#  $Id$
#
#  Copyright (C) 2003 Rational Discovery LLC
#     All Rights Reserved
#
import sys

from rdkit.VLib.Node import VLibNode

class SupplyNode(VLibNode):
  """ base class for nodes which supply things

  Assumptions:
    1) no parents
  
  Usage Example:
    >>> supplier = SupplyNode(contents=[1,2,3])
    >>> supplier.next()
    1
    >>> supplier.next()
    2
    >>> supplier.next()
    3
    >>> supplier.next()
    Traceback (most recent call last):
        ...
    StopIteration
    >>> supplier.reset()
    >>> supplier.next()
    1
    >>> [x for x in supplier]
    [1, 2, 3]
    

  """
  def __init__(self,contents=None,**kwargs):
    VLibNode.__init__(self,**kwargs)
    if contents is not None:
      self._contents = contents
    else:
      self._contents = []
    self._pos = 0

  def reset(self):
    VLibNode.reset(self)
    self._pos = 0
  def next(self):
    if self._pos == len(self._contents):
      raise StopIteration

    res=self._contents[self._pos]
    self._pos += 1
    return res
  def AddParent(self,parent,notify=1):
    raise ValueError,'SupplyNodes do not have parents'

  
#------------------------------------
#
#  doctest boilerplate
#
def _test():
  import doctest,sys
  return doctest.testmod(sys.modules["__main__"])

if __name__ == '__main__':
  import sys
  failed,tried = _test()
  sys.exit(failed)