CryptoSwift/Sources/CryptoSwift/BytesSequence.swift

//
//  BytesSequence.swift
//  CryptoSwift
//
//  Created by Marcin Krzyzanowski on 26/09/15.
//  Copyright © 2015 Marcin Krzyzanowski. All rights reserved.
//

struct BytesSequence<D: RandomAccessCollection>: Sequence where D.Iterator.Element == UInt8, D.IndexDistance == Int, D.SubSequence.IndexDistance == Int, D.Index == Int {
    let chunkSize: D.IndexDistance
    let data: D

    func makeIterator() -> AnyIterator<D.SubSequence> {
        var offset = data.startIndex
        return AnyIterator {
            let end = Swift.min(self.chunkSize, self.data.count - offset)
            let result = self.data[offset..<offset + end]
            offset = offset.advanced(by: result.count)
            if !result.isEmpty {
                return result
            }
            return nil
        }
    }
}