Issue-2748 - Add ByteBuffer Hex init & write

[ali-ahsan-ali]

Add ability for below two functions
ByteBuffer(hexEncodedBytes: "68 65 6c 6c 6f 20 77 6f 72 6c 64 0a")
buffer.writeHexEncodedBytes("68656c6c6f20776f726c640a")

Motivation:

#2748

[ali-ahsan-ali]

@weissi please take a look when you find the time

[Lukasa]

Ok awesome, this is getting a lot closer. Only a few little notes here.

[Lukasa]

This enum needs to be private, or we can't safely use this type.

[ali-ahsan-ali]

Are you suggesting internal? Private would mean this would be impossible (to my understanding) to initialise (atleast the way I have done so).

[Lukasa]

Private should be fine, you'd use public static lets on the parent to access the fields:

public struct HexDecodingError: Error {
    private let kind: Kind

    private enum Kind {
        case invalidHexLength
        case invalidCharacter
    }
    
    public static let invalidHexLength = HexDecodingError(kind: .invalidHexLength)
    public static let invalidCharacter = HexDecodingError(kind: .invalidCharacter)
}

[ali-ahsan-ali]

thanks will find time to implement.

[ali-ahsan-ali]

Made HexDecodingError equatable. Makes sense to be able to see what kind of error you have and if it is not by making kind public, then I think the alternative is the equatable comformance. It also helps with tests. LMK what you think.

[Lukasa]

Fantastic, this is looking really good. A pair of very minor textual tweaks and then I'm happy. Thanks for sticking with this!

[ali-ahsan-ali]

Fantastic, this is looking really good. A pair of very minor textual tweaks and then I'm happy. Thanks for sticking with this!

Doing a bit of travelling. Actually flying to London for the swift conference. Will find time to push the changes.

[Lukasa]

Awesome, I'm happy with this! Well done getting through the gauntlet again @ali-ahsan-ali, it's really good that you were able to stick with it. Much appreciated ✨ .