json_case_parse.nim

import macros, json


type Event = ref object of RootObj
  id: string

type TestMade = ref object of Event
  name: string

type Test = ref object of Event
  `result`: string

let data = parseJson("""{ "id" : "test" ,"name": "diego"}""")

macro mcase(val, prefix: static[string], events: varargs[typed]): untyped =
  result = nnkStmtList.newTree()
  var event_vars =  nnkStmtList.newTree()
  var caseNode = nnkCaseStmt.newTree()
  caseNode.add(newLit(val))

  for event in events:
    let name = toNimIdent(prefix & "_" & $event)
    event_vars.add quote do:
      var `name` = `event`()
    
    caseNode.add(
      nnkOfBranch.newTree(
        newLit($event),
        quote do:
          `name` = to(data, `event`)
      )
    )

  result.add(event_vars)
  result.add(caseNode)

mcase("TestMade", "e",
    TestMade,
    Test,
)

echo e_TestMade[]
echo e_Test[]