Hashable in swift 1

Hash-Part1.swift

/// A point in an x-y coordinate system.
struct GridPoint {
    var x: Int
    var y: Int
}

extension GridPoint: Hashable {
    static func == (lhs: GridPoint, rhs: GridPoint) -> Bool {
        return lhs.x == rhs.x && lhs.y == rhs.y
    }

    var hashValue: Int {
      return x ^ y
    }
}