match.swift

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

// Thank you Mike Ash
extension String {
    func contains(query: String, caseSensitive: Bool = false) -> Bool {
        if query.isEmpty { return true }
        let (s, q) = caseSensitive ? (self, query) : (self.lowercaseString, query.lowercaseString)
        var chars = s.characters; let qchars = q.characters

        while !chars.isEmpty {
            if chars.startsWith(qchars) { return true }
            chars.removeFirst()
        }
        
        return false
    }
    
    func prefixedBy(query: String, caseSensitive: Bool = false) -> Bool {
        let (s, q) = caseSensitive ? (self, query) : (self.lowercaseString, query.lowercaseString)
        return s.characters.startsWith(q.characters)
    }
}