Very basic initial version. Covering only naively implemented writers

serialization.nim

@@ -0,0 +1,11 @@
+import streams
+export streams
+
+proc encode*(Writer: type, value: auto): auto =
+  # TODO: define a concept for the Writer types
+  mixin init, writeValue, getOutput
+
+  var w = Writer.init
+  w.writeValue value
+  return w.getOutput
+

serialization.nimble

@@ -0,0 +1,21 @@
+mode = ScriptMode.Verbose
+
+packageName   = "serialization"
+version       = "0.1.0"
+author        = "Status Research & Development GmbH"
+description   = "A modern extensible serialization framework for Nim"
+license       = "Apache License 2.0"
+skipDirs      = @["tests"]
+
+requires "nim >= 0.19.0"
+
+proc configForTests() =
+  --hints: off
+  --debuginfo
+  --path: "."
+  --run
+
+task test, "run tests":
+  configForTests()
+  setCommand "c", "tests/all.nim"
+

serialization/streams.nim

@@ -0,0 +1,86 @@
+# This module will be overhauled in the future to use concepts
+
+type
+  MemoryStream* = object
+    output: seq[byte]
+
+  StringStream* = object
+    output: string
+
+  AnyStream = MemoryStream | StringStream
+
+const
+  initialStreamCapacity = 4096
+
+# Memory stream
+
+proc init*(s: var MemoryStream) =
+  s.output = newSeqOfCap[byte](initialStreamCapacity)
+
+proc getOutput*(s: var MemoryStream): seq[byte] =
+  shallow s.output
+  result = s.output
+
+proc init*(T: type MemoryStream): T =
+  init result
+
+proc append*(s: var MemoryStream, b: byte) =
+  s.output.add b
+
+proc append*(s: var MemoryStream, c: char) =
+  s.output.add byte(c)
+
+proc append*(s: var MemoryStream, bytes: openarray[byte]) =
+  s.output.add bytes
+
+proc append*(s: var MemoryStream, chars: openarray[char]) =
+  # TODO: this can be optimized
+  for c in chars:
+    s.output.add byte(c)
+
+template append*(s: var MemoryStream, str: string) =
+  s.append(str.toOpenArrayByte(0, str.len - 1))
+
+# String stream
+
+proc init*(s: var StringStream) =
+  s.output = newStringOfCap(initialStreamCapacity)
+
+proc getOutput*(s: var StringStream): string =
+  shallow s.output
+  result = s.output
+
+proc init*(T: type StringStream): T =
+  init result
+
+proc append*(s: var StringStream, c: char) =
+  s.output.add c
+
+proc append*(s: var StringStream, chars: openarray[char]) =
+  # TODO: Nim doesn't have add(openarray[char]) for strings
+  for c in chars:
+    s.output.add c
+
+template append*(s: var StringStream, str: string) =
+  s.output.add str
+
+# Any stream
+
+proc appendNumberImpl(s: var AnyStream, number: BiggestInt) =
+  # TODO: don't allocate
+  s.append $number
+
+proc appendNumberImpl(s: var AnyStream, number: BiggestUInt) =
+  # TODO: don't allocate
+  s.append $number
+
+template toBiggestRepr(i: SomeUnsignedInt): BiggestUInt =
+  BiggestUInt(i)
+
+template toBiggestRepr(i: SomeSignedInt): BiggestInt =
+  BiggestInt(i)
+
+template appendNumber*(s: var AnyStream, i: SomeInteger) =
+  # TODO: specify radix/base
+  appendNumberImpl(s, toBiggestRepr(i))
+