I honestly don’t know how much the coproduct stuff was used but looking back now, the Discriminated/Discriminator implicit stuff was too fancy
Main issue was replacing HList with tuples
But that’s a trivial port in most cases - 0 changes needed in common cases
hmm I think I'll have an idea, or maybe a contribution, for the derived codecs
but the derived codec gives me 8 bits
not sure if this is intentional...
yeah
what's scala's limit? hah
we could be smarter there but generally folks like byte alignment
okay found a test case for my thing
mappedEnum(uint8, Color.Red -> 10, Color.Green -> 20, Color.Blue -> 30)
given Codec[Arrows] = mappedEnum(
uint4,
Arrows.Up -> 0,
Arrows.UpRight -> 1,
Arrows.Right -> 2,
Arrows.DownRight -> 3,
Arrows.Down -> 4,
Arrows.DownLeft -> 5,
Arrows.Left -> 6,
Arrows.UpLeft -> 7,
Arrows.Neither -> 8
)
There are some downsides there where you could forget to map a case but I think the simplicity outweighs the exhaustiveness
and the shiny new scaladoc
Oh ha, no, I think scala3doc is still disabled in sbt-spiewak? Or if not, then it should be published
hello do you have any examples on how should I build a StreamEncoder from scodec-stream? I have a large binary file which I want to encode/decode that contains a huge list of elements, so I would like to be able to stream encode-decode those elements, but I cannot get a hold of how should I approach it. I do have codecs defined for the items in the file which compose a product codec that represent the whole file. Sorry if this is trivial.
Generally, use the constructors on the
StreamEncoder companion object - e.g., StreamEncoder.many(myCodec).toPipe[IO]
That's what I first tried, using the example provided in scala-stream for the StreamDecoder. But, it just tells me that the symbol many cannot be resolved and as I went inside to see what StreamEncoder contained, indeed the companion object had only the apply and instance methods. Maybe I imported the wrong thing? though I added to my build file the latest dependency from the releases page.
the scodec.org releases page is out of date with versions -- really need to get that site cleaned up
Hi! I’m trying to write a codec for macaroons:
macaroon: VERSION opt_location IDENTIFIER EOS caveats EOS SIGNATURE
caveats: caveat caveats
|
caveat: opt_location IDENTIFIER opt_vid EOSI’ve got:
private val caveat: Codec[Caveat] =
"caveat" | (optionalLocation :: identifier :: optionalVerificationKeyId <~ endOfSection)
.as[Caveat]
private val caveats: Codec[Vector[Caveat]] =
"caveats" | vector(caveat)
val macaroonV2: Codec[Macaroon] =
(version ~> optionalLocation :: identifier :: endOfSection ~> caveats :: endOfSection ~> authenticationTag)
.as[Macaroon]but when trying to decode, the vector codec fails upon endOfSection right before the authenticationTag. How do I find/create a variant of vector that just returns the result so far and remaining bits as soon as its codec.decode fails?
I think I’ve got it:
def seeWhatHappensVector[A](codec: Codec[A]): Codec[Vector[A]] =
Codec[Vector[A]](
Encoder.encodeSeq(codec.asEncoder)(_),
(bits: BitVector) => {
@tailrec def helper(rest: BitVector,
acc: Vector[A]): Attempt[DecodeResult[Vector[A]]] =
codec.decode(rest) match {
case Successful(DecodeResult(v, rem)) => helper(rem, v +: acc)
case Failure(_) => successful(DecodeResult(acc, rest))
}
helper(bits, Vector.empty)
}
)
Ah, I found it under releases.
I am trying to decode a fixed amount of bytes, into N number of elements that are variably sized. Concretely, I am trying to write a parser for ID3v2 MP3 tags. There is a header which tells you how many bytes to decode, then there are N "frames", each with their own header which tells you how many bytes to decode. I've got the lower level parser, but I'm struggling to write the higher level one (list of N). I don't think
listOfN will work because I don't know how many frames there are ahead of time.
For the frame content, I wrote a codec like so:
def fromHeader(header: TagFrameHeader): Codec[TagFrameContent] =
fixedSizeBytes(header.size.size, utf8)
.xmap(TagFrameContent.apply, (x: TagFrameContent) => x.content)
which is used for the Frame codec like so:
TagFrameHeader.codec.flatZip(TagFrameContent.fromHeader)