Re: Code generation from AST with annotations in Nim like in C

[komerdoor]

I managed to create a macro that creates a wrapper for functions that have the 
"scriptExport" pragma. It was easier than I expected.
    
    
    import macros
    
    proc expandFormalParamsForCall(formalParamsNode: NimNode): seq[NimNode] 
{.compileTime.} =
      result = @[]
      for i in 1 ..< formalParamsNode.len:
        if formalParamsNode[i].kind == nnkIdentDefs:
          for j in 0 ..< formalParamsNode[i].len - 2:
            result.add(formalParamsNode[i][j])
    
    proc expandFormalParamsForProc(formalParamsNode: NimNode): seq[NimNode] 
{.compileTime.} =
      result = @[]
      for i in 0 ..< formalParamsNode.len:
        if formalParamsNode[i].kind == nnkIdent:
          result.add(formalParamsNode[i])
        if formalParamsNode[i].kind == nnkIdentDefs:
          for j in 0 ..< formalParamsNode[i].len - 2:
            result.add(newNimNode(nnkIdentDefs).add(formalParamsNode[i][j], 
formalParamsNode[i][^2], newEmptyNode()))
    
    macro scriptExport(definition: untyped): typed =
      case definition.kind
      of nnkProcDef:
        var scriptDefinition = newProc(newIdentNode($definition.name & 
"_script"), expandFormalParamsForProc(definition.pa
          newCall(!"echo", newStrLitNode($definition.name & "_script called.")),
          newCall(definition.name, expandFormalParamsForCall(definition.params))
        ))
        return newStmtList(definition, scriptDefinition)
      else:
        error("Only works with procedures for now")
    
    proc sum(x, y: int): int {.noSideEffect,scriptExport.} =
      x + y
    
    echo(sum(1, 2))
    echo(sum_script(1, 2))
    

Still have to do the same for other types etc. as well. From this I can write 
code that will create bindings etc.