import gdb

import gdb.types

import sys

if sys.version_info[0] > 2:

    long = int

    imap = map

class cons_pp(object):

  def __init__(self, val):

    self._val = val

  def to_string(self):

    if long(self._val) == 0:

      return "nil"

    else:

      return "(...)"

  def children(self):

    if long(self._val) == 0:

      return []

    else:

      return [

        ('car' , self._val["slots"][0]),

        ('cdr' , self._val["slots"][1])

      ]

def cons_pp_lookup(val):

  if str(val.type) == 'struct _cons *':

    return cons_pp(val)

  else:

    return None

del gdb.pretty_printers[1:]

gdb.pretty_printers.append(cons_pp_lookup)