gistfile1.nim

import unsigned, macros

type
  TokenType = enum
    comment, qstr, phrase, local_dot_atom_pre_comment, local_dot_atom, local_quoted_string, domain, obs_domain_list, angle_addr, address, group_name, msg_id, date, time, received_tokens, major_digits, minor_digits, param_val, param_attr, main_type, sub_type, encoding, disp_type, ctime_date, token_string
  EventType = enum
    enter, exit
  Event = object
    tokentype: TokenType
    position: int
    eventtype: EventType
  Token = object 
    tokentype: TokenType
    position: Slice[int]

macro genCActions(mailstart, container): stmt =
  result = newStmtList()
  for token in TokenType:
    let iToken = ident($token)
    let sToken = ident($token & "_s")
    let eToken = ident($token & "_e")
    result.add quote do:
      {.emit: "action `sToken` { `sToken`(p) }".}
      {.emit: "action `eToken` { `eToken`(p) }".}
      proc `sToken`(fpc: uint) {.exportc.} = 
        let position = int(fpc - mailstart)
        container.add(Event(tokentype: `iToken`, position: position, eventtype: enter))
      proc `eToken`(fpc: uint) {.exportc.} = 
        let position = int(fpc - mailstart)
        container.add(Event(tokentype: `iToken`, position: position, eventtype: exit))

{.emit: """
%%{
  machine common;
  write init;
}%%
""" .}
proc parse*(email: cstring): seq[Event] =
  var container: seq[Event] = @[]
  var p {.exportc.} = cast[uint](email)
  var pe {.exportc.} = uint(len(email)) + p
  let mailstart = p
  genCActions(mailstart, container)
  {.emit: """
  %%{
  include common "common.rl";
  write init;
  write exec;
  }%%
  """.}
  result = container