sincemacro.nim

import macros, strutils

macro since*(version: string; symbol: untyped): untyped =
  proc toVersion(s: string): int =
    let v = s.split('.')
    var w: array[3, int]
    for i in 0 .. min(2, v.len):
      w[i] = parseInt(v[i])
    result = w[0] * 1000_000 + w[1] * 1_000 + w[2]

  let ab = version.strVal.split("..")
  let real = NimMajor * 1000_000 + NimMinor * 1_000 + NimPatch
  var enabled = false
  if ab.len >= 2:
    if real >= toVersion(ab[0]) and real <= toVersion(ab[1]):
      enabled = true
    # check that the version is not blacklisted. Always run over
    # the full blacklist in order to check every version for syntax:
    for i in 2 .. ab.len-1:
      if toVersion(ab[i]) == real: enabled = false
  elif ab.len == 1:
    enabled = real >= toVersion(ab[0])
  else:
    error("invalid version specification: " & version.strVal, version)
  result = if enabled: symbol else: newStmtList()


proc testme() {.since"0.17.0..0.18.0..0.17.4".} =
  echo "yes"

testme()