CryptoSwift/Sources/CryptoSwift/Array+Extension.swift

//
//  ArrayExtension.swift
//  CryptoSwift
//
//  Created by Marcin Krzyzanowski on 10/08/14.
//  Copyright (c) 2014 Marcin Krzyzanowski. All rights reserved.
//

extension Array {
    init(reserveCapacity: Int) {
        self = Array<Element>()
        self.reserveCapacity(reserveCapacity)
    }
}

extension Array {

    /** split in chunks with given chunk size */
    func chunks(size chunksize: Int) -> Array<Array<Element>> {
        var words = Array<Array<Element>>()
        words.reserveCapacity(self.count / chunksize)
        for idx in stride(from: chunksize, through: self.count, by: chunksize) {
            words.append(Array(self[idx - chunksize ..< idx])) // slow for large table
        }
        let reminder = self.suffix(self.count % chunksize)
        if !reminder.isEmpty {
            words.append(Array(reminder))
        }
        return words
    }
}

extension Array where Element: Integer, Element.IntegerLiteralType == UInt8 {

    public init(hex: String) {
        self.init()

        let utf8 = Array<Element.IntegerLiteralType>(hex.utf8)
        let skip0x = hex.hasPrefix("0x") ? 2 : 0
        for idx in stride(from: utf8.startIndex.advanced(by: skip0x), to: utf8.endIndex, by: utf8.startIndex.advanced(by: 2)) {
            let byteHex = "\(UnicodeScalar(utf8[idx]))\(UnicodeScalar(utf8[idx.advanced(by: 1)]))"
            if let byte = UInt8(byteHex, radix: 16) {
                self.append(byte as! Element)
            }
        }
    }
}