cbor.txt

The recommended method of encoding Nim types to CBOR is to implement the
``writeCborHook`` procedure for streaming a given type. Decoding streams with
``CborParse`` is recommended where practical. The ``cbor/bignum`` module
may serve as a working example of both for a custom type.

The ``CborNode`` type can be used to parse data of unknown schema. The ``%``
operator will marshall primitive types to ``CborNode``, which can be encoded
to stream or string. An CBOR stream can be parsed at once into a ``CborNode``
object. Note that a type for which ``writeCbor`` has been implemented can be
converted to the ``CborNode`` type using ``initCborOther``, though it is
intended only as a diagnostic aid.

Examples
--------

Encoding:

.. code-block:: nim
  import cbor, streams

  type Foobar = tuple[foo: int, bar: string]

  proc writeCbor(s: Stream; x: Foobar) =
    s.writeCborArrayLen(2)
    s.writeCbor(x.foo)
    s.writeCbor(x.bar)

Decoding:

.. code-block:: nim
  import cbor, streams

  proc whatIsIt(parser: var CborParser) =
    case parser.kind
    of CborEventKind.cborEof:
      raise newException(EofError, "stream ended early")
    of CborEventKind.cborText:
      echo "found some text: ", parser.nextText()
    of CborEventKind.cborFloat:
      echo "float: ", parser.nextFloat()
    of CborEventKind.cborArray:
      let n = parser.arrayLen
      parser.next()
      for _ in 1..n:
        parser.whatIsIt()
    else:
      echo "other: ", parser.nextNode()

  var parser: CborParser
  open(parser, newFileStream(stdin))
  parser.next()
  parser.whatIsIt()