nfc.makeIterator()
guard let scalar = nfcIter.next(), nfcIter.next() == nil else { return nil }
return scalar
}
/// If the given character contains a single scalar, returns it. If none or
/// multiple scalars are present, returns `nil`.
var singleScalar: UnicodeScalar? {
hasExactlyOneScalar ? unicodeScalars.first! : nil
}
}
extension String {
/// If the given string consists of a single NFC scalar, returns it. If none
/// or multiple NFC scalars are present, returns `nil`.
var singleNFCScalar: UnicodeScalar? {
guard !isEmpty && index(after: startIndex) == endIndex else { return nil }
return first!.singleNFCScalar
}
/// If the given string contains a single scalar, returns it. If none or
/// multiple scalars are present, returns `nil`.
var singleScalar: UnicodeScalar? {
let scalars = unicodeScalars
guard !scalars.isEmpty &&
scalars.index(after: scalars.startIndex) == scalars.endIndex
else { return nil }
return scalars.first!
}
}
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