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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2023 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
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
extension String {
/// Returns this string with the first letter uppercased.
///
/// If the string does not start with a letter, no change is made to it.
func withFirstLetterUppercased() -> String {
if let firstLetter = self.first {
return firstLetter.uppercased() + self.dropFirst()
} else {
return self
}
}
/// Replace the first occurrence of `character` with `replacement`.
///
/// If `character` does not occur in this string, no change is made.
func replacingFirstOccurrence(of character: Character, with replacement: Character) -> String {
guard let match = self.firstIndex(of: character) else {
return self
}
return self[startIndex..<match] + String(replacement) + self[index(after: match)...]
}
/// Replace the last occurrence of `character` with `replacement`.
///
/// If `character` does not occur in this string, no change is made.
func replacingLastOccurrence(of character: Character, with replacement: Character) -> String {
guard let match = self.lastIndex(of: character) else {
return self
}
return self[startIndex..<match] + String(replacement) + self[index(after: match)...]
}
}
extension Collection {
/// If the collection contains a single element, return it, otherwise `nil`.
var only: Element? {
if !isEmpty && index(after: startIndex) == endIndex {
return self.first!
} else {
return nil
}
}
}
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