Created
May 11, 2018 21:11
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| struct Scale { | |
| let notes = ["C", "D", "E", "F", "G", "A", "B"] | |
| } | |
| struct ScaleIterator: IteratorProtocol { | |
| private let scale: Scale | |
| private var index = 0 | |
| init(_ scale: Scale) { | |
| self.scale = scale | |
| } | |
| mutating func next() -> String? { | |
| if index == scale.notes.count { | |
| index = 0 | |
| } | |
| defer { | |
| index += 1 | |
| } | |
| return scale.notes[index] | |
| } | |
| } | |
| extension Scale: Sequence { | |
| func makeIterator() -> ScaleIterator { | |
| return ScaleIterator(self) | |
| } | |
| } | |
| let scale = Scale() | |
| for note in scale.prefix(20) { | |
| print(note) | |
| } |
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