[WIP] Nim Compiler

[sealmove]

meta:
  id: hello_world
seq:
  - id: one
    type: u1

# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

import ../../runtime/nim/kaitai

type
  HelloWorld* = ref object
    one*: uint8
    root*: HelloWorld
    parent*: ref RootObj

proc read*(_: typedesc[HelloWorld], stream: KaitaiStream, root: HelloWorld, parent: ref RootObj): owned HelloWorld =
  result = new(HelloWorld)
  let root = if root == nil: result else: root
  result.one = readU1(stream)
  result.root = root
  result.parent = parent

proc fromFile*(_: typedesc[HelloWorld], filename: string): owned HelloWorld =
  var stream = newKaitaiStream(filename)
  HelloWorld.read(stream, nil, nil)

I think this pattern is flexible and neat:

• The user will be able to create objects of any type (subsections of a format) by simply providing the type and a file path (fromFile()). In this case the object returned will be a root object. For example he will be able to create a Png Chunks object like this: Chunks.fromFile("path/to/partial/file")
• read() is mostly for internal use, but it's also exposed to the user in case he needs to do something more involved (for example construct a png from partial png files).

[sealmove]

hello_world.ksy now compiles correctly!
The basic architecture for Nim compiler is now set up.
Next step is to write all the tests.

[GreyCat]

I guess this refers to the location of these files in test repo vs runtimes repo, but it won't be always true for production use?

[sealmove]

I noticed RuntimeConfig.scala and the relevant command line options (which exist for only ~half of the supported languages) but I am a little unsure about the approach here. Is it safe to say that it's simply a matter of having a saner default and adding a command line option for specifying the module's path?

Proposal:

• default = "kaitai" (root folder of user's project)
• command line option = --nim-runtime-path

[GreyCat]

Looks good to me, thanks for this contribution! Merging in.