Missing Streaming Interface for Swift

[herzi]

I was assessing PLzmaSDK to see if it could be useful for my Swift based project which uses a protocol to abstract over (stream) compression implementations, a bit like this:

protocol DeflateProtocol {
    func append (_ buffer: Data) -> Data
    func finalize () -> Data
}

Possible solutions that I can see for PLzmaSDK to support this kind of interface:

• Make InStream.init(stream:) public, so I can do all the dirty work mapping back and forth between @convention(c) and Swift callbacks.
• Provide an initializer for InStream accepting Swift callbacks.

Which of these sounds more acceptable for the PLzmaSDK project?

[OlehKulykov]

Hi, unfortunately, no one. Because the purpose of InStream is proving raw archive's file data buffer(from file, mem buff., network, etc.). It's not a compressed stream and this SDK is oriented on processing archives. For your needs(compressed streams), this SDK is preaty heavy, and you need only small C part of it.

• In case if your project conforms next versions: iOS 13.0+ iPadOS 13.0+ macOS 10.15+ Mac Catalyst 13.1+ tvOS 13.0+ watchOS 6.0+ and no need to implement any other compression methods and levels, except LZMA method and compression level 6, then I would like to recommend to take a look: https://developer.apple.com/documentation/foundation/nsdata/compressionalgorithm/lzma

• If not, then you can take the only C part of original SDK (Swift works fine with C code) and implement LZMA and/or LZMA2 compression methods with any settings. Here the reference: https://github.com/OlehKulykov/LzmaSDKObjC/blob/master/src/LzmaSDKObjCBufferProcessor.mm