match.swift

#if os(Linux)
  import Glibc
#else
  import Darwin
#endif

extension String {
  func contains(s: String, caseSensitive: Bool = true) -> Bool {
    if !caseSensitive { return lowercaseString.contains(s.lowercaseString) }
    return characters
      .indices
      .lazy
      .map(characters.suffixFrom)
      .contains { tail in tail.startsWith(s.characters) }
  }
}